Initial Evaluation of the  
Performance of Prototype TV- Band  
White Space Devices 
 
 
 
 
July 31, 2007 
 
 
 
 
 
 
 
Technical Research Branch 
Laboratory Division 
Office of Engineering and Technology 
Federal Communications Commission 
 
 
 
 
 
 
 
OET Report Prepared by: 
FCC/OET 07-TR-1006  Steven K. Jones  
  Thomas W. Phillips 
 
 
ii 
 
Table of Contents 
 
Executive Summary..................................................................................................................................... vi 
1 Introduction......................................................................................................................................... 1 
1.1 TV Band Incumbent Uses ............................................................................................................ 2 
1.2 Interference Concerns, and Test Objectives................................................................................ 3 
1.3 Test Scope and Approach ............................................................................................................ 4 
1.3.1 Assessing Sensing Ability and Interference Potential with respect to Television Services.... 5 
1.3.2 Assessing Sensing Ability and Interference Potential with respect to Wireless Microphones 6 
2 White Space Prototype Devices ......................................................................................................... 7 
2.1 Prototype A (Versions 1 and 2) ................................................................................................... 7 
2.2 Prototype B................................................................................................................................ 10 
3 DTV Scanning/Spectrum Sensing Capability Tests....................................................................... 11 
3.1 Test Approach ........................................................................................................................... 11 
3.2 Bench Tests to Determine Minimum DTV Signal Detection Threshold..................................... 12 
3.2.1 Baseline Detection Threshold Tests (Single DTV Input Signal) .......................................... 12 
3.2.2 Multiple-Signal Detection Threshold Tests (Two DTV Input Signal). ................................ 15 
3.3 Field Tests with Over-the-Air Signals ....................................................................................... 18 
3.3.1 Field Test Site 1.................................................................................................................... 20 
3.3.2 Field Test Site 2.................................................................................................................... 25 
3.3.3 Field Test Site 3.................................................................................................................... 29 
3.3.4 Field Test Site 4.................................................................................................................... 33 
3.4 Field Test Summary................................................................................................................... 37 
4 Transmitter Emissions Characterization Measurements.............................................................. 39 
4.1 Transmitter Description ............................................................................................................ 39 
4.2 Measurement Approach............................................................................................................. 39 
4.3 Measurement Equipment Configuration ................................................................................... 40 
4.4 Channel Consistency Test.......................................................................................................... 42 
4.5 Fundamental Channel Emissions Measurements...................................................................... 44 
4.6 Out-of-Channel Emissions Measurements ................................................................................ 46 
4.7 Emissions Characterization Data Summary.............................................................................. 47 
5 Over-The-Air Interference Test....................................................................................................... 49 
5.1 Test Approach ........................................................................................................................... 49 
5.2 Test System ................................................................................................................................ 51 
5.3 Test Procedure .......................................................................................................................... 54 
5.4 Test Results................................................................................................................................ 54 
 
iii 
6 Data Observations Relevant to TV Services................................................................................... 56 
6.1 Scanning/Spectrum Sensing Capability Tests............................................................................ 56 
6.1.1 Prototype A Results.............................................................................................................. 56 
6.1.2 Prototype B Results .............................................................................................................. 57 
6.2 Transmitter Emissions Characterization Measurements........................................................... 58 
6.3 OTA Interference Test ............................................................................................................... 58 
7 Wireless Microphones Measurements............................................................................................. 59 
7.1 Introduction............................................................................................................................... 59 
7.2 Sensing of Wireless Microphones by White Space Devices....................................................... 61 
7.2.1 Prototype A Device .............................................................................................................. 63 
7.2.2 Prototype B Device............................................................................................................... 64 
7.3 Interference to Wireless Microphones....................................................................................... 66 
Appendix A  Measurement Systems ....................................................................................................... 72 
Appendix B  Service Contours of TV Stations at Field Test Sites........................................................ 74 
 
iv 
Figures 
 
 
Figure 2-1.  WSD Prototype A Sensing and Transmitting Device............................................................ 9 
Figure 2-2.  Prototype B WSD................................................................................................................... 10 
Figure 3-1.  Baseline Detection Threshold Test Equipment Configuration. ......................................... 13 
Figure 3-2.  Single-Signal Laboratory-Generated DTV Input. .............................................................. 13 
Figure 3-3.  Baseline Detection Threshold Results for Prototype A....................................................... 14 
Figure 3-4.  Baseline Detection Threshold Results for Prototype B....................................................... 14 
Figure 3-5.  Multiple (Two)-Signal Detection Threshold Test Equipment Configuration................... 16 
Figure 3-6.  Lab-Grade DTV Signals Used in Two-Signal Detection Threshold Tests (N-1)............... 16 
Figure 3-7.  Lab-Grade DTV Signals Used in Two-Signal Detection Threshold Tests (N+2).............. 17 
Figure 3-8.  Two-Channel Detection Threshold Test Results for WSD Prototype A. .......................... 18 
Figure 3-9.  Two-Channel Detection Threshold Test Results for WSD Prototype B............................ 18 
Figure 4-1.  Fundamental Channel Measurement System (without BPF)............................................. 40 
Figure 4-2.  Fundamental Channel Measurement System (with BPF) .................................................. 41 
Figure 4-3.  Adjacent Channel Measurement on WSD without filter.................................................... 41 
Figure 4-4.  Adjacent Channel Measurement on WSD with Filter........................................................ 42 
Figure 4-5.  Prototype A Transmitter Spectral Envelope Centered in Channel 21. ............................. 43 
Figure 4-6.  Prototype A Transmitter Spectral Envelope Centered in Channel 36. ............................. 43 
Figure 4-7.  Prototype A Transmitter Spectral Envelope Centered in Channel 51. ............................. 44 
Figure 4-8.  Prototype A Fundamental Channel Emissions in Channel 30. .......................................... 45 
Figure 4-9.  Prototype A Emissions on Channel 30 and N5 Adjacent Channels................................. 46 
Figure 4-10. Prototype A Spectral Envelope with and without Notch Filter. ....................................... 47 
Figure 5-1.  Service Contour for WMPB-DT on Channel 29. ................................................................ 50 
Figure 5-2.  Measured DTV Signal in TV Channel 29 at DTV Test Receive Antenna Location......... 51 
Figure 5-3.  Test System Block Diagram. ................................................................................................. 52 
Figure 5-4.  Test Receive System............................................................................................................... 52 
Figure 5-5.  Prototype WSD Transmitter on Wheeled Cart................................................................... 53 
Figure 5-6.  WSD Prototype Transmitter Downrange from Test Antenna. .......................................... 53 
Figure 7-1.  WM1 Wireless Microphone Spectrum Characteristics ...................................................... 60 
Figure 7-2.  WM2 Wireless Microphone Spectrum Characteristics ...................................................... 60 
Figure 7-3.  Simulated DTV Signal ........................................................................................................... 61 
Figure 7-4.  Sensing Test Setup ................................................................................................................. 62 
Figure 7-5.   Prototype A Device Transmit Spectrum ............................................................................. 68 
Figure 7-6.   Interference Test Set Up....................................................................................................... 71 
 
 
 
v 
Tables 
 
 
Table 2-1.  Prototype A Manufacturer-Reported Scanner/Sensor Technical Specifications................. 8 
Table 3-1.  Broadcast TV Stations within Prototype Tuning Range (21-51) with Service Contours that 
Include Test Site 1............................................................................................................................. 22 
Table 3-2.  Test Site 1 Field Survey Data.................................................................................................. 23 
Table 3-3.  Summary of Field Data Collected at Test Site 1 ................................................................... 24 
Table 3-4.  Broadcast TV Stations within Prototype Tuning Range (21-51) with Service Contours that 
Include Test Site 2............................................................................................................................. 26 
Table 3-5.  Test Site 2 Field Survey Data.................................................................................................. 27 
Table 3-6.  Summary of Field Data Collected at Test Site 2 ................................................................... 28 
Table 3-7.  Broadcast TV Stations within Prototype Tuning Range (21-51) with Service Contours that 
Include Test Site 3............................................................................................................................. 30 
Table 3-8.  Test Site 3 Field Survey Data.................................................................................................. 31 
Table 3-9.  Summary of Field Data Collected at Test Site 3 ................................................................... 32 
Table 3-10.  Broadcast TV Stations within Prototype Tuning Range (21-51) with Service Contours 
that Include Test Site 4 ..................................................................................................................... 34 
Table 3-11.  Test Site 4 Field Survey Data................................................................................................ 35 
Table 3-12.  Summary of Field Data Collected at Test Site 4 ................................................................. 36 
Table 3-13.  Summary of Field Test Data with Prototype A Version 2.................................................. 37 
Table 4-1.    Summary of Prototype Transmitter Channel Consistency Test Data. ............................. 44 
Table 4-2.    Summary of Emissions Characterization Data................................................................... 48 
Table 4-3.    Summary of Emissions Characterization Data................................................................... 48 
Table 5-1.    Available DTV Test Channels. ............................................................................................. 50 
Table 5-2.    Summary of OTA Interference Test Results....................................................................... 55 
Table 7-1.   Prototype A Sensing ............................................................................................................... 63 
Table 7-2.    Prototype B Sensing with WM1 Microphone at Center of Channel 44............................ 64 
Table 7-3.    Prototype B Sensing with WM1 Microphone 50 kHz from Low End of Channel 44 ...... 65 
Table 7-4.    Prototype B Sensing with WM2 Microphone 200 kHz from High End of Channel 45 ... 65 
Table 7-5.    Prototype B Sensing - Channels Sensed As Occupied ........................................................ 66 
Table 7-6.    Co-channel Undesired Interference Power Level (dBm) ................................................... 68 
Table 7-7.    Adjacent Channel Undesired Interference Power Level (dBm) for Simulated WSD 
Signals ................................................................................................................................................ 69 
Table 7-8.    1
st
 and 2
nd
 Adjacent Channel Prototype A Device Interference Power Level (dBm) ...... 69 
 
 
vi 
Executive Summary 
Introduction.  The Federal Communications Commissions (FCC) Laboratory has 
conducted a measurement study of the spectrum sensing and transmitting functions of 
prototype unlicensed low power radio transmitting devices that would operate on 
frequencies in the broadcast television bands that are unused in each local area.  These 
locally unused frequencies are known as white spaces.  This research is part of the 
FCCs ongoing proceeding to consider rules for permitting such devices to operate on TV 
white spaces.  As established previously by the Commission, fixed white space devices 
(WSDs) will be allowed into the TV spectrum simultaneous with the completion of the 
transition from analog to digital television broadcasts on February 17, 2009.  The 
Commission is also considering whether to allow unlicensed personal/portable WSDs 
to operate in the TV spectrum. 
 
One approach under consideration for determining the unused frequencies in local 
areas is for a WSD to employ a detect and avoid or listen before talk strategy.  This 
approach would use spectrum sensing techniques that listen for the signals of TV 
stations, wireless microphones and perhaps other incumbent services.  The Commission 
has requested comment on whether to require that the sensing capability of devices using 
this approach be able to detect signals as low at -116 dBm.  A second issue is the 
potential for WSDs to interfere with TV reception and wireless microphone operations.  
To address these issues, the Commission announced that it would conduct testing of 
WSD spectrum sensing and transmitting capabilities.   
 
This report presents an initial evaluation of WSDs based on tests performed on 
prototype devices submitted by industry for evaluation by the FCC Laboratory.    We 
recognize, however, that the devices we have tested represent an initial effort, and do not 
necessarily represent the full capabilities that might be developed with sufficient time and 
resources.  Accordingly, we are open to the possibility that future prototype devices may 
exhibit improved performance. 
 
WSD Prototype Devices Submitted for Evaluation.  The Office of Engineering 
and Technology in December 2006 issued a Public Notice inviting interested parties to 
submit WSD prototype devices for testing at the FCC Laboratory in Columbia, 
Maryland.
1
  Two parties provided prototype personal/portable WSDs to the Laboratory 
for testing.  The devices submitted by these parties are designated Prototype A and 
Prototype B herein; both have a sensing capability but only the Prototype A device has 
a transmitter.  The test project was provided three units of Prototype A and one unit of 
Prototype B.    These devices are not intended as actual consumer products but rather are 
development tools for evaluating the viability of spectrum sensing and potential 
interference.  They do not communicate with other devices.    
 
                                                 
1
 FCC Public Notice DA 06-2571, Office of Engineering and Technology Invites Submittal of Prototype 
TV Band Devices for Testing, ET Docket No. 04-186, December 21, 2006.  
 
vii 
Spectrum Sensing of TV broadcasting signals.  This portion of the study 
examined the ability of the prototype devices to detect whether channels are occupied by 
TV signals.  Measurements were limited to TV signals on UHF channels 21-51, the 
operating range of the prototype devices. Both bench and field tests were performed for 
the Prototype A devices.  Only bench tests were performed for the Prototype B device 
because the supplier formally declared that the device was not suitable for field testing 
and requested that it not be included in those tests.   
 
The bench testing of the sensing function of the Prototype A device found that 
this device is generally not able to detect DTV signals on any of the tested channels at the 
-116 dBm/6 MHz level detection threshold for DTV signals on which the Commission 
requested comment or at the -114 dBm level detection threshold suggested by the 
devices manufacturer.  Prototype A is able to detect DTV signals reliably, that is, in a 
very high percentage of instances, at levels of -95 dBm or higher.  The testing found that 
the Prototype A device takes approximately 27 seconds to scan each channel, or 
approximately 14 minutes to scan the full range of all 31 channels that it covers. 
 
 Field testing was performed with one unit of the Prototype A device (the last unit 
submitted) in order to assess the scanning/sensing capability under real-world 
conditions.  The selected unit of the Prototype A device was tested at a number of sites 
representative of typical residences where over-the-air television broadcasts, including 
DTV, are currently being received.  The sample sites were limited to residences already 
set up for and receiving over-the-air (OTA) DTV broadcasts in order to provide a means 
for verifying the OTA stations (and associated RF channels) that could actually be 
successfully received at the site using a typical DTV receiving system.  Several 
independent test locations were identified within each test site (e.g., the tests were 
performed within several rooms of each house).  In these tests the prototypes scanning 
feature was activated and the scanning results were recorded for each location.     
 
 The sensing field tests investigated the Prototype A devices performance with 
respect to two aspects:  1) correct identification of channels as occupied and 2) correct 
identification of channel as available, i.e., unoccupied.  The field tests also investigated 
performance in certain subcategories for identification of occupied channels:  1) detection 
of analog TV signals, 2) detection of DTV signals where the signal could not be received 
on the sites TV receiver (in these cases it was assumed that the signal strength at the site 
was too low for the TV receiver to receive the signal), and 3) detection of DTV signals 
where the signal could be received on sites TV receiver.   
 
In general, the Prototype A scanner did not provide consistently accurate 
determinations on an overall basis or with respect to any of the subcategories in the field 
tests.  First, these tests found that the Prototype A scanner often reports a channel to be 
available, or vacant, when the broadcast signal is expected to be present.  The summary 
results for the four subcategories in this area of performance are (note that in all cases the 
test site was within the predicted service contour of TV signals considered): 
 
 
viii 
1. In the cases where the NTSC signal is being broadcast, the scanner reports the 
channel to be free or available between 11.1% and 27.8% of the time, with the 
average of 19.4% of the time.  
2. Where a DTV signal was being broadcast but was not received on the sites TV 
set, the scanner reported its channel to be free or available 81.3% to 91.7% of the 
time, with an average of 85.4% of the time. 
3. Where a DTV signal was strong enough to be received on the TV, the scanner 
reported its channel to be free or available 40% to 75% of the time with an 
average of 58.2% of the time.  These percentages are particularly high for Sites 3 
and 4. 
4. When no signal was expected to be present, the scanner reported the channel to be 
free or available from 78.1% to 91.7 % of the time, with an average of 85.2 % of 
the time. 
 
With respect the Prototype B, the bench tests results indicate that, under Laboratory 
conditions, this device is generally able to reliably detect DTV signals at -115 dBm in the 
single channel tests and at -114 dBm in the two-channel tests.  Prototype Bs sensing 
performance declines very rapidly as the signal levels are reduced.  The testing found that 
the Prototype B device takes approximately 8 seconds to scan each channel or slightly 
more than 4 minutes to scan the full channel range.  
 
 Spectrum Sensing of Wireless Microphones.  The wireless microphone portion of 
the testing looked at the ability of the Prototype A and Prototype B sensors to scan for 
and detect Part 74 wireless microphones.  It also looked at the susceptibility of wireless 
microphones to the signals emitted by the Prototype A transmitter and simulated 
broadband signals modulated using several alternative methods.  Wireless microphone 
testing was conducted in the laboratory only; no field tests were performed for these 
devices.  Bench tests of the Prototype A and Prototype B devices ability to sense wireless 
microphones were performed using signals generated by wireless microphones.  These 
signals were coupled directly to the input terminals of the prototype devices.  Wireless 
Microphone interference testing was performed using both simulated signals and signals 
from the Prototype A transmitter.  Three different Part 74 wireless microphone systems 
were used in these tests. 
 
The results of these tests indicated that the Prototype A was generally unable to 
sense wireless microphones.  This device was tested with wireless microphone signals at 
various power levels and locations within a TV channel, and with and without the 
presence of a DTV signal on a different channel at different power levels. In many cases, 
the device incorrectly sensed the wireless microphone signal as a DTV signal.  In view of 
the performance of the Prototype A device in the initial tests under moderate conditions, 
there appeared to be no additional insight to be gained at this time from testing this 
device under other conditions and so further measurements were not performed. 
   
The performance of Prototype B device was mixed when tested in a variety of 
situations and conditions.  This device was found to be able to sense wireless microphone 
signals located in the center of a TV channel in all scans at a signal levels as low as 
 
ix 
-120 dBm.  However, on some scans it also incorrectly indicated the presence of a 
microphone on channel 24.   In addition, when the wireless microphone signal was at the 
-36.6 dBm level, Prototype B also incorrectly sensed wireless microphone signals on six 
additional channels.  The testing further found that the devices ability to sense wireless 
microphones decreases somewhat as the location of the microphone signal is moved 
closer to the edge of the TV channel on which it operates.  The test results show that 
Prototype A tends to make more false detections of microphone signals on adjacent 
channels as the power level of the operating microphone is increased.  When tested in the 
presence of both DTV and wireless microphone signals the device also tends to make 
more false detections of DTV signals, analog TV signals, and wireless microphone 
signals as the level of the DTV signal increases. 
 
Tests were conducted to characterize the susceptibility of Part 74 wireless 
microphone systems to possible interference from unlicensed WSDs.  Before the 
Prototype A became available, this test project examined the potential for interference to 
wireless microphones using the three Part 74 wireless microphone systems and WSD 
signals that were simulated using an audio modulated FM signal, a wideband noise signal 
and a wideband OFDM signal.  When the Prototype A WSD became available, it was 
tested for interference to a wireless microphone system.  In these tests, interference was 
defined to occur at the point where the signal-to-noise plus distortion (SINAD) ratio 
reading at the audio output of the microphone receiver was 30 dB.  The results show that 
in most cases the wireless microphones are generally at least 15 dB less susceptible to 
interference from the simulated WSD signals on first adjacent channels than on the same 
channel.   
 
 Transmitter Characterization and Interference Testing.  Tests were performed to 
characterize the transmitter signal, which is an important element for assessing the 
interference potential of these devices.   Field tests were performed to evaluate potential 
interference, however, for reasons explained below these tests were quite limited. 
 
The Commission has proposed to establish an average limit on power at the 
fundamental frequency of a device in terms of an equivalent isotropic radiated power 
(EIRP) as integrated over the 6-MHz TV channel bandwidth.  Measurements of the 
fundamental power were performed on a conducted basis (via a coaxial connection 
between the transmit antenna output port and the input to the measurement instrument). 
These measurements showed that the adjusted output power of the prototype as integrated 
over the 6-MHz TV channel is approximately 22 dBm, which is slightly higher than the 
FCC proposed power level of 100 mW (20 dBm) EIRP, assuming an omni-directional 
antenna.  However, when operated with an external filter required to achieve compliance 
with FCCs current out-of-band emissions limits, the power level was seen to be 
approximately 14 dB lower, or 8 dBm.  
 
 The prototype devices that were submitted do not lend themselves to extensive 
field tests for evaluating interference potential.  Moreover, only the Prototype A device 
included a transmitter and it operated independently of the sensing function.  While the 
transmitters power level can be adjusted manually, its maximum level was below the 
 
x 
FCC proposed power level of 100 mW EIRP when used with the required filter.  Certain 
techniques that are claimed to reduce interference potential, such as adaptive power 
control and reducing the transmitter power based on measurements of DTV signal levels 
in adjacent channels, were not implemented in the prototype device.  The time to perform 
scans of the TV channels, which took up to 14 minutes, also impacted the pace of testing. 
 
 The record in the Commissions rule making proceeding includes differing views 
as to the appropriate analytical models and criteria that should be used to evaluate the 
interference potential of WSDs.   This includes discussion of the signal levels that should 
be protected, physical relationship and separation distances between the devices, assumed 
path losses, etc.  A large number of field tests would be required to be statistically valid 
relative to the scenarios and assumptions in the record.  We anticipate the technical 
arguments will be fully explored in the Commissions rule making and that the data from 
this report will be one factor, together with a complete analysis of the record that is taken 
into account in arriving at a decision on final rules.     
 
  However, this project conducted limited, or anecdotal, tests in the field of the 
prototype WSD transmitter to provide information on its potential to interfere with TV 
reception.  These tests were performed in a large outdoor area to evaluate the 
performance with an unobstructed line-of-sight (LOS) propagation path between the 
WSD transmit antenna and the DTV test receiver antenna.  A test DTV receiver was 
placed in the area and connected to an indoor antenna with the antenna oriented towards a 
DTV transmitter on channel 29.  The WSD transmitter was then placed in the 
mainbeam of the receive antenna, tuned to the same channel, and activated at 
incremental distances from the DTV receive antenna while observing for interference 
effects to the picture quality.  Tests were also performed with the WSD tuned to a first 
(N+1) and second (N+2) adjacent channel.  These adjacent channel tests were performed 
both with and without the use of the external transmit filter.  Co-channel interference 
with the WSD transmitting without the transmit filter was observed out to a distance of 
87 meters.  First adjacent-channel interference with the WSD transmitting without the 
external filter was observed out to a distance of 47-50 meters, and second adjacent-
channel interference was observed at a distance of 11-14 meters.  First adjacent-channel 
interference with the external transmit filter applied was observed at a maximum distance 
of 2 meters, but as indicated above, the transmit power with the filter attached is 
attenuated by an additional 14 dB.  In practice, the distance at which adjacent channel 
interference occurs would be expected to be greater if the device were operating at the 
proposed output power level of 100 mW EIRP. 
 
 Conclusions. This report determined that the sample prototype White Space 
Devices submitted to the Commission for initial evaluation do not consistently sense or 
detect TV broadcast or wireless microphone signals.  Our tests also found that the 
transmitter in the prototype device is capable of causing interference to TV broadcasting 
and wireless microphones.  However, several features that are contemplated as possible 
options to minimize the interference potential of WSDs, such as dynamic power control 
and adjustment of power levels based on signal levels in adjacent bands, are not 
 
xi 
implemented in the prototype devices that were provided.  Given these results, further 
testing of these devices was not deemed appropriate at this time. 
 
 
 
 
 
1 
1 Introduction 
 
The measurement project described herein was undertaken in support of the 
Federal Communications Commissions (FCC) ongoing proceeding to consider rules for 
permitting low power radio transmitting devices to operate on an unlicensed basis in the 
frequency bands that are currently allocated to the Television Broadcast and certain other 
licensed services.
2
  Such unlicensed operations would be allowed on frequencies that are 
not used by TV stations or other services in each local area.  These unused, or vacant, 
frequencies available in local areas are often termed spectrum white spaces.  As 
established previously by the Commission, fixed unlicensed white space devices 
(WSDs) will be allowed into the TV spectrum simultaneous with the completion of the 
transition from analog to digital television broadcasts on February 17, 2009.
3
  The 
Commission is now considering whether to allow unlicensed personal/portable WSDs 
to operate in the TV spectrum. 
 
An issue in the white spaces matter is how to ensure that unlicensed devices 
operate only on vacant frequencies.  One approach under consideration for determining 
the unused frequencies at a WSD location is for the WSD to employ a detect and avoid 
or look before talk strategy.  This approach would be dependent on the performance of 
spectrum sensing techniques for detection of signals of TV stations, wireless 
microphones and perhaps other incumbent services.  A second issue is the interference 
potential from low power WSDs to TV reception and wireless microphone operations.  
The Commission indicated that it would perform testing to collect the information 
necessary to evaluate both of these issues. 
 
Consistent with the Commissions plan for white space testing, the Office of 
Engineering and Technology (OET) issued a Public Notice on December 21, 2006, 
inviting interested parties to submit white space devices for testing at the FCC 
Laboratory.
4
  The Public Notice indicated that the Laboratory intended to test these 
devices for their ability to operate on unused TV band frequencies without causing 
interference to broadcast television and other authorized services.  Two parties responded 
to this notice and provided prototype personal/portable WSDs to the Laboratory for 
testing.  The devices submitted by these two parties are designated Prototype A and 
                                                 
2
 First Report and Order and Further Notice of Proposed Rule Making in the Matter of Unlicensed 
Operation in the TV Broadcast Bands, ET Docket No. 04-186 and 02-380, October 18, 2006 (hereinafter 
FNPRM).  While the focus of this proceeding is on unlicensed operation, the Commission has also 
requested comment on issues relevant to whether TV band low power devices should be allowed on a 
licensed or hybrid licensed/unlicensed basis.  It also requested comment as to whether, if unused TV 
spectrum were made available on a licensed basis, licensed devices should be required to incorporate the 
same type of interference avoidance mechanisms and be subject to the same low power limits that it 
proposed for unlicensed devices. 
3
 Id. 
4
 FCC Public Notice DA 06-2571, Office of Engineering and Technology Invites Submittal of Prototype TV 
Band Devices for Testing, ET Docket No. 04-186, Dec 21, 2006. 
 
2 
Prototype B herein.
5
  Both of these prototypes have a sensing capability but only one, 
the Prototype A device, has a transmitter.   
 
This report describes the tests and measurements performed on the prototype 
WSDs to acquire the data needed for an electromagnetic compatibility (EMC) evaluation, 
with focus on broadcast television and wireless microphone operations.  In particular, this 
report provides the results of tests of the spectrum sensing capabilities of the prototype 
devices as a means for identifying TV band channels unoccupied by TV or wireless 
microphone operations and, where the devices included transmission capability, their 
emissions characteristics and potential for causing interference to those services.  While 
other incumbent services operate in the TV bands, those services were not specifically 
examined in this testing as the Commission has proposed other methods for protecting 
them from WSD operations.   
1.1 TV Band Incumbent Uses 
 
 The TV bands are primarily occupied by stations in the broadcast television 
service, which operates under Part 73 of the FCC rules.
6
  TV stations broadcast in 6-MHz 
channels and after the transition to all digital operation will operate on channels 2 to 51 in 
the very-high frequency (VHF) and ultra-high frequency (UHF) portions of the 
electromagnetic spectrum (54-72 MHz, 76-88 MHz, 174-216 MHz, and 470-698 MHz).
7
  
In addition to full-service TV stations operating under Part 73 of the rules, other related 
licensed services are also permitted to operate in the spectrum allocated to Broadcast TV.  
These include Class-A TV stations, low-power TV stations, TV translators and TV 
booster stations.  Part 74 of the rules permits certain broadcast auxiliary and wireless 
microphone operations to operate on TV frequencies on a limited (i.e., non-interference) 
basis.  The prototype WSDs were designed to detect signals from TV and wireless 
microphone transmitters operating within these radio services.   
 
 In 13 metropolitan areas, one to three channels in the range of channels 14-20 are 
used by licensees in the Private Land Mobile Radio Service (PLMRS) under Part 90 of 
the rules and the Commercial Mobile Radio Service (CMRS) under Part 20 of the rules.
8
  
In addition, medical telemetry equipment is permitted to operate on an unlicensed basis 
on vacant TV channels 7-46, and unlicensed remote control devices are allowed to 
operate on any TV channel above 70 MHz (channel 4), except for channel 37.
9
  TV 
                                                 
5
 As discussed below, we received three units of the Prototype A device and one unit of the Prototype B 
device. 
6
 47 C.F.R. Part 73 
7
 See 47 C.F.R.  73.603(a).  Television stations currently also operate on channels 52-69 (698-806 MHz), 
however, those channels have been reallocated to new uses and will not be available for use by WSDs, see 
First Report and Order in WT Docket No. 99-168, 15 FCC Rcd 476 (2000), Report and Order in ET 
Docket No. 97-157, 12 FCC Rcd 22953 (1998) and Report and Order in GN Docket No. 01-74, 17 FCC 
Rcd 1022 (2002). 
8
 See 47 C.F.R.  90.301-.317 and 47 C.F.R.  20.625. 
9
 See 47 C.F.R.  15.231, 15.241 and 15.242.  Effective October 16, 2002, the Commission ceased 
granting certification for new medical telemetry equipment that operates on TV channels, but there is no 
cutoff on the sale or use of equipment that was certified before that date.  See 47 C.F.R.  15.37(i). 
 
3 
channel 37 is allocated for radio astronomy and the wireless medical telemetry service 
(WMTS) and is not used for TV broadcasting.  Under the Commissions proposals in the 
white space proceeding, these services would be protected by means other than spectrum 
sensing.  Since it is not anticipated that WSDs would need to protect PLMRS, CMRS, 
and WMTS services by spectrum sensing, they were not tested for that functionality.
10
   
1.2 Interference Concerns, and Test Objectives 
 
 When assessing the potential impact from the introduction of a new radio service 
into an occupied segment of the electromagnetic spectrum, a priority consideration is the 
preservation of electromagnetic compatibility with respect to spectrum incumbents (i.e., 
the avoidance of harmful radio frequency interference (RFI) to the operations of existing 
radio services).  In order to address the differences in the potential for RFI to incumbent 
operations from WSDs operating at different power levels and for somewhat different 
applications, the Commission proposed classifying unlicensed WSDs into two general 
functional categories.
11
  The first category consists of low-power personal/portable 
WSDs that will function similar to WiFi applications in laptop computers and wireless in-
home local area networks (LANs).  The second category consists of higher-powered 
fixed/access WSDs that would typically be operated from a fixed location and used to 
provide a commercial service such as wireless broadband access.   
 
 The tests described herein focused exclusively on the ability of personal/portable 
category of unlicensed WSDs to detect TV and wireless microphone signals and to their 
potential to interfere with the reception of those signals.  The interference mechanisms of 
principal concern to incumbent services from the introduction of WSDs involve co-
channel and adjacent channel interactions.
12
  The co-channel interference potential 
represents RFI that is likely to occur when a WSD transmits on the same 6-MHz channel 
that is also being locally used to receive over-the-air television broadcast programming or 
Part 74 wireless microphone signals.   
 
 Adjacent-channel RFI becomes a concern when a WSD transmits on a channel 
adjacent to one being used locally to receive over-the-air (OTA) television broadcast 
programming or to establish wireless microphone links.  This interference potential is 
typically a function of the combination of the radio frequency (RF) filtering employed in 
                                                 
10
 Notice of Proposed Rulemaking in ET Docket Nos.  04-186 and 02-380, 19 FCC Rcd 10018 (2004), at 
paragraphs 33-37. 
11
 Notice of Proposed Rulemaking in ET Docket Nos. 02-380 and 04-186, 19 FCC Rcd 10018 (2004). 
12
 Direct pick-up of signals by receivers of WSDs signals is also a concern.   Direct pick-up interference 
occurs when the output power of a transmitter is at a level high enough that interference occurs to a victim 
receiver via the unconventional means of cable- or case-penetration rather than through the typical 
antenna/receiver path.  This interference mechanism is of particular concern to cable television providers, 
since unlike over-the-air (OTA) broadcast operations, cable operations can use all of the frequencies 
between 54 MHz and 698 MHz (cable operations also typically use additional, higher frequencies).   Thus, 
regardless of the OTA scenario, a WSD may select a channel that is also being used to provide television 
content via coaxial cable.  These DPU interactions were characterized in a separate study conducted by the 
FCC Laboratory as part of the Commissions white spaces testing program.  See Stephen R. Martin, 
Direct-Pickup Interference Tests of Three Consumer Digital Cable Television Receivers Available in 
2005, OET Report FCC/OET 07-TR-1005, July 31, 2007. 
 
4 
both the victim receiver and the interfering transmitter and typically involves the 
immediately adjacent channels (relative to the victim receiver operating channel), but 
depending on the level of RF filtering employed in the transmitter circuit, can also extend 
to channels even further removed. All radio transmitters emit some level of energy into 
adjacent frequency bands, and it is, of course, desirable to minimize such emissions as 
they can cause interference.  Out of band emissions (OOBE) are controlled with proper 
transmitter design and filtering. 
  
 The Commission has proposed to allow the RFI potential of personal/portable 
WSD devices to be controlled by implementing a detect and avoid or look before talk 
strategy whereby WSD operation on channels already occupied with television 
broadcasts or wireless microphone transmissions would be avoided, thus eliminating the 
possibility of co-channel interference interactions.  The detection function in this 
approach would be performed by a spectrum scanning/sensing capability whereby the 
WSD will scan all TV channels in its tuning range while real-time sensing for ambient 
signals, process the detected signals, and then use the resulting data to determine which 
channels are occupied and which are vacant.  Those channels deemed to be vacant could 
then be utilized to provide the desired unlicensed services (e.g., wireless LAN 
connectivity).  The Commission has requested comment on whether to require that the 
sensing capability of devices using this approach be able to detect signals as low at 
-116 dBm, consistent with the most conservative threshold under consideration by IEEE 
802.22.
13
  The Commission also requested comment on alternative values for the sensing 
threshold and several parties representing the interests of incumbent TV band services 
have submitted comments arguing that the detection threshold should be significantly 
lower. 
 
 Other variations on this approach involve augmenting the scanning/sensing 
capability with geo-location (e.g., an embedded Global positioning Satellite (GPS) 
receiver), database look-up, distributed sensing, and/or beacon identification techniques.  
Assuming that these detect and avoid strategies are adequate to identify any and all 
incumbent users, co-channel interference interactions can be avoided.  Thus, control over 
the channels RFI potential arising from the introduction of unlicensed WSDs will be 
predicated on the successful detection and avoidance of occupied channels. 
1.3 Test Scope and Approach 
 
 This section describes the approach taken to collect data on the ability of the 
unlicensed personal/portable devices as represented by the prototype devices to detect 
whether channels are occupied by TV or wireless microphone signals and to assess the 
potential for the transmitters of those devices to cause interference to the reception of TV 
and wireless microphone signals.  The TV portion of the sensor testing examined the 
                                                 
13
 See First Report and Order and Further Notice of Proposed Rule Making at paragraph 37; see also 
Institute of Electrical and Electronics Engineers (IEEE), Working Group 802.22; 
http://standards.ieee.org/announcements/pr_80222.html.  The proposal under consideration by IEEE 802.22 
is for fixed devices.  Broadcasters and other parties representing incumbent services in the TV bands argue 
that the threshold should be lower than the -116 dBm level for personal/portable devices. 
 
5 
ability of the prototype devices to detect the signals of both analog and digital full service 
stations.  The results of these tests are also applicable to analog and digital low-power 
television operations (Class A, low power TV, and TV translator stations) that use the 
same transmission standards as full service television stations.  The transmitter of the 
Prototype A was evaluated for its potential to interfere with digital TV signals.  The 
wireless microphone portion of the testing looked at the ability of the prototype sensors to 
detect wireless microphones.  It also looked at the susceptibility of wireless microphones 
to the signals emitted by the Prototype A transmitter and simulated broadband signals 
modulated using several alternative methods.  Testing was limited to TV and wireless 
microphone signals on UHF channels 21-51, the operating range of the prototype devices.   
 
 If portable/personal WSDs operate in the television spectrum on an unlicensed 
basis (i.e., under Part 15 of the FCC rules), they must accept interference from licensed 
incumbents while not creating harmful interference to the licensed operations.  The 
Commissions EMC concerns thus are only for potential interference interactions from 
WSD transmitters to those receivers associated with incumbent licensed operations (i.e., 
there will be no requirement to assess the interference potential to WSD receivers).  This 
test project therefore did not examine interference from TV and other signals to the 
prototype WSD receivers 
1.3.1 Assessing Sensing Ability and Interference Potential with respect to 
Television Services 
 
 Under the proposed detect and avoid approach, control over co-channel, and to 
some extent, adjacent channel interference from personal/portable WSD transmitters is 
predicated on the successful detection of incumbent signals occupying TV band channels 
or frequencies.  A television broadcast signal originating from a distant location (or as a 
result of terrain blockage) may be at very low power levels at the WSD location 
(particularly under conditions described by the hidden node scenario discussed in the 
record).
14
  The scanner/sensor of WSDs therefore must be capable of reliably detecting 
TV signals (and particularly DTV signals) at extremely low levels.   
 
 Bench and field tests were performed to assess the scanning/sensing sensitivity 
and reliability of the prototype WSDs.  In the case of bench testing, guidance and draft 
recommendations published to date by IEEE 802.22 for testing the spectrum sensing 
capability of fixed/access WSDs were considered where applicable.  Two tests utilizing 
laboratory-grade DTV signals were used to determine 1) the baseline minimum 
discernable signal that could successfully be detected by the scanner/sensor component of 
the prototype and 2) the impact to the baseline from signals present on nearby channels.   
 
 Field tests were performed with one unit of the Prototype A device in order to 
assess the scanning/sensing capability under real-world conditions (the manufacturer of 
the Prototype B device formally declared that the device was not suitable for field testing 
and requested that it not be included in these tests).  The scanning/sensing capability of 
the selected prototype device was tested at a number of sites representative of typical 
                                                 
14
 See FNPRM at 39 
 
6 
residences where over-the-air television broadcasts, including DTV, are currently being 
received.  Several independent test locations were identified within each test site (e.g., the 
tests were performed within several rooms of each house).  In cases where the test site 
was located within the service contour of a station occupying a channel and where the 
content of that channel could be received and displayed on the existing DTV receiving 
system, it was expected that the scanning/sensing component of the WSD prototype 
should be able to reliably identify that channel as being occupied.
15
   
 
 In order to assess the interference potential of the WSD to TV receivers, an effort 
was made to characterize the transmitters emission technical parameters through 
laboratory measurements.  In addition, a recently published FCC report documents an 
extensive effort to determine the susceptibility of modern DTV receivers to 
interference.
16
  The combined information from the study of the transmitters and the 
DTV receiver susceptibility to interference can provide a much better assessment of the 
interference potential when used for link budget analyses under various assumptions 
regarding the interaction scenarios.   
 
 Finally, an anecdotal test to demonstrate the interference potential from a WSD 
transmitter to a DTV receiver using live over-the air (OTA) broadcast was conducted.  
Since there were so many parameters of the tests which could not be controlled, the 
results only provide an illustration of interference. 
1.3.2 Assessing Sensing Ability and Interference Potential with respect to 
Wireless Microphones 
 
Wireless microphone testing was conducted in the laboratory only; no field tests 
were performed for these devices.  Bench tests of the Prototype A and Prototype B 
devices ability to sense wireless microphones were performed using signals generated by 
wireless microphones. These signals were coupled directly to the input terminals of the 
prototype devices.  Wireless Microphone interference testing was performed using both 
simulated signals and signals from the Prototype A transmitter.  Three different Part 74 
wireless microphone systems were evaluated in these tests.  The simulated signals 
consisted of an audio modulated FM signal, a wideband noise signal and a wideband 
OFDM signal.  
                                                 
15
 The locus of points at the outer edge of the area served by a TV station is termed the stations service 
contour and corresponds to the range at which reception is noise-limited.  At locations within its service 
contour, a stations signal is generally assumed to be receivable.  TV service contours are defined on the 
basis of field strengths.  For analog TV stations, service areas are based on the Grade B contour, which 
for UHF channels is the F(50,50) contour for a field strength of 64 dBu; for DTV stations service areas are 
based on the noise-limited contour, which for UHF channels is the F(50,90) contour for a field strength of 
41 dBu.  See Sections 73.622(e), 73.683, 73.684, and 73.699 of the Commissions rules, 47 C.F.R.  
73.622(e), .683, .684, and .699.   
16
 Stephen R. Martin, Interference Rejection Thresholds of Consumer Digital Television Receivers 
Available in 2005 and 2006, Report FCC/OET 07-TR-1003, March 30, 2007 (hereinafter, DTV 
Susceptibility Study). 
 
7 
2 White Space Prototype Devices 
 
The two prototype personal/portable WSDs submitted for testing were both 
devices intended as product development platforms rather than finished products ready 
for the market.  The Prototype A units had both sensing and transmitting capabilities, but 
the two features were not linked.  There was no provision for these devices to transmit 
automatically on channels found to be vacant; rather the transmitter function was 
activated manually by the operator.  The Prototype B device only had sensing capability.  
Further, as indicated by its manufacturer to the Laboratory staff, this Prototype was not 
likely to endure the rigors of field testing and therefore was exempted from the field tests.   
2.1 Prototype A (Versions 1 and 2) 
 
 The Prototype A WSD platform consists of two core system subassemblies: 1) a 
wide-band spectrum scanner, a network processor and a tunable UHF half-duplex 
transceiver controlled by the network processor and 2) a Windows-based laptop computer 
that utilizes the Internet Explorer browser to establish a command and control user 
interface via an Ethernet connection. 
 
 The scanner/sensor function of the Prototype A devices consists of a broadband 
(521-698 MHz) computer-controlled frequency scanner and high-speed digitizer that is 
used to incrementally scan over UHF TV channels 21-51 in 6-MHz segments.  The 
accumulated digitized time-domain information is then passed to the network analyzer 
where a 2048-point Fast Fourier Transform (FFT) is performed.  Signal feature templates 
for DTV, analog TV, and wireless microphone waveforms are sequentially compared to 
the resulting FFT output to determine channels occupied by DTV or analog TV signals.  
Channels determined not to be occupied by DTV or analog TV signals are subsequently 
analyzed for potential narrowband incumbent signals such as wireless microphones.  
Those channels determined not to be occupied by either DTV, analog TV, or wireless 
microphone signals are declared to be available white space channels.  User control and 
scanner results are provided via the laptop computer connection.  Table 2-1 provides the 
manufacturers statement of the basic specifications for the scanner/sensor component of 
the Prototype A WSDs. 
 
 
8 
 
 
Table 2-1.  Prototype A Manufacturer-Reported Scanner/Sensor Technical Specifications 
 
Technical Parameter Specification 
Frequency Range 512-698 MHz (TV Channels 21-51) 
Frequency Step 1 MHz 
Scan Frame Bandwidth 8 MHz 
Scan Frame FFT Size 2048 points 
FFT Bin Size 3.9 kHz 
Minimum Discernible DTV Pilot Tone Sensitivity -114 dBm 
Minimum Discernible Wireless Microphone Detection 
Sensitivity 
-114 dBm 
Gain Selections In-line 20 dB, High-Intercept LNA 
Measurement Accuracy  3 dB 
 
 The UHF transceiver assembly consists of three sub-components: 1) an S-Band 
(2.4 GHz) 802.11g OFDM modem; 2) a Half-duplex S-Band to UHF block converter; 
and 3) and a network processor browser to exercise control over frequency and power. 
 
 Two versions of the Prototype A personal/portable WSD were provided to the 
Laboratory.  The first version (version 1) was delivered on March 13, 2007 and 
implemented a scanning/sensing capability and a UHF transceiver, with control between 
the two via a manual, human interface.  This unit was used to become acquainted with 
Prototype A operation and to measure the output emissions of the UHF transmitter.  
However, problems were encountered with the operation of its sensing/scanning function 
(unintended emissions from the three separate power supplies in the device resulted in a 
high level of false detections) and therefore measurements were not made of the scanning 
performance of that unit.  Two units of a second version of this prototype WSD (version 
2) were provided on May 3, 2007.  The two separate version 2 units were provided to 
enable simultaneous testing with respect to incumbent TV service and wireless 
microphone signals.  The primary differences between versions 1 and 2  were: 1) the 
addition of an external transmission filter on channel 30 to improve the transmitters 
OOBE (two separate external filters were provided),
17
 2) a change in the scanner receiver 
antenna from a separate tripod-mounted discone to the same whip antenna used by the 
transceiver, 3) the consolidation of the three separate power supplies into one (which 
eliminated the unintended emissions problem), and 4) some minor modifications to the 
user interface, primarily to enhance file management capability. The version 2 units were 
used in all of the measurements reported herein. 
 
The algorithm associated with the sensor/scanner component of the Prototype A 
device is proprietary and was not disclosed to the FCC.  Nonetheless, it can be discerned 
                                                 
17
 Notice of Ex Parte Communication, ET Docket Nos. 04-186, 02-380, submitted by Harris, Wiltshire & 
Grannis LLP on  behalf of Dell, Inc., Earthlink, Inc., Google, Inc., the Hewlett-Packard Co., Intel Corp, 
Microsoft Corp., and Philips Electronics North America Corp submitted on March 14, 2007, see also 
Notice of Ex Parte Communication, TV White Spaces Proceeding, ET Docket Nos. 04-186, 02-380, 
submitted by Harris, Wiltshire & Grannis LLP on behalf of The White Spaces Coalition submitted on May 
3, 2007 (herinafter White Space Coalition Communications).  
 
9 
from observing the sensor/scanner operation that the basic premise of the algorithm is to 
correlate on anticipated spectral features associated with the signal being detected.  For 
example, the pilot tone associated with a DTV signal appears to be the feature used to 
identify an ATSC waveform.  Similarly, an analog TV signal appears to be identified 
based on the presence and location in the channel of the picture carrier, the audio carrier 
and/or the chrominance subcarrier associated with an NTSC waveform.  Additionally, it 
appears that a scoring system is utilized whereby a score is applied based on the detection 
of these anticipated spectral features.  A final determination as to whether the detected 
signal is a digital TV, analog TV, or wireless microphone signal is made based on the 
accumulated scores.  The prototype WSD device reports the results via an Ethernet 
connection to a laptop computer. 
 
 User manuals, including a system description and equipment specifications, were 
entered into the proceeding record for both versions in ex-parte filings submitted on 
behalf of Dell, Inc., Earthlink Inc., Google, Inc., the Hewlett-Packard Co., Intel Corp, 
Microsoft Corp., and Philips Electronics North America Corp. (the White Spaces 
Coalition or WSC).
18
  Figure 1 shows a version 2 unit of the Prototype A device (with 
the external bandpass filter). 
 
 
 
 
 
 
 
Figure 2-1.  WSD Prototype A Sensing and Transmitting Device 
 
                                                 
18
 See White Space Coalition Communications. 
 
 
10 
2.2 Prototype B 
 
 The Prototype B WSD device contains only a sensing/scanning component with 
no UHF transmitter capability.  This device consists of a desktop computer (for user-
interface, control and processing), a commercial TV tuner card (for tuning to a specified 
TV channel and translating to an IF frequency), and a digital processing board (for A/D 
conversion and processing).  The Prototype B device was delivered to the FCC laboratory 
on May 18, 2007.  The manufacturer formally requested that this unit not be used in field 
tests since the device cannot tolerate much jostling.
19
 
 
 The Prototype B device provides a sensing capability representative of that which 
might be incorporated in personal/portable WSDs to implement a detect and avoid 
strategy to circumvent co-channel interference interactions.  The manufacturer claims 
that the device can scan UHF channels (21-51) and detect DTV, analog TV, or wireless 
microphone signals down to -114 dBm signal strength within a 6-MHz channel. 
 
User manuals for this device, with a system description and equipment 
specifications, were entered into the proceeding record in an ex-parte filing submitted on 
behalf of the White Spaces Coalition.
20
  Figure 2-2 shows a photograph of the Prototype 
B WSD. 
 
 
 
Figure 2-2.  Prototype B WSD 
                                                 
19
 Ex parte letter to Steven K. Jones, FCC/OET Laboratory Division, June 6, 2007 (hereinafter Philips 
Letter). 
20
 Notice of Ex Parte Communication, TV White Spaces Proceeding, ET Docket Nos. 04-186, 02-380, 
submitted by Harris, Wiltshire & Grannis LLP on behalf of The White Spaces Coalition submitted on May 
21, 2007. 
 
 
11 
3 DTV Scanning/Spectrum Sensing Capability Tests 
 
The tests described in this section were intended to evaluate the performance of 
the scanner/spectrum sensing component of the prototype WSDs.  In particular, these 
tests were designed to assess the ability of the scanning function to reliably detect 
occupied television channels and to determine the minimum signal level that can be 
successfully detected.  A combination of bench tests and field tests were performed to 
assess the scanner/sensor performance under both laboratory and real world conditions. 
3.1 Test Approach 
  
There are no known procedures that have been established to guide the testing of 
this type of scanning/sensing capability.  A working group within IEEE standards 
committee 802.22 is in the process of developing a measurement standard for similar 
scanning/sensing capabilities being implemented in fixed WSDs, but this effort is still in 
its early stages.
21
   
 
 While the fixed and personal/portable WSD applications are similar in many 
respects, subtle distinctions actually exist between the two, particularly with respect to 
their likely operational scenarios.  One example is the slight inconsistency with respect to 
a proposed minimum threshold for the detection of low-level DTV signals.  The 802.22 
committee is considering a detection threshold of -116 dBm for fixed WSDs, assuming a 
rooftop or tower-mounted sensing antenna.  However, the WSC has proposed a threshold 
of -114 dBm for portable devices using a small (inefficient) antenna and sensing from 
locations at or near ground level.
22
  Both of the prototype devices delivered to the 
laboratory are manufacturer-specified with respect to the WSC-proposed minimum 
detection threshold of -114 dBm.
23
 
 
 Notwithstanding these subtle operational distinctions between fixed and 
personal/portable WSD applications, the existing recommendations from 802.22 were 
considered in the design and performance of the tests described herein. 
 
 The current 802.22 draft measurement standard recommends that to fully 
characterize the detection threshold of an unlicensed device, three separate tests are 
required. The first test is intended to determine the baseline performance of the WSD 
relative to an unimpaired, laboratory-generated DTV signal.  The second test, a co-
channel only test, is recommended to be performed with field-captured DTV input 
signals for testing the sensing algorithm and determining the detection threshold.  The 
third test is to be performed using a combination of field-captured DTV signals with 
additional strong DTV signals on alternate (adjacent) channels. 
                                                 
21
 See http://grouper.ieee.org/groups/802/22/Meeting_documents/2007_Jan/22-06-0202-02-
0000_Sensing_Test_Plan.doc  (last checked July 12, 2007) 
22
 Comments of Dell Inc., Google, Inc., The Hewlett-Packard Company, Intel Corp., Microsoft Corp., and 
Philips Electronics North America Corp., Jan 31, 2007 @ 5-7. 
23
 See White Spaces Coalition Communications 
 
12 
 
 While the tests described herein deviated slightly from those recommended in the 
developing standard, the underlying objectives are similarly met.  For example, the 
baseline tests recommended as the first test in the draft standard were effectively applied 
herein to determine a baseline minimum detection threshold using a single laboratory-
generated DTV signal.  Similarly, a limited set of tests were performed analogous to the 
third 802.22 test recommendation; however, the potential amplitude and channel spacing 
combinations associated with this test are nearly limitless and the draft standard offers no 
guidance on which are the most relevant.  The scope of this project limited the 
examination herein to two possible channel spacing combinations with one signal 
amplitude combination.   
 
 The greatest deviation between the tests recommended in the draft standard and 
those performed herein is with regard to the second test recommended by the working 
group.  The recommended detection threshold test utilizing a field-recorded DTV signal 
as the input was not performed as a part of this test program.  Instead, an actual field test 
was performed to assess the scanning/spectrum sensing performance using live OTA 
signals rather than field-recorded OTA signals.  This test was intended to be applied to 
both of the prototype devices, but the manufacturer of Prototype B requested that the 
device not be utilized in field tests.
24
  
 
 Through a combination of bench and field testing, the primary issues underlying 
the 802.22 draft test procedures are effectively addressed in the approach adopted for the 
tests described herein. 
3.2 Bench Tests to Determine Minimum DTV Signal Detection Threshold 
 
 Two separate bench tests were performed to determine the minimum DTV signal 
detection threshold for each of the two prototype devices delivered to the laboratory.  The 
first bench test utilized a single, unimpaired, laboratory-grade DTV signal as the test 
input.  The second bench test utilized two unimpaired, laboratory-grade signals as the 
input, one on the detection channel and the other placed on one of two adjacent channels 
and held at constant amplitude. 
3.2.1 Baseline Detection Threshold Tests (Single DTV Input Signal) 
 
 The baseline detection threshold tests were performed consistent with the first of 
three tests recommended in the developing IEEE 802.22 measurement standard.  A clean 
laboratory-grade DTV signal was produced by the ATSC signal generator component of 
a Rhode and Schwarz Broadcast Test System (model SFU) and connected via coaxial 
cable through a bank of calibrated step attenuators and to the scanner antenna input of the 
prototype under test.  Figure 3-1 provides a block diagram representation of the test 
system configuration and Figure 3-2 shows the spectral envelope of the laboratory-grade 
ATSC (DTV) signal used in the test.   
 
                                                 
24
 See Philips Letter 
 
13 
 The input DTV signal was initially set to a low, but measurable, level and then 
further attenuated incrementally with the calibrated step attenuator bank while exercising 
the scanner over the occupied channel.  At each attenuation step (input power level), 
thirty independent trials were performed in order to determine the percentage of 
successful detections with some statistical relevance.  The percentage of successful 
detections observed over the thirty independent trials performed at each attenuator step 
was plotted as a function of the input power level.  
 
 
Figure 3-1.  Baseline Detection Threshold Test Equipment Configuration. 
 
-110
-100
-90
-80
-70
600 602 604 606 608 610
TV Channel 36
Integrated Channel Power = -60 dBm/6-MHz
Frequency (MHz)
S
i
gn
al A
m
p
l
it
ud
e 
(
d
B
m
)
Single DTV Signal Test Input
 
Figure 3-2.  Single-Signal Laboratory-Generated DTV Input. 
 
 These tests were performed on three channels in the lower (channel 21), middle 
(channel 36) and upper (channel 51) portions of the WSD tuning range, in order to 
investigate potential frequency-related differences in performance.  An analysis of the 
test results revealed that the sensing performance of the devices was consistent over the 
Spectrum 
Analyzer 
Prototype 
WSD 
SFU 
RF Attenuator 
Bank 
 
14 
test channels.  Therefore, the remaining tests were performed on a single channel in the 
middle of the tuning range. (i.e., channel 36) for both prototype WSDs.  
 
 The results obtained from the baseline detection threshold tests are presented in 
Figures 3-3 and 3-4, for WSD Prototypes A and B, respectively. 
 
0
20
40
60
80
100
-102 -101 -100 -99 -98 -97 -96 -95
Channel 21
Channel 36
Channel 51
Channel Power Applied to Antenna Input (dBm/6-MHz)
% o
f
 
Su
cces
sfu
l
 D
e
t
ecti
o
n
s
 (3
0 Ind
e
p
e
nd
en
t T
r
ia
ls)
WSD PROTOTYPE A DTV SENSING/SCANNING SENSITIVITY
 
Figure 3-3.  Baseline Detection Threshold Results for Prototype A. 
 
 
0
20
40
60
80
100
-119 -118 -117 -116 -115 -114 -113
Channel 21
Channel 51
Channel 36
Channel Power Applied to Antenna Input (dBm/6-MHz)
%
 o
f
 S
u
cce
ssf
ul D
e
te
ctio
n
s
 (
30 In
d
e
pe
nd
en
t T
r
ials
)
WSD PROTOTYPE B DTV SENSING/SCANNING SENSITIVITY
 
Figure 3-4.  Baseline Detection Threshold Results for Prototype B. 
 
 The following information was also noted from these tests.  The Prototype A 
WSD demonstrated a scan time of approximately 27-seconds per channel for a total scan 
period over the entire channel space (31 channels) of approximately 14 minutes.  The 
Prototype B device scanned a single channel in approximately 8-seconds and was capable 
 
15 
of performing a full scan over the available channel space in a period of approximately 4 
minutes. 
3.2.2 Multiple-Signal Detection Threshold Tests (Two DTV Input Signal). 
 
 This test is intended to examine the scanner/sensor performance in the presence of 
another DTV signal occupying an adjacent channel and is similar to the third test 
recommended in the draft 802.22 measurement standard.  The draft standard recommends 
that a strong incumbent DTV signal be represented on an alternate TV channel but does 
not specify the level that constitutes a strong signal nor what alternate TV channels 
should be utilized. 
 
 A previous FCC test program, performed to assess the interference susceptibility 
of DTV receivers, demonstrated that receiver sensitivity can be degraded by the presence 
of out-of-channel signals.
25
  The tests performed as a part of that program included both 
single-channel undesired signals and specific pairings of undesired signals spaced so as to 
generate third-order intermodulation distortion within the tuner.  It was found that 
receiver sensitivity degradation was dependent on both channel spacing and signal 
amplitude.  
 
 Although receivers used for sensing the presence of DTV signals might also be 
subject to similar performance degradations, such an intricate test as was performed in 
the previous FCC effort was deemed to be outside the scope of this project.  Rather, 
within this project, tests were performed with only one additional DTV signal placed first 
on an immediately adjacent channel (N-1) and then on a second adjacent channel (N+2).   
 
 Based on the channel consistency observed in the results of the baseline detection 
threshold tests, these tests were performed on only one detection channel in the WSD 
tuning range  (i.e. channel 36)  under the presumption that the observed performance will 
be representative of the anticipated performance on the remaining available channels. 
 
 The methodology used in these tests is similar to that used in the baseline 
detection tests but with the addition of a second DTV input signal (produced with a 
second, but identical SFU).  Figure 3-5 provides a block diagram of the test system 
configuration and Figures 3-6 and 3-7 show the spectral envelope of the laboratory-
generated ATSC (DTV) signals used in the test  with the additional DTV channel placed 
first on the N-1 adjacent channel (35) and then with the additional DTV channel on the 
N+2 adjacent channel (38).  Both prototype WSDs were subjected to this test. 
 
                                                 
25
 See DTV Susceptibility Study. 
 
16 
 
Figure 3-5.  Multiple (Two)-Signal Detection Threshold Test Equipment Configuration. 
 
 
-110
-100
-90
-80
-70
594 596 598 600 602 604 606 608 610
TV Channel 36
         (N)
TV Channel 35
        (N-1)
Frequency (MHz)
S
i
gn
al
 Am
pli
t
ud
e (
d
Bm
)
Two DTV Signal Test Input (N-1)
 
Figure 3-6.  Lab-Grade DTV Signals Used in Two-Signal Detection Threshold Tests (N-1). 
   
Spectrum 
Analyzer 
Prototype 
WSD 
SFU 1 
SFU 2 
Signal 
Combiner 
RF Attenuator 
Bank 
 
17 
-110
-100
-90
-80
-70
600 602 604 606 608 610 612 614 616 618 620 622
TV Channel 38
       (N+2)
TV Channel 36
         (N)
Frequency (MHz)
Si
gna
l Am
plitude
 (dBm
)
Two DTV Signal Test Input (N+2)
 
Figure 3-7.  Lab-Grade DTV Signals Used in Two-Signal Detection Threshold Tests (N+2). 
 
 The DTV signal in the detection channel was initially set to a low but measurable 
level and then further attenuated incrementally with the calibrated step attenuator bank 
while exercising the scanner over the occupied channel.  The second DTV signal was 
introduced on an adjacent channel and held at a constant level of -60 dBm (strong 
signal level relative to the amplitude in the detection channel).  At each attenuation step 
(power level in detection channel), thirty independent trials were performed in order to 
determine the percentage of successful detections with some statistical relevance.  The 
percentage of successful detections observed over the thirty independent trials performed 
at each attenuator step was plotted as a function of the input power level.  
 
 The results obtained from the baseline detection threshold tests are presented in 
Figures 3-8 and 3-9, for WSD Prototypes A and B, respectively. 
 
 
18 
0
20
40
60
80
100
-102 -101 -100 -99 -98 -97 -96 -95
Single-Channel Results
2-Channel Results (N-1)
2-Channel Results (N+2)
Channel Power Applied to Antenna Input (dBm/6-MHz)
% of
 Successf
ul Det
ections (
30 Independ
ent Tr
ials)
WSD PROTOTYPE A DTV SENSING/SCANNING SENSITIVITY
 
Figure 3-8.  Two-Channel Detection Threshold Test Results for WSD Prototype A. 
   
0
20
40
60
80
100
-119 -118 -117 -116 -115 -114 -113
Two-Signal Results (N-1)
Two-Signal Results (N+2)
Single-Signal Results
Channel Power Applied to Antenna Input (dBm/6-MHz)
%
 of 
Su
ccessf
ul D
e
te
ctio
ns (
30 Ind
e
pen
d
en
t T
r
ial
s
)
WSD PROTOTYPE B DTV SENSING/SCANNING SENSITIVITY
 
Figure 3-9.  Two-Channel Detection Threshold Test Results for WSD Prototype B. 
 
3.3 Field Tests with Over-the-Air Signals 
 
 This section presents a description of, and the results obtained, from field tests 
performed with the Prototype A personal/portable white space device.  As previously 
explained, the Prototype B WSD was not subjected to these tests at the request of the 
manufacturer.   
 
 These tests were performed as an alternate to the 802.22-recommended bench test 
utilizing field-recorded DTV signals.  The objective of both approaches is to assess the 
scanner/sensor performance under real world conditions, but  the tests described herein 
 
19 
utilized live rather than recorded OTA television signals (both DTV and NTSC) to assess 
the performance of the prototype scanner/sensor component.  
 
 The scanning/sensing performance of the prototype device was tested at a number 
of sites representative of typical residences where over-the-air television broadcasts, 
including DTV broadcasts, are currently being received.  Residential sites were sought 
within the Washington/Baltimore TV markets and candidate test sites were limited to 
residences that were already set up for and receiving OTA DTV broadcasts in order to 
provide a means for verifying those OTA stations that could be successfully received at 
the site with a typical DTV receiving system. 
 
 At each test site, several independent locations were identified for testing (e.g., 
tests were performed within several rooms of each house).  At each of these independent 
locations, the prototype was used to scan over its entire channel space (21-51) and the 
results were recorded.  This process was repeated to produce results from three 
independent trials at each test location.  The results from each scan were manually 
recorded (the prototype did not provide the ability to electronically record the results 
from a scan) in a manner consistent with the way they were reported via the prototypes 
scanning program.  For example, the device interface reports the results sequentially on a 
channel-by-channel basis, identifying each channel as either occupied by a DTV signal 
(D), an NTSC TV signal (N), a wireless microphone (W), or else as an available channel 
(A).  
 
 The received TV signal levels at each measurement location were not made. 
Instead, map-based plots showing the service contour associated with each licensed full 
service and low power TV broadcast station within a 150-km (94 miles) radius of the test 
site coordinates was generated for each test site.  These plots are provided in Appendix B 
for each of the four sites where field tests were performed.   
 
 The information provided in the service contour plots in Appendix B provides a 
means for readily (i.e., visually) identifying the obvious white spaces (unoccupied 
channels) at each test site as well as those channels assigned to TV broadcast stations 
with service contours that include the site.  This information was used to provide an 
indication of those channels most likely to be occupied at each test site.  However, it 
should be recognized that the contour plots do not include possible signal blockage from 
terrain, foliage, or man-made structures that may be present in the actual signal 
propagation path.  Thus, a second technique was used to verify occupied channels at the 
site with the existing DTV receiver system.   
 
 This secondary channel occupancy check utilized the sites existing DTV receiver 
to tune through the WSD scanning range (21-51).  Antenna adjustments were made as 
necessary in an attempt to successfully receive and decode the signal from each licensed 
TV station whose signal reached the site as indicated on the service contour plots.  The 
first table under the reported test results for each site lists the stations whose contour 
encompasses that site.  Each channel that could be verified as occupied by this method 
was recorded and is reported in the last column of those tables. 
 
20 
 
 With this information, the fundamental premise underlying the tests was that for 
those cases where the test site is located within the interior of a television broadcast 
stations service contour and where the stations signal can be successfully received by 
the existing DTV receive system, then that stations channel should be reliably identified 
by the scanning/sensing component as being occupied.   
 
 The following subsections describe the particulars of the tests performed at each 
site, including a complete description of the site and those locations where tests were 
performed.  A description of the existing OTA DTV receive system is also provided.  In 
addition, three tables of information are provided for each of the four test sites.  As 
indicated above, the first of these tables provides a listing of the full service broadcast TV 
stations (both digital and analog) whose service contours encompass the test site.
26
  This 
information was extracted from licensee records contained within the FCCs 
Consolidated Database of Broadcast Stations (CDBS) and is publicly accessible at 
http://www.fcc.gov/mb/cdbs.html.
27
 
 
 The second table presents the raw sensing data obtained from running the 
prototype scanner/sensor at each test location.  The channels are listed in sequential order 
to match the output format of the user interface.  The information in the third table 
represents a summary of the raw data and an attempt to quantify the results in terms of a 
simple detection probability based on whether or not each channel identified as occupied 
was successfully detected. While results obtained from only three independent trials at 
each test location are of marginal statistical significance, this information nonetheless 
represents a useful metric for assessing the sensing capability of the prototype WSD. 
3.3.1 Field Test Site 1 
 
 Test site 1 is located in Hanover, Maryland at GPS coordinates 39 08.xxx' North 
latitude and 076 43.xxx' West longitude.
28
  The site is a single story home with an 
unfinished basement.  It is considered to be within a suburban residential/commercial 
area.  The DTV receiving system at this residence consisted of a long-range rooftop-
mounted VHF/UHF antenna with an in-line amplifier in the coaxial cable feeding two 
DTV receivers, both with third-generation tuner capability.  The antenna radial direction 
is controlled with an electronic rotor. 
 
                                                 
26
  None of the test sites were within the service contour of any low power television stations (Class A TV 
stations, low-power television stations, and television translators).  Thus, no low power stations appear on 
the list of stations in the first table of information for each test sire.  Low power stations are, however, 
licensed and operating in the Baltimore and Washington market areas and their transmitter locations and 
service contours are depicted on the service contour plots in Appendix B (see description of this appendix 
below). 
27
 Note that the CDBS is not a fixed database but rather is modified on a daily basis as changes are made to 
authorized station facilities through on FCC actions.  The plots in Appendix B were prepared using this 
database as it existed in April, 2007. 
28
 Note that we are not reporting the full coordinates of the test site residences to protect the privacy of their 
occupants. 
 
21 
 The tests at this site were performed between 12:00 PM and 7:00 PM EDT on 
Wednesday, May 9, 2007.  The scanning capability of the prototype WSD was tested at 
each of four locations within the site; a central location on the rooftop (L1), the first floor 
living room on the NW end of the house (L2), a first floor bedroom on the SE end of the 
house (L3), and in the basement (L4).  Tables 3-1, 3-2, and 3-3 provide the TV station 
information and scanning/sensing results for this test site. 
 
 
22 
Table 3-1.  Broadcast TV Stations within Prototype Tuning Range (21-51) with Service Contours that Include Test Site 1 
 
RF 
Channel 
Call 
Sign 
TX 
Location 
 
Tower 
Coordinates 
(NAD 83) 
Tower 
Height 
(m above 
MSL) 
Bearing  
(degrees) 
Distance 
(mi/km) 
Channel 
Reception 
Verified 
w/DTV 
22 WMPT-TV Annapolis, MD 39 00' 36.7" N; 076 36' 31.8" W 319.7 147 11.3/18.2 Y 
24 WUTB-TV Baltimore, MD 39 17' 15.0" N; 076 45' 37.0" W 458.7 349 9.9/15.9 Y 
26 WETA-TV Washington D.C. 38 57' 50.1" N; 077 06' 14.9" W 319.8 238 24.0/38.6 Y 
27 WETA-DT Washington D.C. 38 53' 30.0" N; 077 07' 54.0" W 263.8 231 28.1/45.2 Y 
28 WFPT-DT Frederick, MD 39 15' 38.0" N; 077 18' 43.6" W 308.7 284 32.4/52.2 N 
29 WMPB-DT Baltimore, MD 39 26' 49.9" N; 076 46' 47.2" W 472.1 352 20.9/33.6 Y 
32 WHUT-TV Washington D.C. 38 57' 49.4" N; 077 06' 16.9" W 290.0 238 24.0/38.6 Y 
33 WHUT-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 235 23.4/37.7 N 
34 WUSA-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 235 23.4/37.7 Y 
35 WDCA-DT Washington D.C. 38 57' 22.0" N; 077 04' 58.0" W 319.6 236 23.3/37.5 Y 
36 WTTG-DT Washington D.C. 38 57' 22.0" N; 077 04' 58.0" W 319.6 236 23.3/37.5 Y 
38 WJZ-DT Baltimore, MD 39 20' 05.0" N; 076 39' 02.0" W 401.0 17 13.5/21.8 Y 
39 WJLA-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 235 23.4/37.7 Y 
40 WNUV-DT Baltimore, MD 39 20' 10.0" N; 076 38' 58.0" W 472.1 352 13.1/21.2 Y 
41 WUTB-DT Baltimore, MD 39 17' 15.0" N; 076 45' 37.0" W 458.7 349 9.9/15.9 Y 
42 WMPT-DT Annapolis, MD 39 00' 36.7" N; 076 36' 31.8" W 319.7 147 11.3/18.2 Y 
43 WPXW-DT Manassas, VA 38 47' 16.2" N; 077 19' 46.3" W 285.8 233 40.9/65.8 N 
45 WBFF-TV Baltimore, MD 39 20' 10.0" N; 076 38' 58.0" W 472.1 17 13.7/22.0 Y 
46 WBFF-DT Baltimore, MD 39 20' 10.0" N; 076 38' 58.0" W 472.1 17 13.7/22.0 Y 
47 WPMT-DT York, PA 40 01' 41.4" N; 076 35' 58.9" W 562.9 6 61.1/98.4 N 
48 WRC-DT Washington D.C. 38 56' 24.0" N; 077 04' 53.0" W 319.7 233 24.0/38.5 Y 
50 WDCW-TV Washington D.C. 38 57' 44.0" N; 077 01' 35.0" W 319.7 232 20.6/33.2 Y 
51 WDCW-DT Washington D.C. 38 57' 44.0" N; 077 01' 35.0" W 319.7 232 20.6/33.2 Y 
 
 
23 
Table 3-2.  Test Site 1 Field Survey Data 
 
Test Site:  1 
Location:  39 08.xxx' N; 076 43.xxx' W 
Description:  Single Story Home with Unfinished Basement 
DTV Installation:  High-grade, long-range UHF/VHF rooftop-mounted antenna and electronic 
rotor with in-line amplifier feeding dual 3
rd
 generation DTV receivers 
Location: 
Rooftop 
(L1) 
Location: 
1
st
 flr LR 
(L2) 
Location: 
1
st
 flr BR 
(L3) 
Location: 
Basement 
(L4) 
Trial # Trial # Trial # Trial # 
RF 
Channel 
TV 
Channel 
Viewable 
On DTV 
Installation? 
1 2 3 1 2 3 1 2 3 1 2 3 
21 - No A A A A A A A A A A A A 
22 22 Yes N N N N N N N N N N N N 
23 - No A A A A A A A A A A A A 
24 24 Yes N N N N N N N N N N N N 
25 - No A A A A A A A A A A A A 
26 26 Yes N N N N N N N N N N N N 
27 26.1 Yes A A A A A A A A A A A A 
28 62.1 No A A N A A A A A A A A A 
29 67.1 Yes A D A D D D D A A D D D 
30 - No A A A A A A A A A A A A 
31 - No A A A A A A A A A A A A 
32 32 Yes N N N N N N N W N A A A 
33
2 
33 No A A A A A A A A A A A A 
34 9.1 Yes A D D A A A D A A A A A 
35 20.1 Yes A A A D A A D A A A A A 
36 5.1 Yes A A A D A A D A A A A A 
38 13.1 Yes D D D D D D D A A D D D 
39 7.1 Yes D A D D A A D A A D D A 
40 54.1 Yes A D D D A D D A A D D D 
41 24.1 Yes D A D D A A D A A D A A 
42 22.1 Yes D D D D A A D A A D A A 
43 - No A A N N A A N A A N A A 
44 - No A A D D A A D A A D A A 
45 45 Yes N N N W N N N N N N N N 
46 45.1 Yes A A D D A A D A D D D A 
47 - No A A D D A A D A A D A A 
48 4.1 Yes A A D D A A D A A D A A 
49 - No A A N N A A N A A A A A 
50 50 Yes N N N N N N N A A A A A 
51 50.1 Yes A A D D A A D A A A A A 
NOTES: 
1.  A = available, D = occupied by DTV, N = occupied by NTSC, W = occupied by wireless 
microphone 
2.  Channel 33 not on the air during these tests 
 
 
24 
 
Table 3-3.  Summary of Field Data Collected at Test Site 1 
 
Successful Detections Probability of Successful Detection 
Channel Call Sign 
L1 L2 L3 L4 L1 L2 L3 L4 
ATSC (DIGITAL TV)-OCCUPIED CHANNELS 
27 WETA-DT 0/3 0/3 0/3 0/3 0 0 0 0 
28
 
WFPT-DT 1/3 0/3 0/3 0/3 0.33 0 0 0 
29 WMPB-DT 1/3 3/3 1/3 3/3 0.33 1.00 0.33 1.00 
33
 
WHUT-DT - - - - - - - - 
34 WUSA-DT 2/3 0/3 1/3 0/3 0.67 0 0.33 0 
35 WDCA-DT 0/3 1/3 1/3 0/3 0 0.33 0.33 0 
36 WTTG-DT 0/3 1/3 1/3 0/3 0 0.33 0.33 0 
38 WJZ-DT 3/3 3/3 1/3 3/3 1.00 1.00 0.33 1.00 
39 WJLA-DT 2/3 1/3 1/3 2/3 0.67 0.33 0.33 0.67 
40 WNUV-DT 2/3 2/3 1/3 3/3 0.67 0.67 0.33 1.0 
41 WUTB-DT 2/3 1/3 1/3 1/3 0.67 0.33 0.33 0.33 
42 WMPT-DT 3/3 1/3 1/3 1/3 1.0 0.33 0.33 0.33 
43
 
WPXW-DT 1/3 1/3 1/3 1/3 0.33 0.33 0.33 0.33 
46 WBFF-DT 1/3 1/3 2/3 2/3 0.33 0.33 0.67 0.67 
47
 
WPMT-DT 1/3 1/3 1/3 1/3 0.33 0.33 0.33 0.33 
48 WRC-DT 1/3 1/3 1/3 1/3 0.33 0.33 0.33 0.33 
51 WDCW-DT 1/3 1/3 1/3 0/3 0.33 0.33 0.33 0 
NTSC (ANALOG TV)-OCCUPIED CHANNELS 
22 WMPT-TV 3/3 3/3 3/3 3/3 1.00 1.00 1.00 1.00 
24 WUTB-TV 3/3 3/3 3/3 3/3 1.00 1.00 1.00 1.00 
26 WETA-TV 3/3 3/3 3/3 3/3 1.00 1.00 1.00 1.00 
32 WHUT-TV 3/3 3/3 3/3 0/3 1.00 1.00 1.00 0 
45 WBFF-TV 3/3 3/3 3/3 3/3 1.00 1.00 1.00 1.00 
50 WDCW-TV 3/3 3/3 1/3 0/3 1.00 1.00 0.33 0 
AVAILABLE CHANNELS 
21 - 3/3 3/3 3/3 3/3 1.00 1.00 1.00 1.00 
23 - 3/3 3/3 3/3 3/3 1.00 1.00 1.00 1.00 
25 - 3/3 3/3 3/3 3/3 1.00 1.00 1.00 1.00 
30 - 3/3 3/3 3/3 3/3 1.00 1.00 1.00 1.00 
31 - 3/3 3/3 3/3 3/3 1.00 1.00 1.00 1.00 
44 - 2/3 2/3 2/3 2/3 0.67 0.67 0.67 0.67 
49 - 2/3 2/3 2/3 3/3 0.67 0.67 0.67 1.00 
NOTES: 
1.  Channel 33 not on the air during these tests 
 
 
 
25 
3.3.2 Field Test Site 2 
 
 The test site is located in Columbia, Maryland at GPS coordinates 39 10.xxx' 
North latitude and 076 49.xxx' West longitude.  The site is a two-story farmhouse with 
an unfinished basement located on several acres of cleared property.  The site is 
considered to be within a suburban residential area.  The DTV receiving system at this 
residence consisted of an attic-mounted smart antenna with an in-line amplifier feeding 
a DTV converter box connected to an analog TV receiver.  The converter box did not 
include an NTSC tuner thus it was not possible to not verify whether analog TV signals 
could be viewed on the DTV receiving system at this location. 
 
 The tests at site 2 were performed on Tuesday, May 15, 2007 between the hours 
of 11:30 AM and 5:30 PM EDT.  The scanning capability of the prototype WSD was 
tested at each of five locations within this residence; a central location in the attic (L1), a 
second floor hallway on the N end of the house (L2), a second floor room on the S end of 
the house (L3), the first floor foyer (L4), and the basement (L5).  Tables 3-4, 3-5, and 3-6 
provide the TV station information and scanning/sensing results for test site 2. 
 
26 
Table 3-4.  Broadcast TV Stations within Prototype Tuning Range (21-51) with Service Contours that Include Test Site 2 
 
RF 
Channel 
Call 
Sign 
TX 
Location 
 
Tower 
Coordinates 
(NAD 83) 
Tower 
Height 
(m above 
MSL) 
Bearing  
(degrees) 
Distance 
(mi/km) 
Channel 
Reception 
Verified 
w/DTV 
22 WMPT-TV Annapolis, MD 39 00' 36.7" N; 076 36' 31.8" W 319.7 133 15.9/25.5 N 
24 WUTB-TV Baltimore, MD 39 17' 15.0" N; 076 45' 37.0" W 458.7 22 8.9/14.3 N 
26 WETA-TV Washington D.C. 38 57' 50.1" N; 077 06' 14.9" W 319.8 227 20.7/33.2 N 
27 WETA-DT Washington D.C. 38 53' 30.0" N; 077 07' 54.0" W 263.8 221 25.3/40.7 Y 
28 WFPT-DT Frederick, MD 39 15' 38.0" N; 077 18' 43.6" W 308.7 284 27.0/43.5 Y 
29 WMPB-DT Baltimore, MD 39 26' 49.9" N; 076 46' 47.2" W 472.1 7 19.4/31.2 Y 
32 WHUT-TV Washington D.C. 38 57' 49.4" N; 077 06' 16.9" W 290.0 227 20.7/33.3 N 
33 WHUT-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 223 20.4/32.8 N 
34 WUSA-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 223 20.4/32.8 Y 
35 WDCA-DT Washington D.C. 38 57' 22.0" N; 077 04' 58.0" W 319.6 224 20.2/32.5 Y 
36 WTTG-DT Washington D.C. 38 57' 22.0" N; 077 04' 58.0" W 319.6 224 20.2/32.5 Y 
38 WJZ-DT Baltimore, MD 39 20' 05.0" N; 076 39' 02.0" W 401.0 39 14.8/23.8 Y 
39 WJLA-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 223 20.4/32.8 Y 
40 WNUV-DT Baltimore, MD 39 20' 10.0" N; 076 38' 58.0" W 472.1 39 14.9/23.8 Y 
41 WUTB-DT Baltimore, MD 39 17' 15.0" N; 076 45' 37.0" W 458.7 22 8.9/14.3 Y 
42 WMPT-DT Annapolis, MD 39 00' 36.7" N; 076 36' 31.8" W 319.7 133 15.9/25.5 Y 
43 WPXW-DT Manassas, VA 38 47' 16.2" N; 077 19' 46.3" W 285.8 226 37.8/60.9 N 
45 WBFF-TV Baltimore, MD 39 20' 10.0" N; 076 38' 58.0" W 472.1 39 14.9/23.9 N 
46 WBFF-DT Baltimore, MD 39 20' 10.0" N; 076 38' 58.0" W 472.1 39 14.9/23.9 Y 
47 WPMT-DT York, PA 40 01' 41.4" N; 076 35' 58.9" W 562.9 11 60.5/97.4 N 
48 WRC-DT Washington D.C. 38 56' 24.0" N; 077 04' 53.0" W 319.7 221 21.0/33.8 Y 
50 WDCW-TV Washington D.C. 38 57' 44.0" N; 077 01' 35.0" W 319.7 218 17.9/28.8 N 
51 WDCW-DT Washington D.C. 38 57' 44.0" N; 077 01' 35.0" W 319.7 218 17.9/28.8 Y 
 
 
27 
Table 3-5.  Test Site 2 Field Survey Data 
 
Test Site: 2  
Location:  GPS (WGS-84) coordinates:  39 10.xxx' N; 076 49.xxx' W 
Description:  Two-story farmhouse with basement 
DTV Installation:  Smart antenna located in attic feeding an ATSC converter box with no NTSC tuner. 
Location 
Attic  
(L1) 
 
Location 
2
nd
 floor, 
north end 
(L2) 
Location 
2
nd
 floor, 
south end 
(L3) 
Location 
1
st
 floor 
foyer  
(L4) 
Location 
Basement 
(L5) 
 
Trial # Trial # Trial # Trial # Trial # 
RF 
Channel 
TV 
Channel 
Viewable 
On DTV 
Installation? 
1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 
21 - No N N N A A A A A A A D D A A A 
22 22 No
2 
N N N N W N N N N W N N W N N 
23 - No A A A A A A N N N N A A N A A 
24 24 No
2
 N N N W N N W W W N N N N N N 
25 - No N A A A A A A N A A A A A A A 
26 26 No
2
 N N N W N N W W N N N N N N N 
27 26.1 Yes D A A A A A D D A A A A A A A 
28 62.1 Yes A A A A A A D D A A A A A A A 
29 67.1 Yes W A A A A A D D A D A A A A A 
30 - No A A A A A A A A A A A A A A A 
31 - No A A A A A A A A A A A A A A A 
32 32 No
2
 W N N N N N N N N N W N N N N 
33
2 
33 No A A A A A A A A A A A A A A A 
34 9.1 Yes D D D D D D D D D D D D D D D 
35 20.1 Yes D A A D D A D D D D D D D A A 
36 5.1 Yes D D D A D D D D D D D D D A A 
38 13.1 Yes D D D D D A D D D D D A D A A 
39 7.1 Yes D D D D A A D D D D D D D D D 
40 54.1 Yes D A D D D D N N N D D D N N N 
41 24.1 Yes D A A A A A D D D D A A A A A 
42 22.1 Yes D A D D D A D D D D D A D D D 
43 - No D A A A D A D D A D D A A A A 
44 - No D A A A A A D W A D D A A A A 
45 45 No
2
 N N W N N N N N N N N W N N N 
46 45.1 Yes D A A A D D D D A D D A D A A 
47 47 No D A A A N A N N N D A A A A A 
48 4.1 Yes D A D D D D D D A D D D D A A 
49 - No D A A A D A D D A D A A D A A 
50 50 No
2
 N N N N N N N N N W N N N N N 
51 50.1 Yes D A A A D A D D A D A A D A A 
Notes: 
1.  Scanner/Sensor data point indicators: A=available; D=occupied by DTV; N=occupied by NTSC; W=occupied 
by wireless microphone 
2.  OTA NTSC (analog) TV reception could not be verified on the television installation in place due to lack of an 
NTSC tuner (reliant on digital reception only) 
3.  Channel 33 not on the air during these tests 
 
 
28 
Table 3-6.  Summary of Field Data Collected at Test Site 2 
 
Successful Detections Probability of Successful Detection 
Channel Call Sign 
L1 L2 L3 L4 L5 L1 L2 L3 L4 L5 
ATSC (DIGITAL TV)-OCCUPIED CHANNELS 
27 WETA-DT 1/3 0/3 2/3 0/3 0/3 .33 0 .67 0 0 
28 WFPT-DT 0/3 0/3 2/3 0/3 0/3 0 0 .67 0 0 
29 WMPB-DT 1/3 0/3 2/3 1/3 0/3 .33 0 .67 .33 0 
33
 
WHUT-DT - - - - - - - - - - 
34 WUSA-DT 3/3 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 1.0 
35 WDCA-DT 1/3 2/3 3/3 3/3 1/3 .33 .67 1.0 1.0 .33 
36 WTTG-DT 3/3 2/3 3/3 3/3 1/3 1.0 .67 1.0 1.0 .33 
38 WJZ-DT 3/3 2/3 3/3 2/3 1/3 1.0 .67 1.0 .67 .33 
39 WJLA-DT 3/3 1/3 3/3 3/3 3/3 1.0 .33 1.0 1.0 1.0 
40 WNUV-DT 2/3 3/3 3/3 3/3 3/3 .67 1.0 1.0 1.0 1.0 
41 WUTB-DT 1/3 0/3 3/3 1/3 0/3 .33 0 1.0 .33 0 
42 WMPT-DT 2/3 2/3 3/3 2/3 3/3 .67 .67 1.0 .67 1.0 
43 WPXW-DT 1/3 1/3 2/3 2/3 0/3 .33 .33 .67 .67 .33 
46 WBFF-DT 1/3 2/3 2/3 2/3 1/3 .33 .67 .67 .67 .33 
47 WPMT-DT 1/3 1/3 3/3 1/3 0/3 .33 .33 1.0 .33 0 
48 WRC-DT 2/3 3/3 2/3 3/3 1/3 .67 1.0 .67 1.0 .33 
51 WDCW-DT 1/3 1/3 2/3 1/3 2/3 .33 .33 .67 .33 .67 
NTSC (ANALOG TV)-OCCUPIED CHANNELS
1
 
22 WMPT-TV 3/3 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 1.0 
24 WUTB-TV 3/3 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 1.0 
26 WETA-TV 3/3 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 1.0 
32 WHUT-TV 3/3 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 1.0 
45 WBFF-TV 3/3 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 1.0 
50 WDCW-TV 3/3 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 1.0 
AVAILABLE CHANNELS 
21 - 0/3 3/3 3/3 1/3 3/3 0 1.0 1.0 .33 1.0 
23 - 3/3 3/3 0/3 2/3 2/3 1.0 1.0 0 .67 .67 
25 - 2/3 3/3 2/3 3/3 3/3 .67 1.0 .67 1.0 1.0 
30 - 3/3 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 1.0 
31 - 3/3 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 1.0 
44 - 2/3 3/3 1/3 1/3 2/3 .67 1.0 .33 .33 .67 
49 - 2/3 2/3 1/3 2/3 2/3 .67 .67 .33 .67 .67 
NOTES: 
1.  Channel 33 not on the air during these tests  
 
 
 
 
29 
3.3.3 Field Test Site 3 
 
 Test site 3 is located in Mount Airy, Maryland at GPS coordinates 39 20.xxx' 
North latitude and 077 05.xxx' West longitude.  The site is a two-story colonial home 
with an unfinished basement surrounded by several acres of mostly wooded property.  It 
is considered to be in a rural/suburban area. 
 
 The DTV receiving system consists of a roof-mounted two-element antenna array 
made from two individual long-range UHF/VHF log-periodic antennas; one points in the 
direction of the Baltimore market and the other points in the direction of the Washington 
D.C. market.  An in-line amplifier is included in the coaxial connection between the 
antenna array and an ATSC converter box, which feeds a DTV receiver.  
 
 These tests were performed on Thursday, May 17, 2007 between the hours of 
10:00 AM and 4:00 PM EDT.  The scanning capability of the prototype WSD was tested 
at each of four locations; a central location in the attic (L1), the second floor 
foyer/hallway central to the house (L2), a dining room centrally located on the first floor 
with a sliding glass door representing one exterior wall (L3), and the basement (L4).  
Tables 3-7, 3-8, and 3-9 present the TV station information and scanning/sensing results 
for test site 3.
 
30 
Table 3-7.  Broadcast TV Stations within Prototype Tuning Range (21-51) with Service Contours that Include Test Site 3 
 
RF 
Channel 
Call 
Sign 
TX 
Location 
 
Tower 
Coordinates 
(NAD 83) 
Tower 
Height 
(m above 
MSL) 
Bearing  
(degrees) 
Distance 
(mi/km) 
Channel 
Reception 
Verified 
w/DTV 
22 WMPT-TV Annapolis, MD 39 00' 36.7" N; 076 36' 31.8" W 319.7 132 35.2/56.7 Y 
24 WUTB-TV Baltimore, MD 39 17' 15.0" N; 076 45' 37.0" W 458.7 103 18.7/30.0 Y 
26 WETA-TV Washington D.C. 38 57' 50.1" N; 077 06' 14.9" W 319.8 181 26.6/42.8 Y 
27 WETA-DT Washington D.C. 38 53' 30.0" N; 077 07' 54.0" W 263.8 183 31.6/50.9 Y 
28 WFPT-DT Frederick, MD 39 15' 38.0" N; 077 18' 43.6" W 308.7 242 13.0/20.8 Y 
29 WMPB-DT Baltimore, MD 39 26' 49.9" N; 076 46' 47.2" W 472.1 68 18.4/29.6 Y 
30 WGCB-DT Red Lion, PA 39 54' 18.3" N; 076 34' 57.2" W 413.9 35 47.2/76.0 N 
31 WWPB-TV Hagerstown, MD 39 39' 04.0" N; 077 58' 14.0" W 565.4 294 51.0/82.1 N 
32 WHUT-TV Washington D.C. 38 57' 49.4" N; 077 06' 16.9" W 290.0 181 26.6/42.8 Y 
33 WHUT-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 178 27.6/44.4 N
 
34 WUSA-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 178 27.6/44.4 Y 
35 WDCA-DT Washington D.C. 38 57' 22.0" N; 077 04' 58.0" W 319.6 178 27.2/43.7 N 
36 WTTG-DT Washington D.C. 38 57' 22.0" N; 077 04' 58.0" W 319.6 178 27.2/43.7 Y 
38 WJZ-DT Baltimore, MD 39 20' 05.0" N; 076 39' 02.0" W 401.0 92 24.1/38.7 Y 
39 WJLA-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 178 27.6/44.4 Y 
40 WNUV-DT Baltimore, MD 39 20' 10.0" N; 076 38' 58.0" W 472.1 92 24.1/38.7 Y 
41 WUTB-DT Baltimore, MD 39 17' 15.0" N; 076 45' 37.0" W 458.7 103 18.7/30.0 Y 
42 WMPT-DT Annapolis, MD 39 00' 36.7" N; 076 36' 31.8" W 319.7 132 35.2/56.7 Y 
43 WPXW-DT Manassas, VA 38 47' 16.2" N; 077 19' 46.3" W 285.8 198 40.7/65.5 N 
44 WWPB-DT Hagerstown, MD 39 39' 04.0" N; 077 58' 14.0" W 565.4 294 51.0/82.1 N 
45 WBFF-TV Baltimore, MD 39 20' 10.0" N; 076 38' 58.0" W 472.1 92 24.1/38.8 Y 
46 WBFF-DT Baltimore, MD 39 20' 10.0" N; 076 38' 58.0" W 472.1 92 24.1/38.8 Y 
47 WPMT-DT York, PA 40 01' 41.4" N; 076 35' 58.9" W 562.9 29 53.9/86.7 N 
48 WRC-DT Washington D.C. 38 56' 24.0" N; 077 04' 53.0" W 319.7 178 28.3/45.5 Y 
50 WDCW-TV Washington D.C. 38 57' 44.0" N; 077 01' 35.0" W 319.7 172 27.0/43.5 N 
51 WDCW-DT Washington D.C. 38 57' 44.0" N; 077 01' 35.0" W 319.7 172 27.0/43.5 Y 
 
 
31 
Table 3-8.  Test Site 3 Field Survey Data 
 
Test Site: 3  
Location:  GPS (WGS-84) coordinates:  39 20.xxx' N; 077 05.xxx' W 
Description:  Two-story Colonial with basement 
DTV Installation:  Roof-mounted antenna array (2-elements consist of VHF/UHF log-
periodic antennas, one pointing in direction of Baltimore market and the other pointed in 
direction of Washington market) feeding a DTV with external ATSC converter box . 
Location: 
Attic (L1) 
Location: 
2
nd
 Flr Foyer 
(L2) 
Location: 
1
st
 Flr 
Dinette (L3) 
Location: 
Basement 
(L4) 
Trial # Trial # Trial # Trial # 
RF 
Channel 
TV 
Channel 
Viewable 
On DTV 
Installation? 
1 2 3 1 2 3 1 2 3 1 2 3 
21 - No A A A A A A A A A A A A 
22 22 Yes W N N N N N N N N N N N 
23 - No N A A N W A N A A A A A 
24 24 Yes N N N N N W N N N N N N 
25 - No A A A A A A A A A A A A 
26 26 Yes N N N N N N N N N N N N 
27 26.1 Yes A A A A A A A A A A A A 
28 62.1 Yes
3 
A A A A A A A A A A A A 
29 67.1 Yes D D D A A A D A A A A A 
30 - No A A A A A A A A A A A A 
31 - No A A A A A A A A A A A A 
32 32 Yes A A A A A A A A A A A A 
33
2 
33 No A A A A A A A A A A A A 
34 9.1 Yes D D D A A A D A A D A A 
35 20.1 No D D D A A A A A A A A A 
36 5.1 Yes D A D A A A A A A A A A 
38 13.1 Yes D A A D A A D A A D A A 
39 7.1 Yes D A A D A A D A A A A A 
40 54.1 Yes N N N D A A N N N N N N 
41 24.1 No D A A A A A D A A A A A 
42 22.1 Yes D A A D A A D A A A A A 
43 - No D A A A A A D A A A A A 
44 - No D N A A A A D A A A A A 
45 45 Yes W N N N N N N N N N N N 
46 45.1 Yes D A A D A A D A A A A A 
47 - No D A A A A A A A A A A A 
48 4.1 Yes D A A A A A D A A W A A 
49 - No D A A A A A A A A A A A 
50 50 No D N N N N A N N A A A A 
51 50.1 Yes
3 
D A A A A A A A A A A A 
Notes: 
1.  Scanner/Sensor data point indicators: A=available; D=occupied by DTV; N=occupied by 
NTSC; W=occupied by wireless microphone 
2.  Channel 33 not on the air during these tests 
3.  Intermittent reception observed on available DTV installation 
 
 
32 
Table 3-9.  Summary of Field Data Collected at Test Site 3 
 
Successful Detections Probability of Successful Detection 
Channel Call Sign 
L1 L2 L3 L4 L1 L2 L3 L4 
ATSC (DIGITAL TV)-OCCUPIED CHANNELS 
27 WETA-DT 0/3 0/3 0/3 0/3 0 0 0 0 
28 WFPT-DT 0/3 0/3 0/3 0/3 0 0 0 0 
29 WMPB-DT 3/3 0/3 1/3 0/3 1.0 0 .33 0 
30 WGCB-DT 0/3 0/3 0/3 0/3 0 0 0 0 
31 WWPB-TV 0/3 0/3 0/3 0/3 0 0 0 0 
33
1 
WHUT-DT 0/3 0/3 0/3 0/3 0 0 0 0 
34 WUSA-DT 3/3 0/3 1/3 1/3 1.0 0 .33 .33 
35 WDCA-DT 3/3 0/3 0/3 0/3 1.0 0 0 0 
36 WTTG-DT 2/3 0/3 0/3 0/3 .67 0 0 0 
38 WJZ-DT 1/3 1/3 1/3 1/3 .33 .33 .33 .33 
39 WJLA-DT 1/3 1/3 1/3 0/3 .33 .33 .33 0 
40
 
WNUV-DT 3/3 1/3 3/3 3/3 1.0 .33 1.0 1.0 
41 WUTB-DT 1/3 0/3 1/3 0/3 .33 0 .33 0 
42 WMPT-DT 1/3 1/3 1/3 0/3 .33 .33 .33 0 
43 WPXW-DT 1/3 0/3 1/3 0/3 .33 0 .33 0 
44 WWPB-DT 2/3 0/3 1/3 0/3 .67 0 .33 0 
46 WBFF-DT 1/3 1/3 1/3 0/3 .33 .33 .33 0 
47 WPMT-DT 1/3 0/3 0/3 0/3 .33 0 0 0 
48 WRC-DT 1/3 0/3 1/3 1/3 .33 0 .33 .33 
51 WDCW-DT 1/3 0/3 0/3 0/3 .33 0 0 0 
NTSC (ANALOG TV)-OCCUPIED CHANNELS 
22 WMPT-TV 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 
24 WUTB-TV 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 
26 WETA-TV 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 
32 WHUT-TV 0/3 0/3 0/3 0/3 0 0 0 0 
45 WBFF-TV 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 
50 WDCW-TV 3/3 2/3 2/3 0/3 1.0 .67 .33 0 
AVAILABLE CHANNELS 
21 - 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 
23 - 2/3 1/3 2/3 3/3 .67 .33 .67 1.0 
25 - 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 
49 - 2/3 3/3 3/3 3/3 .67 1.0 1.0 1.0 
NOTES: 
1.  Channel 33 not on the air during these tests 
 
 
33 
3.3.4 Field Test Site 4 
 
 Test site 4 is located in King George, Virginia at GPS coordinates 38 17.xxx' 
North latitude and 077 17.xxx' West longitude.  The site is a single-story ranch-style 
home with an unfinished basement.  The home is located on the top of a relatively high 
ridge (~220 ft MSL) and is surrounded by several acres of wooded property.  The site is 
considered to be in a rural population area. 
 
 The DTV receiving system at this residence consists of a set-top (indoor) antenna 
feeding a DTV receiver.  These tests were performed on Thursday, June 14, 2007 
between the hours of 10:00 AM and 4:00 PM EDT.  The scanning capability of the 
prototype WSD was tested at each of four locations; the living room where the DTV and 
antenna are located (L1), an exterior deck off the back of the house (L2), a bedroom at 
the opposite end of the house (L3) and the basement (L4).  Tables 3-10, 3-11, and 3-12 
present the TV station information and scanning/sensing results for test site 4.  
 
34 
Table 3-10.  Broadcast TV Stations within Prototype Tuning Range (21-51) with Service Contours that Include Test Site 4 
 
RF 
Channel 
Call 
Sign 
TX 
Location 
 
Tower 
Coordinates 
(NAD 83) 
Tower 
Height 
(m above 
MSL) 
Bearing  
(degrees) 
Distance 
(mi/km) 
Channel 
Reception 
Verified 
w/DTV 
22 WRIC-DT Petersburg, VA 37 30' 45.5" N; 077 36' 03.9" W 421.9 198 56.9/91.6 N 
25 WTVR-DT Richmond, VA 37 30' 45.5" N; 077 36' 03.9" W 421.9 198 56.9/91.6 N 
26  WRLH-DT Richmond, VA 37 30' 45.5" N; 077 36' 03.9" W 421.9 198 56.9/91.6 Y 
27 WETA-DT Washington D.C. 38 53' 30.0" N; 077 07' 54.0" W 263.8 12 41.7/67.1 Y 
30 WNVT-DT Goldvein, VA 38 37' 43.1" N; 077 26' 19.7" W 319.8 340 24.1/38.9 Y 
32 WHUT-TV Washington D.C. 38 57' 49.4" N; 077 06' 16.9" W 290.0 12 46.9/75.4 Y 
33 WHUT-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 14 46.3/74.5 N 
34 WUSA-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 14 46.3/74.5 Y 
35 WDCA-DT Washington D.C. 38 57' 22.0" N; 077 04' 58.0" W 319.6 14 46.6/75.0 N 
36 WTTG-DT Washington D.C. 38 57' 22.0" N; 077 04' 58.0" W 319.6 14 46.6/75.0 Y 
39 WJLA-DT Washington D.C. 38 57' 01.0" N; 077 04' 46.0" W 335.8 14 46.3/74.5 Y 
43 WPXW-DT Manassas, VA 38 47' 16.2" N; 077 19' 46.3" W 285.8 356 33.8/54.3 Y 
47 WUPV-DT Ashland, VA 37 44' 32.0" N; 077 15' 14.0" W 302.1 177 38.5/61.9 N 
48 WRC-DT Washington D.C. 38 56' 24.0" N; 077 04' 53.0" W 319.7 14 45.6/73.3 Y 
50 WDCW-TV Washington D.C. 38 57' 44.0" N; 077 01' 35.0" W 319.7 17 47.8/77.0 Y 
51 WDCW-DT Washington D.C. 38 57' 44.0" N; 077 01' 35.0" W 319.7 17 47.8/77.0 N 
 
 
 
35 
Table 3-11.  Test Site 4 Field Survey Data 
 
Test Site: 4  
Location:  GPS (WGS-84) coordinates:  39 17.xxx' N; 077 17.xxx' W 
Description:  Single-story Rancher with basement located on ridge-top. 
DTV Installation:  Set-top (rabbit ears) antenna connected to DTV receiver. 
Location: 
LR  
(L1) 
Location: 
Rear Deck 
(L2) 
Location: 
BR 
 (L3) 
Location: 
Basement 
(L4) 
Trial # Trial # Trial # Trial # 
RF 
Channel 
TV 
Channel 
Viewable 
On DTV 
Installation? 
1 2 3 1 2 3 1 2 3 1 2 3 
21 - No A A A A A A A A A A A A 
22  No N A A A A A A A A A A A 
23 - No N A A A A A N A A N N N 
24  No A A A A A A A A A A W A 
25 - No A A A A A A A A A A A A 
26
2 
26 Yes N N N N N A N N N N N N 
27 26.1 Yes A A A A A A D A A A A A 
28 - No A A A A A A A A A A A A 
29 - No N W A A A A W A A A A A 
30 - Yes D D A D A A D D D D D A 
31 - No A A A A A A A A A A A A 
32  Yes N N N N N A N N N N N N 
33
 
 No A A A A A A A A A A A A 
34 9.1 Yes D A A A A A D A A A A A 
35  No D A A A A A D A A D A A 
36 5.1 Yes D A A A A A D A A D A A 
38  No D A A A A A A A A A A A 
39 7.1 Yes D A A A A A D A A D A A 
40  No N N N A A A N N N N N N 
41  No D A A A A A A A A A A A 
42  No D A A A A A A A A A A A 
43 - Yes D A A A A A D A A A A A 
44 - No D A A A A A A A A A A A 
45  No D A A A A A A A A A A A 
46  No D A A A A A A A A A A A 
47 - No D A A A A A A A A A A A 
48 4.1 Yes D A A A A A D A A A A A 
49 - No D A A A A A A A A A A A 
50 50 Yes N A A N A A N A A N A A 
51  No D A A A A A A A A A A A 
Notes: 
1.  Scanner/Sensor data point indicators: A=available; D=occupied by DTV; N=occupied by 
NTSC; W=occupied by wireless microphone  
2.  Site is located between the service contours of WETA-TV and WRLH-DT 
3.  Channel 33 not on the air during these tests 
 
 
36 
Table 3-12.  Summary of Field Data Collected at Test Site 4 
 
Successful Detections Probability of Successful Detection 
Channel Call Sign 
L1 L2 L3 L4 L1 L2 L3 L4 
ATSC (DIGITAL TV)-OCCUPIED CHANNELS 
22 WRIC-DT 1/3 0/3 0/3 0/3 0.33 0 0 0 
25 WTVR-DT 0/3 0/3 0/3 0/3 0 0 0 0 
26
1 
WRLH-DT - - - - - - - - 
27 WETA-DT 0/3 0/3 1/3 0/3 0 0 .33 0 
30 WNVT-DT 2/3 1/3 3/3 2/3 .67 .33 1.0 .67 
33
 
WHUT-DT 0/3 0/3 0/3 0/3 0 0 0 0 
34 WUSA-DT 1/3 0/3 1/3 0/3 .33 0 .33 0 
35 WDCA-DT 1/3 0/3 1/3 1/3 .33 0 .33 .33 
36 WTTG-DT 1/3 0/3 1/3 1/3 .33 0 .33 .33 
39 WJLA-DT 1/3 0/3 1/3 1/3 .33 0 .33 .33 
43 WPXW-DT 1/3 0/3 1/3 0/3 .33 0 .33 0 
47 WUPV-DT 1/3 0/3 0/3 0/3 .33 0 0 0 
48 WRC-DT 1/3 0/3 1/3 0/3 .33 0 .33 0 
51 WDCW-DT 1/3 0/3 0/3 0/3 .33 0 0 0 
NTSC (ANALOG TV)-OCCUPIED CHANNELS 
26 WETA-TV 3/3 2/3 3/3 3/3 1.0 .67 1.0 1.0 
32 WHUT-TV 3/3 2/3 3/3 3/3 1.0 .67 1.0 1.0 
50 WDCW-TV 1/3 1/3 1/3 1/3 .33 .33 .33 .33 
AVAILABLE CHANNELS 
21 - 3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 
23 - 2/3 3/3 2/3 0/3 .67 1.0 .67 0 
24  3/3 3/3 3/3 2/3 1.0 1.0 1.0 .67 
28  3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 
29 - 1/3 3/3 2/3 3/3 .33 1.0 .67 1.0 
31  3/3 3/3 3/3 3/3 1.0 1.0 1.0 1.0 
38  2/3 3/3 3/3 3/3 .67 1.0 1.0 1.0 
40  0/3 3/3 0/3 0/3 0 1.0 0 0 
41  2/3 3/3 3/3 3/3 .67 1.0 1.0 1.0 
42  2/3 3/3 3/3 3/3 .67 1.0 1.0 1.0 
44  2/3 3/3 3/3 3/3 .67 1.0 1.0 1.0 
45  2/3 3/3 3/3 3/3 .67 1.0 1.0 1.0 
46  2/3 3/3 3/3 3/3 .67 1.0 1.0 1.0 
49  2/3 3/3 3/3 3/3 .67 1.0 1.0 1.0 
NOTES: 
1.  Test site was between service contours of WRLH-DT and WETA-TV.  Only the analog (WETA) signal 
could be received with existing DTV receiving configuration. 
2.  Channel 33 not on the air during these tests 
 
 
37 
3.4 Field Test Summary 
 
Table 3-13.  Summary of Field Test Data with Prototype A Version 2. 
 
    Scanner Report 
Site 
Broadcast 
Signal Type 
Viewable 
on TV 
Total Number 
of 
Measurements 
No. of times 
Channel 
reported 
available 
(free) for each 
signal type 
Percent 
Channel 
reported 
available (free) 
for each signal 
type 
      
Site 1 None No 84 77 91.7% 
 ATSC No 48 39 81.3% 
 ATSC Yes 156 93 59.6% 
 NTSC Yes 72 8 11.1% 
 
Site 2 None No 105 82 78.1% 
 ATSC No 45 33 73.3% 
 ATSC Yes 210 84 40.0% 
 NTSC N/A
29
 90 0 0.0% 
 
Site 3 None No 48 43 89.6% 
 ATSC No 96 85 88.5% 
 ATSC Yes 144 106 73.6% 
 NTSC Yes 72 17 23.6% 
 
Site 4 None No 168 143 85.1% 
 ATSC No 72 66 91.7% 
 ATSC Yes 84 63 75.0% 
 NTSC Yes 36 10 27.8% 
 
Total None No 405 345 85.2% 
 ATSC No 261 223 85.4% 
 ATSC Yes 594 346 58.2% 
 NTSC Yes 180 35 19.4% 
 
 
When no signal is expected to be present, the scanner reports the channel to be available 
or free from 78.1 % to 91.7 % of the time with average number at 85.4% of the time.   
 
                                                 
29
 At Site 2 there was no NTSC (analog) tuner available to verify the presence of the signal. 
 
38 
However, the scanner also reports the channel to be available or free when the broadcast 
signal is expected to be present.  Three different cases are summarized in the results. 
 
1. In the cases where the NTSC signal is being broadcast, the scanner reports the 
channel to be free or available between 11.1 % and 27.8 % of the time, with the 
average of 19.4 % of the time. 
2. When the ATSC signal is broadcast two different situations were noted.  The first 
the signal was such that the TV receiver was not able to detect the signal.  It is 
assumed that the signal strength was low for the image not to be viewable on the 
TV set.  In these cases, the scanner reported the channels to be available 81.3 % to 
91.7% of the times, with the average at 85.4 % of the time. 
3. When the ATSC signal is strong enough to result in a viewable image on the TV, 
the scanner reported the channel to be available 40 % to 75 % of the times, with 
the average at 58.2 % of the time.  The numbers are particularly high for Sites 3 
and 4. 
 
 
 
 
 
39 
4 Transmitter Emissions Characterization Measurements 
 
This section describes the laboratory measurements performed to quantify the 
output spectral emissions associated with the Prototype A WSD transmitter (the 
Prototype B WSD does not have a transmit component).  These measurements were not 
intended to empirically model every potential interference scenario; rather selected 
attributes of the prototype transmitters performance were measured to acquire data that 
can be used in conjunction with previously published data on DTV interference 
susceptibility
30
 in subsequent analytical models to assess the potential for co-channel 
and/or adjacent channel EMC under various interaction scenario assumptions.   
4.1 Transmitter Description 
 
 The transmitter component of the prototype WSD utilizes an IEEE 802.11 
compliant transceiver card that has been modified to down-convert the operating 
frequency from the S-band (2.4 GHz) to the relevant UHF frequency range (512-698 
MHz) and clocked to occupy one-fourth of the 802.11 transmission bandwidth, or 
approximately 4.25 MHz.  The transmitter power is variable between -10 and +20 dBm 
and is manually controlled via the computer interface.  Since the data from these 
measurements are intended for future analytical use, the output power was kept constant 
at the maximum (worst-case) setting (this also represents the default setting).  Data 
transmission is simulated with an OFDM-modulated pseudo-random packet stream, 
producing a spectral waveform very similar to additive white Gaussian noise (AWGN). 
 
 The transmitter is tunable to the center frequency of any TV channel from 21 to 
51 (512-698 MHz).  An external band-pass filter (BPF), fixed tuned to channel 30, was 
delivered with the second version of the Prototype A WSD so as to demonstrate the 
capability for improving the out-of-band emissions spilling into adjacent channels. 
4.2 Measurement Approach 
 
The transmitter emissions measurements were performed on a conducted basis 
(i.e., a shielded RF coaxial cable was used to connect the WSD transmit antenna output 
port directly to the input port of the spectrum analyzer used to measure the emissions).  
As a result, the output power levels reported herein do not include any signal gain 
associated with the transmit antenna.  The transmit antenna supplied with the prototype 
WSD is a small whip antenna and can reasonably be assumed to provide no directionality 
(gain) over an ideal omnidirectional pattern. No attempt was made to specifically 
characterize the pattern of the WSD antenna.   
 
Measurements were first performed to assess the transmitter output consistency 
over the available tuning range.  On each of channels 21 (lower), 36 (middle) and 51 
(upper), the spectral envelope over the occupied channel and N5 adjacent channels was 
                                                 
30
 See DTV Susceptibility Study. 
 
40 
measured.  Spectral parameters, including the occupied bandwidth and the average 
channel power, were determined from the measured data and compared among each of 
the three test channels for consistency.  The results of this test were examined to 
determine if the transmitter output was consistent across the test channels.  As 
demonstrated in Section 4.3, the transmitter emission characteristics are consistent across 
all of the channels tested.  Therefore, it was presumed that the results from remaining 
measurements performed on a single channel will be representative of the output on all 
available transmit channels.   
 
Channel 30 was chosen as the representative channel for these measurements in 
order to accommodate an examination of the WSD spectral characteristics associated 
with the fixed-tuned BPF and also to facilitate the use of an available fix-tuned (channel 
30) band-reject (notch) filter in order to improve the instrument sensitivity to 
accommodate the out-of-band emissions measurements. Subsequent measurements were 
made of the average power in the fundamental channel and in the N5 adjacent channels, 
both with and without the external BPF inserted into the transmit circuit.  The resulting 
data was summarized for use in future link budget analyses to be performed under 
various interference interaction scenario assumptions. 
4.3 Measurement Equipment Configuration 
 
 The emissions produced by the WSD transmitter were measured by connecting 
the transmit antenna port directly to the measurement instrument (i.e., no radiated 
measurements were performed).  The instrument utilized for the measurements described 
in this section was a state-of-the art spectrum analyzer.  Analyzer settings, including 
resolution bandwidth (RBW), video bandwidth (VBW), sweep time, number of 
measurement bins, etc., were maintained across all of the measurements for consistency.  
Data analysis functions available in the spectrum analyzer were utilized to determine 
parameters from the measured data such as the average broadband power in each 6-MHz 
TV channel examined. 
 
 Measurements of the emissions in the fundamental channel (without the external 
BPF) were performed utilizing the simple equipment configuration depicted in the block 
diagram shown in Figure 4-1.    
 
 
 
Figure 4-1.  Fundamental Channel Measurement System (without BPF) 
 
 The equipment configuration used for measuring the fundamental emissions after 
insertion of the external BPF is represented by the block diagram in Figure 4-2.  A 10-dB 
in-line attenuator (pad) was added to the transmit circuit to ensure impedance matching 
Spectrum 
Analyzer 
Prototype 
WSD 
 
41 
between the WSD antenna output port and the BPF input port (this set-up was specified 
by the manufacturer). 
 
 
 
Figure 4-2.  Fundamental Channel Measurement System (with BPF) 
 
 Figures 4-3 and 4-4 show the equipment configurations used for measuring the 
out-of-band spectral characteristics in the N5 adjacent channels for the WSD transmitter 
without the external transmit BPF and with the BPF, respectively.  The primary 
difference between this system relative to that used to measure in the fundamental 
channel is the incorporation of an RF band-reject (notch) filter.  This filter was utilized to 
suppress the fundamental channel energy in order to improve the dynamic range of the 
amplitude space, facilitating the measurement of low out-of-band signal levels. 
 
 
 
 
 
Figure 4-3.  Adjacent Channel Measurement on WSD without filter 
 
 
 
White Space 
Device 
 
Spectrum 
Analyzer 
 
Notch 
Filter 
Spectrum 
Analyzer 
Prototype 
WSD 
10-dB Pad
Tx BPF 
 
42 
 
 
Figure 4-4.  Adjacent Channel Measurement on WSD with Filter 
 
4.4 Channel Consistency Test 
 
 On each of channels 21 (lower), 36 (middle) and 51 (upper), the spectral envelope 
over the occupied channel and N5 adjacent channels was measured at the transmitter 
antenna output port.  Spectral parameters including the occupied bandwidth and the 
average broadband power were determined from the measured data and compared among 
each of the three test channels for consistency.  These tests were performed without the 
external BPF which is fixed-tuned to operate only on channel 30. 
 
 Figures 4-5 through 4-7 present the spectral plots obtained from these 
measurements and Table 4-1 summarizes the parameters used to assess consistency 
among the test channels.  Based on these results, it was determined that the spectral 
output is consistent over the channels measured and thus, can be presumed to also be 
consistent across the entire transmit channel space (21-51).  As a result, all subsequent 
emissions measurements were performed on channel 30 as previously discussed.   
 
 
White Space 
Device 
 
10 dB 
Pad 
 
Bandpass 
Filter 
 
Notch  
Filter 
 
Spectrum 
Analyzer 
 
43 
-85
-70
-55
-40
-25
-10
5
48
2
48
8
49
4
50
0
50
6
51
2
51
8
52
4
53
0
53
6
54
2
54
8
Average (rms)-Detected in 10-kHz RBW
Frequency (MHz)
Me
asured Si
gn
a
l
 
Amplitude 
(dB
m
)
Prototype WSD Channel 21 Spectral Envelope
 
Figure 4-5.  Prototype A Transmitter Spectral Envelope Centered in Channel 21. 
 
-85
-70
-55
-40
-25
-10
5
572 578 584 590 596 602 608 614 620 626 632 638
Average (rms)-Detected in 10-kHz RBW
Frequency (MHz)
Measur
ed S
i
gnal Amplitude (dBm)
Prototype A WSD Channel 36 Spectral Envelope
 
Figure 4-6.  Prototype A Transmitter Spectral Envelope Centered in Channel 36. 
 
 
44 
-85
-70
-55
-40
-25
-10
5
662 668 674 680 686 692 698 704 710 716 722 728
Average (rms)-Detected in 10-kHz RBW
Frequency (MHz)
Measur
ed S
i
gnal Amplitude (dBm)
Prototype A WSD Channel 51 Spectral Envelope
 
Figure 4-7.  Prototype A Transmitter Spectral Envelope Centered in Channel 51. 
 
 
Table 4-1.    Summary of Prototype Transmitter Channel Consistency Test Data. 
 
Occupied 
Bandwidth 
(MHz) 
Test 
Channel 
Center 
Frequency 
(MHz) 
Measured Average 
Channel Power 
(dBm/6-MHz) 
-3 dB -20 dB
21 515 21.8 4.19 5.86 
36 605 22.4 4.21 5.95 
51 695 21.9 4.18 6.14 
 
4.5 Fundamental Channel Emissions Measurements   
 
 Measurements were performed to characterize the spectral parameters associated 
with the WSD output signal as it appears within the television channel used for 
transmission (i.e., the fundamental channel).  These measurements were performed with 
the WSD transmitter tuned to the center frequency of TV channel 30 (569 MHz) in order 
to compare the spectral output with and without the use of the manufacturer-supplied 
fixed-tuned BPF.  The spectral plots presented in Figure 4-8 show the output spectrum of 
the prototype WSD transmitter within the channel 30 bandwidth (566-572 MHz) as 
measured at the transmit antenna output port.  Two curves are shown on this graph, one 
 
45 
depicting the measured output spectrum with the external BPF transmit filter and one 
showing the output spectrum without the BPF.  Similarly, Figure 4-9 shows an extended 
spectral envelope, both with and without the use of the external BPF, spanning over the 
fundamental channel and the N5 adjacent channels. 
 
 The measured power in the fundamental channel can be seen to be approximately 
14 dB less when the BPF is inserted into the transmission circuit (relative to the 
unfiltered spectra).  This effective BPF insertion loss represents the sum of the actual 
insertion loss of the BPF, the 10-dB attenuation in the impedance-matching pad and any 
additional attenuation in the extra connections. 
 
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
56
6
567 568 569 570 571 572
Unfiltered Spectral Envelope
BPF Spectral Envelope
Noise Floor
Noise Floor
Frequency (MHz)
Meas
u
r
ed
 S
i
g
n
al
 
A
m
p
l
i
t
u
d
e (
d
B
m
)
WSD Prototype A Fundamental Channel Emissions (with and without BPF)
 
Figure 4-8.  Prototype A Fundamental Channel Emissions in Channel 30. 
 
  
 
 
 
46 
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
536 542 548 554 560 566 572 578 584 590 596 602
BPF Spectral Envelope
Unfiltered Spectral Envelope
Spectrum Analyzer
    Noise Floor
Spectrum Analyzer
    Noise Floor
Frequency (MHz)
Meas
u
r
ed Sig
nal 
Amplitud
e (dB
m
)
WSD Prototype A Wide-Span Spectral Envelope (with and without BPF)
 
Figure 4-9.  Prototype A Emissions on Channel 30 and N5 Adjacent Channels. 
  
 
4.6 Out-of-Channel Emissions Measurements 
 
 Measurements were performed to quantify the out-of-channel power in each of 
the five adjacent channels above and below the fundamental transmit channel (N5).  A 
fixed-tuned (channel 30) RF band-reject (notch) filter was utilized to suppress the 
fundamental channel energy in order to improve the dynamic range of the amplitude 
space, thus facilitating the measurement of the relatively low signal levels (with respect 
to the fundamental energy) in the adjacent channels.  Figure 4-10 demonstrates the 
characteristics of the transmitter output with the notch filter as compared to the extended 
spectral envelope of the WSD prototype transmitter (without the external BPF).  This 
notch filter suppresses the average broadband power by 25 dB over the channel and the 
measured insertion loss of the filter is 2.9 dB (including any loss due to cables).   
 
 
47 
-80
-70
-60
-50
-40
-30
-20
-10
0
536 542 548 554 560 566 572 578 584 590 596 602
Spectral Envelope with Notch Filter
Spectral Envelope without Notch Filter
Frequency (MHz)
Meas
u
r
ed Sig
nal 
Amplitud
e (dB
m
)
WSD Prototype A Spectral Envelope (w/ and wo/ Channel 30 Notch Filter)
 
Figure 4-10. Prototype A Spectral Envelope with and without Notch Filter. 
 
4.7 Emissions Characterization Data Summary  
 
 Table  4-2 summarizes the channel power data obtained from the emissions 
characterization measurements described in this section.   
 
 Table 4-3 shows the results of a comparison between the out-of-channel 
emissions from the WSD transmitter operating with and without the BPF.  When 
assessing filter performance, one accepted notation is to express the power in an adjacent 
channel relative to the power in the carrier (i.e., in the fundamental channel).  This 
convention facilitates a comparison of filter characteristics and is applied to the data 
presented in this table.  Therefore, the power shown in the adjacent channels is expressed 
relative to the fundamental power in units of dBc. 
 
48 
 
Table 4-2.    Summary of Emissions Characterization Data. 
 
Average Channel Power 
(dBm/6-MHz)
2 
Test 
Channel 
Center 
Frequency 
(MHz) w/o BPF w/ BPF 
30/(N) 569 22.1 8.2 
29/(N-1) 563 -6.1 -64.3 
31/(N+1) 575 -5.7 -69.5 
28/(N-2) 557 -23.0 -90.2 
32/(N+2) 581 -23.0 -92.6 
27/(N-3) 551 -31.1 < -95.5 
33/(N+3) 587 -30.0 < -95.5 
26/(N-4) 545 -31.4 < -95.5 
34/(N+4) 593 -30.4 < -95.5 
25/(N-5) 539 -33.7 < -95.5 
35/(N+5) 599 -32.8 < -95.5 
Notes:   
1. WSD w/BPF channel power measurements noise-limited beyond N2
 
2. Adjusted for notch filter insertion loss where appropriate.  
 
 
Table 4-3.    Summary of Emissions Characterization Data. 
 
Channel Power relative to 
Fundamental Channel Power 
(dBc)
 
Test 
Channel 
Center 
Frequency 
(MHz) 
w/o BPF w/ BPF 
30/(N) 569 - - 
29/(N-1) 563 -28.2 -72.5 
31/(N+1) 575 -27.8 -77.7 
28/(N-2) 557 -45.1 -98.4 
32/(N+2) 581 -45.1 -100.8 
27/(N-3) 551 -53.2 < -103.7 
33/(N+3) 587 -52.1 < -103.7 
26/(N-4) 545 -53.5 < -103.7 
34/(N+4) 593 -52.5 < -103.7 
25/(N-5) 539 -55.8 < -103.7 
35/(N+5) 599 -54.9 < -103.7 
 
49 
5 Over-The-Air Interference Test 
 
 An outdoor test was performed to demonstrate the potential for the transmitter 
emissions from the Prototype A WSD to cause radio interference to the OTA reception of 
DTV broadcasts under real-world conditions.  An examination of a wide range of 
possible interference interaction scenarios was beyond the scope of this project.  Thus, a 
simple interaction scenario was chosen for examination under the premise that the results 
can serve as a baseline for modeling more complex scenarios. 
5.1 Test Approach 
 
 The interaction scenario assumed for this test can be considered to be near worst-
case in that it utilized an unobstructed line-of-sight (LOS) propagation path between the 
WSD transmit antenna and the receive antenna used with the DTV test receiver.  
Additionally, main-beam coupling was assumed between the antennas and they were 
restricted to the same elevation plane.  Live OTA DTV signals were utilized in the test 
and therefore no control could be exercised over desired signal parameters such as the 
received DTV power level.  As a result of this limitation (and others, such as the 
statistical significance of a limited number of tests over a limited receiver sample space), 
this test should be considered anecdotal in nature and the results used accordingly. 
 
 The FCC Laboratory compound was utilized for the test because it permitted 
locating the prototype device at varying distances from the test receive antenna.  In 
addition, these separation distances could be realized with little or no potential for 
interference to local residential OTA reception.   
 
 An open area test range was set-up over the Laboratorys parking lot and 
extending into an adjacent open field to accommodate this test (see Figure 5-6).  The test 
range was marked in 10-meter increments, out to a maximum distance of 120 meters.  
The test DTV receiver (identified as DTV receiver sample I1 in a previous FCC study
31
) 
was connected to a tripod-mounted calibrated log-periodic antenna through 20 feet of 
RG-55 coaxial cable and tuned to the channel selected for the test.  A spectrum analyzer 
with internal pre-amplifier was used to measure the DTV spectral signature and the 
average broadband channel power. 
 
 The orientation of the test site required that the DTV test receiver antenna be 
pointed north to avoid close in obstructions.  Thus, the candidate OTA broadcast signals 
available for the test were limited to those located to the north of the test site (i.e., stations 
in the Baltimore market).  Table 5-1 lists relevant information for all of the available 
DTV stations broadcasting in the Baltimore market.  The last column in the table shows 
the relative measured signal strength at the test location for each of the available DTV 
broadcasts (not adjusted for antenna gain or cable loss). 
 
                                                 
31
 See DTV Susceptibility Study. 
 
50 
Table 5-1.    Available DTV Test Channels. 
 
RF 
Channel 
Call 
Sign 
Tx 
Location 
Bearing 
Distance 
(mi/km) 
Received Power 
(dBm) 
29 WMPB-DT Baltimore 7 19.4/31.2 -63.5 
38 WJZ-DT Baltimore 39 14.8/23.8 -42.9 
40 WNUV-DT Baltimore 39 14.9/23.8 -47.8 
41 WUTB-DT Baltimore 22 8.9/14.3 -68.7 
46 WBFF-DT Baltimore 39 14.9/23.9 -51.8 
 
 The selection of an appropriate test channel was also limited by the need to insert 
Prototype As fixed-tuned bandpass filter (BPF) into the transmission circuit for a portion 
of these tests.  This filter is tuned to channel 30, so tests for adjacent channel interactions 
can only be made on a test channel close to channel 30.  Given these scenario limitations, 
channel 29 appeared to be the best available option for performing these tests, despite the 
fact that the signal power was observed to be lower in channel 41.  In addition, the 
orientation of the test range better accommodated the use of this channel (i.e., 7 vs. 22 
bearing).  Thus, channel 29 was selected for use as the test channel.  A plot depicting the 
noise-limited service contour of WMBP-DT, the DTV station assigned to channel 29, is 
provided in Figure 5-1. 
 
 
Figure 5-1.  Service Contour for WMPB-DT on Channel 29. 
 
 
 Figure 5-2 shows the channel 29 broadcast DTV signal as measured with the test 
antenna.  The average broadband channel power was determined to be -63.5 dBm for this 
signal at the DTV receive antenna input.  This is 20.5 dB higher than the threshold of 
visibility (TOV) for a typical DTV receiver (-84 dBm). 
 
51 
 
-130
-120
-110
-100
-90
-80
-70
56
0
56
1
56
2
56
3
56
4
56
5
56
6
Average-Detected in 10-kHz RBW
Measured Average Channel Power = -63.5 dBm/6-MHz
Frequency (MHz)
M
ea
sure
d
 (Unadjusted) Sig
n
a
l
 
Amplitude (dBm)
Channel 29 Measured OTA Signal @ Laboratory Compound
 
Figure 5-2.  Measured DTV Signal in TV Channel 29 at DTV Test Receive Antenna Location. 
 
5.2 Test System 
 
 Figure 5-3 presents a block diagram representation of the instrumentation system 
used to perform this test and Figures 5-4, 5-5 and 5-6 provide photographic 
documentation of the test set up.  An Agilent E4440 Spectrum analyzer (with internal 
pre-amp) was used to measure the OTA signal levels.  An A.R.A. log periodic antenna 
(model number LPB-2520/A) was connected to the test DTV receiver (or the spectrum 
analyzer for signal measurements) with a 20-ft length of RG-55 coaxial cable. 
 
52 
 
 
Figure 5-3.  Test System Block Diagram. 
 
 
 
 
 
 
Figure 5-4.  Test Receive System. 
 
 
 
 
DTV 
 
Spectrum 
Analyzer 
 
White Space 
Device 
Log-periodic Antenna 
 
0 m 
120  m 
 
Distance of test range between 
DTV and WSD marked in 10 m 
increments 
 
53 
 
 
Figure 5-5.  Prototype WSD Transmitter on Wheeled Cart. 
 
 
 
 
 
 
 
Figure 5-6.  WSD Prototype Transmitter Downrange from Test Antenna. 
 
 
54 
 
5.3 Test Procedure 
 
 The DTV receiver was tuned to channel 29 and the receive antenna oriented 
towards the WMPB-DT transmitter located at a bearing of 7.  The displayed picture 
quality was observed and found to be acceptable (no frame freeze or pixilation observed).  
The WSD transmit system was placed on a non-conductive wheeled cart (see Figure 5-5) 
and placed within the receive antenna main-beam at the far end of the test range (120 
meters distant from test antenna).   
 
 The prototype transmitter (without the BPF) was first tuned to channel 29 in order 
to determine the maximum co-channel interference distance.  While transmitting on 
channel 29, the cart was slowly moved toward the DTV test antenna until interference 
was observed.  Although freeze-frame and/or pixilation were considered to be valid 
picture degradation metrics, the most common interference observation was a complete 
loss of picture.  Once the distance was reached where interference was first observed, a 
fine tuning process was used to determine the precise interference distance.  This process 
consisted of moving the transmitter towards and/or away from the test antenna in small 
increments while turning the transmitter on and off and observing the effect to the test 
DTV picture quality.  The interference distance determined by this method was recorded. 
 
 This procedure was repeated to determine the interference distances associated 
with first adjacent channel interactions (N1 or channels 28 and 30) and second adjacent 
channel interactions (N2 or channels 27 and 31) without the external BPF.   
 
 Finally, the procedure was repeated once again to determine the interference 
distance with respect to an adjacent-channel interaction with the WSD transmitter 
utilizing the external BPF.  Since the BPF is fixed-tuned to channel 30, the N+1 (first) 
adjacent channel interaction was the only one that could be examined as a part of this 
test.  Also, since it was found from the measurements reported in Section 4 that there is 
an effective insertion loss of 14 dB associated with the external BPF circuit, a co-channel 
test was not performed with the WSD transmitter utilizing the external BPF. 
5.4 Test Results 
 
 Table 5-2 presents a summary of the results obtained from this test.  It is 
recognized that many of the variable parameters in this test are statistical in nature (e.g., 
time-varying desired signal levels) and thus, multiple measurements would be needed to 
establish statistically-relevant results.  In addition, the test was performed with a very 
small sample size of victim DTV receivers (one), so its results cannot be characterized as 
statistically representative of the population of DTV receivers.  Nonetheless, these results 
provide a demonstration of the interference potential to DTV receivers that may be 
introduced by the operation of unlicensed personal/portable WSD applications in the 
broadcast television spectrum even under favorable DTV reception conditions (e.g., with 
a received DTV signal level well above TOV). 
 
55 
 
 
Table 5-2.    Summary of OTA Interference Test Results. 
 
Interference Interaction Interference Distance (meters)* 
Prototype WSD without BPF 
Co-Channel 87 
1
st
 Adjacent Channel (N-1) 47 
1
st
 Adjacent Channel (N+1) 52 
2
nd
 Adjacent Channel (N-2) 11 
2
nd
 Adjacent Channel (N+2) 14 
Prototype WSD with BPF 
1
st
 Adjacent Channel (N-1) 2 
*
These interference distances are specific to the interaction scenario examined.  The measured DTV 
signal level is more than 20 dB above the typical TOV signal level.  Thus, a similar test performed 
with the DTV signal at TOV will likely result in much greater interference distances. 
 
 
56 
 
6 Data Observations Relevant to TV Services 
  
This section offers observations based on the data resulting from the tests and 
measurements performed on the prototype WSDs delivered to the FCC laboratory for 
evaluation.  The observations offered are limited to the data resulting from 1) tests 
performed to assess the capability for detecting TV signals (Section 3), 2) measurements 
to characterize the transmitter emissions (Section 4) and 3) an anecdotal test to 
demonstrate the capability for introducing electromagnetic interference to broadcast DTV 
operations (Section 5).  These observations are based on measurements performed both in 
the laboratory and in the field.   
6.1 Scanning/Spectrum Sensing Capability Tests 
 
Three separate tests were designed to assess the detection capability of the 
prototype WSDs.  A bench test was performed on each prototype, utilizing a laboratory-
generated DTV signal, to determine a baseline minimum detection threshold and 
associated detection reliability.  A second bench test was performed on each prototype 
utilizing two laboratory-generated DTV signals with one signal in the channel to be 
scanned and the second placed in an adjacent channel to determine the minimum 
achievable detection threshold in the presence of nearby occupied channels.  The third 
test involved a set of field measurements to assess the WSD scanner performance under 
real world conditions.  Prototype B was exempted from the field test at the 
manufacturers request. 
6.1.1 Prototype A Results 
 
 The scanning/spectrum sensing component of prototype A did not meet 
expectations as demonstrated by these tests.  The results of the bench test for determining 
the baseline minimum detection sensitivity demonstrates that the device will not meet the 
manufacturer-specified threshold of -114 dBm (or the IEEE 802.22 proposed threshold of 
-116 dBm for fixed devices) and in fact, fails to meet both of the thresholds by about 20 
dB.  The results of the field tests also demonstrate inconsistent performance.  When 
consideration is limited only to relatively strong DTV signals (i.e., those that could be 
verified by reception on a DTV set), the likelihood of them being successfully detected 
and identified as occupied was very low.  When consideration is extended to include 
broadcasts from distant stations (where the test site was at or near the service contour 
periphery), the demonstrated detection performance was poorer. 
 
 One possible explanation for the poor detection performance represented by this 
prototype may involve a misinterpretation of the detection threshold.  The minimum 
detection threshold as specified in the manufacturers literature is the minimum 
discernible DTV pilot tone sensitivity.  If this statement is interpreted literally then it 
may explain the observed performance demonstrated by the prototype device.  The pilot 
signal amplitude is nominally 11.6 dB less than the integrated average power in the 6-
 
57 
MHz channel (11.3 dB less than the data signal power
32
).  Therefore, a threshold 
specification of -114 dBm relative to the pilot signal amplitude actually represents a 
detection threshold level of -102.7 dBm when expressed relative to the broadband 
channel power.  But, the -114 dBm threshold put forth by the White Space Coalition in 
the proceeding record is predicated upon protecting DTV operation to a threshold of 
visibility (TOV) signal level of -84 dBm with an additional 30 dB included to offset 
worst-case interaction assumptions (e.g., the hidden node scenario)
33
 and the TOV is 
expressed in terms of the average broadband power in the channel.  While this 
inconsistency may explain a large part of the discrepancy between the specified and 
observed detection thresholds, it is not a complete explanation (i.e., it only explains 11.6 
dB of the discrepancy). 
 
 The results of the field tests indicate that the scanning/spectrum sensing function 
of Prototype A  for detecting TV channels occupied with NTSC signals is better than for 
the DTV signal but it is still not reliable. 
 
 The scan period of this prototype device is 27-seconds per channel for a total 
period of 14 minutes to complete a full-channel scan.   
6.1.2 Prototype B Results 
 
 The results from the baseline detection threshold tests indicate that the 
scanning/spectrum sensing component of Prototype B performs as specified by the 
manufacturer.  The test results verify the ability of the prototype to reliably detect 
television channels occupied with DTV signals down to the specified level of -114 dBm.  
However, it is also noted that the reliability begins to degrade below the threshold level.  
The two-signal test results seem to show that the detection reliability below -114 dBm 
may be even further degraded by the introduction of a second DTV signal on a nearby 
channel.  Since this prototype was exempted from field tests, the scanning/spectrum 
sensing performance was not determined under real-world conditions.  Therefore, the 
overall detection capability with live signals of this device is unknown. 
 
 The scan period of the Prototype B WSD is 8 seconds for an individual channel 
scan and 4 minutes to complete a scan of the full tuning range. 
 
 
 
                                                 
32 
The ATSC specifies that the power of the pilot tone of a transmitted 8-VSB DTV signal shall be 11.3 dB 
below the average data signal power.  (Advanced Television Systems Committee, ATSC Digital 
Television Standard:  Part 2RF/Transmission System Characteristics, ATSC Doc. A/53 Part 2:2007, 3 
January 2007, p.40).  Because the presence of the pilot raises the total signal power by 0.3 dB, the pilot 
power is 11.6 dB below the total signal power.  This specification applies to the transmitted signal.  
Multipath effects during transmission can cause the pilot level in the received signal to be higher or lower 
than this relative to the total received signal power. 
33
 Comments of Dell Inc., Google, Inc., The Hewlett-Packard Company, Intel Corp., Microsoft Corp., and 
Philips Electronics North America Corp., Jan 31, 2007 @ 5-7. 
 
58 
6.2 Transmitter Emissions Characterization Measurements 
 
Measurements were performed to characterize the spectral parameters associated 
with the WSD prototype transmitter.  Since Prototype B did not have a transmit/receive 
capability, this discussion is limited to the transmitter contained in the Prototype A WSD.  
The spectral parameters associated with the prototype transmitter were characterized both 
for operation with and without the use of an external band-pass-filter (BPF) that was 
supplied with the prototype, apparently to demonstrate the level of transmission filtering 
that can be achieved.   
 
 The data produced from these measurements is intended for use in future 
analytical efforts.  A previous report released by OET very thoroughly detailed the 
interference susceptibility associated with modern DTV receivers and can be utilized 
with the transmitter emissions data presented herein to perform link budget analyses 
performed to assess the potential for electromagnetic compatibility under various 
interaction scenario assumptions.
34
  
 
 The measured out-of-channel emissions data demonstrate that without additional 
filtering, the out-of-band emissions from the prototype transmitter are likely to be 
inadequately suppressed in the immediately adjacent channels (approximately -28 dBc) 
and the skirts fall off very gradually out to five channels removed from the fundamental 
channel (-55 dBc).  With the external BPF, the out-of-channel emission performance is 
greatly improved (-75 dBc in the adjacent channel and more than -100 dBc five channels 
removed).  This data demonstrates that such a band pass filter can significantly reduce the 
out-of-channel emissions. However, it remains to be seen whether or not this degree of 
filtering can actually be realized in a tunable BPF implemented at base-band.   
6.3 OTA Interference Test 
 
 The results of the test to determine interference potential of a WSD to over-the-air 
TV reception must be treated as anecdotal given the many variable parameters that were 
beyond control.  For example, an available OTA DTV signal broadcast on channel 29 
was used to represent the desired signal in this test.  However, the measured signal level 
was more than 20 dB above the TOV level typically assumed in worst-case interference 
analyses.  Thus, the interference distances resulting from the test are likely to be 
considerably less than what would be determined for interactions with a desired DTV 
signal at the TOV level. 
 
 Notwithstanding the above caveats, this test does demonstrate that interference 
can occur at significant distances from a victim DTV receiver, even under favorable DTV 
reception conditions (i.e., received signal significantly above TOV).  This was seen to be 
particularly true for co-channel interactions that may occur as a result of unreliable 
detection of occupied channels. 
                                                 
34
 See DTV Susceptibility Study. 
 
59 
7 Wireless Microphones Measurements 
7.1 Introduction 
 
The WSD performance capabilities examined in this test project with respect to 
wireless microphones are the ability of the Prototype A and Prototype B devices to sense 
wireless microphones and the potential for the Prototype A device to interfere with 
wireless microphone signals when transmitting. 
 
Three Part 74 wireless microphone systems, designated Systems 1, 2, and 3 were 
used in the testing with the WSD.
35
  Systems 1 and 3 consist of a receiver and two 
microphones and System 2 is a receiver and one microphone.  These microphone systems 
are capable of operating on TV channels 41 to 51. Measurement of the RF transmit 
spectrum of each of these microphones revealed that the signals of the System 1 and 3 
microphones were virtually identical, including a 32 kHz pilot tone, while the signals of 
the System 2 microphone were similar to those of Systems 1 and 3, but with a 19 kHz 
pilot tone.  The microphones signals are frequency modulated and are limited to a 200 
kHz occupied bandwidth.  The results of tests for co-channel interference to the System 1 
and 3 microphones using simulated undesired signals with each microphone/receiver 
combination (these were the first wireless microphone tests performed) were consistent 
with the assumption that the signals were similar.  Thereafter, only one microphone was 
used for testing each system.  The microphones used are designated WM1 for System 1, 
WM2 for System 2 and WM3 for System 3.  The spectrum characteristics of the WM1 
and WM2 units when modulated by a 1000 Hz tone at 24 kHz deviation are shown in 
Figures 7-1 and 7-2  
 
                                                 
35
 These wireless microphones are all Shure Incorporated products that were loaned to the Commission for 
this testing.   
 
60 
-120
-100
-80
-60
-40
-20
0
-150 -100 -50 0 50 100 150
Freq kHz
dB
m
 
  
Figure 7-1.  WM1 Wireless Microphone Spectrum Characteristics 
 
-120
-100
-80
-60
-40
-20
0
-150 -100 -50 0 50 100 150
Freq kHz
dB
m
 
Figure 7-2.  WM2 Wireless Microphone Spectrum Characteristics 
 
61 
7.2 Sensing of Wireless Microphones by White Space Devices 
 
 In the tests for sensing of wireless microphones, WM1 and WM2 were used to 
generate the signals to be sensed.  The test signals were modulated at 1000 Hz with 24 
kHz deviation as shown in Figures 7-1 and 7-2 above (note that WM1 has a pilot tone at 
32 kHz and WM2 has a pilot tone at 19 kHz).  It is recognized that the modulation used 
for testing may not represent the best case signal for detection by a white space device.  
For the wireless microphone tests which required a DTV signal, that signal was simulated 
with a Rohde & Schwarz SFU signal generator with a channel 48 filter.  The emissions 
characteristics of this signal are shown in Figure 7-3 along with the emissions mask for 
DTV signals specified in Section 73.622(h) of the Commissions rules.
36
    These tests 
were performed with the wireless microphone in the FCC Laboratorys anechoic chamber 
to isolate the microphone from the receiver which was found to be sensitive to direct 
pickup of radiated emissions from the microphone and to minimize interference from 
ambient signals.  .  The wireless microphone sensing measurements were performed with 
the test setup shown in Figure 7-4. 
Simulated DTV Signal
-120
-100
-80
-60
-40
-20
0
20
-12-9-6-3036912
Freq MHz
dB
Emission Mask Simulated DTV
 
 
Figure 7-3.  Simulated DTV Signal
                                                 
36
 See 47 C.F.R.  73.622(h). 
 
62 
 
 
Figure 7-4.  Sensing Test Setup 
 
Anechoic Chamber  
Wireless 
Microphone 
Transmitter 
8903B 
Audio 
Analyzer 
E7405A 
Spectrum 
Analyzer 
8901A 
Modulation 
Analyzer 
RF 
Attenuator 
Minicircuits 
ZFSC-2-4 
Combiner 
Minicircuits 
ZFSC-2-4 
Splitter 
White Space 
Device 
Control Room 
E4437B 
Vector Signal 
Gen (Noise) 
 
63 
7.2.1 Prototype A Device 
 
The Prototype A device was generally unable to sense wireless microphones.  
This device was tested with wireless microphone signals at various power levels and 
locations in a TV channel, and with and without the presence of a DTV signal on a 
different channel at different power levels. Table 7-1 shows the results of scanning 
channels 48 and 49 with the simulated DTV signal in channel 48 and the WM1 
microphone signal in the center of channel 49 at a power level of -66 dBm.  In many 
cases, the device incorrectly sensed the WM1 signal as a DTV signal on channel 49.  The 
Prototype A device produces a score for the three different types of signals when it scans.  
It then declares a channel to be occupied or available depending on whether or not the 
score for each type of signal exceeds a predetermined threshold which is unknown.  
 
Multiple scans were run with the DTV power level set at -84 dBm and the device 
reported a score of zero for the microphone, except once a score of 4, indicating the 
presence of a wireless microphone on Channel 49, as shown in the following table.  The 
results in Table 7-1 were obtained after repeating the tests a number of times to ensure 
consistency in the results. In spite of the poor performance of the Prototype A device, 
further testing was performed using a higher modulation frequency and greater deviation 
and with no modulation to see if this would improve the sensing capability of the device.  
However, using a modulation frequency of 2500 Hz and a deviation of 40 kHz or using 
no modulation showed no improvement.   
 
 
Table 7-1.   Prototype A Sensing 
 
DTV Power 
DBm 
Scan Channel Detection 
48 D -53 1 
49 D 
48 D -68 1 
49 D 
48 D 1 
49 D,W 
48 D 2 
49 A 
48 D 
 
 
-84 
3 
49 D 
NOTES: 
1.  A = available, D = occupied by DTV, N = occupied by analog TV, W = occupied by 
wireless microphone 
 
 
 
 
64 
7.2.2 Prototype B Device 
 
The Prototype B device was tested for its ability to sense wireless microphone 
signals using the same procedure and test set up as that used to test Prototype As 
wireless microphone sensing ability.  In these tests, the input signal to the receiver was 
adjusted to several power levels within its normal range. The Prototype B device was 
tested in a variety of situations and conditions and its performance was mixed.  In the 
initial, informal testing of this device it was found that the devices performance did not 
vary significantly with the TV channel on which the wireless microphone was operated.  
Therefore the tests were conducted with the wireless microphones operating on only a 
few channels in the range of channels 44-49.  Table 7-2 shows the results of the tests of 
Prototype B with the WM1 wireless microphone is operating at 653 MHz, which is the 
middle of channel 44.  These results indicate that the Prototype B device is able to sense 
WM1 on this channel in all scans at signal levels as low as -120 dBm.  However, on some 
scans from channel 21 to 51 the device also incorrectly indicated the presence of a 
microphone on channel 24.  In addition, when WM1 signal was at the -36.6 dBm level, 
the prototype also incorrectly sensed wireless microphone signals on six additional 
channels.  Using a modulation frequency of 2500 Hz and a deviation of 40 kHz showed 
no improvement in sensing capability, but with no modulation the device was able to 
sense the microphone at about a 5 dB lower signal level. 
 
 
Table 7-2.    Prototype B Sensing with WM1 Microphone at Center of Channel 44 
 
Microphone 
Power 
dBm 
 
Scan 
Microphone Sensed 
on Channels 
 
-36.6 1 26,28,29,31,35,44,46
1 44 
2 44 
 
-76.3 
3 44 
1 44 
2 24,44 
 
-106.3 
3 44 
1 24,44 
2 24,44 
 
-116.3 
3 24,44 
1 24,44 
2 24 
 
-120.3 
3 24,44 
 
 
As shown on Table 7-3, when the WM1 microphone frequency is changed to 
650.05 MHz, which is 50 kHz from the low end of channel 44, the device senses a 
microphone on channels 43 and 44 at signal levels as low as -106 dBm, but senses 
nothing at signal levels of -110 dBm or lower. 
 
65 
Table 7-3.    Prototype B Sensing with WM1 Microphone 50 kHz from Low End of Channel 44 
 
Microphone 
Power 
dBm 
 
Scan 
Microphone Sensed 
on Channels 
 
-36.6 1 26,29,31,40,43-47 
1 43,44 
2 43,44 
 
-76.3 
3 43,44 
1 43,44 
2 43,44 
 
-106.3 
3 43,44 
1 None 
2 None 
 
-110.3 
3 None 
1 None 
2 None 
 
-116.3 
3 None 
 
Table 7-4 provides the results for the WM2 wireless microphone operating at 
661.8 MHz, which is 200 kHz from the high end of channel 45.  At low power levels the 
prototype correctly sensed a microphone on channel 45 and also incorrectly sensed a 
microphone on channel 46.  With the WM2 signals at the moderate power level of -67.1 
dBm, the device correctly sensed a wireless microphone on channel 45 and also 
incorrectly sensed microphones on channels 46 and 47. The tests for WM1 and WM2 
were performed at their operating frequencies which are different.  
 
 
Table 7-4.    Prototype B Sensing with WM2 Microphone 200 kHz from High End of Channel 45 
 
Microphone 
Power 
dBm 
 
Scan 
Microphone 
Channels 
Sensed 
1 45,46,47 
2 45,46,47 
 
-67.1 
3 45,46,47 
1 45 
2 45 
 
-107 
3 45 
1 45 
2 45 
 
-114 
3 45 
 
 
Tests of the Prototype B devices ability to sense wireless microphones were also 
performed with the simulated DTV signal shown in Figure 7-3 on channel 48 and the 
 
66 
WM1 microphone signal on channel 49 at 680.125 MHz, which is 125 kHz from the low 
end of channel 49.  In these tests, the device was again used to scan all channels from 21 
to 51 searching for DTV, analog TV, and wireless microphone signals.  The results of 
these tests with the microphone signal at -114 dBm and a variable DTV signal level are 
shown in Table 7-5. 
 
Table 7-5.    Prototype B Sensing - Channels Sensed As Occupied 
 
DTV 
Power 
dBm 
DTV Channels 
(48) 
Analog TV  
Channels 
(none) 
Microphone 
Channels 
(49) 
 
-28 
 
48,49,50 
 
47,48,49,50 
 
33,34,44,45,46,51 
 
-53 
 
48,49 
 
48,49 
 
47,50 
 
-68 
 
48 
 
48 
 
27,47,49,50 
 
-84 
 
48 
 
48 
 
44,46,49 
 
 
On this table, the number in parentheses at the head of the column is the correct 
response.  The device correctly identified the presence of DTV signal on channel 48 but 
also incorrectly indicated the presence of DTV signals on channels 49 and 50 when the 
DTV signal on channel 48 was at -53 dBm and higher.  It incorrectly indicated the 
presence of an analog TV signal on the channel occupied by the DTV signal at all levels 
of the DTV signal actually present and also incorrectly indicated the presence of analog 
TV signals on other channels, especially as the level of the DTV signal present was 
raised.  The prototype correctly sensed the wireless microphone only at the two lowest 
DTV power levels and incorrectly sensed its presence on several other channels at all 
power levels.  In a separate trial in which the device was instructed to scan only channel 
49 and to search only for microphones and with the microphone on channel 49 at -114 
dBm and a DTV signal on channel 48, it correctly sensed the microphone signal on 
channel 49 over the DTV signal power range -28 to -84 dBm. 
7.3 Interference to Wireless Microphones 
 
Tests were conducted to gauge the susceptibility of Part 74 wireless microphone 
systems to possible interference from unlicensed WSDs.  Before the Prototype A device 
became available, this test project first examined the potential for interference to wireless 
microphones using the three Part 74 wireless microphone systems described above and 
WSD signals that were simulated using an audio modulated FM signal, a wideband noise 
signal and a wideband OFDM signal.  When the Prototype A WSD became available, it 
was tested for interference to a wireless microphone system.  In these tests, interference 
 
67 
was defined to occur at the point where the signal-to-noise plus distortion (SINAD) ratio 
reading at the audio output of the microphone receiver was 30 dB. The desired wireless 
microphone signals were modulated at 1000 Hz with 24 kHz deviation level and were 
input to the receiver at -80 dBm.  The microphone transmitter spectrum characteristics for 
the System 1, 2, and 3 signals are shown in Figures 7-1 and 7-2.  The undesired signals 
were:  1) an FM signal audio modulated with a 400 Hz tone at 24 kHz deviation, 2) a 
white Gaussian noise signal with a 3 dB bandwidth of 5.4 MHz, and 3) an OFDM signal 
with a 3 dB bandwidth of approximately 4.75 MHz.  The signal from the Prototype A 
device was an OFDM signal with a 3 dB bandwidth of 4.125 MHz as shown in Figure 
7-5.  No additional filtering was used because no filters were available for the channels 
on which the wireless microphones operated. 
 
Testing was performed using the test setup of Figure 7-6.  Preliminary tests 
revealed that the Prototype A device was very susceptible to direct pickup of the RF 
signal from the microphone.  It was therefore necessary to isolate the microphone from 
the Prototype A device and the test equipment.  The test procedure consisted of 
modulating the microphone as specified and adjusting the band power to -80 dBm input 
to the microphone receiver.  The undesired signal input to the receiver was then increased 
until the SINAD decreased to 30 dB as indicated on the audio analyzer.  The band power 
of the undesired signal at the input to the receiver was then recorded.  Tests were made 
for co-channel and first and second adjacent channel interference.  For co-channel tests 
the desired signal was located near the center of the TV channel.  For adjacent channel 
tests the desired signal was located near the center or the upper or lower edge of a TV 
channel and the undesired signal was located in the first or second adjacent channel 
nearest to the desired signal.  The test results are shown on Tables 7-6, 7-7 and 7-8. 
 
 
68 
-80
-70
-60
-50
-40
-30
-20
-10
0
644 646 648 650 652 654 656 658 660 662
Freq MHz
dBm
 
 
Figure 7-5.   Prototype A Device Transmit Spectrum 
 
Table 7-6 below shows the undesired signal power level for each type of signal 
above which the SINAD was less than 30 dB for co-channel interference for each 
microphone transmitter and receiver combination.  Note that the power level for the 
undesired signals, except the FM signal, is for a wideband signal as compared to the 
relatively narrowband desired signal. The power of the broadband signals (noise, ODFM 
and Prototype A) is spread over a wider bandwidth compared to the FM signal.  The 
difference in the power level below is because of the difference in the occupied 
bandwidth. 
 
Table 7-6.    Co-channel Undesired Interference Power Level (dBm) 
 
Microphone WM1 WM1-2 WM2 WM3 WM3-2 
System 1 2 3 
    
FM -87.0 -87.0 -88.0 -87.5 -87.0 
Noise -75.4 -75.3 -88.0 -74.3 -74.3 
OFDM -76.1 -76.0 -88.9 -74.2 -74.2 
Prototype A -76.5  -89.0 -76.7  
 
 
 
69 
Table 7-7 shows the undesired signal power level above which the SINAD was 
less than 30 dB for first adjacent channel interference from the simulated WSD signals.  
In some cases the desired signal was lost before the SINAD indication decreased to 30 
dB as the undesired signal level was increased.  The undesired FM signal was located 50 
kHz from the edge of the desired signal channel nearest to the desired signal.  These 
measurements show wide variability in the microphone systems susceptibility to both 
FM and wideband signals.  These results show that in most cases the wireless 
microphones are 15 dB or more less susceptible to interference from the simulated WSD 
signals on first adjacent channels than on the same channel.  As might be expected, the 
results for System 1 also show that this system tends to be more susceptible to an 
undesired signal on an adjacent frequency closer to the frequency used by the system.  
However, the System 1 measurements at the closer 50 kHz spacing show less 
susceptibility to interference than the wideband measurements for Systems 2 at greater 
frequency spacings. 
 
Table 7-7.    Adjacent Channel Undesired Interference Power Level (dBm) for Simulated WSD 
Signals 
 
Microphone WM1 WM2 WM3 
System 1 2 3 
Distance of desired 
signal from edge 
of channel 
 
50 kHz 
 
200 kHz 
 
200 kHz 
 
200 kHz 
     
FM -89.9 -22.8 -46.9 -45.0 
Noise -60.3 -55.4 -70.1 -51.5 
OFDM -26.0 -24.3 -35.9 -16.3 
 
 
Table 7-8 shows the results from measurements with the Prototype A device operating in 
the first and second adjacent channels.  These measurements show that wireless 
microphones susceptibility to interference from Prototype As signals decrease 
significantly as the frequency difference between the desired and undesired channels 
increases. 
 
Table 7-8.    1
st
 and 2
nd
 Adjacent Channel Prototype A Device Interference Power Level (dBm) 
 
Microphone WM1 WM2 WM3 
System 1 2 3 
Distance of desired 
signal from edge of 
channel 
50 
kHz 
200 
kHz 
Center 200 
kHz 
Center 200 
kHz 
Center 
        
1
st
 Adj Channel -51.8- -52.6 -38.7 -63.3 -48.5 -51.5 -37.3 
2
nd
 Adj Channel -32.0 -30.4 -28.4 -48.7 -35.4 -31.5 -27.4 
 
 
 
70 
Beside the white space device power level, the two main factors that determine 
the susceptibility of wireless microphone systems to interference from those devices are 
the RF spectrum occupied by the undesired signal and the selectivity of the microphone 
receiver.  The spectrum characteristics of the Prototype A device as delivered to the FCC 
Laboratory for testing is as shown in Figures 7-5 above.  The interference susceptibility 
data in Table 7-8 demonstrates the effect of these two factors.  In all cases, interference 
occurs at lower device power levels when the microphone operating frequency is 200 
kHz from the channel edge closest to the undesired signal than when it is at the center of 
the TV channel in which it is operating.  This is caused by the out-of-channel skirts of the 
device spectrum.  However, System 2 suffers interference at lower device power levels 
because of the wider selectivity of its receiver. 
 
71 
 
 
Figure 7-6.   Interference Test Set Up 
 
Wireless 
Microphone 
Transmitter 
White Space 
Device 
E4438C 
Vector Signal 
Gen (OFDM) 
E4437B 
Vector Signal 
Gen.(Noise) 
8640B 
FM Mod 
RF Gen 
Anechoic Chamber  Control Room 
RF  Atten. 
Minicircuits  
ZFSC-2-4 
Combiner 
RF  
Attenuator 
8903B 
Audio 
Analyzer 
Minicircuits 
ZFSC-2-4 
Splitter 
E7405A 
Spectrum 
Analyzer 
8901A 
Modulation 
Analyzer 
Wireless 
Microphone 
Receiver 
 
72 
Appendix A  Measurement Systems 
 
This appendix provides information regarding the measurement equipment used 
to perform this test/measurement program.  Table A-1 provides a list of the equipment 
used, including the manufacturer and model number, a brief description and where 
appropriate, the most recent manufacturer calibration date. Calibration information 
resulting from measurements performed in the laboratory to determine the signal 
attenuation in various circuits used to support the test/measurements is also provided.  
 
Table A-1.  List of Measurement Equipment 
 
Equipment Quantity Manufacturer and Model Specifications 
Last 
Calibrated 
Spectrum Analyzer 1 Agilent E4448 PSA 3 Hz-50 GHz 06/09/06 
Spectrum Analyzer 1 Agilent E4440 PSA 
3 Hz  26.5 GHz 
(w/ internal PA) 
07/18/06 
Spectrum Analyzer 1 Agilent E7405A EMC 9 kHz  26.5 GHz 09/01/06 
Modulation Analyzer 1 Agilent 8901A  02/27/06 
Audio Analyzer 1 Agilent 8903B  09/25/03 
Signal Generator 1 Agilent E4437B ESG 250 kHz-4 GHz 05/25/06 
Signal Generator 1 Agilent 4438C ESG 250 kHz  6 GHz 02/22/05 
Signal Generator 1 Agilent 8640B 
500 kHz  1024 
MHz 
09/06 
Broadcast Test System 2 Rhode and Schwarz SFU 
w/ ATSC Signal 
Generator 
- 
Step Attenuator 1 Hewlett-Packard 355D 10-dB steps - 
Step Attenuator 1 Hewlett-Packard 355 C 1-dB steps - 
Step Attenuator 1 Agilent  8494B 
0 to 11 dB 
DC  18 GHz 
11/09/04 
Step Attenuator 1 Agilent 8495B 
0 to 70 dB 
DC  18 GHz 
08/05/05 
TV Channel Rejection 
Filter 
1 TLE Model CE7569-N30 566-572 MHz - 
Signal Combiner 2 MiniCircuits ZFSC-2-1W 50 ? - 
Log Periodic Antenna 1 A.R.A. LPB-2520/A 25 MHz  2.0 GHz - 
Impedance Matching 
Transformer 
1 Trilithic ZMT-57 75-50 ? - 
 
 The following information is provided with respect to calibrations performed as a 
part of this program to determine the signal attenuation (or gain) associated with the 
various components used to support the test/measurements. 
 
 The input signal level used in the detection threshold was set at the input to the 
WSD scanner antenna input port and thus, no signal calibration was necessary. 
 
 A short length (2-feet) of RG-223/U coaxial cable was used to connect the WSD 
transmitter output port directly to the spectrum analyzer for performing the transmitter 
emissions measurements.  The signal attenuation in this cable was measured and found to 
 
73 
exhibit a maximum loss of 0.4 dB over the frequency range involved (512-698 MHz).   
The insertion loss associated with the channel-reject (notch) filter is 2.9 dB, including the 
additional coaxial cable used to integrate into the measurements system. 
 
 The OTA interference test utilized a log periodic antenna as the test antenna and it 
was connected to the DTV receiver (or spectrum analyzer) with a 20-ft length of RG-55 
coaxial cable.  The signal attenuation in the cable run was measured and determined to be 
a maximum of 2.3 dB.  In addition, there was a measured signal loss associated with the 
impedance-matching transformer of 0.9 dB and the antenna gain over the 512-698 MHz 
frequency range is 7.1-7.5 dBi. 
 
74 
 
Appendix B  Service Contours of TV Stations at Field Test Sites 
 
 
This appendix contains plots depicting the service contours of each full service 
and low power TV station (including auxiliary transmitting antennas) on channels within 
the prototype WSD tuning range that have been authorized for use by a licensed 
television broadcaster relative to each site where field measurements were performed.  
The test location is represented on these plots by a red star.  All broadcast licensees and 
construction permits within a 150-km (94-mile) of the test site were included in the 
contour plots.  Red circles indicate DTV stations; blue circles indicate analog TV 
stations.  There are a total of thirty plots provided for each test site, one for each channel 
in the WSDs tuning range. 
 
 
 
(See Separate File)