of the 8580, which was related to the peak power seen by the
radar receiver. This relationship was established by in-
jecting a calibration signal at the input of the radar re-
ceiver through a waveguide coupler of known loss characteristics
and measuring this signal with the 8580. This measurement was
made at different input amplitudes to obtain a transfer
characteristic for the radar receiver front end characteristics,
including noise and saturation.

CLOSED SYSTEM MEASUREMENTS

Closed system measurements were made on an analog radar
(ASR-4,5,6) and a digital radar (ASR-7). The measurements
were made on the space channel of the radar while the radar
and air traffic control was normally operating. The objec-
tive of these sets of measurements was to determine the syn-
chronous and nonsynchronous pulse PPI MDS level for several
operational modes of the radars, and what radar fixes need
to be modeled in order to accurately predict the pattern of
the interference as it appears on the PPI scope. Video tape
recordings of the PPI display and A-scope were made for the
various radar-operating modes during these measurements.

The result of these measurements will be given in a subse-
quent report.


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APPENDIX F

LOS ANGELES AND SAN FRANCISCO AREA MEASUREMENT PLAN

INTRODUCTION

This appendix discusses the measurement plan used in the
2.7 to 2.9 GHz Spectrum Resource Assessment of the Los Angeles
and San Francisco areas. A description of the RSMS van measure-
ment system and application programs associated with the measure-
ment plan is given in Appendix G. The major objective of the
measurements was the validation of radar-to-radar interference
prediction techniques including the radar performance degrada-
tion model. This required on-site verification of predicted
interference situations, and the use of the RSMS van to deter-
mine the accuracy of the various input component models (i.e.,
propagation, emission spectrum, antenna pattern, and frequency-
dependent-rejection). Measurements results were also to be com-
pared with the radar performance degradation model.

MEASUREMENT PLAN

The 2.7-2.9 GHz test plan was divided into the following
three measurement areas:

A. Preliminary radar site visits where video tape record-
ings (VTR) and photographs of PPI display were taken.

B. Detailed open system measurements at 2 radar sites
which involves measuring emission spectrums, antenna
patterns and received power from potential interferers.
The open system measurements also included video tape
recordings of the PPI display with the RF input power
level of the interfering signal being recorded on
the VTR.

Cc. Closed system measurements to determine the effect
which various radar fixes (e.g., MTI, STC, integrator,
etc.) have on the processing of interfering signals
of various signal levels and PRF's. Video tape
recordings will be used to document this set of
experiments. These measurements were made on the
radar spare channel during normal operation of
radar and air traffic control.


PRELIMINARY RADAR SITE VISITS

The purpose of these measurements was to verify pre-
dicted interference situations to the extent that the live
environment conditions and parameters used to predict the
interference exist. This set of measurements was shallow
in depth with the main objective to compare predicted inter-
ference with the live environment conditions for 12 victim
radar sites.

Preliminary observations of potential victim radars were
conducted with the victim radars in regular operational con-
figuration. The AS-330 Pulse Train Separator was used as an
aid in identifying the interfering radars. The AS-330 was
set up for three PRF's of potential interferer radars, using
a small audio oscillator and a pulse-forming circuit or a
normal pulse generator. The local radar was set for non-
stagger operation so that the de-stagger circuits would not
alter the sequence of the received interference pulses, and
the AS-330 was connected to one of the radar's video outputs.
Although the video channel contained mostly pulses with the
PRF of the local radar, the AS-330 sorted out the pulses
belonging to the interfering radars with the PRF's set up
previous to the measurements. The only output used from the
AS-330 was the indicator lights on the AS-330 front panel.
The AS-330 was positioned so that the video tape recordings
made of the interference also included the indicator lights
of the AS-330. Interferers were also identified by the
relative bearing to the victim radar when possible. Also,
the RSMS van WB scan program was used to verify the operational
frequencies of the victim radar and potential interferer radars
during these measurements. Without this capability, positive
verification of proper operating frequency of the predicted
interferers would not have been possible.

DETAILED RADAR MEASUREMENTS

The purpose of these sets of measurements was to determine
why there was disagreement between predicted and observed
interference at the visited preliminary radar sites. The
preliminary radar observations resulted in two radar sites
being selected for more detailed measurements. The following
set of measurements were made at the victim radar site using
the RSMS van, and involved:

a. Locating the RSMS van as close as possible to the
victim radar site.


b. Scanning the 2.7 to 2.9 GHz band to identify all
significant emitters, and verifying the operation
of all predicted interferers.

c. Measuring the power received from each predicted and
unpredicted interferer for a period of at least one
half hour to determine propagation path loss. The
right hand circular CBS was used when possible. If
the dish was required, approximate dish azimuth and
elevation angles were obtained from RAPIT (Propa-
gation Model) bearing and radio horizon elevation
data.

d. Measuring the interfer antenna patterns at victim
radar site.

e. Measuring the victim radar antenna pattern.

Measurements made at the predicted and unpredicted
interferer sites using the RSMS van included:

a. Measuring the emission spectrum of the interferer
radar to levels of 60-80 dB down from the peak.

b. Measuring interferer antenna patterns.

Arrangements were also made during the detailed measure-
ment program to shut the victim radar transmitters down, so
that no pulses would be received from its own transmitter.
Thus isolated, the interfering radar pulses could be studied
more carefully. With this arrangement, all of the traces on
the PPI display were caused by interference. For this experi-
ment, the RSMS van was connected to the radar as shown in
Figure F-l1. The RSMS van was tuned to 30 MHz and measured
the peak power delivered to the 8580 every second. The
operator in the RSMS van watched a TV monitor showing the
interference traces on the PPI display. Whenever a pulse of
interest shows up, the operator read the power measured by
the 8580 into the intercom to the radar PPI display, where
the audio was picked up by the video tape recording equipment.

In addition to measuring the peak input power, the 8580
generated a log video signal which was fed back to the radar
building for further analysis. The AS-330 pulse train sepa-
rator was driven from this signal to indicate the PRF of the
interfering signal, similar to the technique used in the
preliminary radar measurements. Thus, a peak power measure-
ment was tied to a given interferer. The peak power measured
by the 8580 was a measurement of the peak power at the input