# Before the

# Federal Communications Commission

# Washington, D.C. 20554

In the Matter of )

)

Revision of Part 15 of the Commission's Rules )

Regarding Ultra-Wideband Transmission ) ET Docket 98-153

Systems )

# NOTICE OF PROPOSED RULE MAKING

**Adopted: May 10, 2000 Released: May 11, 2000**

**Comment date:** **\[insert date 90 days from publication in Federal
Register\]**

**Reply comment date:** **\[insert date 120 days from publication in
Federal Register\]**

By the Commission:

SUMMARY

1.  By this *Notice of Proposed Rule Making* (\"*Notice*\"), we propose
    to amend Part 15 of the Commission's rules to pave the way for new
    types of products incorporating ultra-wideband (\"UWB\") technology.
    UWB devices may have the capability to provide for significant
    benefits for public safety, businesses and consumers. While
    comprehensive tests have not been completed, UWB devices appear to
    be able to operate on spectrum already occupied by existing radio
    services without causing interference, which would permit scarce
    spectrum resources to be used more efficiently. We are moving
    forward with this *Notice* to begin the process of identifying
    potential rule changes and alternatives necessary for the deployment
    of UWB technology. The proposals in this *Notice* are designed to
    ensure that existing and planned radio services, particularly safety
    services, are adequately protected. UWB technology is relatively
    new. Further testing and analysis is needed before the risks of
    interference are completely understood. Such testing is already
    being planned by a number of organizations. We will provide ample
    opportunity to complete these tests and ensure that analyses of the
    test results are submitted in the record for public comment before
    adopting any final rules in this proceeding. We invite broad comment
    on this *Notice* so that the Commission may ultimately provide for
    the introduction of this new and exciting technology.

    **BACKGROUND**

2.  The Commission, on its own motion, issued a *Notice of Inquiry*
    ("*NOI*") in this proceeding to investigate the possibility of
    permitting the operation of UWB devices on an unlicensed basis under
    Part 15 of the FCC rules.[^1] Part 15 of the Commission\'s
    regulations permits the operation of RF devices without a license
    from the Commission or the need for frequency coordination.[^2] The
    technical standards contained in Part 15 are designed to ensure that
    there is a low probability that these devices will cause harmful
    interference to other users of the radio spectrum.[^3] Intentional
    radiators, *i.e.*, transmitters, are permitted to operate under a
    set of general emission limits[^4] or under provisions that allow
    higher emission levels in certain frequency bands.[^5] Intentional
    radiators generally are not permitted to operate in certain
    sensitive[^6] or safety-related frequency bands, designated as
    restricted bands,[^7] or in the frequency bands allocated for
    television ("TV") broadcasting.

3.  The *NOI* observed that recent advances have enabled the development
    of UWB technology for a variety of applications. UWB devices can be
    used for precise measurement of distances or locations and for
    obtaining the images of objects buried under ground or behind
    surfaces. UWB devices can also be used for wireless communications,
    particularly for short-range high-speed data transmissions suitable
    for broadband access to the Internet. UWB radio systems typically
    employ pulse modulation whereby extremely narrow pulses are
    modulated and emitted to convey or receive information. The emission
    bandwidths generally exceed one gigahertz.[^8] In some cases,
    "impulse" transmitters are employed where the pulses do not modulate
    a carrier. Instead, the radio frequency emissions generated by the
    pulses are applied to an antenna, the resonant frequency of which
    determines the center frequency[^9] of the radiated emission. The
    bandwidth characteristics of the antenna will act as a low-pass
    filter, further affecting the shape of the radiated signal.

4.  The *NOI* observed that the current Part 15 rules pose two primary
    obstacles to the implementation of UWB technology. First, the wide
    bandwidth that is intrinsic to the operation of UWB devices can
    result in transmission of the fundamental emission[^10] into
    restricted frequency bands or into the television ("TV") broadcast
    frequency bands, which is prohibited under the Part 15 rules.
    Second, the current emission measurement procedures specified in our
    Part 15 rules were developed for narrowband systems and may be
    inappropriate for, and pose unnecessary restrictions to, UWB
    technology, particularly impulse systems. For example, Part 15
    measurement procedures require the application of a pulse
    desensitization correction factor.[^11] The application of this
    correction factor can cause UWB systems to exceed the peak emission
    limits currently specified under the Part 15 rules.[^12]

5.  The *NOI* requested comment on the potential applications for UWB
    devices and their technical characteristics, such as frequency
    ranges of operation, bandwidths, power levels, and operating
    distances. In addition, the *NOI* requested comments concerning what
    regulatory treatment would be most appropriate for UWB devices,
    including whether they should be regulated under Part 15 or some
    other rule part. The *NOI* asked how the Commission should define
    UWB devices. Further, the *NOI* sought comments on whether UWB
    devices should be prohibited from operating in the restricted
    frequency bands and TV broadcast frequency bands or if there are
    certain restricted frequency bands where the Commission should
    permit UWB operation. Comments were sought concerning what emission
    limits and measurement procedures would be appropriate for UWB
    devices. The *NOI* invited comments on any other matters or issues
    that may be pertinent to the operation of UWB systems. In response
    to the *NOI*, 42 parties filed comments and 37 parties filed reply
    comments.[^13] The list of the commenting parties is shown in
    Appendix B.

6.  In the *NOI* the Commission noted that three requests for waivers of
    the Part 15 rules were filed to permit the operation of UWB
    systems.[^14] U.S. Radar Inc. filed a Petition for Waiver to permit
    the operation of a ground penetrating radar system that could be
    used to detect buried objects.[^15] Time Domain Corp. filed a
    Petition for Waiver to permit systems that would be used by public
    safety personnel for high resolution imaging of persons and objects
    behind walls or under debris.[^16] Zircon Corporation also filed a
    Request for Waiver to permit radar systems that would be used by the
    construction industry to detect objects hidden inside walls or other
    building materials.[^17] Because the waiver requests included
    frequency bands allocated to the U.S. Government, they were
    coordinated closely with the National Telecommunications and
    Information Administration (NTIA).[^18] The three waiver requests
    were granted on June 25, 1999 by the Chief of the Office of
    Engineering and Technology, based on a number of technical and other
    conditions requested by NTIA to protect against interference to
    radio services.[^19]

    **DISCUSSION**

7.  We have thoroughly reviewed all of the comments and reply comments
    filed in this proceeding. Based on this review, we believe that UWB
    devices may offer significant benefits for public safety, businesses
    and consumers, as discussed in detail below. Further, we observe
    that most UWB devices cannot operate under our current regulations.
    Therefore, we tentatively conclude that the Commission's rules
    should be amended to provide for UWB devices. At the same time, we
    recognize that any new rule provisions for UWB devices must ensure
    that radio services are protected against interference. Many of the
    comments suggested that further testing and analysis is needed
    before the potential for interference is fully understood,
    particularly potential interference to safety services such as the
    Global Positioning System (GPS). We note that the NTIA, the U.S.
    Department of Transportation, and other organizations are planning
    such tests. We plan to allow a reasonable period of time for
    submittal of test results into the record in this proceeding and
    will provide an opportunity for public comment on the test results
    before reaching any conclusions. However, we believe it is
    appropriate at this juncture to issue a *Notice of Proposed Rule
    Making* to begin the process of identifying possible rule amendments
    and alternatives. This *Notice* provides an important framework for
    considering the various technical issues. We invite broad comment on
    these issues.

######### ***Applications and General Characteristics*** 

8.  We believe that UWB technology holds promise for a vast array of new
    or improved devices that could have enormous benefits for public
    safety, consumers and businesses. Further, we anticipate the UWB
    technology could create new business opportunities for
    manufacturers, distributors and vendors that will enhance
    competition and the economy. UWB technology may also enable
    increased use of scarce spectrum resources by sharing frequencies
    with other services without causing interference. It is important
    that we find ways to encourage the development and deployment of
    technologies that may allow more efficient use of the spectrum. We
    note that Section 7 of the Communications Act of 1934, as amended,
    requires the Commission \"to encourage the provision of new
    technologies and services to the public.\"[^20] Accordingly, we
    conclude that the Commission should develop reasonable regulations
    that will foster the development of UWB technology while continuing
    to protect radio services against interference.

9.  The *NOI* invited comment on the potential applications and general
    technical characteristics for UWB technology, noting that UWB
    systems appeared to fall into two categories: systems that use radar
    techniques for precise measurements of distance, and detection or
    imaging of objects; and communications systems that can be used for
    voice, data and control signals.

***[Radar Applications]{.underline}***

10. The comments described a wide assortment of existing and potential
    applications for UWB technology that employ radar principles.
    Several parties note that UWB technology has been in use for some
    time for ground penetrating radar (\"GPR\") applications.[^21] GPR
    devices are used for purposes such as: determining the structural
    soundness of bridges, roadways, and airport runways; locating buried
    containers that may contain hazardous wastes; determining the
    location of underground utilities, such as natural gas, electricity,
    water and sewage lines, irrespective of the composition of the
    piping or conduit; geologic surveys; archeological digs; and, law
    enforcement and forensic investigations. The comments stated that
    UWB technology is being developed for new types of imaging systems
    that would enable police, fire and rescue personnel to locate
    persons hidden behind a wall or under debris in situations such as
    hostage rescues, fires, collapsed buildings, or avalanches. Imaging
    devices also could be used to improve the safety of persons in the
    construction and home repair industries by allowing individuals to
    locate steel reinforcement bars (*i.e.*, re-bar) in concrete, or
    wall studs, electrical wiring and pipes hidden inside walls.

11. Numerous other applications for UWB technology using radar
    techniques were brought to our attention. Potential automotive uses
    include forward-looking and lane change collision avoidance systems,
    backup warning systems, air bag proximity measurement for safe
    deployment, sensors that detect bumps in the road and automatically
    adjust suspension systems, and fluid level detectors for radiator,
    oil and gas levels. Potential medical uses include the development
    of a mattress-installed breathing monitor to guard against Sudden
    Infant Death Syndrome, and heart monitors that act like an
    electrocardiogram except that they measure the heart's actual
    contractions instead of its electrical impulses. Some potential home
    safety uses include intrusion detection systems that are less
    susceptible to false alarms, and space heaters that turn themselves
    off when a child comes nearby. Other interesting UWB applications
    include liquid level sensors for everything from water conserving
    toilets to oil refinery tanks and the use of UWB technology to allow
    auto focus cameras to calculate distances more accurately.

***[Communications Applications]{.underline}***

12. Several parties noted that UWB devices can be used for a variety of
    communications applications involving the transmission of very high
    data rates over short distances without suffering the effects of
    multi-path interference. Such devices could be used to wirelessly
    distribute services such as phone, cable, and computer networking
    throughout a building or home. UWB communications devices could also
    be utilized by police, fire, and rescue personnel to provide covert
    secure communications devices. Some parties believe that UWB
    technology would be useful for outdoor wide area communication
    systems.

***[General Characteristics]{.underline}***

13. The comments suggest that UWB devices will have a variety of
    technical characteristics depending upon the intended application.
    U.S. Radar Inc., Geophysical Survey Systems, Inc. (GSSI), and the
    U.S. Geologic Survey indicate that GPRs operate with center
    frequencies of up to 3 GHz, and with bandwidths of up to 2 to 3
    times the center frequency.[^22] Lawrence Livermore National
    Laboratories (LLNL) expects that UWB devices will operate with a
    center frequency anywhere between 20 MHz and 60 GHz, with bandwidths
    ranging from 150 MHz to 30 GHz.[^23] Multi Spectral Solutions, Inc.
    (MSSI) indicates that it has developed systems for the U.S.
    Government operating in the bands 30 -- 50 MHz, 225 -- 400 MHz, 1.3
    -- 1.7 GHz, 2.2 --2.7 GHz, 5.4 -- 5.9 GHz and 9.0 -- 11.0 GHz using
    bandwidths from 20 MHz to 2 GHz.[^24] Time Domain provides a table
    of potential UWB applications and the frequency ranges in which they
    are likely to operate.[^25] In this table, Time Domain suggests that
    GPRs and long range military communications will tend to operate at
    frequencies below 1 GHz; law enforcement and emergency motion and
    imaging devices, high performance microphones, security fences, and
    other devices will operate in the 1 -- 2 GHz region; and devices
    such as road and runway inspection radars, law enforcement and
    emergency service mobile imagers, buried victim rescue, RF Asset ID
    and tracking devices, collision avoidance sensors, etc. will operate
    in the 2 -- 8 GHz region and above. Time Domain states that it has
    built a number of UWB radars and communications systems operating
    below 2 GHz with bandwidths of up to 800 MHz.

14. GSSI indicates that GPRs typically have no more than 10 mW average
    power and 10 W peak power, but it has designed GPRs for the U.S.
    Government that use up to 200 mW average power and 1 kW peak power.
    [^26] ANRO Engineering, Inc., notes that it has designed intrusion
    sensors for protecting defined perimeters on water and land with
    average powers of up to 1 mW and peak powers of up to 1 kW.[^27]
    MSSI also indicates that it has developed a variety of devices for
    the U.S. Government and the military with average powers between 2
    μW and 100 mW and peak powers ranging between 0.2 W and 16 W. MSSI
    anticipates that commercial UWB applications can be met with the
    same power levels given for spread spectrum and UNII devices of 1 W
    transmitter output power with a 6 dBi antenna.[^28]

15. The *NOI* also requested comment concerning the expected or desired
    operating distances for unlicensed UWB devices. GSSI expects GPRs to
    operate at depths from one meter up to tens of meters.[^29] Some
    parties suggest that most UWB devices will typically have operating
    distances from 1 cm to 30 meters.[^30] LLNL expects low power
    devices to have operating distances of 5 cm, and up to 1000 meters
    for high power, long range devices.[^31]

16. We observe that UWB technology may have a variety of technical
    characteristics, depending upon the intended application. We have
    considered the technical information provided in the comments as the
    basis for developing proposed rule amendments and alternatives, as
    discussed further below.

***Regulatory Treatment\
***

17. In the *NOI*, the Commission suggested that most UWB devices should
    be regulated on an unlicensed basis under Part 15 of the rules.
    However, the *NOI* requested comment on whether there are certain
    types of UWB devices or applications that should be regulated on a
    licensed basis under some other FCC rule part. The Ultra-Wideband
    Working Group (UWBWG), Zircon Corp., Clifford Harter, TEM
    Innovations, Time Domain Corp., Rosemount Measurements, and ANRO
    Engineering favor utilizing an unlicensed regulatory approach under
    Part 15 of the rules.[^32] The Wireless Information Networks Forum
    (WINForum) believes that some form of licensing is appropriate for
    UWB devices that deliberately emit energy in restricted frequency
    bands.[^33] Oak Ridge National Laboratory, TEM Innovations, LLNL,
    and Arthur D. Little, Inc. believe that some form of licensing
    should be provided for low volume, higher power UWB device
    operations.[^34] Zircon generally supports unlicensed operation for
    UWB devices that meet the emissions limits for Class B digital
    devices.[^35] Zircon argues that the Commission should also permit
    UWB devices that meet the emissions limits for Class A digital
    devices to operate on an unlicensed basis under Part 15, but these
    devices should be coordinated with NTIA and registered in a data
    base listing the users and their locations. Zircon asserts that
    individual licensing may be necessary for devices operating above
    the Class A limits.[^36] GSSI suggests that UWB devices that radiate
    less that 10 mW average power and 1 kW peak power should be
    unlicensed.[^37]

18. Upon reviewing all the comments, we observe that most of the
    near-term applications for UWB technology involve relatively low
    powers and short operating ranges. Further, we note that most UWB
    devices are intended to be mass marketed to businesses and consumers
    and that individual licensing of each device would be impractical.
    These characteristics are largely consistent with devices that
    operate on an unlicensed basis under Part 15 of the rules.
    Accordingly, we tentatively conclude that it is appropriate to
    regulate under Part 15 of the rules low power UWB devices intended
    to be mass marketed to businesses and consumers.

19. We request comment on our proposal to accommodate very low power UWB
    devices within Part 15 of the FCC rules. We recognize that UWB
    technology may be developed for higher power applications such as
    wide-area mobile radio services. However, we find that such
    applications raise many new and novel questions, such as consistency
    with the international and domestic table of frequency allocations,
    and how such services might be licensed to share spectrum across
    broad frequency ranges used by multiple existing services and
    licensees. We observe that there is insufficient information in the
    record to address such issues. Accordingly, we are not making any
    proposals at this time to allow high power UWB devices to operate
    under Part 15 or on a licensed basis.[^38]

    ***UWB Definition***

20. In the *NOI* the Commission recognized that rules may need to be
    developed specifically for UWB devices and invited comment as to an
    appropriate definition for UWB. Several of the commenters[^39]
    suggested that we adopt the UWB definition established by the
    OSD/DARPA UWB radar review panel.[^40] That definition states that
    UWB devices must have a -20 dB fractional bandwidth of at least
    0.25.[^41] In order for the fractional bandwidth to equal or exceed
    0.25, the --20 dB bandwidth must be at least 25% of the center
    frequency. Under this formula, the minimum --20 dB bandwidth is 250
    megahertz if the center frequency is 1 GHz, 1.25 gigahertz if the
    center frequency is 5 GHz, and 2.5 gigahertz if the center frequency
    is 10 GHz. Alternatively, M/A-Com suggests that a distinction
    between devices that operate above and below 10 GHz is needed
    because at higher frequencies the benefits of UWB may be achieved
    with lower fractional bandwidths.[^42] M/A-Com believes that UWB
    should be defined as a fractional bandwidth of at least 25 percent
    for devices operating below 10 GHz and a bandwidth of at least 2.5
    GHz for devices operating above 10 GHz, based upon -20 dB.[^43]
    Milltronics offers that we should allow UWB to comprise a pulse
    transmission using a burst of controlled or stabilized carrier
    frequency where burst length is less than 3 nS and the pulse
    repetition frequency (\"PRF\") is less than 5 MHz.[^44] Interval
    Research Corp. (Interval) believes that UWB devices should be
    defined as any device having a fractional bandwidth greater than
    .25.[^45] MSSI suggests that, instead of defining the term UWB, we
    should define and apply the term \"bandlimited short impulse,\" or
    \"bandlimited impulse,\" because UWB devices are better categorized
    by their duty cycle, or excess bandwidth ratio[^46], rather than by
    their fractional bandwidth.[^47] Rosemount Measurement believes that
    any device that has a spectrum usage greater than 1.5 GHz should be
    considered UWB.[^48] Other commenters[^49] made similar suggestions,
    but asked that we take antenna characteristics into account when
    determining emission bandwidth. SAAB Marine Electronics asserts that
    a device using a fairly smooth frequency spectrum with a bandwidth
    greater than 5 percent of the center frequency should be considered
    UWB.[^50]

21. We preliminarily believe that the definition established by the
    OSD/DARPA UWB radar review panel is appropriate with some
    modifications. Specifically, we are proposing to define UWB devices
    as any device where the fractional bandwidth is greater than 0.25 or
    occupies 1.5 GHz or more of spectrum.[^51] This modified definition
    will avoid situations where devices operating at several gigahertz
    and above might unnecessarily use wide bandwidths simply to qualify
    as an UWB device. We are also proposing to base the definition of an
    UWB device on the -- 10 dB bandwidth rather than the -- 20 dB
    bandwidth. We propose this modification because UWB devices will
    operate so close to the noise floor that in many cases it will not
    be possible to measure the -- 20 dB bandwidth. For the purpose of
    this definition, we will define the center frequency of the
    transmission as the average of the upper and lower --10 dB points,
    *i.e.*, (f~H~+f~L~)/2, as noted earlier.[^52] Finally, we are
    proposing that the bandwidth be determined using the antenna that is
    designed to be used with the UWB device. We invite comment on this
    proposed definition and whether the fractional bandwidth should be
    changed to account for the narrower bandwidth that would be measured
    using the --10 dB emission points instead of the --20 dB points. We
    request comment on whether we should use some other method to
    determine the emission bandwidth, such as a calculated bandwidth
    based on pulse width. We also request comment on whether we should
    define UWB devices as limited to devices that solely use pulsed
    emissions where the bandwidth is directly related to the narrow
    pulse width. We recognize that other types of modulation, such as
    linear sweep FM, could be employed to produce UWB equipment.
    However, we do not believe that we have sufficient information to
    propose limits and measurement procedures for such systems. Until
    more experience is gained, we believe that our initial rule making
    proposals should reflect a conservative approach. In addition, we
    request comment on whether extremely high speed data systems that
    comply with the UWB bandwidth requirements only because of the high
    data rate employed, as opposed to meeting the definition solely from
    the narrow pulse width, should be permitted. Finally, we request
    comment on any alternative definitions that may be appropriate.

***Frequency Bands of Operation***

22. In the *NOI*, the Commission noted that Part 15 designates certain
    sensitive and safety-related frequency bands as restricted
    bands.[^53] Only spurious emissions[^54] not exceeding the general
    emission limits are permitted within these restricted bands or, with
    few exceptions, within the frequency bands allocated for TV
    broadcasting. Comments were requested on whether the Commission
    should eliminate the requirement that only spurious emissions be
    permitted within the restricted bands and the TV broadcast bands.
    Comments were also requested on whether UWB operation should be
    permitted in certain restricted bands and the impact that retaining
    certain restricted bands may have on the viability of UWB
    technology.

23. Most of the commenting parties agree that the majority of UWB
    systems cannot avoid transmitting within the restricted bands.[^55]
    In some cases, particularly with GPRs, it is necessary that the
    equipment operate in the restricted bands and TV broadcast bands
    below 2 GHz in order to obtain sufficient ground penetration to
    detect or image objects.[^56] A number of parties raised concerns
    that UWB devices could cause harmful interference to existing radio
    operations in the restricted frequency bands, TV broadcast bands,
    amateur radio frequency bands and others.[^57] Several parties
    raised particular concerns about potential interference to GPS
    operating in the frequency band 1559 -- 1610 MHz. The U.S. GPS
    Industry Council argues that UWB operation should be limited to
    spectrum well above 1610 MHz, preferably above 3 GHz, to protect GPS
    operations from harmful interference.[^58] With regard to retaining
    certain restricted bands, several comments opposed the use of
    filters to avoid operation within those bands.[^59] As stated by
    Time Domain, the addition of filters to notch out portions of the
    transmitted spectrum would result in higher cost and would disperse
    the waveform over time due to complex ringing modes of the filter
    tuned circuits.[^60] Time Domain adds that the requirement to use
    notch filters would render UWB infeasible by decreasing the signal
    to noise ratio, reducing available processing gain, decreasing
    ranging and positioning capability and removing multipath immunity
    and jamming resistance. MSSI argues that UWB operations should be
    confined to frequencies above 2 GHz.[^61] Interval suggests that we
    initially allow UWB operations only in the frequency band 2.9-4.99
    GHz.[^62]

24. We have considered a number of factors in addressing what frequency
    bands should be made available for UWB devices. First, we believe
    that it is vitally important that critical safety systems operating
    in the restricted frequency bands, including GPS operations, are
    protected against interference. Second, we believe that there are a
    broad variety of potential applications for UWB technology, each of
    which has unique spectrum attributes and requirements. Third, we
    note that the various regions of the spectrum have different
    propagation characteristics. As Arthur D. Little, Inc. points out,
    for example, an UWB signal operating at the general emission limits
    in 47 C.F.R. § 15.209 would fall below a victim receiver's thermal
    noise at a distance of 40 meters at 500 MHz, and at a distance of 10
    meters at 5 GHz.

25. We have developed a number of alternative proposals based on these
    considerations. We observe that GPRs must operate at frequencies in
    the region below 2 GHz in order to obtain the penetration depth and
    resolution necessary to detect and obtain the images of buried
    objects. [^63] GPRs can neither avoid nor notch out the restricted
    frequency bands. We believe the risk of interference from GPRs is
    negligible because the overwhelming majority of their energy is
    directed into the ground where most of the energy is absorbed.
    Emissions in other directions can be easily shielded without
    affecting the operating characteristics of the GPR. In addition,
    GPRs are expected to have a low proliferation and usually operate at
    infrequent intervals. Thus, the interference potential of these
    devices should be low. We also note that, according to the comments,
    these devices have been used in limited numbers for quite some time
    for both government and non-government applications without any
    known instances of harmful interference. Accordingly, we propose to
    allow GPRs to operate in any part of the spectrum, subject to the
    emissions limits discussed below. We propose to define a GPR as an
    UWB device that is designed to operate only when in contact with, or
    in close proximity (*i.e.*, 1 meter) to, the ground for the purpose
    of detecting or obtaining the images of buried objects. We also
    propose to require GPRs to include a switch or other mechanism to
    ensure that operation occurs only when it is activated by an
    operator and the unit is aimed directly down at the ground. We
    invite comment on these proposals.

26. The situation is less clear with regard to UWB devices that would be
    used to detect or obtain the images of objects inside or behind
    walls or other surfaces. In particular, it is unclear whether the
    same arguments that apply to GPRs concerning penetration depth and
    resolution similarly apply to other imaging devices. [^64] In
    contrast to GPRs, where signals are aimed at the ground,
    through-wall imaging devices could aim their energy in any
    direction. While the wall could attenuate these signals, the amount
    of attenuation can vary widely depending on the composition of the
    wall. We note that such systems would be expected to have a low
    proliferation and would be operated infrequently. One option would
    be to treat all imaging devices the same way as GPRs. Alternatively,
    we could restrict the operation of such devices below a certain
    frequency. We invite comment on these alternatives and any other
    approaches that may be appropriate. Comments also are requested on
    what provisions are needed to ensure that these systems operate only
    when they are in contact with a wall.[^65] In addition, comments
    should address whether the operation of through-wall imaging systems
    should be limited to parties eligible for licensing under the Public
    Safety Pool of frequencies in Part 90 of our rules, as required
    under the earlier waiver to Time Domain.[^66] Comments also are
    requested on whether through-wall imaging systems should be required
    to incorporate automatic power control features that would reduce
    power levels to the minimum necessary to function based on the
    composition of the surface and its absorption of RF energy.

27. We observe that most other applications for UWB technology could
    operate in a variety of regions of the spectrum. To realize the full
    benefits of this technology, we believe that we should establish as
    few restrictions as possible on the operating frequencies, except as
    necessary to protect existing services against interference. We
    believe that UWB devices can generally operate in the region of the
    spectrum above approximately 2 GHz without causing harmful
    interference to other radio services. The UWB signals will quickly
    fall off below the background noise because of the high propagation
    losses at 2 GHz and above. Further, most radio services operating
    above 2 GHz use directional antennas that generally discriminate
    against reception of undesired signals. Accordingly, we are not
    proposing any restrictions on UWB devices operating at frequencies
    above approximately 2 GHz. We invite comment on this proposal.

28. We have a number of concerns about generally permitting the
    operation of UWB devices in the region of the spectrum below
    approximately 2 GHz. This is perhaps the most heavily occupied
    region of the spectrum and is used for public safety, aeronautical
    and maritime navigation and communications, AM, FM and TV
    broadcasting, private and commercial mobile communications, medical
    telemetry, amateur communications, and GPS operations. We note that
    41 of the 64 restricted frequency bands are at or below 2 GHz, not
    counting the TV broadcast bands. We are particularly concerned about
    the impact of any potential interference to the GPS band at 1559 --
    1610 MHz. We also would be concerned about interference to any
    additional frequencies allocated to GPS, *e.g.*, the planned L5
    frequency in the 960-1215 MHz band. As pointed out by many of the
    comments, GPS will be increasingly relied upon for air navigation
    and safety, and is a cornerstone for improving the efficiency of the
    air traffic system. We note also that GPS may be used by commercial
    mobile radio E-911 services to enable police and fire departments to
    quickly locate individuals in times of emergency. Moreover, use of
    GPS is expanding for use by businesses and consumers for all sorts
    of applications, such as for navigation by automobiles, boats and
    other vehicles, surveying, hiking, and geologic measurements.
    Therefore, any harmful interference to GPS could have a serious
    detrimental impact on public safety, businesses and consumers. We
    note, in addition, that propagation losses are not as great below 2
    GHz, and services in this region of the spectrum tend to employ
    omni-directional antennas that do not discriminate against undesired
    signals. These factors tend to increase the risks of interference
    below 2 GHz.

29. In light of these factors, we have significant concerns about the
    operation of UWB devices, except for GPRs and possibly through-wall
    imaging devices, in the region of the spectrum below approximately 2
    GHz. As explained earlier, we believe that it is vitally important
    to ensure that critical safety systems, including GPS operations,
    are protected from harmful interference. We invite comments on UWB
    operations, potential restrictions on operation for UWB below 2 GHz,
    and the impacts such restrictions would have on any potential
    applications for UWB technology. We also invite comment as to the
    precise frequency below which operations of UWB devices may need to
    be restricted.[^67] For example, should we restrict operations below
    the GPS band at 1610 MHz, or below the restricted band at 1718.8 -
    1722.2 MHz, or below the Personal Communication Service band at
    1850 - 1990 MHz, or some other frequency? What should be the limit
    of any restrictions?

30. We also wish to consider a number of alternative approaches to
    expressly prohibiting operations in the frequency bands below 2 GHz.
    For example, we note that certain UWB applications may be feasible
    using extremely low signal levels. We invite comment as to whether
    and at what levels, if any, we should permit operation in the
    restricted bands below 2 GHz for devices that can operate using
    extremely low signal levels. While we recognize that UWB technology
    generally cannot completely notch out frequency bands that are a
    subset of their operating frequencies, we invite comment as to the
    viability of establishing a general emission limit for UWB devices
    below 2 GHz, and whether a very stringent limit, or notch, should be
    applied to the GPS band. Comments are invited on these alternatives
    and any others that may be appropriate for regulating the
    frequencies of operation of UWB devices. Even though we are
    considering restricting the operation of UWB devices from use below
    approximately 2 GHz, we will consider allowing access to this
    spectrum provided that test results and detailed technical analyses
    are submitted demonstrating that there is no risk of harmful
    interference to GPS, to other services operating in restricted
    frequency bands, or to TV broadcasting.

***Further Testing and Analyses***

31. As noted above, we understand that various parties are planning
    experimental programs to study the interference potential of UWB
    devices. NTIA is planning a study at its Institute for
    Telecommunication~~s~~ Sciences in Colorado. The Department of
    Transportation has already contracted with Stanford University for
    tests to examine potential interference to GPS receivers. We also
    understand that certain manufacturers of UWB devices and other
    interested parties are planning tests. We welcome these testing
    programs and believe that the information they yield will be
    important for developing emission limits for UWB devices that will
    protect other radio services against interference. Commission staff
    will monitor the progress of these tests. We would like to encourage
    all of the interested parties to work together cooperatively so that
    this work can be completed in a timely and efficient manner. We
    encourage parties to submit the test results into the record in this
    proceeding by October 30, 2000. At the appropriate time, we will
    issue a public notice to provide an opportunity to provide comments
    and replies on the test results and analyses.

32. We recognize that the establishment of emissions limits requires a
    firm understanding of the characteristics of UWB signals, their
    impact on victim receivers, and the minimum separation distance
    between UWB devices and victim receivers. Almost any transmitter
    will cause interference if it is too close to a receiver. For
    example, in the case of personal computer emissions our goal has
    been to provide TV broadcast receivers with a 45 dB
    signal-to-interference ratio within the grade A contour where the
    personal computer is separated from the TV receiver by 10 meters
    with an 8 dB separating wall.[^68] Thus, as parties perform
    measurements and analyses of UWB devices we ask that they consider
    and provide information on receiver susceptibility to UWB signals
    along with the spatial geometries assumed for the susceptibility
    studies.

33. There are several possible interference mechanisms for receivers. We
    request that comments discussing interference risk to a particular
    service identify the specific interference mechanisms they are
    concerned about and provide the following information, if
    possible: 1) typical desired signal strengths at receivers in that
    service; 2) receiver inherent noise level or noise figure; 3)
    typical antenna patterns for the system and frequency response of
    the antenna for out-of-band signals indicating expected differential
    antenna gain for UWB signal and desired signal if applicable; 4)
    typical front end bandwidths before the first mixer in receivers; 5)
    typical dynamic range limits of receiver mixers -- preferably third
    order intercept points; 6) typical IF bandwidths; 7) required
    signal-to-interference ratios for reliable performance of the system
    assuming interference is white gaussian noise and with others types
    of interference; 8) required interference to noise ratio; and 9)
    minimum distance to an interference source that is not under the
    control of the user. While it is helpful to know the signal level of
    a particular UWB emission that causes interference to a class of
    receivers, we would like to extrapolate measurements to a variety of
    UWB signals so that the designers of UWB devices will have
    flexibility in their waveform design. For example, some of the
    parties filing comments on the NOI felt that emission limits should
    be based on the unintentional emission limits for digital devices
    contained in Section 15.109 of our Rules, with a possible adjustment
    of the quantitative limit. Above 1 GHz, this rule limits average
    field strength emissions to 150 uV/m at a distance of 10 meters
    measured over a bandwidth of 1 MHz. We request experiments and
    comments of whether this framework is an appropriate model for
    interference potential of UWB signals to other systems. For example,
    what types of systems are effectively modeled by such a protection
    criterion? [^69] What types of systems need a different type of
    protection criterion?

**Emission Limits\
**

34. In order to control harmful interference from UWB devices, it is
    important that we establish appropriate emission limits. In the NOI,
    the Commission noted that the current Part 15 rules are based on the
    equivalent of a power spectral density, i.e., a field strength limit
    is specified along with a measurement bandwidth. These emission
    bandwidths were chosen to protect various classes of receivers from
    interference. Further, the emission limits were established based on
    the potential interference from a single Part 15 device and do not
    take into account cumulative effects that could occur if a number of
    devices are located closely together. Comments were sought on the
    following questions: 1) Are the existing general emission limits
    sufficient to protect other users, especially radio operations
    within the restricted bands, from harmful interference or should
    different limits be applied to UWB systems; 2) Should standards be
    based on spectral power density and should those standards be
    designed to ensure that the UWB emissions appear to be background
    noise; 3) What is the potential for interference due to the
    cumulative impact of emissions from multiple transmitters; 4) Should
    a limit on the total peak level apply to UWB devices; 5) Can
    emissions below or above a certain frequency range be further
    filtered to reduce interference potential without affecting UWB
    performance; 6) Are the existing limits on the amount of energy
    permitted to be conducted back onto the AC power lines appropriate
    for UWB devices; 7) What operational restrictions, if any, should be
    required to protect existing spectrum users;[^70] and 8) Is the use
    of UWB modulation techniques necessary for certain types of
    communication systems and, if so, for what purposes?

35. As noted above, several comments filed in response to the NOI
    suggested that the Commission should adopt the same emissions limits
    for UWB devices as already exist for unintentional radiators, such
    as digital devices. Others argue that we should apply the general
    emissions limits for intentional radiators, but disregard pulse
    desensitization when performing measurements, effectively allowing
    higher peak levels than permitted under the current rules. The
    radiated emissions limits below 1 GHz are based on measurements with
    a quasi-peak detector, which effectively provides an average reading
    with some weighting for peak signal levels. The radiated emissions
    limits for both intentional and unintentional radiators above 1 GHz
    are based on measurements using an average detector. However,
    intentional radiators are also subject to a requirement that the
    total peak levels of emissions above 1 GHz must be no greater than
    20 dB above the average limits.[^71] Based on the comments on the
    NOI, it appears that the peak levels for UWB devices could be up to
    60 dB higher than the average levels. This difference is significant
    because these higher peak levels could lead to an increased risk of
    interference to certain receivers. For example, if the pulse
    repetition frequency of the UWB signal is much greater than the
    bandwidth of a receiver, the emission may appear to be random noise,
    the effect of which is proportional to the average power in the UWB
    signal within the receiver's bandwidth. However, if the PRF is less
    than the receiver's bandwidth, the UWB signal may appear to the
    receiver as impulsive noise and the effect would be proportional to
    the peak power of the UWB signal. We also note that UWB devices
    spread their emissions over a wide bandwidth as compared to most
    current intentional and unintentional radiators. As a result,
    receivers that use wide bandwidths are likely to receive more total
    energy from UWB devices than from most other existing Part 15
    devices. Accordingly, we believe that special consideration is
    needed to develop emissions limits for UWB devices.

36. We tentatively conclude that it is necessary to regulate both the
    peak and average emission levels above 1 GHz and the quasi-peak
    emission levels below 1 GHz from UWB transmitters, just as we
    regulate these emission levels for most other types of Part 15
    transmission systems. The impact of UWB signals on a receiver
    appears to depend on the randomness of the UWB signal and the
    relationship between the pulse repetition frequency (PRF) of the UWB
    signal and the bandwidth of the receiver[^72]. If the UWB pulses are
    spaced evenly in time and each pulse is exactly the same (as in many
    radar systems), then classic communications theory shows that the
    spectrum consists of narrow spectral lines spaced at the PRF. The
    impact of these signals on a receiver can be modeled by treating
    each spectral line as a narrowband conventional signal. This gives
    rise to one possible way to increase protection to GPS receivers
    from UWB GPR and through-wall imaging devices. Since repetitive
    identical pulses are often applicable to GPRs and through-wall
    imaging devices, it may be possible for designers to select system
    parameters to avoid GPS signal bands and thus avoid co-channel
    interference. It also may be possible to space the UWB signal's
    spectral lines in places within the GPS band where GPS receivers are
    less sensitive to interference. We request comment on whether this
    technique is applicable to all types of GPRs and through-wall
    imaging devices and the cost implication of using a stable frequency
    reference to ensure the PRF creates a signal avoiding the GPS bands.

37. For UWB communications systems, the emitted spectrum depends on the
    information being sent. If the information is unchanging, such as a
    steady string of zeroes in the case of digital information, the
    transmitted signal may become a set of spectral lines that has
    different interference potential than the noise‑like spectrum that
    would be produced under normal modulation. Depending on exactly
    where these spectral lines are, the interference potential may
    increase. This could be avoided by using scrambler technology, often
    used in digital wireline and optical communications systems, which
    prevents long strings of unchanging bits. We seek comment on whether
    we should require such scrambler technology for UWB communications
    systems or, alternatively, a performance requirement that would show
    that the transmitted spectrum remains noise like in the case of
    unchanging input data.

38. [Average and quasi-peak emission levels]{.underline}. Several
    commenting parties indicated that the general emission limits
    contained in Part 15 appear to be sufficient to control potential
    interference problems, noting that there has been no increase in
    interference complaints regarding Part 15 devices despite the
    geometric increase in the number of these devices.[^73] Some of the
    commenters stated that the interference would be no greater than
    that caused by the many unintentional radiators currently operating
    under Part 15.[^74] Interval and the UWBWG, among others, requested
    that the same levels applied to digital devices be applied to UWB
    products, including the higher limits currently applied to Class A
    digital devices used in non-residential environments.[^75] On the
    other hand, some of the comments requested that UWB be permitted to
    operate at power levels that would exceed the general emission
    limits. For example, ANRO Engineering, GSSI and Krohne request that
    an average power of 10 mW be permitted.[^76] MA/COM requests levels
    as high as 250 mV/m at 3 meters.[^77] Most of the commenting parties
    agreed that output limits should be based on spectral power density
    to reduce potential interference.[^78] However, other commenting
    parties expressed concern that operation at the general emission
    levels could result in harmful interference to GPS, Federal Aviation
    Administration systems, and weather radars at airports.[^79] The
    ARRL also expressed concern about interference to amateur operations
    should emissions be permitted at the general limits, requesting that
    additional experience with equipment operating under waivers is
    needed before rules are developed.[^80]

39. The Part 15 general emission limits[^81] have a long and successful
    history of controlling interference to other radio operations.
    However, we also recognize that the general emission limits were
    never designed to protect against all possibilities of harmful
    interference. Rather, these limits were designed to protect
    neighbors from causing interference to each other.[^82] These limits
    were designed as a reasonable compromise to protect the authorized
    radio services from receiving harmful interference without requiring
    an analysis of the individual needs of every type of receiver design
    used in every radio service. We remain committed to protecting the
    authorized radio services from receiving harmful interference from
    Part 15 devices. We are especially concerned about protecting radio
    services used for safety-of-life applications, such as GPS, from
    such interference. Accordingly, we believe that the general emission
    limits contained in 47 C.F.R. Section 15.209 appear appropriate for
    UWB operations. These emission limits are already based on a
    spectral power density, measuring signal level per unit
    bandwidth.[^83] As discussed above, we also are proposing that
    additional protection be provided below approximately 2 GHz for
    emissions from UWB devices. For emissions from UWB devices other
    than GPRs and, possibly, through-wall imaging systems, we
    tentatively propose that emissions that appear below approximately 2
    GHz be attenuated by at least 12 dB below the general emission
    limits. We believe that this attenuation below the general emission
    levels will provide additional protection to the congested spectrum
    below 2 GHz without affecting the viability of UWB operations.
    Comments are requested on whether such an attenuation level is
    necessary, or whether additional attenuation below 2 GHz is possible
    or necessary. We also seek comment on whether the proposed reduction
    in the emission levels should apply to all emissions below 2 GHz or
    only to emissions below 2 GHz that fall within the restricted bands
    shown in 47 C.F.R. § 15.205. Comments also are requested on whether
    UWB devices other than GPRs, and possibly through-wall imaging
    systems, should be permitted to operate below 2 GHz provided they
    comply with these reduced emission levels. Commenting parties should
    address any additional changes to the technical standards or to the
    operational parameters of UWB transmitters that could be employed to
    facilitate the operation of these products below 2 GHz.

40. We do not agree with the assessment of some of the comments that
    characterize the emissions from UWB systems as having the same
    potential for causing harmful interference as emissions from
    unintentional radiators. Unintentional radiators are permitted to
    radiate anywhere within the spectrum at the general emission limits.
    In most cases, unintentional radiators, as well as most conventional
    Part 15 transmitters, generate emissions on only a few narrow
    frequencies that approach the general limits; the other emissions
    are well below these limits. However, the emissions from UWB
    transmission systems are considerably different from those of
    unintentional radiators and conventional Part 15 transmitters. The
    high peak to average ratio of emissions, the extremely narrow pulse
    widths, and the pulse repetition frequencies employed by UWB devices
    serve to differentiate UWB products from other Part 15 devices. In
    particular, the emissions from UWB transmitters could be near the
    maximum permitted levels over several gigahertz of spectrum. Because
    UWB devices produce a wider range of emissions approaching the
    maximum emission levels, we also disagree with the comments that we
    should apply the Class A digital device emission limits to UWB
    products used in non-residential environments. [^84] Further, the
    difficulty in controlling the location of UWB devices, as
    demonstrated with our past experience with computers, and the
    potential that UWB products could have higher incidences of
    unshielded outdoor applications than digital devices could result in
    UWB devices causing a greater amount of harmful interference to
    other radio operations than digital devices. In addition, we do not
    agree with the comments that emission levels should be based on
    measurements taken outside of the building in which the equipment is
    located. Building attenuation varies widely based on the location of
    the equipment within the building and the composition of the
    building. It would be necessary to test UWB devices in every
    installation to ensure compliance with the standards; this presents
    an unreasonable test condition for the Commission, the manufacturers
    and the product users. Further, many of the proposed UWB products
    would be mobile devices, and it hardly seems likely that these
    products would be operated only within buildings. We believe that
    the emission limits being proposed in this *Notice* are a reasonable
    starting point for establishing standards. As equipment continues to
    be developed and additional experience is gained with this
    equipment, future changes to the standards may be considered.

41. [Peak emission limits]{.underline}. Those parties wishing to
    manufacture UWB devices expressed concern that establishing too low
    of a peak limit would preclude UWB devices that inherently have a
    high peak to average ratio.[^85] As indicated by WINForum, peak
    output does not directly impact interference seen by a narrowband
    receiver; it is the power spectral density of the pulse and the
    pulse repetition frequency that are important for controlling
    potential interference.[^86] On the other hand, the comments also
    expressed concern that the peak emission levels produced by UWB
    devices could cause harmful interference.[^87]

42. We believe that a limit on peak emissions is necessary to reduce the
    potential for UWB emitters to cause harmful interference to radio
    operations above 1 GHz. However, before we can propose a limit for
    peak emissions we first must clarify what is meant by peak for UWB
    applications. In the past, we have used a variety of peak
    definitions for different types of Part 15 devices in order to match
    the interference potential of the system being regulated to the
    necessary parameters. For example, for unlicensed spread spectrum
    systems we regulate the "maximum peak output power"[^88] while for
    unlicensed National Information Infrastructure ("U-NII") devices we
    use a definition based on average peak power over the transmitting
    interval.[^89] For most Part 15 devices, peak emission levels are
    field strength levels measured with a spectrum analyzer that is
    calibrated in terms of an RMS-equivalent voltage. Thus, the peak
    level measured by a spectrum analyzer results in an RMS value of the
    true peak. For the purposes of regulating UWB emissions, we propose
    two methods of measurement: 1) the peak level of the emission when
    measured over a bandwidth of 50 MHz which we believe is comparable
    to the widest victim receiver that is likely to be encountered,
    and 2) the absolute peak output of the emission over its entire
    bandwidth. Comments are requested on the suitability of these two
    measurements with regard to the potential for interference from UWB
    transmitters to wideband receivers used in the licensed radio
    services.

43. In the case of the first definition of peak level, *i.e.*, the peak
    signal strength measured over a 50 MHz bandwidth, we propose to
    apply a 20 dB limit with respect to the maximum permitted average
    emission level. This limit is consistent with the limit currently
    contained in 47 C.F.R. § 15.35(b). We further propose that the
    absolute peak limit for the emission over its entire bandwidth be
    variable based on the amount the --10 dB bandwidth of the UWB
    emission exceeds 50 MHz. We propose to use the following formula to
    calculate the amount that the absolute peak emission level over the
    entire bandwidth of the UWB emission would be permitted to exceed
    the Part 15 average emission limit: \[20 + 20log~10~(-10 dB
    bandwidth of the UWB emission in Hertz/50 MHz)\] dB. In addition, we
    propose that the absolute peak emission level not be permitted to
    exceed the average limit by more than 60 dB. This 60 dB limit is
    comparable with the limit permitted under the waivers recently
    issued to Time Domain Corporation, U.S. Radar Inc. and Zircon
    Corporation.[^90] For example, an UWB emission with a --10 dB
    bandwidth of one gigahertz would be permitted an absolute peak
    emission level over the total bandwidth of the emission of 46 dB
    above the maximum permitted Part 15 average emission level.
    Similarly, an UWB emission with a --10 dB bandwidth of 5 gigahertz
    or greater would be permitted an absolute peak emission level over
    the total bandwidth of 60 dB above the maximum permitted average
    emission level.

44. We do not believe that allowing such a high absolute peak signal
    relative to the Part 15 average limit will significantly increase
    the potential for harmful interference to other radio operations due
    to the wide spreading of the transmitted energy that is being
    required.[^91] We request comment as to whether the higher absolute
    peak limit will cause increased interference problems, especially
    using the proposed measurement procedures described below and with
    the limitations on frequency bands of operation described above.
    Comments are requested on the proposed method of varying the
    absolute peak emission limit and whether other features, such as the
    excess bandwidth, *i.e.*, the amount of the occupied
    bandwidth/effective data rate exceeds a specified level such as 10
    dB, should be employed in calculating a peak limit. Comments also
    are requested on whether wideband receivers used in the licensed
    services are sensitive to peak signal level in a unit bandwidth,
    such as the 50 MHz reference above, or to the total peak emission
    produced by the USB device, and whether both peak limits are needed
    to reduce potential interference to the authorized radio services.
    If only one peak limit is needed, the comments should indicate which
    limit is appropriate. We intend to rely heavily on submitted test
    data in determining what peak emission standards should apply to UWB
    products.

45. [AC power line conducted limits]{.underline}. The commenters were in
    agreement that the existing AC power line conducted limits are not a
    burden and should be applied to UWB devices.[^92] However, several
    potential UWB manufacturers requested that a higher limit be
    permitted for UWB devices used in non-residential environments,
    equivalent to the limits applied to Class A digital devices.[^93]
    For the same reasons cited above for the radiated emission levels,
    we do not agree that higher conducted limits should be permitted in
    non-residential environments. Besides the difficulty in controlling
    the location in which the product will be used, as demonstrated with
    our past experience with computers, UWB devices could have a higher
    incidence of outdoor applications with negligible shielding of
    emissions radiated from the AC power lines. We believe that the
    existing limit in 47 CFR Section 15.207 for controlling the amount
    of energy permitted to be conducted onto the AC power lines is a
    reasonable starting point for establishing standards until
    additional experience can be gained with this equipment.[^94] We
    seek comment on this conclusion.

46. [Cumulative impact]{.underline}. There was considerable variation
    among the comments regarding the effect of cumulative emissions from
    multiple, co-located UWB devices. Many parties indicated that a
    proliferation of UWB devices would have a negligible impact on the
    background noise level.[^95] Other parties express concern that
    there would be a cumulative effect and that this could impact
    vulnerable GPS and FAA radar systems.[^96] In particular, we note
    that the Commission's Technology Advisory Council, Spectrum
    Management Focus Group, reviewed analysis papers from four UWB
    technology firms, Time Domain, Interval Research, XtremeSpectrum,
    and A. D. Little Corp., and concluded that there would be no
    significant rise in the RF noise floor.[^97] Rather, that noise
    floor would be set by the closest UWB transmitters.

47. Nevertheless, as discussed above we believe that further testing and
    analysis is desirable on this issue. The cumulative impact appears
    to be negligible at the power levels and with the modulation types
    being proposed, especially when compared to the interference
    potential from a single land mobile transmitter. This leads us to
    believe that only the closest transmitter placing an emission on the
    frequency of concern would be of importance, obviating the need for
    additional attenuation to compensate for cumulative effects.
    However, the cumulative impact of several UWB devices may be
    different depending on their individual emission and transmission
    characteristics. For example, how does the cumulative impact of
    those UWB transmitters that emit a line spectrum compare to those
    that have a high level of random pulse positioning or dithering and
    may appear as Gaussian noise?[^98] Further, what is the relationship
    between pulse repetition frequency and the cumulative impact of a
    number of UWB devices? We look forward to receiving comments and
    test data from various parties along with relevant input from the
    Commission's Technical Advisory Council.

***Measurement Procedures***

48. In the *NOI*, the Commission addressed several questions on the
    measurement procedures that should be applied to UWB devices. The
    *NOI* noted that the current measurement procedures specify the
    frequency range over which measurements are to be made, as well as
    the measurement detector functions and bandwidths to be
    employed.[^99] It also noted that with conventional narrowband Part
    15 transmitters the peak level provides an indication of the
    interference potential of the device by measuring the total amount
    of energy that may appear in the passband of a receiver. Comments
    were requested on the following questions: 1) Does the peak output
    level continue to be indicative of the interference potential of an
    UWB system; 2) Is a pulse desensitization factor appropriate for
    measuring UWB emissions or should another measurement procedure be
    employed; 3) Is the frequency of the fundamental emission readily
    discernible and are the current measurement ranges appropriate for
    UWB devices;[^100] 4) Are the current measurement detector functions
    and bandwidths appropriate for UWB devices or should these standards
    be modified; and 5) Are there any other changes to the measurement
    procedures that should be applied to UWB devices?

49. Under the existing rules, below 1 GHz the emission levels are
    measured with a CISPR quasi-peak detector, and above 1 GHz emissions
    are based on average and peak measurements.[^101] The comments
    offered several methods for measuring UWB emissions. Some parties
    requested the use of a simple procedure that employs a spectrum
    analyzer with resolution bandwidth (RBW) and video bandwidth (VBW)
    settings of 1 MHz.[^102] WINForum provided a detailed analysis of
    the different measurements that are needed to characterize the
    interference potential of UWB emissions.[^103] WINForum asserts that
    different measurement bandwidths are necessary depending on the
    pulse repetition frequency of the UWB transmitter and the bandwidth
    of the receiver being protected from interference. We recognize that
    WINForum raises a valid point. However, we believe it is important
    to develop measurement procedures that are reasonably simple and
    straightforward and can apply to a wide range of UWB devices. We
    hope that the additional testing of UWB devices that is expected to
    occur will provide valuable insight into the measurement procedures
    that should be applied. In the interim, the following paragraphs
    contain our tentative proposals.

50. [Average and quasi-peak measurements]{.underline}. Below 1 GHz, we
    propose to require emissions to be measured using a quasi-peak
    detector, which effectively provides a weighted average. This
    approach is identical to the approach used under our current Part 15
    rules for intentional and unintentional radiators.[^104] We invite
    comment on this proposal. Above 1 GHz, we propose to require average
    measurements to be made with a 1 MHz resolution bandwidth (\"RBW\"),
    as we currently do for intentional and unintentional radiators. We
    also propose that spectrum analyzer video averaging with a video
    bandwidth (\"VBW\") of no greater than 10 kHz or less than 10 Hz be
    used in conjunction with peak hold to determine the average level as
    a function of frequency. We believe that this is a simple and
    effective way to make the measurement but will consider alternative
    techniques that can be shown to give comparable or more accurate
    results.[^105]

51. [Peak measurements]{.underline}. Most of the comments objected to
    applying a pulse desensitization correction factor (PDCF)[^106] to
    determine the total peak emission, stating that the PDCF has little
    meaning for an UWB emitter that may spread its energy over several
    gigahertz of spectrum.[^107] Magnetrol International states that
    peak levels can not be measured with a spectrum analyzer and
    suggested, along with ANRO Engineering, the use of a fast sampling
    oscilloscope or similar device to measure peak levels.[^108] As GSSI
    correctly points out, the PDCF was designed for use with pulse
    modulated sinusoidal carriers.[^109] We agree with the comments that
    the PDCF was not designed for the measurement of impulse systems due
    to the lack of a sufficient number of zero crossings in the
    waveform.

52. Based on these concerns, we now propose to measure the peak emission
    level of UWB signals directly in the time domain. The first proposed
    definition of peak output, *i.e.*, peak level based on a measurement
    bandwidth of 50 MHz, is an untraditional one in the electromagnetic
    compatibility ("EMC") area and can not be measured with normal
    commercial EMC test equipment. However, microwave receivers designed
    for radar interception and analysis are available with such
    characteristics and have costs comparable to normal EMC test
    equipment. The IF output of a microwave receiver that uses a wide
    bandwidth, *e.g.*, 50 MHz, can be analyzed using a conventional
    oscilloscope in order to measure the peak level of the waveform in
    the time domain. We seek comments on the feasibility of this testing
    technique as well as its utility as a model for the interference
    potential of peak UWB levels.

53. Under the second definition of peak emission level, *i.e.*, the
    total peak output, we believe that this can be readily done with
    standard sampling oscilloscope techniques for UWB signals with
    evenly spaced identical elements, such as radar signals. For signals
    with modulation of their amplitude or spacing we believe that
    sampling oscilloscope technology can be used to measure the peak
    signal.[^110] We recognize that such measurement technology is more
    expensive than the equipment normally used for equipment
    authorization measurements, however such technology is typically
    used for the development of UWB systems. We also request comments on
    allowing peak measurements to be made with a spectrum analyzer using
    the PDCF, provided the applicant can show that the measurement as
    corrected by the PDCF is the true peak for the waveform being
    tested.[^111] We recognize that the peak level measured with a
    spectrum analyzer is the RMS peak and must be adjusted to obtain the
    true peak level. We seek comment on the types of UWB signals, if
    any, for which this latter measurement technique would be
    appropriate. Recognizing that the width of the fundamental lobe
    would be affected by the measurement antenna bandpass
    characteristics, particularly with impulse systems, comments also
    are sought on whether the PDCF employed in the latter measurements
    should be calculated based on an effective pulse width, *i.e.*, two
    divided by the bandwidth, in Hertz, of the emitted fundamental
    lobe.[^112]

54. For peak measurements of UWB signals, the antenna used in the
    measuring equipment could have an effect on the measured value. In
    particular, it is important that the receiving antenna system have
    no phase dispersion[^113] over the bandwidth of the signal. While
    this is easy to achieve for conventional signals whose bandwidth is
    small compared to the frequency, not all antennas have this
    characteristic in the case where the bandwidth is a significant
    fraction of the frequency. For example, a log periodic antenna has a
    different phase center at a different distance from the emitter for
    each frequency, which would result in phase dispersion for UWB
    signals. On the other hand, cavity-backed spiral antennas and horn
    antennas would be less vulnerable to this phenomenon. We seek
    comment on what type of measurement antennas are needed to make
    accurate peak measurements and the least restrictive way we might
    specify this in our final rules.

55. [Frequency range of measurement]{.underline}. The comments generally
    agreed that the existing ranges of frequencies over which
    measurements are required are appropriate.[^114] LLNL suggested
    basing the frequency range of measurement on a function of the pulse
    rise time for an impulse system.[^115] For impulse systems, we
    believe that the center frequency of the emission bandwidth, as
    determined by the --10 dB points, should be used as the reference
    for determining the upper frequency range over which emissions
    should be measured.[^116] Noting that the emission spectrum will
    change depending on the specific measurement procedures employed,
    *e.g.*, the use of average versus peak measurements, comments are
    requested on any specific measurement procedures that should be
    employed to determine the center frequency. For a carrier modulated
    system, we believe that the carrier frequency should continue to be
    used as the reference for determining the upper frequency range over
    which emissions should be measured. However, we are concerned that a
    manufacturer could employ a low frequency carrier with an extremely
    narrow pulse or a narrow pulse impulse system could be used with a
    low frequency antenna, resulting in emissions extending far beyond
    the tenth harmonic, the normal upper range of measurement.
    Accordingly, comments are requested on whether a different method of
    determining the frequency measurement range should be employed,
    *e.g.*, a system based on pulse rise time and width. In addition,
    commenting parties should note that the lower frequency range of
    measurements would continue to be determined by the lowest radio
    frequency generated in the device. Comments are requested on whether
    the pulse repetition frequency, pulse dithering frequency,
    modulating frequency or other factors would permit the investigation
    of a low enough frequency range to address possible amplification of
    the emitted signal due to antenna resonances below the fundamental
    emission.

######### ***Prohibition Against Class B, Damped Wave Emissions***

56. In the *NOI*, the Commission noted that the rules prohibit the use
    of Class B, damped wave emissions.[^117] This prohibition stems from
    a similar International Telecommunication Union regulation and is a
    throwback to the days when spark gap transmitters were
    employed.[^118] There is no longer a clear definition of a Class B,
    damped wave emission.[^119] In the *NOI*, the Commission questioned
    whether the prohibition against damped wave emissions should apply
    to UWB systems or if the prohibition was relevant in light of the
    relatively low power levels employed by UWB devices.

57. Except for MSSI, all of the comments agreed that we should eliminate
    the prohibition against Class B, damped wave emissions as this does
    not appear to be relevant at the power levels being proposed for UWB
    transmissions.[^120] We agree. These levels appear to be low enough
    to prevent harmful interference to other users of the spectrum.
    Further, unlike conventional damped wave transmissions it is likely
    that the receivers associated with UWB transmitters would attempt to
    recover as much of the transmitted bandwidth as possible for
    information processing purposes. Accordingly, we propose to
    eliminate this prohibition for UWB transmitters, and seek further
    comment on this proposal.

***Other Matters***

58. Several proponents of UWB devices have questioned whether such
    devices can operate under the standards contained in 47 C.F.R. §§
    15.217-15.255. This would result in a transmitter that may have a
    fundamental emission bandwidth greater than one gigahertz operating
    under the standards developed for a narrowband signal, *e.g.*, the
    30 MHz available for radar systems operating at 5800 MHz under 47
    C.F.R. § 15.245. These requests were submitted in an attempt to
    permit the manufacturers to avail themselves of the higher power
    levels permitted under these rule sections. However, in this
    *Notice* we are proposing specific regulations regarding the
    frequency of operation and emission levels that would apply to UWB
    devices. We believe that the existing rules should be amended to
    clarify that they do not apply to UWB devices. Accordingly, we
    propose to amend 47 C.F.R. § 15.215(c) to state that intentional
    radiators operated under the provisions of 47 C.F.R. §§
    15.217-15.255 or Subpart E of the current regulations must be
    designed to ensure that the main lobe or the necessary bandwidth,
    whichever is less, is contained within the frequency bands
    designated in those rule section under which the equipment is
    operated. The requirement to contain the fundamental emission within
    one of the specified frequency bands would include the effects from
    frequency sweeping, frequency hopping and other modulation
    techniques that may be employed as well as the frequency stability
    of the transmission over variations in temperature and supply
    voltage. If a frequency stability is not specified, the regulation
    would continue to recommend that the fundamental emission be kept
    within at least the central 80 percent of the band in order to
    minimize the possibility of out-of-band operation.

59. We propose to require that the regulations proposed in this *Notice*
    become effective 60 days from the date of publication of the Report
    and Order in this proceeding in the Federal Register. Comments are
    requested on this proposed transition provision.

    **PROCEDURAL MATTERS**

60. As required by Section 603 of the Regulatory Flexibility Act, 5
    U.S.C. § 603, the Commission has prepared an Initial Regulatory
    Flexibility Analysis (IRFA) of the expected impact on small entities
    of the proposals suggested in this document. The IRFA is set forth
    in Appendix A. Written public comments are requested on the IRFA.
    These comments must be filed in accordance with the same filing
    deadlines as comments on the rest of the *Notice of Proposed Rule
    Making ("Notice")*, but they must have a separate and distinct
    heading designating them as responses to the IRFA. The Commission's
    Consumer Information Bureau, Reference Information Center, SHALL
    SEND a copy of this *Notice*, including the IRFA, to the Chief
    Counsel for Advocacy of the Small Business Administration in
    accordance with Section 603(a) of the Regulatory Flexibility Act, 5
    U.S.C. § 603(a).

61. This is a permit-but-disclose notice and comment rule making
    proceeding. *Ex parte* presentations are permitted, except during
    the Sunshine Agenda period, provided they are disclosed as provided
    in the Commission\'s rules. *See generally* 47 C.F.R. §§ 1.1202,
    1.1203, and 1.2306(a).

62. Pursuant to Sections 1.415 and 1.419 of the Commission\'s Rules, 47
    C.F.R. §§ 1.415 and 1.419, interested parties may file comments on
    or before \[**insert date 90 days from date of publication in the
    Federal Register**\] and reply comments on or before \[**insert date
    120 days from date of publication in the Federal Register**\].
    Comments may be filed using the Commission\'s Electronic Comment
    Filing System (ECFS), <http://www.fcc.gov/e-file/ecfs.html>, or by
    filing paper copies. *See Electronic Filing of Documents in
    Rulemaking Proceedings*, 63 Fed. Reg. 23,121 (1998).

63. Comments filed through the ECFS can be sent as an electronic file
    via the Internet to <http://www.fcc.gov/e-file/ecfs.html>.
    Generally, only one copy of an electronic submission must be filed.
    If multiple docket or rule making numbers appear in the caption of
    this proceeding, however, commenters must transmit one electronic
    copy of the comments to each docket or rule making number referenced
    in the caption. In completing the transmittal screen, commenters
    should include their full name, Postal Service mailing address, and
    the applicable docket or rule making number. Parties may also submit
    an electronic comment by Internet e-mail. To get filing instructions
    for e-mail comments, commenters should send an e-mail to
    ecfs@fcc.gov, and should including the following words in the body
    of the message, \"get form \<your e-mail address.\" A sample form
    and directions will be sent in reply.

64. Parties who choose to file by paper must file an original and four
    copies of each filing. If more than one docket or rule making number
    appear in the caption of this proceeding, commenters must submit two
    additional copies for each additional docket or rule making number.
    All filings must be sent to the Commission\'s Secretary, Magalie
    Roman Salas, Office of the Secretary, Federal Communications
    Commission, 445 12th Street, S.W., TW‑A325, Washington, D.C. 20554.
    Comments and reply comments will be available for public inspection
    during regular business hours in the FCC Reference Center of the
    Federal Communications Commission, Room TW-A306, 445 12th Street,
    S.W., Washington, D.C. 20554.

65. The proposed action is authorized under Sections 4(i), 301, 302,
    303(e), 303(f), 303(r), 304 and 307 of the Communications Act of
    1934, as amended, 47 USC Sections 154(i), 301, 302, 303(e), 303(f),
    303(r), 304, and 307.

66. To make cited sources more easily available to the readers, we are
    testing the use of hyperlinks to some FCC documents that are cited
    in this document. The World Wide Web addresses/URLs that we give
    here were correct at the time this document was prepared but may
    change over time. We do not have dedicated staff to update these
    URLs, however, so readers may find some URLs to be out of date as
    time progresses. We also advise that the only definitive text of FCC
    documents is the one that is published in the FCC Record. In case of
    discrepancy between the electronic documents cited here and the FCC
    Record, the version in the FCC Record is definitive.

67. For further information regarding this *Notice of Proposed Rule
    Making*, contact John A. Reed, Office of Engineering and
    Technology, (202) 418-2455.

#  FEDERAL COMMUNICATIONS COMMISSION

Magalie Roman Salas

Secretary

**APPENDIX A**

**Initial Regulatory Flexibility Analysis**

As required by Section 603 of the Regulatory Flexibility Act,[^121] the
Commission has prepared an Initial Regulatory Flexibility Analysis
(IRFA) of the expected significant economic impact on small entities by
the policies and rules proposed in this *Notice of Proposed Rule Making
("Notice")*. Written public comments are requested on the IRFA. Comments
must be identified as responses to the IRFA and must be filed by the
deadlines for comments on the *Notice* provided above. The Commission
shall send a copy of this *Notice*, including the IRFA, to the Chief
Counsel for Advocacy of the Small Business Administration in accordance
with paragraph 603(a) of the Regulatory Flexibility Act.

**A. Reason for Action.**

This rule making proposal is initiated to obtain comments regarding
proposed changes to the regulations for radio frequency devices that do
not require a license to operate. The Commission seeks to determine if
its standards should be amended to permit the operation of
ultra-wideband transmission systems.

**B. Legal Basis.**

The proposed action is taken pursuant to Sections 4(i), 301, 302,
303(e), 303(f), 303(r), 304 and 307 of the Communications Act 10 1934,
as amended, 47 U.S.C. Sections 154(i), 301, 302, 303(e), 303(f), 303(r),
304, and 307.

**C. Description and Estimate of the Number of Small Entities to Which
the Proposed Rules Will Apply.**

For the purposes of this *Notice*, the RFA defines a \"small business\"
to be the same as a \"small business concern\" under the Small Business
Act, 15 U.S.C. § 632, unless the Commission has developed one or more
definitions that are appropriate to its activities.[^122] Under the
Small Business Act, a \"small business concern\" is one that: (1) is
independently owned and operated; (2) is not dominant in its field of
operations; and (3) meets any additional criteria established by the
Small Business Administration (SBA).[^123] SBA has defined a small
business for Standard Industrial Classification (SIC) category 4812
(Radiotelephone Communications) to be small entities when they have
fewer than 1500 employees.[^124] Given this definition, nearly all such
companies are considered small.

**D. Description of Projected Reporting, Recordkeeping and Other
Compliance Requirements.**

Part 15 transmitters are already required to be authorized under the
Commission\'s certification procedure as a prerequisite to marketing and
importation. The reporting and recordkeeping requirements associated
with these equipment authorizations would not be changed by the
proposals contained in this *Notice*. These changes to the regulations
would permit the introduction of an entirely new category of radio
transmitters.

**E. Significant Alternatives to Proposed Rules Which Minimize
Significant Economic Impact on Small Entities and Accomplish Stated
Objectives.**

We do not expect that the rules proposed in this Notice of Proposed Rule
Making will have a significant negative impact on small businesses.

**F. Federal Rules that May Duplicate, Overlap, or Conflict with the
Proposed Rule.**

None.

**APPENDIX B**

**Commenting Parties**

Parties filing comments:

1\. American Radio Relay League, Inc. (ARRL)

2\. ANRO Engineering, Inc.

3\. Arthur D. Little Inc. (ADL)

4\. Dwain K. Butler, U. S. Army Corps of Engineers

5\. Chesapeake Computer Consultants, Inc.

6\. Consumer Electronics Manufacturers Association (CEMA) and National
Association of

Broadcasters (NAB) - joint filing

7\. Endress + Hauser GmbH & Co. (Endress Hauser)

8\. Geophysical Survey Systems, Inc. (GSSI)

9.  David R. Hughes, Principal Investigator, National Science Foundation
    Wireless Field Test

> Project (corrected copy)

10\. Interval Research Corporation (Interval)

11\. George L. Johnston

12\. Jeff Kramer

13\. Lawrence Livermore National Laboratory, U.S. Department of Energy
(LLNL)

14\. Low Tech Designs, Inc. (LTD)

15\. M/A-Com

16\. Magnetrol International

17\. MALA GeoScience USA, Inc.

18\. Multispectral Solutions, Inc. (MSSI)

19\. NeoVac

20\. Gary R. Olhoeft

21\. Pulson Medical, Inc. (PMI)

22\. Quality Research

23\. Radar Solutions International

24\. Rosemount Measurement

25\. SAAB Marine Electronics

26\. SAT COM Consultants, Inc.

27\. Robert A. Scholtz

28\. Enrico M. Staderine

29\. Technos Inc.

30\. TEM Innovations

31\. Time Domain Corporation (Time Domain or TDC)

32\. TRW Electronics & Technology Division

33\. UltraPulse Communications, Inc. (UCI) (2 comments)

34\. Ultra-Wideband Working Group (UWBWG)

35. U.S. Department of Transportation, Federal Aviation Administration

36\. U.S. Geological Survey

37\. U.S. GPS Industry Council (Council)

38\. U.S. Radar Inc.

39\. Kathryn Vestal

40\. Wireless Information Networks Forum (WINForum)

41\. XtremeSpectrum, Inc.

42\. Zircon Corporation (Zircon)

Parties filing reply comments:

1\. American Radio Relay League, Inc. (ARRL)

2\. Arthur D Little Inc. (ADL)

3\. Broadband Telecom Systems

4\. Janice Bradley, Director, Lewistown Public Library

5\. Frank Burns

6\. California Geophysical Group, Inc.

7\. Barbara Dean Clark

8\. Thomas N. Cokenias

9\. Community Technology Centers\' Network

10\. ENSCO, Inc.

11\. Geo-Recovery Systems, Inc.

12\. E. Renee Gross, Sidney Public Library

13\. Clifford Harter

14\. David R. Hughes

15\. Interval Research Corporation (Interval)

16\. Robert W. Jacob

17\. Krohne, Inc.

18\. M/A-COM

19\. Milltronics

20\. Oak Ridge National Laboratory

21\. Jim Rezowalli

22\. Rosemount Inc.

23\. Saab Marine Electronics (Saab)

24\. Timothy J. Shepard

25\. Southwestern Bell Wireless, Inc.

26\. SPARTA, Inc., Simulation Technology Division

27\. Sub-Surface Informational Surveys, Inc.

28\. TEM Innovations (2 replies)

29\. Time Domain Corporation

30\. Kathryn Vestal

31\. XtremeSpectrum, Inc.

32\. Ultra-Wideband Working Group

33. U.S. GPS Industry Council, American Airlines, The General Aviation
    Manufacturers Association, Stanford University (The GPS Research
    Program) and United Airlines

34\. John A. Williams

35\. Bonnie Williamson, Havre-Hill County Library

36\. Zircon Corporation

37\. Brian Zisk

[^1]: *See Notice of Inquiry* in ET Docket No. 98-153, 63 Fed. Reg.
    50184, September 21, 1998,
    <http://www.fcc.gov/Bureaus/Engineering_Technology/Documents/fedreg/63/50184.pdf>.

[^2]: *See* 47 C.F.R. §§ 15.1 *et seq*.

[^3]: The primary operating conditions under Part 15 are that the
    operator must accept whatever interference is received and must
    correct whatever interference is caused. Should harmful interference
    occur, the operator is required to immediately correct the
    interference problem, even if correction of the problem requires
    ceasing operation of the Part 15 system causing the interference.
    *See* 47 C.F.R. § 15.5.

[^4]: *See* 47 C.F.R. § 15.209.

[^5]: *See* 47 C.F.R. §§ 15.215-15.407. In some cases, operation at the
    higher emission levels within these designated frequency bands is
    limited to specific applications.

[^6]: The sensitive bands referenced here are bands employed by radio
    services that must function, as a nature of their operation, using
    extremely low received signal levels. These systems may be passive,
    such as radio astronomy, or active, such as satellite down links and
    wildlife tracking systems.

[^7]: *See* 47 C.F.R. § 15.205.

[^8]: Typical pulse widths currently are on the order of 2-0.1
    nanoseconds, or less, in width. The emission spectrum appears as a
    fundamental lobe with adjacent side lobes that can decrease slowly
    in amplitude. Annex J of Chapter 5 of the National
    Telecommunications and Information Administration's Manual of
    Regulations and Procedures for Federal Frequency Management contains
    a procedure to calculate the 20 dB bandwidth of a non-FM pulsed
    radar using the equation B = 1.79/√(τ~r~τ) or 6.36/τ, whichever is
    less, where B is the bandwidth in megahertz, τ is the emitted pulse
    duration, in microseconds, at the 50% amplitude (voltage) points and
    τ~r~ is the emitted pulse rise time in microseconds from the 10% to
    the 90% amplitude points on the leading edge. As an example, for a
    pulse with τ = 1.0 nS, ignoring rise time, the 20 dB bandwidth of
    the emission is calculated to be 6.36 gigahertz. The spectrum
    produced by a pulsed emission consists of a line spectrum with the
    spectral lines separated by 1/T where T is the time, in seconds, of
    the pulse spacing.

[^9]: A definition of center frequency is proposed in paragraph 21 of
    this Notice.

[^10]: The fundamental emission, as used herein for pulsed UWB emission
    systems, consists of the main lobe when viewed on a spectrum
    analyzer. The sidelobes are not considered part of the fundamental
    emission. For a pulse modulated emission, the fundamental emission
    is calculated as 2/τ.

[^11]: HP Application Note 150-2 specifies the use of a pulse
    desensitization correction factor.

[^12]: *See* 47 C.F.R. §§ 15.35(b) and 15.209. Because UWB systems
    normally have a low duty cycle, the peak levels are quite high
    compared to the average emission levels.

[^13]: Several of the comments addressed long range spread spectrum
    systems. These are not ultra-wideband systems, and the comments are
    considered to be outside the scope of this proceeding.

[^14]: In addition, there have been several applications for grants of
    equipment authorization and an even greater number of inquiries to
    the staff to permit these systems.

[^15]: The U.S. Radar system employs different antennas, depending on
    the specific application. While the bandwidth employed by the radar
    can occupy up to several gigahertz of spectrum, the antennas are
    centered at 250 MHz, 500 MHz, 1 GHz and 2 GHz. U.S. Radar predicts
    that approximately 25 systems per year would be imported into the
    U.S. over a ten year period.

[^16]: The Time Domain systems have emissions centered in the 2-4 GHz
    band and occupy several gigahertz of spectrum. Time Domains
    indicates that sales would be restricted to no more than 2500 units
    which would be marketed to fire and police departments.

[^17]: The Zircon system has its emissions centered within the 200 MHz
    to 4 GHz band and emits an average radiated power of approximately
    125 uW. Zircon states that it would limit sales to \"professional
    tradespeople for use primarily in high noise construction
    environments.\"

[^18]: The NTIA is responsible for managing spectrum allocated to
    Federal government users.

[^19]: The U.S. GPS Industry Council, American Airlines, and United
    Airlines filed a consolidated petition for reconsideration of the
    waivers based on potential interference to Global Positioning System
    (GPS) operations in the 1559 -- 1605 MHz band.

[^20]: *See* 47 U.S.C. § 157(a) (1998).

[^21]: To date, the Commission has granted three waivers for devices
    using UWB technology. *See supra*. Separate from this proceeding, we
    will consider waiver requests on a case by case basis or if
    necessary enforcement action as appropriate.

[^22]: *See* U.S. Radar Inc. comments at 3, GSSI comments at 3, and U.S.
    Geological Survey comments at 1.

[^23]: *See* LLNL comments at 3.

[^24]: *See* MSSI comments at 4.

[^25]: *See* Time Domain comments at 20.

[^26]: *See* GSSI comments at 3.

[^27]: *See* ANRO Engineering comments at 3.

[^28]: *See* MSSI comments at 5.

[^29]: *See* GSSI comments at 3.

[^30]: *See* Rosemount Measurement comments at 4. *See also*, TEM
    Innovations comments at 7.

[^31]: *See* LLNL comments at 3.

[^32]: *See* UWBWG comments at 10, Zircon comments at 5-6, Clifford
    Harter comments at 1, TEM Innovations comments at 7, Time Domain
    Corporation comments at 27, Rosemount Measurement comments a 4-5,
    and ANRO Engineering comments at 3.

[^33]: *See* WINForum comments at 6.

[^34]: *See* Oak Ridge National Laboratory reply comments at 3, Tem
    Innovations comments at 7, LLNL comments at 6, and Arthur D. Little,
    Inc. comments at 6.

[^35]: The Class B limits are designed to protect against interference
    from digital devices used in residential environments. The Class A
    limits are designed to control interference from digital devices
    used exclusively in commercial or industrial environments. The Class
    A limits are approximately 10 dB less stringent than the Class B
    limits.

[^36]: *See* Zircon comments at 5-6.

[^37]: *See* GSSI comments at 3.

[^38]: With appropriate conditions, UWB systems can be licensed on an
    experimental basis under Part 5 of the FCC rules.

[^39]: *See*, for example, comments from ANRO Engineering at 3, Arthur
    D. Little at 7, GSSI at 3, Interval Research Corp. (Interval) at
    7-8, LLNL at 3, Pulson Medical, Inc. (PMI) at 3, Robert A. Scholtz
    at 1, Time Domain at 25-26, UWBWG at 8-10, WINForum at 5-6,
    XtremeSpectrum at 5-6, and Zircon at 3-4.

[^40]: *Assessment of Ultra-Wideband (UWB) Technology*, OSD/DARPA,
    Ultra-Wideband Radar Review Panel, R-6280, Office of the Secretary
    of Defense, Defense Advanced Research Projects Agency, July 13,
    1990.

[^41]: The formula for calculating fractional bandwidth is
    2(f~H~-f~L~)/( f~H~+f~L~) where f~H~ is the upper frequency of the
    --20 dB emission point and f~L~ is the lower frequency of the --20
    dB emission point. This formula can also be written as
    (f~H~-f~L~)/f~C~ where f~C~ is the center frequency. The center
    frequency is calculated as (f~H~+f~L~)/2.

[^42]: *See* M/A-Com reply comments at 3-4.

[^43]: *Id*.

[^44]: *See* Milltronics comments at 2.

[^45]: *See* Interval comments at 7-8.

[^46]: The excess bandwidth ratio is the amount that the occupied
    bandwidth/effective data rate exceeds a specified level.

[^47]: *See* MSSI comments at 9.

[^48]: *See* Rosemount Measurements comments at 5 and 8.

[^49]: *See*, for example, comments of Arthur D. Little at 7, Rosemount
    Measurement at 5 and 8, and SAAB Marine Electronics at 3.

[^50]: *See* SAAB Marine Electronics comments at 6.

[^51]: Under our proposed definition of an UWB device, the 1.5 GHz
    maximum bandwidth limit would only apply where the center frequency
    is greater than 6 GHz. We note that most of the UWB systems that
    have been brought to our attention employ fundamental emissions
    greater than 1.5 GHz.

[^52]: In some UWB systems, there is no clear center frequency as with
    other modulation techniques, such as AM and FM. Furthermore, the
    shape of the transmitted spectrum may be significantly modified by
    the frequency response of the antenna such that even the carrier
    frequency, where employed, may not represent the center frequency.

[^53]: *See* 47 C.F.R. § 15.205.

[^54]: Spurious emissions are defined as emissions outside of the
    necessary bandwidth, the level of which may be reduced without
    affecting the transmission of information. *See* 47 C.F.R. § 2.1.

[^55]: *See*, for example, comments of Time Domain at 36-37, Rosemount
    Measurement at 1, 2 and 8, Interval at 12, LLNL at 4, and the UWBWG
    at 10, and the reply comments of M/A-COM at 1 and Interval at 11 and
    16. MSSI, however, promotes a system that employed pulse and/or
    spectral shaping to avoid operation within the TV broadcast and
    restricted bands. *See* comments of MSSI at 3-4.

[^56]: *See* comments of UWBWG at 10.

[^57]: *See*, for example, joint comments of Consumer Electronics
    Manufacturers Association (CEMA) and National Association of
    Broadcasters (NAB) at 2-3, comments of SAAB Marine at 7, TEM
    Innovations at 7-8, U.S. Dept. of Transportation, Federal Aviation
    Administration (FAA) at 1-2, and the U.S. GPS Industry Council at
    1-5, and the reply comments of American Radio Relay League (ARRL) at
    1-5, and Oak Ridge National Laboratory at 6.

[^58]: *See* comments of U.S. GPS Industry Council at 6.

[^59]: *See*, for example, comments of Arthur D. Little Inc. at 9, GSSI
    at 4, Interval at 13, LLNL at 4-5, Rosemount Measurement at 2, U.S.
    Radar at 3, UWBWG at 11, Zircon at 7-8, and reply comments of
    Interval at 13.

[^60]: *See* comments of Time Domain at 37-40.

[^61]: *See* MSSI *ex parte* comments filed March 1, 2000.

[^62]: *See* Fantasma (formerly Interval) *ex parte* comments filed
    April 6, 2000.

[^63]: *See* comments of U.S. Radar at 3, GSSI at 3 and U.S. Geological
    Survey at 1.

[^64]: Time Domain's through-wall imaging system, authorized under a
    waiver issued on June 29, 1999, by the Chief, Office of Engineering
    and Technology, operates over a frequency band ranging from a few
    hundred Hertz to greater than 4 GHz. Through-wall imaging systems
    are limited to products that detect objects located on the other
    side of a wall. Under the waiver, operation was limited to parties
    eligible for licensing under the Public Safety Pool of frequencies
    in Part 90 of this chapter.

[^65]: *See* comments of TEM Innovations at 12.

[^66]: Consumer through-wall imaging systems, such as stud finders,
    could have a high proliferation. Accordingly, it may not be
    appropriate to include such devices in the same category as other
    through-wall imaging systems.

[^67]: Our concerns apply to all emissions within the --10 dB bandwidth
    of the UWB signal, not just at the center frequency.

[^68]: *See* Appendix C of the *First Report and Order -- Technical
    Standards for Computing Equipment*, Docket No. 20780, 44 Fed. Reg.
    59530, October 16, 1979.

[^69]: For an example of a case where this might not be a good model of
    interference protection, consider an unmodulated UWB signal
    containing no information (such as a radar signal) with even spacing
    of impulses interacting with a GPS receiver. The spectrum of such a
    UWB signal would consist of discrete lines evenly spaced at the
    pulse repetition frequency. It is reasonable to suppose that the
    impact of such a signal on a GPS receiver depends on the exact
    location of the frequency domain lines with respect to the GPS
    signals. Thus, interference would vary somewhat with details of the
    UWB signal parameter that would give the same exact reading with
    respect to uV/m with a 1 MHz measurement bandwidth.

[^70]: Comments on this subject concerned limits on products such as
    GPRs. These issues were addressed above under "Frequency of
    Operation."

[^71]: *See* 47 C.F.R. § 15.35(b).

[^72]: This assumes that the UWB signal is far enough from the receiver
    that it does not overload the receiver causing nonlinear operation.
    We believe that the emission limits we are considering will avoid
    such overloading in practical use.

[^73]: *See*, for example, comments of Interval at 10, Gary R. Olheoft
    at 1 and 3, and U.S. Radar at 2, and reply comments of Milltronics
    at 3, and Thomas N. Cokenias at 1.

[^74]: *See*, for example, reply comments of Interval at 2-3.

[^75]: *See* reply comments of Interval at 12 and comments of UWBWG at
    11-13. UWBWG also requests that the emission levels be measured
    outside of the building in which the equipment is operated. *See*
    also comments of Time Domain at 27-28 and WINForum at 6.

[^76]: *See* comments of ANRO Engineering at 5 and GSSI at 3 and reply
    comments of Krohne at 2. ANRO Engineering requests that peak powers
    of up to 2000 W be permitted, and GSSI requests that peak powers of
    up to 1000 W be permitted.

[^77]: *See* reply comments of MA/COM at 5. MA/COM also requests peak
    levels ranging from 10 W to 10,000 W.

[^78]: *See*, for example, comments of Arthur D. Little Inc. at 11, GSSI
    at 4, LLNL at 5, Rosemount Measurement at 1 and 4, and WINForum at
    5-6, and reply comments of Interval at 11, Milltronics at 3-4, and
    MA/COM at 1 and 5.

[^79]: *See* comments of TEM Innovations at 10, U.S. Dept. of
    Transportation, Federal Aviation Administration at 1-2, and U.S. GPS
    Industry Council at 1-5.

[^80]: *See* comments of ARRL at 1-4.

[^81]: *See* 47 C.F.R. §§ 15.109(a) and 15.209.

[^82]: While it would be possible to establish emission limits that
    would protect a user from his own interference at separation
    distances on the order of one meter, such limits would significantly
    add to the cost of all Part 15 devices, including computers,
    cordless telephones and receivers.

[^83]: Emissions below 1 GHz are measured using a CISPR quasi-peak
    detector with a resolution bandwidth of 120 kHz [+]{.underline} 20
    kHz. Emissions above 1 GHz are measured using a 1 MHz resolution
    bandwidth. *See* 47 C.F.R. § 15.35.

[^84]: Slightly higher emission limits are permitted for digital devices
    used in non-residential environments, *i.e.*, Class A digital
    devices. *See* 47 C.F.R. § 15.109(b).

[^85]: *See*, for example, comments of MSSI at 11-12, and TEM
    Innovations at 11, and reply comments of Milltronics at 4.

[^86]: *See* comments of WINForum at 6.

[^87]: *See*, for example, reply comments of Oak Ridge National
    Laboratory at 2.

[^88]: *See* 47 C.F.R. § 15.247(b).

[^89]: *See* 47 C.F.R. § 14.403(e).

[^90]: *See* waivers issued on June 29, 1999, by the Chief, Office of
    Engineering and Technology. While the waivers stated that the
    maximum peak to average ratio was limited to 30 dB, these ratios
    were calculated using 10 log~10~\[(pulse width) x (pulse repetition
    frequency)\] dB. For conventional pulses, the calculation would have
    been based on a 20 log~10~ factor, resulting in a maximum 60 dB peak
    to average ratio.

[^91]: The absolute peak power to the power in a line spectrum for a
    conventional pulse modulated signal at the fundamental emission may
    be equal to 20log~10~\[(pulse width in seconds) x (pulse repetition
    frequency in Hertz)\] dB.

[^92]: *See*, for example, comments of ANRO Engineering at 6, Arthur D.
    Little Inc. at 14, Endress Hauser at 5, GSSI at 5, MSSI at 15,
    Rosemount Measurement at 6, SAAB Marine Electronics at 8, and TEM
    Innovations at 12, and reply comments of Milltronics at 4.

[^93]: *See* comments of Interval at 13, Magnetrol International at 7,
    LLNL at 6, Time Domain at 32, and UWBWG at 13, and reply comments of
    Interval at 11.

[^94]: Commenting parties should note that the Commission has proposed
    to modify the AC power line conducted emission limits in 47 C.F.R. §
    15.205. *See Notice of Proposed Rule Making* in ET Docket No. 98-80,
    64 Fed. Reg. 62159, November 16, 1999,
    <http://www.fcc.gov/Bureaus/Engineering_Technology/Notices/1999/fcc99296.wp>.

[^95]: *See*, for example, comments of Endress Hauser at 5, Interval at
    9, UWBWG at 14, and WINForum at 6, and reply comments of Arthur D.
    Little Inc. at 8, ENSCO at 1, and Interval at 8.

[^96]: *See*, for example, joint comments of CEMA and NAB at 3, and
    comments of MSSI at 12, and TEM Innovations at 11.

[^97]: *See Cumulative Issues and Ultra-Wideband*, TAC White Paper,
    Spectrum Management Focus Group, (undated), addressing the following
    papers: *Cumulative Electromagnitic Radiation from Multiple UWB
    Transmitters*, Time Domain Systems, Inc., December 4, 1998; *An
    Analysis of Noise Aggregation from Multiple Distributed RF
    Emitters*, Interval Research Corporation, December 6, 1998; *Short
    Analysis on the Effects of a Large Number of UWB Systems*,
    XtremeSpectrum Inc., Technical Report TR-98-1, Fall 1998; *The
    Effect of Proliferation of Wideband Devices*, A. D. Little
    Corporation, C5803-R-001a, February 3, 1999; *Cumulative Impact of
    Large Numbers of TM-UWB Users*, Time Domain.

[^98]: Most UWB transmitters produce a line spectrum while those
    employing high levels of random pulse positioning can appear more as
    Gaussian noise. For the former devices, the emission only appears as
    noise depending on the settings of the measurement instrumentation.

[^99]: *See* 47 C.F.R. §§ 15.31-15.35.

[^100]: *See* 47 C.F.R. § 15.33.

[^101]: *See* 47 C.F.R. §§ 15.35(b) and 15.209(d). There are also
    certain rule sections that specify the application of a total peak
    power limit over a wider bandwidth. *See*, for example, 47 C.F.R. §§
    15.247(b) and 15.255(e).

[^102]: *See*, for example, comments of Endress Hauser at 4 and 6,
    Interval at 11, and Rosemount Measurement at 1-2.

[^103]: *See* comments of WINForum at 6 and Attachments 1 and 2.

[^104]: Under the general emission limits for intentional radiators, the
    bands 9-90 kHz and 110-490 kHz were specified based on average
    emission limits to accommodate equipment designs prior to 1989.
    *See* 47 C.F.R. § 15.209(d). We are not proposing to continue the
    use of average limits below 1 GHz for UWB devices.

[^105]: In particular, we request comments on applying the measurement
    procedures specified in HP Application Note 150-2. Under this note,
    if there was no dithering of the pulse position or pulse position
    modulation, the average level of the fundamental and harmonic
    emissions would be measured using a spectrum analyzer adjusted to
    produce a line spectrum with the VBW equal to or greater than the
    RBW. This requires that the RBW be less than, or equal to, 0.3 times
    the pulse repetition frequency. The level of the highest line in the
    emission line spectrum being measured would be the average level. If
    the dithering or pulse position modulation could not be turned off,
    the emission would be measured with the spectrum analyzer settings
    adjusted to obtain a true pulse spectrum. The VBW must be equal to,
    or greater than, the RBW. A pulse desensitization correction factor,
    based on the calculations provided in HP Application Note 150-2,
    would be added to the measurement to obtain a peak level, and the
    average would be calculated using the duty cycle factor in dB.

[^106]: The pulse desensitization correction factor is a technique used
    to determine the true pulse amplitude based on measurements taken
    from a spectrum analyzer. The analyzer is unable to respond fast
    enough and is not using sufficient bandwidth to measure all of the
    energy in the pulsed signal. A pulse desensitization correction
    factor was designed specifically for measuring the peak output level
    of pulsed radar transmissions.

[^107]: *See*, for example, comments of Arthur D. Little Inc. at 15,
    Endress Hauser at 4, Interval at 10, TEM Innovations at 13, Time
    Domain at 41-43, UWBWG at 15, WINForum at 3, and Zircon at 9, and
    reply comments of Interval at 5, MA/COM at 1 and 4-5, Milltronics at
    4, and Rosemount Measurement at 1.

[^108]: *See* comments of ANRO Engineering at 3-4 and Magnetrol
    International at 7.

[^109]: *See* comments of GSSI at 6.

[^110]: We recognize that sampling oscilloscopes can not be used to view
    the transmitted waveform directly for such signals, but in the
    context of measuring the peak signal it is not necessary to view the
    signal details, only to measure the magnitude of its peak amplitude.

[^111]: As with average emission levels, the measurement procedures
    specified in HP Application Note 150-2 would be applied. Under this
    note, if there was no dithering of the pulse position or pulse
    position modulation, the average level of the fundamental and
    harmonic emissions would be measured using a spectrum analyzer
    adjusted to produce a line spectrum with the VBW equal to or greater
    than the RBW. This requires that the RBW be less than, or equal to,
    0.3 times the pulse repetition frequency. The level of the highest
    line in the emission line spectrum being measured would be the
    average level. The peak level would be calculated based on the
    application of the PDCF which is calculated as 20 log~10~ \[(pulse
    width) x (pulse repetition frequency)\] dB. If the dithering or
    pulse position modulation could not be turned off, the emission
    would be measured with the spectrum analyzer settings adjusted to
    obtain a true pulse spectrum. The VBW must be equal to, or greater
    than, the RBW. A pulse desensitization correction factor, based on
    the calculations provided in HP Application Note 150-2, would be
    added to the measurement to obtain a peak level.

[^112]: The PDCF is calculated as 20 log~10~\[(pulse width) x (pulse
    repetition frequency)\] dB if a line spectrum can be resolved or is
    based on the choice of resolution bandwidth and pulse width if the
    emission if viewed in a pulse spectrum mode. *See* HP Application
    Note 150-2.

[^113]: Phase dispersion occurs when different frequencies are delayed
    by different amounts of time.

[^114]: *See*, for example, comments of Arthur D. Little Inc. at 16,
    Endress Hauser at 7, and TEM Innovations at 14.

[^115]: *See* comments of LLNL at 7.

[^116]: While several references to the --20 dB emission points were
    made in the comments for defining UWB emissions, we believe that the
    --10 dB emissions points are more appropriate for determining the
    center frequency as it is unlikely that the --10 dB points would be
    below the noise floor of a spectrum analyzer.

[^117]: *See* 47 C.F.R. §§ 2.201(f) and 15.5(d).

[^118]: *See* Chapter II, Article 5, Section 8 of the Radio Regulations
    of the International Telecommunication Union.

[^119]: The term "damped waves (Type B)" was last defined in Article 5,
    Section 1 of the 1938 version of the ITU regulations as "\[w\]aves
    composed of successive series of oscillations the amplitude of
    which, after obtaining a maximum, decreases gradually, the wave
    trains being keyed according to a telegraph code." A more modern
    version of the term "damped wave" is defined in the IEEE Standard
    Dictionary of Electrical and Electronic Terms, IEEE Std 100-1972, as
    "\[a\] wave in which, at every point, the amplitude of each
    sinusoidal component is a decreasing function of time."

[^120]: *See*, for example, comments of ANRO Engineering at 7-8, Arthur
    D. Little Inc. at 16, Endress Hauser at 7, GSSI at 6, Interval at
    11, LLNL at 8, MSSI at 15-16, and UWBWG at 15-16.

[^121]: 5 U.S.C. § 603.

[^122]: *See* 5 U.S.C. § 601(3) incorporating by reference the
    definition of \"small business concern\" in 5 U.S.C. § 632.

[^123]: *See* 15 U.S.C. § 632.

[^124]: *See* 13 C.F.R. § 121.201.