##  JRG-43

June 17, 2005

## Revised Work Program

#### JRG 1A-1C-8B

1\. Background

Unwanted emission masks in the out-of-band domain for primary radar
systems are contained in Recommendation ITU-R SM.1541, Annex 8. The
ITU-R out-of-band emission masks for primary radar systems are intended
to recommend an acceptable degree of electromagnetic compatibility among
radar systems, and between such systems and those of other radio
services sharing the frequency spectrum.

In the development of the out-of-band emission masks for primary radar
systems, it was the view of several administrations that there was a
need to further investigate the state-of-the-art radar systems and their
ability to suppress unwanted emissions. This review of radar unwanted
emissions in the out-of-band domain is to be completed by 2006. See
Recommendation ITU-R SM.1541, Annex 8, Note 3. The outstanding issue
concerns the "design objectives" highlighted in this document. This
"design objective" concerns the possibility of making more stringent the
requirement for radars with regard to the "roll-off\" of out‑of-band
(OOB) emissions.

The outcome of this study may result in revisions to Recommendation
ITU-R SM.1539, which addresses the boundary between the out-of-band and
spurious domains, and Recommendation ITU‑R SM.1541, which addresses
out-of-band emissions domain.

Pursuant to initiating this study, Working Party 8B revised Question
202/8 to provide guidance to administrations in conducting their
investigation.

2\. Objective

The objective of this work program is to review the current ITU-R limits
for unwanted emissions in the out-of-band domain contained in Annex 8 of
Recommendation ITU-R SM.1541, and assess the feasibility of establishing
guidance to promote more effective and efficient use of the spectrum.

3\. Approach

In order to accomplish the above objective, the following tasks will be
undertaken:

a\) Develop a software tool that will provide current ITU-R emission
masks and alternative emission masks for comparison with measured radar
emission data (Priority 1).

b\) Review the current necessary bandwidth (-20 dB) formulas and --40 dB
bandwidth formulas for the various types of modulations used by radar
systems, and develop new formulas as appropriate (Priority 1).

c\) Identify, through measurements, characteristic radar emission
spectra considering such parameters as: waveforms (e.g. pulse shape and
modulation); types of output devices; RF filter technologies; and
antenna types (Priority 1).

d\) Analyze the measured emission characteristics to assess the
feasibility of establishing more spectrum efficient emission masks
(Priority 2).

e\) Discuss draft revised emission masks, and identify state-of-the-art
capabilities which may allow radars to operate more efficiently while
recognizing economic impacts and mission requirements to achieve
efficient and effective operation.

f\) Draft a report, including a DRAFT Revision of Recommendation ITU-R
SM.1541, Annex 8, and provide the results of these studies to Working
Party 1A, 1C and 8B.

4\. Specific areas requiring studies

1)  Develop a software tool that will provide current ITU-R emission
    masks and alternative emission masks for comparison with measured
    radar emission data (Priority1). See documents: JRG-2, 3, 4, 5, 29,
    30, 31.

2)  Review the necessary bandwidth (-20 dB) and --40 dB bandwidth
    formulas given in ITU-R SM.1541 and develop new formulas as
    appropriate, particularly for the following types of modulations
    (Priority 1):

    a.  Non-FM pulses (unmodulated pulses), including radars using
        magnetrons with low pulse width to rise time ratio (Doc. JRG-7,
        9, 10, 35 rev.1).

    b.  FM-pulsed modulated waveforms, including non-linear FM. Analysis
        and measurements have shown that the current formulas especially
        for FM-pulsed modulated waveforms are too generous for large
        time-bandwidth products (compression ratios). (Doc. JRG-7, 10,
        12, 13, 17, 19, 21, 32, 33, 37, and 38)

    c.  FMCW, including radars operating at long wavelengths. Analysis
        indicates that the current --40 dB bandwidth formula for FMCW
        modulated waveforms may not be representative for all cases.
        (Doc. JRG-7, 39)

    d.  stepped chirp, phase-coded pulses (PSK/QPSK, MSK/GMSK, and
        Taylor quadriphase), phase-coded CW, step FM, multi-carrier
        radars (Doc. JRG-7).

3)  Identify, through analysis and measurements, the achievable roll-off
    from the --40 dB bandwidth for the following output devices as a
    function of the class of amplification (Priority 2):

    a.  cross-field (Doc. JRG-14, 16, 20, 22, 34, 40, 42)

    b.  linear beam (Doc. JRG-7)

    c.  solid state (Doc. JRG-36 and 39).

4)  Investigate the feasibility of implementing pulse shaping and
    filters between solid state Transmit-Receive (T/R) Modules and the
    antenna elements. These studies should consider the type of platform
    (e.g. ground based, ship borne, airborne, space borne) (Doc. JRG-7
    and 33) (Priority 1).

5)  Review the definition and description of rise and fall time (Note 1
    of Annex 8 of Rec. ITU-R SM.1541). Measurements have shown that the
    pulse forms are sometimes not nearly trapezoidal, especially for
    radars using magnetrons that tend to overshoot the maximum level for
    a very short time at the beginning of the pulse (Priority 2).

6)  Determine the characteristics of airborne radar systems (Doc.
    JRG-41), obtain emission spectrum measurements on representative
    airborne systems with different output devices, and identify factors
    that could affect the emission spectrum (Doc. JRG-41).

7\) Impact of ITU-R out-of-band emission limits on radars operating at
long wavelengths (Doc. JRG-39) (Priority 1).

5\. Drafting groups

Three drafting groups were formed at the second meeting of the JRG.
Correspondence for the drafting groups will be conducted via e-mail.
Drafting Group leads will establish e-mail groups.

##### **JRG-DG1: FMCW Modulated Waveforms**

##### **JRG-DG2: FM-Pulse Modulated Waveforms**

**JRG-DG3: Magnetron Emission Mask:**

The Terms-of-Reference and lead contacts for the above JRG Drafting
Groups are provided on the JRG web site:
<http://www.its.bldrdoc.gov/meetings/itu-r/>

6\. Action items

Four action items were identified at the second meeting of the JRG. A
description of the action items, and administration responsible for the
task are provided on the JRG web site:
<http://www.its.bldrdoc.gov/meetings/itu-r/>.

7\. Next meeting date / location and aims

3^rd^ meeting: January 17-19, 2006. Hosted by the U.S. at the Institute
of Telecommunication Sciences, Boulder, Colorado.

a.  Further structuring of final report

b.  First proposed revision of Rec. ITU-R SM.1541

4th meeting: Hosted by Germany