**Report of the Joint Rapporteurs**

**Group 1A-1C-8B (JRG-1A/1C/8B)**

1\. [Introduction]{.underline}. Joint Rapporteurs Group 1A/1C/8B was
formed to present proposals to the ITU-R for the development of unwanted
emission limits in the out-of-band (OOB) domain of primary radar
systems. Specifically, Recommendation ITU-R SM.1541 contains recommended
out-of-band limits with a 20 dB/decade roll-off slope and, additionally,
contains a design objective out-of-band mask of 40 dB/decade.

Note 3 of the 40 dB/decade mask states "***The design objective mask is
valid as such until the 2006 Radiocommunication Assembly. This is based
on the understanding that these studies will lead to the revision of
this Recommendation to either replace the OoB masks in the preceding
sections with the design objective mask; or to include other appropriate
arrangements depending on the type of radar.***"

The studies referenced in Note 3 are addressed in Notes 1 and 2 which
state "***The feasibility of this mask is to be investigated in future
studies within ITU-R, taking account of the practical experience of its
application to some types of radar systems and technical developments in
radar technology*"**, and "***OoB domain emission limits within bands
allocated to the radiodetermination service on an exclusive basis are
the subject of further study. This study may result in a different
design objective mask inside these bands*,** respectively."

Finally, Note 4 recognizes that some radar systems may not be able to
meet the design objective by stating "***Some future systems may not be
able to achieve the design objective taking account of such factors as:
radar mission (safety of life, threat, etc.), type and size of the
platform (e.g. fixed, mobile, ship-borne, airborne, etc.), available
technologies and economic considerations.***"

The JRG Terms of reference were established as follows:

> 1\. 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 by radar
> stations in the radiodetermination service. Propose draft revisions to
> ITU-R SM.1541 as appropriate;
>
> 2\. conduct studies on the boundary between the out-of-band and
> spurious domains of primary radars using magnetrons taking into
> consideration ITU-R Recommendation 75 (WRC-03);
>
> 3\. review and propose modifications to other ITU Recommendations and
> Reports associated with radar unwanted emissions as appropriate; and
>
> 4\. make efforts to conduct the work of JRG 1A/1C/8B by correspondence
> to the extent possible.

In summary, the objective of the JRG was 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.

Addressing item 4 of the Terms of Reference first, it was hoped that
much of the work could be conducted by correspondence, limiting the need
for meetings. However, due to the complexity of the issues before the
JRG and the need to set aside time where participants were fully engaged
in the JRG tasks and away from other distractions, a total of five
meetings were held. Many input documents were received on the issue of
revising Annex 8 of ITU-R SM.1541 and other associated topics.

The JRG began under the Co-chairmanship of Mr. Jian Wang (WP 1A
Rapporteur), Mr. Thomas Hasenpusch (WP 1C Rapporteur) and Mr. Robert
Hinkle (WP 8B Rapporteur). Mr. David Franc took over as Co-chair and WP
8B Rapporteur at the Fourth meeting in November 2006. Mr. Jian Wang
informed the JRG in March 2007 that he is no longer able to serve as
Co-chair and was not replaced prior to the completion of the JRG work.
The final meeting of the JRG was held in April 2007 in London. The
following is the report of the work completed by the JRG and summarizes
the agreed changes to Annex 8 of ITU-R SM.1541. A revised version of
Annex 8 is attached in Annex 1 of this report.

2\. [Complexity of the JRG Task]{.underline}. When the JRG was formed
the task before it appeared simple enough; it is specified in the terms
of reference discussed above. However, as work progressed, the JRG began
to uncover more questions than answers it was finding.

One of the first items that arose was the inaccuracy of some of the -40
dB bandwidth formulas in the in-force version of SM.1541. This issue
posed a significant obstacle to reaching conclusions on the
applicability of a more stringent roll-off mask since the -40 dB
bandwidth point is the reference point for applying the roll-off mask.
No determination could be made on the applicability of the 40 dB/decade
design objective, or any other roll off slope, until an accurate -40 dB
bandwidth calculation could be performed for each radar type. Addition
details are provided in the next section of this report.

Other issues arose during the work of the JRG which presented less
significant impediments to the JRG progress. Efforts were made to take
note of these issues and move on with the work defined in the Terms of
Reference. These issues are discussed later in this report with
recommendations to Working Parties 1A, 1C and 8B on how they should be
addressed in the future. While there are issues to be resolved, they
were outside the scope of the JRG. The JRG has reached the end of its
existence and the JRG does not propose that its life should be extended
or that a similar group should be formed to address these identified
issues. On the contrary, the issues should be addressed in the
appropriate working parties.

3\. [Summary of JRG Discussions]{.underline}. This section presents a
summary of the JRG discussions and the conclusions reached for each of
the four Terms of Reference items. Where appropriate, a document
containing detailed text or changes is provided in an Annex to this
report.

3.1 [Terms of Reference - Item #1]{.underline}

Item 1 of the Terms of Reference calls for the consideration of more
stringent out-of-band masks for radars, and that the agreed masks be
reflected in a revision of Annex 8 of ITU-R SM.1541. As stated above,
the review of the current Annex 8 to ITU-R SM.1541 revealed that many of
the -40 dB bandwidth formulas did not provide accurate representations
of the proper -40 dB bandwidth. From the start, the JRG was presented
with the challenge of attempting to determine the correct formulas for
the -40 dB bandwidth. Since the reference point for the out-of-band mask
is based on the -40 dB bandwidth point, the -40 dB bandwidth equations
must be accurately established before the applicability any roll-off
slope can be determined. The summary of JRG discussions regarding each
radar signal type is provided below, discussing the issues encountered
and the conclusions reached. When considering the proposals made below,
the timing of implementation of the effective date of new emission masks
must be considered, as discussed in a later section.

> 3.1.1 [Unmodulated Pulse Radars]{.underline}. Unmodulated pulse radars
> use a variety of output devices. For the work of the JRG, these radars
> were divided into two sub-categories; those where magnetrons are used
> as the output device, and those using all other types of output
> devices. The JRG concluded the -40 dB bandwidth formula currently
> contained in ITU-R SM.1541 is correct for all unmodulated pulse
> radars, greatly simplifying the work.
>
> The JRG concluded the non-magnetron-based, unmodulated pulse systems
> can achieve the 40 dB/decade roll off design objective.
>
> Meeting the 40 dB/decade design objective is more problematic for
> radars based on magnetron technology. Initial studies submitted to the
> JRG appear to indicate that certain new magnetron-based systems may
> also meet the 40 dB/decade roll-off with the exception of airborne
> systems, and the performance is representative of other magnetron
> radars. However this conclusion is based on a new magnetron technology
> patented by a single manufacturer. Consideration needs to be given to
> the fact that the ITU-R should remain technology neutral, and adopting
> limits that can only be met by one patented design of a single
> manufacturer and is not representative of all radars using magnetrons.
>
> It is a requirement of the International Convention for the Safety of
> Life at Sea (SOLAS) published by the International Maritime
> Organization (IMO) that ships to which the Convention applies carry
> radar. There are worldwide 70,000 such radars using magnetrons which
> assist in the safety of persons and the ship, and more than a million
> smaller magnetron-based radars in service. Representatives of the
> maritime community are concerned that application of a new mask to
> maritime radars that need to be low cost and small, thereby using
> magnetrons, would hamper the development of new maritime radar designs
> since the older designs would already be considered approved and new
> designs would have the difficult task of meeting the spectrum mask.
>
> In summary, the flowing changes are proposed to Annex 8 of ITU-R
> SM.1541 (contained in Annex 1 of this report):

-   The existing -40 dB bandwidth formula is adequate for unmodulated
    pulse systems and should be retained.

-   Non-magnetron, unmodulated pulse systems can meet the design
    objective. Therefore the 40 dB/decade roll-off applies to
    non-magnetron, unmodulated pulse systems.

-   Magnetron-based unmodulated pulsed systems (with the exception of
    airborne and possibly maritime) may be able to meet the design
    objective. A roll-off of \[TBD\] is proposed to apply to these
    systems.

-   Recognizing the challenges associated with controlling out-of-band
    emissions in magnetron-based airborne and maritime radars, a roll
    off of \[TBD\] is proposed to apply these systems.

> 3.1.2 [FM pulse (LFM) radars]{.underline}. Both the -40 dB bandwidth
> and a more stringent roll-off slope was studied by the JRG for FM
> pulse systems. Review within the JRG showed the existing -40 dB
> bandwidth formula contained in ITU-R SM.1541 was inaccurate and
> provided an excessively wide bandwidth for higher time-bandwidth
> products (compression ratios). Work needs to be completed on the
> appropriate -40 dB bandwidth before the applicability of a more
> stringent emission mask could be determined. At its fourth meeting the
> JRG tentatively concluded on a formula based on theory, however the
> implementation factor to account for hardware implementation of a
> radar system has not been agreed. The tentative -40 dB bandwidth
> formula is :

$B_{- \text{40}\text{dB}_{\text{New}}} = R \ast B + N \ast \sqrt{\pi} \ast \lbrack\text{ln}(B \ast \tau)\rbrack^{0\text{.}\text{53}} \ast \lbrack\text{Min}(B_{\text{rise}},B_{\text{fall}},B_{\text{rise} \land \text{fall}}) + \text{Max}(B_{\text{rise}},B_{\text{fall}},B_{\text{rise} \land \text{fall}})\rbrack$
EQ-1

where,

  ------------------------------------------------------------------------------------------------------- --------------------------------------------- ------
  $$B_{\text{rise}} = \frac{1}{\sqrt{\tau \ast t_{r}}}$$                                                  To account for the rise time                  EQ-2

  $$B_{\text{fall}} = \frac{1}{\sqrt{\tau \ast t_{f}}}$$                                                  To account for the fall time                  EQ-3

  $$B_{\text{rise}_{\text{fall}}} = \frac{1}{\left( \tau \ast t_{r} \ast t_{f} \right)^{\frac{1}{3}}}$$   To account for both the rise and fall times   EQ-4
                                                                                                          combination                                   

                                                                                                          Pulse length (us) including rise and fall     
                                                                                                          times                                         

  t~r~                                                                                                    Pulse rise time (us)                          

  t~f~                                                                                                    Pulse fall time (us)                          

  B                                                                                                       LFM bandwidth (MHz)                           

  W                                                                                                       Implementation factor (not determined by JRG) 

  V                                                                                                       Implementation factor (not determined by JRG) 
  ------------------------------------------------------------------------------------------------------- --------------------------------------------- ------

> Since the -40 dB bandwidth could not be concluded by the JRG, the JRG
> did not conclude on the applicability of a more stringent roll-off
> slope to FM pulse radars.
>
> In summary, the JRG proposes that Annex 8 to ITU-R SM.1541, be revised
> to reflect the new -40 dB bandwidth formula, and that the appropriate
> implementation factors be resolved by Working Party \[8B\]. These
> implementation factors include the parameters "W" and "V" that are
> defined above. Furthermore, Working Party \[8B\] should complete the
> work on the applicability of a more stringent mask once the
> implementation factors are decided.
>
> [\[Editor's Note: There is a need to carry text forward, from one or
> more JRG submissions, as an annex to this report that would provide
> additional information needed to complete the work on the
> implementation factor and the applicability of a more stringent
> mask?\]]{.mark}
>
> 3.1.3 [FMCW radars]{.underline}. As with FM pulse systems, the JRG
> agreed that an appropriate -40 dB bandwidth formula must be agreed
> prior to a determination of whether a more stringent roll-off can be
> applied. The existing -40 dB formula in Annex 8 of ITUI-R SM.1541 is
> not an accurate representation of the bandwidth required for FMCW
> systems. More specifically, the formula results in unrealistically
> narrow bandwidths for systems operating below 50 MHz. The JRG
> tentatively concluded on a -40 dB bandwidth formula, however the
> implementation factor to account for differences between theory and
> real systems was not agreed. The tentative formula is:

![](media/image1.wmf) EQ 5

> where B~c~ is the total frequency deviation, τ is the time over which
> the main chirp occurs, k~40~ is the implementation factor to account
> for accepted differences between theory and real system output. Since
> the final bandwidth formula has not been agreed, no final
> determination was made on the applicability of a more stringent mask
> for FMCW systems.
>
> In summary, the JRG proposes that Annex 8 to ITU-R SM.1541, be revised
> to reflect the new -40 dB bandwidth formula, and that the appropriate
> implementation factor be resolved by Working Party \[8B\]. The
> implementation factor includes the parameter "k~40~" that is defined
> above. Furthermore, Working Party \[8B\] should complete the work on
> the applicability of a more stringent mask once the implementation
> factors are decided.
>
> [\[Editor's Note: There is a need to carry text forward, from one or
> more JRG submissions, as an annex to this report that would provide
> additional information needed to complete the work on the
> implementation factor and the applicability of a more stringent
> mask?\]]{.mark}
>
> 3.1.4 [Phase coded radars and other radar signal types]{.underline}.
> ITU-R SM.1541 does not address in detail phase coded radar signals or
> other more advanced radar signal types that may be in development or
> are already developed and used in a limited number of applications.
> The JRG was unable to reach any conclusions on these radar types so
> that revisions to ITU-R SM.1541 could be proposed. One limiting factor
> on this work is that many of the radars employing more advanced
> signals are sensitive in nature and administrations have been unable
> to share the needed details in the JRG forum. Also, considering just
> phase coded radars, the number of codes that need study made the
> completion of work impossible within the timeframe of the JRG.
>
> Since the current version of Annex 8 of ITU-R SM.1541 does not address
> phase coded radars or other advanced signal types, the JRG proposes
> that the existence of these signal types be noted in the
> recommendation at this time. The task of following the development of
> these radar types and collecting the required information should be
> assigned to Working Party \[8B\]. Once enough material is openly
> available to Working Party \[8B\] a future revision of Annex 8,
> containing the appropriate -40 dB bandwidth formula and roll-off, can
> be prepared and forwarded to Working Party 1A.
>
> [\[Note: Insufficient information is available to determine the
> applicability of the design objective to phase coded and other
> advanced radar signals. As an alternative to the paragraph above, the
> revision of ITU-R SM.1541 could conclude on a mask of 20 dB/decade for
> these systems. It is the view of the WP 8B Rapporteur that it is not
> prudent to apply a more stringent mask when insufficient information
> is available to make such a determination.\]]{.mark}
>
> 3.2 [Terms of Reference -- Item #2]{.underline}
>
> Item #2 of the Terms of Reference calls for the study on the boundary
> between the out-of-band and spurious domains of primary radars using
> magnetrons, taking into consideration ITU-R Recommendation 75
> (WRC-03). This item has been addressed by the JRG to the extent of
> available information and time, and the relevant conclusions are
> addressed fore unmodulated pulse radar section under Item #1. In
> summary, the 40 dB bandwidth formula in Annex 8 of ITU-R SM.1541 is
> accurate for magnetron-based radars. With respect to the out-of-band
> roll off and the transition to the spurious region, the JRG has
> concluded \[TBD\].
>
> 3.3 [Terms of Reference -- Item #3]{.underline}
>
> Item #3 of the Terms of Reference requests the review and proposal of
> modifications to other ITU-R Recommendations and reports associated
> with radar unwanted emissions. In order to maximize the effort on
> items #1 and #2 of the terms of reference, the JRG considered changes
> to other ITU-R Recommendations that were consequential to the
> proposals of the JRG discussed above.
>
> **Recommendation ITU-R SM.1539**: Recommendation ITU-R SM.1539
> requires revision to section 3.3 to align the text with the proposed
> revisions to ITU-R SM.1541, Annex 8. Refer to Annex 2 of this report
> for the proposed revisions.
>
> **Recommendation ITU-R SM.853**:
>
> **Recommendation ITU-R M.1177**: The JRG received a number of
> contributions relating to revisions of ITU-R M.1177. The JRG concluded
> that these contributions should be referred to the Radar
> correspondence Group (RCG), which is assigned responsibility for
> revision of M.1177.
>
> 3.4 **[Terms of Reference -- Item #4]{.underline}**
>
> Item #4 is addressed in the introduction section of this report.
>
> 3.5 **[Consequential changes to ITU-R SM.1541]{.underline}**
>
> Other consequential changes are required to Annex 8 of SM.1541 as a
> result of the work of the JRG. These consequential changes are shown
> in Annex 1 to this report and an explanation of the substantive
> changes is provided below.
>
> Section 1- Placing meteorological radars in the meteorological aids
> service is an artifact from some text originating from the rules of a
> particular administration. The text has been updated to reflect that
> meteorological radars operate in the radiodetermination, radiolocation
> and radionavigation services.
>
> Section 2- The text is updated to clarify that the emission mask of a
> radar is based on the -40 dB bandwidth, and that the calculation of
> the necessary bandwidth and -20 dB bandwidth is not needed for
> applying an emission mask. The formulas for necessary bandwidth are
> also deleted since they are outside the scope of this Reccomendation.
>
> Section 3- A statement is added to Section 3 indicating that the
> widest applicable 40 dB bandwidth should be used when applying a mask
> to a multi-waveform radar. All other changes were previously
> addressed.
>
> Section 4- \[TBD\]
>
> Section 5- \[TBD\]
>
> Section 6- As an outcome of the studies that determine the systems to
> which the design objective can be applied, the section on the design
> objective is no longer needed. It is applied to the radars for which
> it is applicable.
>
> 3.6 [Other issues identified by the JRG]{.underline}.
>
> Revisions to Question ITU-R 202/8: The JRG proposes changes to
> Question 202/8 to take into account the unresolved issues passed to
> Working Party 8B for completion. Annex 3 contains the proposed
> revisions for consideration by Working Party 8B.
>
> Necessary and -20 dB Bandwidth Formulas: Working Parties 1A, 1C and 8B
> may maintain other recommendations where formulas for the necessary
> bandwidth B~N~ and -20 dB bandwidth B~-20~ are provided. If the -40 dB
> bandwidth formulas are revised in SM.1541, the -20 dB and Necessary
> Bandwidth formulas need to be reviewed to ensure they are consistent
> with the new -40 dB bandwidth formulas. Cases could arise where
> discrepancies between formulas may result in a calculated -20 dB
> bandwidth wider than the calculated -40 dB bandwidth.

ANNEX 1-

Proposed Revisions to Recommendation

ITU-R SM.1541 for consideration by Working

Parties 1A, 1C and 8B

WORKING DOCUMENT TOWARDS PRELIMIARY DRAFT REVISION OF RECOMMENDATION
ITU-R SM.1541, ANNEX 8

Unwanted emissions in the out-of-band domain

(Question ITU-R 211/1)

# 1 Introduction

The Radio Regulations define "primary radar" as "A *radiodetermination*
system based on the comparison of reference signals with radio signals
reflected from the position to be determined".

Terrestrial primary radars operate in the radionavigation service (air
surveillance radars and navigation radars on aircraft and ships), and
the radiolocation service (most other terrestrial radars). In addition,
meteorological radars can operate in either the radionavigation or
radiolocation service, depending on their specific application.
Space-based radars include active remote sensing satellites operating in
the SRS and EESS, and other radars in the SRS.

The following limits are not applicable inside exclusive
radiodetermination and/or EESS and SRS bands, but do apply at the band
edges. The topic of primary radar emission limits within these exclusive
service bands will be the subject of further studies.

Several categories of primary radars are not included in the OoB
emission limits defined in this Annex. These include pulsed radars with
rated peak power of 1 kW or less, non-pulsed radars with rated average
power of 40 W or less, radars operating above 40 GHz, man-portable
radars, and expendable radars. These categories of radars will also be
the subject of further studies to establish the appropriate limits.

Throughout this Annex, in all formulas, bandwidth (*Bc*, *Bs*, *Bd*,
*B*--40) is expressed in Hertz, while pulse duration and rise/fall time
are expressed in seconds.

# 2 Necessary bandwidth

Due to limitations in technology, the emission of radar systems can not
be limited to the necessary bandwidth in the sense of the definition in
the RR. A realistic 20 dB bandwidth can be calculated using the formulas
given in Recommendation ITU-R SM.853. The OOB emission masks for radar
systems are referenced to the 40 dB bandwidth, knowledge of the
necessary and 20 dB bandwidths is not required for determining the out
of band emission mask.
$B_{N}\  = \ \frac{1\text{.}\text{79}}{\sqrt{t\  \cdot \ t_{r}}}\ \text{or}\ \frac{6\text{.}\text{36}}{t}$
$t_{r}$
$B_{N}\  = \ \frac{1\text{.}\text{79}}{\sqrt{t\  \cdot \ t_{r}}}\  + \ 2\ B_{c}$
$B_{N}\  = \ \frac{1\text{.}\text{79}}{\sqrt{t\  \cdot \ t_{r}}}\  + \ 2\ B_{c} + \ B_{s}$
$B_{N}\  = \ 2\ B_{d}$ TABLE 20

# 

# 3 Formulas for the 40 dB bandwidth

A major difficulty in establishing general OoB domain emission limits
for primary radars is the diversity of systems and transmitted
waveforms. OoB domain emission limits for primary radars are based on
the 40 dB bandwidth of the spectrum of the transmitted waveform.

For radars with multiple waveforms, the 40 dB bandwidth should be
calculated for each individual waveform and the maximum 40 dB bandwidth
obtained shall be used to establish the shape of the emission mask.

# 

# . The following formulas for the 40 dB bandwidth (*B*--40) of primary radar transmitters have been established.

## 3.1 Unmodulated pulse, spread spectrum, and coded pulse radars

For unmodulated pulse radars spread spectrum, and coded pulse radars,
the bandwidth is the lesser of:

$B_{- \text{40}}\  = \ \frac{K}{\sqrt{t\  \cdot \ t_{r}}}\ \text{or}\ \frac{\text{64}}{t}$
(39)

where the coefficient *K* is 6.2 for radars with output power greater
than 100 kW and 7.6 for lower‑power radars and radars operating in the
radionavigation service in the 2 900-3 100 MHz and

9 200-9 500 MHz bands[^1]. The latter expression applies if the rise
time *t~r~* is less than about 0.0094*t* when *K* is 6.2, or about
0.014*t* when *K* is 7.6.

For frequency hopping radars:

$B_{- \text{40}}\  = \ \frac{K}{\sqrt{t\  \cdot \ t_{r}}} + B_{s}$ (40)

where B~s~ is the maximum range over which the carrier frequency will be
shifted.

## 3.2 FM pulse radars

For FM-pulse radars, the 40 dB bandwidth is:

$B_{- \text{40}}\  = \ \frac{K}{\sqrt{t\  \cdot \ t_{r}}} + 2\ \left( B_{c} + \frac{A}{t_{r}} \right)$

$B_{- \text{40}\text{dB}_{\text{New}}} = R \ast B + N \ast \sqrt{\pi} \ast \lbrack\text{ln}(B \ast \tau)\rbrack^{0\text{.}\text{53}} \ast \lbrack\text{Min}(B_{\text{rise}},B_{\text{fall}},B_{\text{rise} \land \text{fall}}) + \text{Max}(B_{\text{rise}},B_{\text{fall}},B_{\text{rise} \land \text{fall}})\rbrack$
(41)

where,

  ------------------------------------------------------------------------------------------------------- --------------------------------------------- --------
  $$B_{\text{rise}} = \frac{1}{\sqrt{\tau \ast t_{r}}}$$                                                  To account for the rise time                  \(42\)

  $$B_{\text{fall}} = \frac{1}{\sqrt{\tau \ast t_{f}}}$$                                                  To account for the fall time                  \(43\)

  $$B_{\text{rise}_{\text{fall}}} = \frac{1}{\left( \tau \ast t_{r} \ast t_{f} \right)^{\frac{1}{3}}}$$   To account for both the rise and fall times   \(44\)
                                                                                                          combination                                   

                                                                                                          Pulse length (us) including rise and fall     
                                                                                                          times                                         

  t~r~                                                                                                    Pulse rise time (us)                          

  t~f~                                                                                                    Pulse fall time (us)                          

  B                                                                                                       LFM bandwidth (MHz)                           

  W                                                                                                       Implementation factor (not determined by JRG) 

  V                                                                                                       Implementation factor (not determined by JRG) 
  ------------------------------------------------------------------------------------------------------- --------------------------------------------- --------

.

For FM-pulse radars with frequency hopping the value of B~s~ needs to be
added to the value of B~40~ (EQ 41) for the frequency hopping radar 40
dB bandwidth[^2].

$B_{- \text{40}}\  = \ \frac{K}{\sqrt{t\  \cdot \ t_{r}}} + 2\ \left( B_{c} + \frac{A}{t_{r}} \right) + B_{s}$
(45)

$B_{- \text{40}}\  = \ \frac{K}{\sqrt{t\  \cdot \ t_{r}}} + B_{s}$ 3.4
CW radars

For un-modulated CW radars, the 40 dB bandwidth is:

$B_{- \text{40}}\  = \ 0\text{.}\text{0003}\ F_{0}$ (46)

**3.5 FM/CW radars**

For FM/CW radars:

\(47\)

where B~c~ is the total frequency deviation, τ is the time over which
the main chirp occurs, k~40~ is the implementation factor to account for
accepted differences between theory and real system output.

$B_{- \text{40}}\  = \ 0\text{.}\text{0003}\ F_{0}\  + \ 2\ B_{d}$

OoB masks

## 

## 

## Figure 26 shows the OoB mask for primary radars, specified in terms of psd and expressed in units of dBpp. The mask rolls off at 20 dB per decade from the 40 dB bandwidth to the spurious level specified in RR Appendix 3[^3]. Figure 27 shows the OoB mask for primary radars, specified in terms of psd and expressed in units of dBpp. The mask rolls off at 40 dB per decade from the 40 dB bandwidth to the spurious level specified in RR Appendix 3. The 40 dB bandwidth can be offset from the frequency of maximum emission level. The [\[necessary bandwidth (RR No. 1.152) and preferably, the\]]{.mark} overall occupied bandwidth (RR No. 1.153), should be contained completely within the allocated band.

\[Editor's Note: Determination of the appropriate 40 dB bandwidth
equation, including implementation factors, is critical to determining
the applicability of a roll-off, ranging from 20 to 40 dB per decade.
The applicability of roll-off requirements to various radar types is
TBD. Figures 26 and 27 may need to be modified to show the spurious
level as defined in RR Appendix 3.\]

Figure 26

OoB mask for primary radars

![](media/image2.wmf){width="2.9770833333333333in"
height="2.036111111111111in"}

## 

## 

Figure 27

OoB mask for radars

![](media/image3.wmf){width="3.5097222222222224in" height="2.3875in"}

## 

## 

## 

## 

## 5 Boundary between the OoB and spurious domains

According to *recommends* 2.2 and RR Appendix 3, the spurious domain
generally begins at a frequency separation equal to 250% of the
necessary bandwidth, with exceptions for certain kinds of systems,
including those with digital or pulsed modulation. However, it is
difficult to apply the general boundary concept of 250% of the necessary
bandwidth to primary radar stations in the radiodetermination and other
services, SRS and EESS.

For primary radar stations, the boundary between the OoB and spurious
domains is defined as at the frequency where the OoB domain emission
limits defined herein are equal to the spurious limit defined in [Table
II of RR Appendix 3]{.mark}.

# 

$5\ B_{- \text{40}}\  = \ 2\text{.}5\ \alpha\ B_{N}\  \rightarrow \ \alpha\  = \ 2\ \frac{B_{- \text{40}}}{B_{N}}$
6 Measurement techniques

The most recent version of Recommendation ITU-R M.1177 provides guidance
regarding the methods of measuring OoB domain emissions from radar
systems.

ANNEX 2

Proposed Revisions to

Recommendation ITU-R SM.1539

WORKING DOCUMENT TOWARDS PRELIMIARY DRAFT REVISION OF RECOMMENDATION
ITU-R SM.1539

Variation of the boundary between the out-of-band and spurious domains\
required for the application of Recommendations ITU-R SM.1541\
and ITU‑R SM.329

(Question ITU-R 211/1)

The following are proposed changes to Item 3.3

## 3.3 Primary radars in the radiodetermination and other services

According to *further recommends* 2.3 of Recommendation ITU-R SM.329,
the spurious domain emission generally begins at a frequency separation
equal to 250% of the necessary bandwidth, with exceptions for certain
kinds of systems, including those with digital or pulsed modulation.
RR Appendix 3 includes similar provisions. However, it is difficult to
apply the general boundary concept of 250% of the necessary bandwidth to
primary radar stations in the radiodetermination and other services,
such as the meteorological aids service, the space research service, and
the Earth exploration-satellite service.

For the case of primary radar systems, the detailed definition of the
OoB/spurious domain boundary is contained in Annex 8 of Recommen­dation
ITU-R SM.1541.

ANNEX 3

Proposed Revisions to Question

ITU-R 202-2/8 for Consideration

By Working Party 8B

[\[NOTE: Revisions to be decided by the JRG at its final meeting, based
on the conclusions reached by the JRG.\]]{.mark}

question itu-r 202-2/8[^4]

Unwanted emissions of primary radar systems

(1993-1997-2001)

The ITU Radiocommunication Assembly,

considering

a\) that the radio spectrum available for use by the radiodetermination
service is limited;

b\) that the radionavigation service is a safety service as specified by
No. 4.10 of the Radio Regulations, and in addition that some other types
of radar systems such as weather radars may perform safety-of-life
functions;

c\) that the necessary bandwidth of emissions from radar stations in the
radiodetermination service is large in order to effectively perform
their function;

d\) that new emerging technology systems may use digital or other
technologies that are more susceptible to interference from unwanted
emissions from radar systems due to their high peak envelope power;

e\) that Radiocommunication Study Group 8 has been studying the question
of efficient use of the radio spectrum by radar systems including the
study of inherent unwanted emission characteristics of various types of
output devices;

f\) that Radiocommunication Study Group 9 completed studies on the
effects of unwanted emissions from radar systems on systems in the fixed
service and developed Recommendations ITU-R F.1097 on Interference
Mitigation Options to Enhance Compatibility between Radar Systems and
Digital Radio-Relay Systems and ITU-R F.1190 on Protection Criteria for
Digital Radio-Relay Systems to Ensure Compatibility with Radar Systems
in the Radiodetermination Service;

g\) that unwanted emissions from radar systems may in some cases cause
unacceptable interference to systems in other radio services operating
in the adjacent and harmonically related bands, especially when the
technical and operational characteristics of the other radio service
systems are changed in ways that make them more susceptible to
interference;

h\) that performance (bandwidth, coherency, etc.), expected lifetime,
cost, weight, size and mechanical ruggedness are important factors that
must be considered in the design-to-performance specifications of
radiodetermination systems;

j\) that Radiocommunication Study Group 1 revised Recommendation ITU‑R
SM.329 which includes spurious emission limits for the
radiodetermination service;

k\) that Radiocommunication Study Group 1 is developing a new
Recommendation on out-of-band emission limits which includes amongst
others out-of-band emission limits for the radiodetermination service
outside their exclusive bands;

l\) that WRC-2000 revised Appendix 3 Table of Maximum Permitted Spurious
Emission Power Levels based on Recommendation ITU-R SM.329, and decided
that radiodetermination service transmitters installed after 1 January
2003 and all transmitters after 1 January 2012 must comply with these
power levels;

m\) Recommendation ITU-R M.1177 on techniques for measurement of
unwanted emissions of radar systems;

n\) Recommendation ITU-R M.1314 on reduction of spurious emissions of
radar systems operating in the 3 GHz and 5 GHz bands,

noting

that the out-of-band limits in bands allocated to the radiodetermination
service on an exclusive basis are under the purview of Study Group 8,

decides that the following Question should be studied

**1** What are the unwanted emission levels from existing and
state-of-the-art radar systems below 26 GHz taking into account:

a\) radar missions such as safety of life, radionavigation,
surveillance, tracking, etc.;

b\) type and size of the platform (e.g. fixed, mobile, shipborne,
airborne, etc.);

c\) available technologies; and

d\) economic considerations?

**2** What mitigation options, such as the choice of output device,
could be taken into consideration in the design and implementation of
radar systems to reduce radar unwanted emissions, and what are their
associated impacts on operational performance (bandwidth, coherency,
etc.) expected lifetime, relative cost, weight, size and mechanical
ruggedness?

**3** What unwanted emission levels can be achieved using these
mitigation options, and what compatibility can then be achieved with
other radio services?

further decides

**1** that the results of the above studies should be included in (a)
Recommendation(s);

> **2** that the above studies should be completed by 2006.

ANNEX 4

Information Forwarded to Working Parties 1A, 1C and 8B

Relating to the Incomplete Work on FM Pulse Radar

-40 dB Bandwidth Formula and Applicable Out-of-Band Mask

\[TBD\]

ANNEX 5

Information Forwarded to Working Parties 1A, 1C and 8B

Relating to the Incomplete Work on FMCW Radar

-40 dB Bandwidth Formula and Applicable Out-of-Band Mask

\[TBD\]

[^1]: ^3^ These coefficients, *K* = 6.2 or 7.6 and 64, are related to
    theoretical values that would prevail in the case of constant
    frequency trapezoidal and rectangular pulses, respectively. Also, in
    the case of the trapezoidal pulses, the coefficient *K* has been
    increased somewhat to allow for implementing output device
    characteristics. For ideal rectangular pulses, the spectrum falls
    off at 20 dB per decade leading to a 20 dB bandwidth of 6.4/*t* and
    a 40 dB bandwidth ten times as large, i.e. 64/*t*. To discourage the
    use of pulses with abrupt rise and fall times, no margin is allowed.
    The spectra of trapezoidal pulses fall off firstly at 20 dB per
    decade and then ultimately at 40 dB per decade. If the ratio of rise
    time to pulse width exceeds 0.008 the 40 dB points will fall on the
    40 dB per decade slope, in which case the *B*--40 would be:

    $$\frac{5\text{.}7}{\sqrt{t \cdot t_{r}}}$$

    Allowance for unavoidable imperfections in implementation requires
    that the mask be based on values of at least:

    $$\frac{6\text{.}2}{\sqrt{t \cdot t_{r}}}\ \text{or}\ \frac{7\text{.}6}{\sqrt{t \cdot t_{r}}}$$

    depending upon the category of radar.

[^2]: ^5^ Equation (45) yields the total composite *B*--40 bandwidth of
    a frequency hopping radar as if all channels included within *Bs*
    were operating simultaneously. For frequency hopping radars, the OoB
    emission mask falls off from the edge of the 40 dB bandwidth as
    though the radar were a single frequency radar tuned to the edge of
    the frequency hopping range.

[^3]: ^6^ RR Appendix** **3 specifies a spurious attenuation of
    43  10 log* *(*PEP*), or 60 dB, whichever is less stringent. (PEP:
    peak envelope power.)

[^4]: ^\*^ This Question should be brought to the attention of
    Radiocommunication Study Groups 1 and 9, the International
    Association of Marine Aids to Navigation and Lighthouse Authorities
    (IALA), the International Maritime Organization (IMO), the
    International Civil Aviation Organization (ICAO), the International
    Maritime Radio Committee (CIRM), and the World Meteorological
    Organization (WMO).