**JRG-84**

**16 April 2007**

**JRG 1A-1C-8B**

**5^th^ and Final meeting -- London -- 24-27^th^ April 2007**

**UNITED KINGDOM**

**Contribution to the Final report**

The terms of reference of the JRG include consideration of the "design
objective" for primary radars contained in Annex 8 of ITU-R
Recommendation SM.1541. The aim through the previous meetings of the JRG
has been to assess the possibility of the design objective being met,
sometime in the future, for various classes of radar.

This work has included --

1.  the applicability of the equations in Annex 8 for the determination
    of the necessary parameters connected with the "roll-off" of the
    mask from the 40 dB bandwidth;

2.  the collection of emission data from operational radar systems to
    assess the current likelihood of the design objective being met
    either now or in the future.

With regard to 1 above, it has been necessary to re-examine the
equations for some types of radar systems, and update them to reflect
current knowledge. (Note that the equations currently in SM.1541 were
derived some 30 years ago and have not yet been updated).

With regard to 2 above, some data has been collected, although
overwhelmingly for maritime mobile radars using magnetrons. Much of this
data had to be rejected during analysis, as it did not conform with the
measurement methods contained in ITU-R M.1177. Of that remaining the
sample size for S Band was small (\< 10). The results included in the
report of the 4^th^ meeting of the JRG demonstrated that the majority of
the cases did not meet the design objective.

At this time no decisions have been made within the JRG as to whether it
is possible to recommend that the design objective be applied to any
types of radar. This remains a key objective of the 5^th^ meeting.

In the event that some agreement is reached on the application of the
design objective, it would be necessary also to include the time scales
for mandatory application.

Concern has been expressed in previous meetings of the JRG that any
agreement to meet the proposed "design objective" for primary radar
systems should be linked to the time-scales for implementation.

There are precedents in ITU-R to agree specific dates for implementation
of new requirements.

A relevant example is that for spurious emissions in Appendix 3 of the
Radio Regulations, in which the agreed limits apply to new installations
for radar from 1 January 2003 and to all radars from 1 January 2012.

Whereas for ***unwanted emissions***, there are no specific dates in the
Radio Regulations.

In Appendix 3 of the Radio Regulations the following applies for the
boundary between out-of-band and spurious domains -

"4 For primary radar stations, the boundary between the out-of-band and
spurious domains is the frequency at which the out-of-band limits
specified in applicable ITU-R Recommendations are equal to the spurious
limit defined in Table II of Appendix **3**. Further guidance on the
boundary between the out-of-band and spurious domains for primary radar
systems is provided in the most recent version of Recommendation ITU-R
SM.1541."

It should be noted that this only refers to "the most recent version of
ITU-R SM.1541" and provides no specific dates for the implementation of
new requirements arising from a revision of SM.1541.

In order to provide the link between agreement of the design objective
for any specific radar systems with the time scales for implementation
it is proposed that the JRG should include in their final report the
following text --

"The agreed mask for future radar systems (as specified in the Final
report) should apply to all new installations from \[1 January 2012\]
and to all radar installations from \[1 January 2022\]".