> Doc.IWG-6/046 (Rev.2)

11 July 2001

Walt Ireland

wireland@mindspring.com

***Informal Working Group 6***

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**PRELIMINARY VIEW ON WRC-03**

**WRC-2003 Agenda Item 1.2:** *to review and take action, as required,
on No. **S5.134** and related Resolutions **517 (Rev.WRC-97)** and **537
(WRC-97)** and Recommendations **515 (REV.WRC-97), 517 (Rev. WRC-2000),
519 (WARC-92)** and Appendix **S11,** in the light of the studies and
actions set out therein, having particular regard to the advancement of
new modulation techniques, including digital techniques, capable of
providing an optimum balance between sound quality, bandwidth and
circuit reliability in the use of the HF bands allocated to the
broadcasting service;*

**ISSUE:** To support the introduction of digital modulation techniques
in the HF bands allocated to the broadcasting service and to prepare the
regulatory way for this introduction.

**BACKGROUND:**

**RESOLUTION 517 (Rev.WRC-97) and its ANNEX**

***considering b)*** states: that single-sideband (SSB) techniques allow
more efficient utilization of the frequency spectrum than
double-sideband (DSB) techniques;

***invites ITU-R*** states: to continue its studies on digital
techniques in HF broadcasting as a matter of urgency with a view to the
development of this technology for future use.

***ANNEX, ITEM 2*** states: All DSB emissions shall cease not later than
31 December 2015, at 2359 hours UTC.

**RESOLUTION 537 (WRC-97)** called for a survey of HF broadcasting
transmitters and receivers with emphasis on the worldwide distribution
SSB transmitters and receivers. This survey was completed in 1999
showing the results that although some countries had or could easily
convert to SSB, there were few SSB receivers at a reasonable cost
available anywhere in the world to justify the conversion from DSB to
SSB.

However, it is recognized that digital modulation design and development
for HF is under way.

**RECOMMENDATION 517 (HFBC-87)** deals with relative protection ratio
values for SSB emissions. ITU-R TG 6/7 is currently developing
protection ratios for digital transmission techniques and is expected to
be completed by the next meeting of SG 6 in September 2001.

**RECOMMENDATION 519 (WARC-92)** deals with the introduction of SSB
emissions and the possible advancement of the date for cessation of the
use of DSB emissions.

***considering d)*** states: that the new extension bands allocated by
WARC-92 for HF broadcasting are reserved only for SSB emissions;

Starting around 1995, active design and experimentation is being done on
the use of digital modulation techniques for use in all the broadcasting
bands below 30 MHz. Because of the special international broadcasting
role at HF, documentation of an essentially regulatory nature began to
be introduced within the ITU-R, initially through SG 10 (now SG 6).

WRC-97, in response to the development up to that time of digital
modulation for HF broadcasting, modified some of the articles,
resolutions and recommendations pertinent to HF broadcasting. However,
there was no agenda item at WRC-2000 associated with HF broadcasting to
deal with these issues.

Since WARC-92 digital modulations technologies have developed to the
field-testing stage. Digital emission systems currently under
development will be compatible with present 9 -10 kHz channels.

**PRELIMINARY VIEW:** The U.S. supports developing the necessary changes
to the resolutions, recommendations, and radio regulations cited in this
agenda item to accommodate the introduction of digital modulation
techniques for those HF bands allocated to the broadcasting service in
accordance with Article S5. (July 11, 2001)