Doug Lung /
06.03.2010 12:00AM
Mobile DTV Receiver Manufacturers Ask for Analog Waiver

Should the mobile DTV receiver in your netbook, cell phone or smart phone be able to receive analog TV? Strictly speaking, FCC rules require it. But adding analog TV reception to mobile DTV receivers would be difficult because ATSC A/153 is based on transmitting RTP UDP/IP data streams, which have more in common with Internet web streams than conventional TV and even the PID based original ATSC A/53 DTV transmissions.

Last week, the FCC put a request from Dell and LG Electronics for a waiver of the analog tuner rule, (C.F.R. Section 15.117) out for public comment. Dell and LG sought the waiver for themselves and any "similarly situated manufacturers to manufacture, import, market, and sell mobile DTV receivers that do not include analog (NTSC) tuners." The waiver request was limited to devices that have an A/153 compliant mobile DTV tuner that are primarily powered by batteries and "designed for nomadic and transient use."

Some of the articles published last week covering the request for comment saw this as a big stumbling block for mobile DTV. I don't. While it would have been convenient for the FCC's Media Bureau to simply grant the request, going through the comment process should remove any second guessing of what I expect to be an approval of the request. The FCC set a very short comment period – comments are due no later than Friday, June 4, with one additional week for reply comments. The first comments started to appear this week on the FCC's Electronic Comment Filing System. To view the comments, enter 10-111 in the "Proceeding" box at the top and change the date search below it to start on May 20, 2010, when the waiver request was submitted. I've summarized some of the comments below. Note that I've not corrected typos in quotes from the filed comments.

There was only one comment filed by an LPTV operator. Keith Leitch said "I agree the future of TV is digital and mobile." However, I think many broadcasters will agree with this request: "I ask that manufacturers making equipment to receive mobile TV make sure that they do all they can to effectively receive lower VHF channels in addition to high VHF channels 7-13." He continues, "It is too easy to create inferior antennas that really only receive UHF antennas [sic] and I request a pledge that mobile devices will not attenuate VHF channels so that their devices only effectively receive UHF TV channels."

Unfortunately, at least without the use of exotic components like metamaterials, the laws of physics are against any electrically small antenna working as well as larger antenna. High VHF DTV broadcasters know the problem all too well. Man-made noise is also an issue at VHF. Allowing broadcasters to transmit more power on VHF can help offset this. Consumer electronics manufacturers want the option to make products of differing quality for a wide range of price points. However, something like the ATSC A/74 recommended practice adapted for A/153 mobile devices would be a good start in providing a benchmark for mobile DTV receivers.

All other comments posted as of Wednesday evening were from device manufacturers that supported the waiver request. Hauppauge listed four reasons not to include NTSC capability in A/153 devices. These include a severe disadvantage in battery life because "analog receivers are power-hungry"; adding analog receivers increases device size; adding an analog receiver adds unnecessary costs to each device; and "an analog receiver has much higher CPU requirements than digital: ATSC digital TV broadcast is 19.2 Mbps/sec [sic]; analog comes out of the A/D converter at 216 Mbits/sec – a ten fold increase."

Elgato Systems, manufacturer of USB DTV receivers widely used on Apple Computers, requested the waiver be extended to include all products that depend on downstream devices to decode and display the signals they receive. Elgato notes that "The technical reason for the increase expense [of supporting NTSC reception in these devices] comes primarily from the fact that NTSC signals occupy too much bandwidth to be sent to downstream devices. In some cases, even if the bandwidth was there, many downstream devices cannot decode NTSC signal. The result is that to facilitate NTSC functionality, peripheral DTV receivers would need to include hardware that essentially converts NTSC signals to an ATSC data stream. That is an expensive proposition." Elgato did not mention A/153 capability in its comments.

Most comments are likely to be filed on Friday, just before the deadline. I'll have updates, if needed, in next week's RF Report. My prediction is few if any comments against the waiver, but I wouldn't be surprised to see more requests like those from Keith Leitch or Elgato for actions beyond those requested in the original request.



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