For starters this band is only 26 Mhz wide and already has very primitive (from an RF sophistication point of view) devices already camping on it. Sorry dear, the garage door opener didn't work because I am on the Internet. The usage rules are also critical. ISM bands have very restrictive power limitations. The new interference rejection concepts in the white spaces allow for higher transmit power, enabling applications which are otherwise not practical.
Speaking of job security, I think it will be interesting to see how the database of protected channels will be handled. How often? If the update fails is the device disabled? How about the device location? The Report and Order should be public soon, now that it's been signed. We should see answers soon.
Remember TDMA systems requires stations in the network to keep time and CDMA, codes. That's easy when stations are in the same network, not so much when they are not.
Gee, I wonder if over-the-air TV viewers can declare themselves as quiet zones?
So, is this decision the "death nail in the coffin" of over the air TV broadcasting?
"Simple frequency channels hogged by single users" is the basis for FCC frequency auctions, but that's another topic.
I'd have to agree with Feory and Larry M. There are lots of ways to split up the spectrum these days; time division multiplexing, CDMA, etc. The days of "walled gardens" and simple frequency channels hogged by single users are over. Is it easy or simple to make sure the users don't interfere with each other - no, of course not. Think of it as job security for those of us who have to design the systems to do so.
I'm not going to say you are wrong, but if the need was so great why haven't we seen greater adoption of the 900 MHz unlicensed band? The band is currently available, has similar co-channel issues as 2450 MHz, but very desirable propagational characteristics similar to those of the UHF TV channels.
The cold reality of the OTA television band is that it is tremendously underutilized. Very large numbers of channels in rural areas are completely unused but were nonetheless verboten until this decision. It was commonly accepted that nothing useful could be done without these Draconian protections until WiFi succeeded in bandwidth that was so bad that no one else wanted it. Personally, I think that this decision is long overdue and a very rare case of government acting in the best interests of its citizens.
Modern ATSC DTV receivers must tolerate -33 dB D/U (desired to undesired) for upper or lower channel DTV into DTV adjacent channel interference. Even the cheap converter boxes with the $40 NTIA coupons had to meet that spec.
That might satisfy the case for wireless microphones, not withstanding the requirements for new capital expenditures. Now let's address the implications on TV over-the-air and CATV headends.
Anyone out there have the numbers for adjacent channel rejection in a modern TV receiver?
The TV broadcast spectrum is grossly under-utilized and the NAB's argument against allowing white space devices is weak -- especially after the FCC set aside dedicated channels for wireless MICs.
After all the studies, analysis and debate of the last few years, the FCC rightfully decided that the public benefits of new unlicensed spectrum far outweigh the risks of inconveniencing performers and other wireless MIC users who might now have to use a different channel that the one they've been using all these years.
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