Whitespace, still a bad idea, part 1

The Economist magazine has an article on the ruling by the FCC to allow white-space devices to use TV channels to send data. Please read my latest article about TV tuners and especially look at the figure in the sidebar. That figure explains how digital and software engineers with absolutely no conception whatsoever of how RF and radio in general work, have conned the US government into allowing a slew of unlicensed intentional interferes to occupy our TV spectrum.
Don’t everybody panic
Now, it is an analog world so I don’t want to be Chicken Little saying the world is going to end. True, the data services will put some competitive pressure on the phone, cable, and TV companies, but not too much since to receive a white-space data broadcast on channel 2, means you have to transmit and receive 54 MHz. That’s a darn big antenna buckaroo, so don’t look for the cell phone companies to be put out of business. Even a high UHF signal needs a pretty big antenna, but if the old analog phones could pull in 900MHz, I suppose cars and big phones and iPads can have an antenna big enough to pull in 700Mhz.

These data broadcasts will not wipe out every TV station in every city. But you need to understand a fundamental problem of receiving broadcast TV that the geeks at Intel and Google obviously don’t understand. That is the near-far problem. See, it is easy to receive and demodulate cable TV since all the channels come in pretty much at the same level. But broadcast TV may have a station physically close to you that is close to the frequency of the station that you want to receive that is physically far from you. The strong signal, called a blocker in TV engineer parlance, will saturate the AGC (automatic gain control) loop and wipe out the weak signal. So if you were the old FCC, the FCC that was full of decent upstanding technical people, you would spend an immense amount of your time and resources trying to keep the strong stations far away in frequency from the weak stations. The old FCC would make FM broadcasters reduce power at night, so the ionization skip to different cities would not clobber other stations. I assume they worried about TV as well, not to mention the problem that the FM radio stations are smack dab in the middle of the VHF band, between TV channels 6 and 7. In case you were not paying attention the last 70 years, here is what are in between Channels 6 and 7, along with the FM radio stations:

• 54-72 and 76-88 MHz TV channels 2 through 6 (VHF-Lo), known as “Band I” internationally; a tiny number of DTV stations will appear here.
• 72-76 MHz: Radio controlled models, industrial remote control, and other devices. Model aircraft operate on 72 MHz while surface models operate on 75 MHz in the USA and Canada, air navigation beacons 74.8-75.2 MHz.
• 88-108 MHz: FM radio broadcasting (88-92 non-commercial, 92-108 commercial in the United States) (Known as “Band II” internationally)
• 108-118 MHz: Air navigation beacons VOR
• 118-137 MHz: Airband for air traffic control, AM, 121.5 MHz is emergency frequency
• 137-138 Space research, space operations, meteorological satellite [3]
• 138-144 MHz: Land mobile, auxiliary civil services, satellite, space research, and other miscellaneous services
• 144-148 MHz: Amateur radio 2 Meters band
• 148-150 Land mobile, fixed, satellite
• 150-156 MHz: “VHF Business band,” the unlicensed Multi-Use Radio Service (MURS), and other 2-way land mobile, FM
• 156-158 MHz VHF Marine Radio; narrow band FM, 156.8 MHz (Channel 16) is the maritime emergency and contact frequency.
• 160-161 MHz Railways [4]
• 162.40-162.55: NOAA Weather Stations, narrowband FM
• 174-216 MHz television channels 7 - 13 (VHF-Hi), known as “Band III” internationally. A minority of DTV channels may appear here.

But it was the old FCC, the sleepy backwater technical organization that drove around in vans with loop antennas on the top looking for interference sources. They worried that all these RF sources would peacefully and fairly coexist.

Then the cell phone got invented. And soon 20 or 30 MHz of spectrum was worth billions of dollars. The FCC morphed from a technical organization full of engineers to a political organization full of politicians. And like all politicians, what is good for us peons is the last thing on their mind.
Applaud the FCC
Now I don’t want to rag on the FCC too hard. I have to admit, their trying to balance power between the cell phone companies, the Internet companies, the cable companies, and old POTs phone companies is admirable. After all, they could have sold off the whitespace in billion dollar auctions, which would have made the only practical data on the new network would be shopping channels. So it remains to be seen how bad the interference caused by these whitespace radiators is, along with how much advertisements or subscription services that Google and Intel will slap onto the data channels. Personally I think the FCC should have given the 700MHz band to this free service, but asking any government bureaucrat to give up billions of dollars in auctions revenue is pretty naive of me. It is a beautiful form of a tax. The government tells us the “people” own the airwaves and then they sell it to some big company who can charge us crazy rates and all it really is a prepayment of taxes on top of all the other phone network taxes we have to pay.

I won’t bore you with Public Choice Theory, but at least the old FCC had some vestige of concern for the citizens of this country. I hope all the people at the FCC that are of this ilk try to convince the FCC politicians to not just listen to the mega conglomerates with the biggest brown envelopes.

(Continued in part 2)