• From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
  • To: <opendtv@xxxxxxxxxxxxx>
  • Date: Wed, 18 Oct 2006 14:22:45 -0400

John Shutt wrote:

>> First, how is this deteremined? Is it manually configured
>> (unlikely) or is it dynamically determined by the device,
>> as IEEE 802.11 access points do? In the latter case, I
>> think my scenario could easily unfold.
> Bert,
> Try Title 47, United States Code of Federal Regulations,
> Part 15:
> http://www.access.gpo.gov/nara/cfr/waisidx_04/47cfr15_04.html

Thanks, John. The pertinent section is 15.242. This applies to the US
high VHF and UHF TV bands.

Assuming that the allowable equipment in this band would no longer be
limited to the medical facilities mentioned here, but instead will
possibly be consumer equipment, I don't see how these rules can continue
to apply as written. Because you can't expect the consumer to measure
distances from the Grade B contour of multiple TV towers, and the
reseller doesn't know where a given consumer will locate the equipment.

Furthermore, this catch-all paragraph at the end is also unlikely to be
of any use for consumer-configured equipment:

"The manufacturers, installers, and users of biomedical telemetry
devices are reminded that they must ensure that biomedical telemetry
transmitters operating under the provisions of this section avoid
operating in close proximity to authorized services using this spectrum.
Sufficient separation distance, necessary to avoid causing or receiving
harmful interference, must be maintained from co-channel operations.
These parties are reminded that the frequencies of the authorized
services are subject to change, especially during the implementation of
the digital television services. The operating frequencies of the part
15 devices may need to be changed, as necessary and in accordance with
the permissive change requirements of this chapter, to accommodate
changes in the operating frequencies of the authorized services."

As a result of this, what I think is likely is that consumer equipment
operating in these white spaces will be auto-configured, like Wi-Fi
access points. And that's where I think you're likely to see problems.
The equipment may think it is "5.5 Km distant from the Grade B contour"
of a UHF station, only because that's what it's signal strength meter
indicates, where the consumer has the equipment located. In fact, this
may interfere with an OTA station that Joe next door was watching
happily in the past.

But if this new equipment is instead professional grade stuff, like
fixed WiMax base stations, then perhaps that's a different matter. Then
the people affected would more likely be limited to TV production folk,
as Ken described earlier.

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