Telemetry

In what they call a "new risk of interference with Wireless Medical Telemetry Systems" (WMTS), the FDA is reiterating the warning they gave in November of 2005. Emphasis mine.

Beginning on January 1, 2006, the Federal Communications Commission
(FCC) started granting licenses for mobile radio transmitters operating
in the 460-470 MHz band. It's estimated that there are several hundred
thousand mobile radio users
waiting for these new channels. Most of the
radio users in this band will include hand-held and other mobile
transmitters such as those operated by police; fire and rescue; taxis;
and commercial trucks. These users could likely operate in and around a
hospital.

FDA recommends that hospitals determine if the
facility’s current wireless medical telemetry systems are operating in
the 460-470 MHz frequency band. Hospitals still operating in that band
should move to less vulnerable frequencies. FCC has reserved a certain
portion of the radio spectrum for wireless medical telemetry. This part
of the spectrum is known as the Wireless Medical Telemetry Service
(WMTS).

Interference from TV stations broadcasting in the
vicinity of hospitals could also be a growing problem because of
Digital TV. The FCC is asking TV broadcasters to operate their new
Digital TV transmitters at maximum power, and that can increase the
potential for interference with medical systems. So if a hospital’s
wireless telemetry equipment is still operating in the commercial TV
frequencies, it's important to migrate out of those channels and into
the bands reserved for medical uses.

The risk is far from new. The FCC has postponed granting licenses for the reuse of old telemetry spectrum on numerous occasions, so often that the real news is that the FCC actually pulled the trigger. The risk from Digital TV transmitters (DTV) is not new either - it all started with a DTV station firing up in Dallas in 1998 and knocking out their telemetry.

What's not plainly stated in this warning is that hospitals that move to the new WMTS bands can also expect interference, depending on what DTV channels are in their markets and which WMTS bands they're using. Something else that's missing is that hospitals may chose to adopt telemetry systems that use the ISM band rather than WMTS.

[Hat tip: Bill Hyman]