The wireless data links in those R/C sensor type things don't operate
near GPS carriers, but their harmonics can land there. The
transmitted power allowed should be too small to interfere with
anyone's receiver farther away - yours is probably pretty close. I
believe that the remote senders do not wait for any polling signals -
if so, they would have to be receiving on a regular basis, taking
precious battery life. It makes more sense for them to just burst
transmit at regular intervals, while the line-powered (or
bigger-battery-powered) base station is always listening, or listens
at various intervals to see if any remotes are calling. That's why it
takes a while to get the initial temperature data when the system starts up.
The base station receivers used for simple, cheap VHF data are
typically super-regenerative type for high sensitivity, so when
they're fired up it may appear that they're transmitting, but
actually are only receiving, with lots of crap kicking out of the
super-regen circuit. A common carrier used for VHF remotes is around
315 MHz - the fifth harmonic of that one is especially bad, landing
almost right on top of GPS. When you add in the loose frequency
stability and modulation, and the regen signals, the transmitters and
receivers can cause quite a spectral mess.
Ed
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