On 7/24/2012 1:16 PM, Dave Platt wrote:
In article ,
Jeff Liebermann wrote:

My guess(tm) is that the higher power 433MHz devices can only be sold
in Europe. Yet, that's not apparent on any of the sites selling
433MHz data radios.

"FCC Compliance testing Using the MICRF112"
http://www.micrel.com/_PDF/App-Notes/an-55.pdf
Page 9 has the calcs for a typical key fob transmitter.
36 microwatts.

I've run into interference in a local shopping mall parking lot, which
is sufficient to almost completely block 433 MHz car keyfobs from
working. It comes from a local noodle restaurant, which uses a
wireless order-taking system... from the sound of the transmissions
over the air, I think the central node is polling the hand-held order
entry units 3-4 times per second (well in excess of the Part 15
periodic radiator limit). It's quite audible for about a city block
around the restaurant, in at least some directions.

I got a look at one of the handheld terminals, and did not see any
sort of FCC licensing or type-acceptance sticker.


Why am I not surprised? I think this could get out of hand just as the
27 MHz band did. There is a slight difference here. The military has an
interest in the 70 cm band, so this may become very interesting. Note
that near some military bases, some gadgets are becoming next to useless
already.