FreeBSD TDMA: Legalizing 440MHz 802.11 modems
Bart Kus
me at bartk.us
Wed Aug 27 22:42:03 UTC 2014
Hello,
I'm wondering if you can tell me if it's possible to modify the FBSD
TDMA code to make this card:
http://www.doodlelabs.com/products/radio-transceivers/sub-ghz-range/420-450-mhz-dl435-30/
legal to use in its intended spectrum. By default the card violates two
Part 97 rules:
1) Emissions are limited to 200kHz bandwidth
2) Symbol rate is limited to 56kSym/s
Is it possible to slow down the subcarrier symbol rate in that Atheros
chip? Is it also possible to then space the subcarriers tighter
together to respect the 200kHz emission bandwidth limit? They'd have to
come closer together anyway to uphold OFDM subcarrier orthogonality.
Thanks for any clues,
--Bart
PS: I'm asking in the interest of the HamWAN.org project. We're trying
to find a more mobile solution, which penetrates through forests and
some buildings. 440MHz seems to fit the bill, but hardware is really
hard to come by.
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