[aprssig] RFM22B UHF Transceiver Module

Matti Aarnio oh2mqk at sral.fi
Thu Dec 13 04:13:49 EST 2012

On Wed, Dec 12, 2012 at 06:22:19PM -0500, Robert Bruninga wrote:
> Fantastic Work, John.  And of course, another tiny device for APRS is
> a great project, but when I first saw this chip and its ability to do 100 kB
> so cheaply, I actually was thinking more of a tiny $20 box that *EVERY*
> ham on the planet might put up on his antenna tower or mast and
> become another node in an all-ham digital backbone.

Maybe such a thing can be made at "low price" but I don't believe
in $20 being possible level.  For that matter, Raspberry Pi has shown
that the resulting thing is not even hobby assemblable.  Giving up
the dear things of "I can assemble it myself", and "it is some surplus",
then we can really create something viable.

To increase network reach, data transmission efficiency, and to
reduce error rate you need a forward-error-correction mechanism
and spectrally efficient modulation, and ...

A digital backbone needs a lot more than just an RF tranceiver, and
sadly the original form of AX.25 just does not do it with Bell-202 modems.

A self-organizing radio router network needs very interesting variation
of the RIP or OSPF protocol running at every participating router node,
and a bit simpler version to be running at every client.
("Hi, I am here, please know me")

How much of the radio time you would permit to be spent on the network
internal topology discovery instead of application traffic?

How much interference from other tranceivers would you permit?

> Just dreaming outloud of that ham cloud ON RF.
> Bob, WB4APR

Good dream, don't let compability with old stuff to limit you.

73 de Matti, OH2MQK

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