Ok, so is the reasoning here that some kind of direct FSK modulation will suffer fewer of the propagation difficulties that we've seen with reception of voice/AFSK?
I'd assume this would be simplex only, which has in fact been by far the most reliable over the few small-area (< 3 miles) urban nets I attended recently. If we could get up to a 10 mile range somehow with some clever digital processing, I'd think that would be very useful indeed for us canyon-dwellers - do you think that might be possible? On Fri, May 23, 2014 at 5:48 PM, Guan Yang <[email protected]> wrote: > I've been talking to a few of you about a project to finally make it easy > to do great digital on 2 meter or 70 cm. The use case is both emergency > communications, based on our frustrations with FM voice and our needs in > the Rockaways during Sandy, and APRS and similar modes, based on our > frustration with AFSK over FM in Manhattan. > > Right now I've ordered some RFM23BP transceiver modules, which can operate > on the entire 70cm amateur band and also 433 MHz ISM. The plan is to do > 9600 bps GFSK, and to test for compatibility with other chips, for example > ADF7023 from Analog. There's also a similar part from Silicon Labs. > > RFM23BP is easier to get started with since it has a single ended 50 ohm > RF output. It can't quite do GMSK with typical bit rates because deviation > has to be a multiple of 625 Hz. I'm thinking we might try 9600 bps with > 2500 Hz deviation. (That's carrier to peak, not peak to peak. I think.) > > The final product might be a circuit board with USB serial, possibly > Bluetooth LE for communication with phones, a battery charging IC, and a > lithium ion battery. > _______________________________________________ > Radio mailing list [email protected] > https://list.hackmanhattan.com/listinfo/radio >
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