[aprssig] PIC processor for APRS info for D-STAR mobiles?
Stephen H. Smith
wa8lmf2 at aol.com
Sun Jul 6 00:27:55 CDT 2008
Wes Johnston, AI4PX wrote:
> Yes, I got a partial answer. So does the low speed GMSK data transit
> a voice grade repeater? I know that afsk 1200baud packet will. Will
> the 4800baud digital voice signal do the same?
I doubt it. GMSK is not FSKed audio tones applied to an audio input
of an FM transmittter. It is essentially direct FSK of the carrier in
a manner somewhat like 9600 baud packet. Just as with 9600 baud
"classic packet" you would have to have a direct (probably DC-coupled)
connection between the receiver discriminator and TX modulator.
Normally it would be repeated in a manner more like a digipeater only
full duplex. I.e. modem attached to RX discriminator to extract
baseband serial data stream, then serial data into a second modem
modulating the TX on another frequency simultaneously. (This allows
the data to be regenerated and retimed before retransmission.)
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