[Date Prev][Date Next][Thread Prev][Thread Next] - [Date Index][Thread Index][Author Index]

Re: CQ PSK31 on Oscar 10



Someone wrote:

> Since PSK31 is a continuous carrier mode it is not compatible with the
> usual transponder satellite system is it???

I think PSk31 is an ideal mode for AO-10 satellite use and could
*greatly* expand the usefulllness of AO-10.

   * Most satellite data uses PSK because of its effeciency
   * High effeciency and narrow bandwidth allow many more users
     per given bandwidth and power.
   * Thus you should be able to have 15 users of PSK31 operating at
     12 dB less uplink power, operating in the same bandwidth and
     using the same satellite power as a normal 1200 baud packet sig

I havent done the math, but lets make some guesses.  PSK-31 uses only 
2% of the bandwidth of SSB, so instead of using 50 watts and a 13 dB gain
antenna to hit AO-10 using voice, you could drop back to an OMNI antenna
and only 20 watts.

Too bad you still need a huge 13 dB two-meter beam for the downlink..
Otherwise, you could go mobile!  

But what if only a few stations served as the downlink, and fed their
signals into the internet (like the APRS network), then mobiles could
transmit via the satellite using only a laptop and UHF mobile rig.
Problems tho, are the extremely narrow bandwidth, combined with doppler,
making every signal must be hand tuned to get within the 5 hz or less
requirement...

But, still, an interesting concept...

----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org



AMSAT Top AMSAT Home