Fascinating write-up as always, Bob.
I promise that my answer for everything isn’t the Raspberry Pi, but on the chance that anyone is not aware, TAPR has a daughter-board for the Pi that transmits 20-meter WSPR.
https://www.tapr.org/kits_20M-wspr-pi.html
While this unit does not allow for frequency or band adjustment, if an alternative APRS WSPR frequency ever comes into being, perhaps a way could be found to adjust the TX frequency of the TAPR board.
Like a lot of folks, I can attest to the amazing propagation of WSPR... with just a random wire strung across my living room, my signal from the TAPR WSPR board was heard across the US and in much of Europe & Australia. When I changed to properly sized dipole outdoors, the reception confirmations multiplied x10 or more.
With the Pi being cheap and having low electrical power requirements, I just wanted to chime in with a mention of the TAPR board.
-Scott, K4KDR
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-----Original Message----- From: Robert Bruninga Sent: Friday, October 07, 2016 5:28 PM To: amsat-bb@amsat.org Subject: Re: [amsat-bb] Global Geo SATCOM system? and WSPR back
Another possible APRS Message return path is to use very low power, reliable WSPR links.
Although WSPR only communicates CALLSIGN and then GRID, and POWER in only 22 bits, we have already exploited simple FIVE DIGIT communications on our next QIKCOM- satellite (awaiting launch). http://aprs.org/qikcom-2.html
Via QIKCOM-2, any user with only a DTMF Ham Radio HT can communicate into the global APRS system using even an ICOM-2AT that is 40 years old. Using 4 digit codes we can communicate:
· Grid position · Any of the 43 ARRL Radiograms · Including a 2 digit modifier in some messages with variables · Such as #30 which can say any of the 14 Maritime emergency codes · And there are still thousands of codes remaining in the 22 bit space.
See now we are proposing to experiment with a parallel WSPR return path for this OUTNET Ham Radio OUTERNET experiment.
So, if you are playing with WSPR in addition to your AMSAT interests, let me know.
Bob Bruninga, WB4APR ==================================================================
*From:* Robert Bruninga [mailto:bruninga@usna.edu] *Sent:* Wednesday, October 05, 2016 6:52 PM *Subject:* Global Geo SATCOM system?
AMSAT tinkerers?
OUTERNET is a free worldwide Geostationary Satellite downlink system designed to bring content to remote areas all over the globe. They have six geostationary birds covering the entire globe EVERYWHERE. All you need is a small 18” (or 36” in some very remote areas) to receive content via your own home-made receiver based on a TV dongle and Rasberry Pi.
Is there anyone on AMSAT-bb that is already receiving this content? We’d like to hear about how easy it is to set up a receiver.
We have some ideas on how this can be used to augment Ham radio in our Emergency Response and remote operations missions. See http://aprs.org/outnet.html
Bob, WB4APR