We successfully sent commands to re-write PSAT EPROM values to correct the Orbit clock. It worked. Over a few days, we will fine tune the value and be able to turn on PSAT Position reporting.
In looking at the orbit timing, we also came up with these factoids.
PSAT passes are almost exacrtly 15 minutes earlier every day. (14.7 minutes actually)
And the time between orbits is almost exactly 100 minutes (1 hour 40 minutes).
You can use these to plan your “free time”… without needin’ no stinkin’ computer
Bob, Wb4APR
An aging Luddite
*From:* Robert Bruninga [mailto:bruninga@usna.edu] *Sent:* Thursday, June 18, 2015 7:34 AM *To:* amsat-bb@amsat.org *Cc:* bruninga@usna.edu *Subject:* PSAT digipeating and Position Knowledge
PSAT continues to work well, both APRS and PSK31. The downlink capture on the PCSAT.APRS.ORG page captures most PSAT packets, but does not capture any digipeated users if they use the ARISS path. Although PSAT supports the VIA ARISS alias so that users can use both ISS and PSAT without changing parameters the FINDU page does not recognize it.
At this point it is unclear what paths that FINDU recognizes.
These paths are supposed to be digipeated by PSAT:
VIA ARISS
VIA APRSAT
VIA PSAT
VIA WIDEn-N
Here is what we know:
ARISS is not recognized by FINDU.
We are not sure if FINDU recognizes APRSAT
We are not sure if PSAT recognizes PSAT
We have seen VIA WIDEn-N work on FINDU
We have been busy with deadlines on our next satellite, but yesterday we figured a workaround on the PSAT ORBIT and MA clock. This morning we sent the commands and will be watching to see if they work. If they did, then PSAT will be able to know where it is, and then we can activate its APRS POSITION packets plus individual beacons over individual continents.
Although the S#OOOMM… telemetry was supposed to be ORBIT number and MINUTE of that orbit, the clock is totally off. SO instead of going from 0 to 95 minutes per orbit, the actual count is more like 0-61 minutes per orbit. So, if this works, then MM is not real minutes, but is a number between 00 to 61 on every orbit. And 0 should be when the satellite crosses the equator (actually 5 South latitude) on every orbit northbound.
Once we get that under control, then PSAT will know where it is, and it will be able to report its own position. And we can activate its attitude control, and we can activate different bulletins over each continent.
Bob, WB4APR