APRS Satellite operators:
We are delivering our next APRS satellite (QIKcom-1) next week and it will have a mission life of maybe 6 months.
It is a very quick reaction short fuse opportunity so we are simply going to fly an APRS digipeater (TinyTrack4) supporting the three digipeater aliases of ARISS, APRSAT and WIDEn-N but it will operate at 4 Watts RF power and be easily heard on any HT..
It has no other CPU on board and so it flies with only the fixed settings set before launch.
But we do have an A/B switch which can be used to switch between two bank settings.
I just cannot think of any neat must-do ideas for how to use the other bank settings.
The host spacecraft has plenty of power, so there is no need for low power options… (they can simply turn us off if needed). Telemetry is a boring Volts, current, and two internal temps. The settings in bank 0 are now:
DIGIPEATER: ON
ALIASES: ARISS, APRSAT, WIDEn-N
BTEXT: USNA-W3ADO APRS Satellite every 2 minutes
TELEMETRY: every 1 minute.
I just cannot think of any use for a separate bank settings?
If you have ideas of how to use the A/B settings let me know.
Bob, WB4aPR
Bob asks:
I just cannot think of any neat must-do ideas for how to use the other bank settings. The settings in bank 0 are now:
BTEXT: USNA-W3ADO APRS Satellite every 2 minutes
I just cannot think of any use for a separate bank settings? If you have ideas of how to use the A/B settings let me know.
If you don't have any other ideas:
Set BTEXT to a short beacon message that includes a few sync bytes, your preferred text message and a few bytes of forward error correction. You would have to pre-compute these and manually enter the FEC bytes at the end of the BTEXT. All of this would be sent INSIDE the AX.25 packet as the BTEXT. That way standard TNCs would still see the BTEXT message and a few binary bytes (if they get a valid CRC) but we could write DSP software to ignore the HDLC flags, look for the sync bytes, and process the FEC too. Depending on your message you might want to 8b10b encode it to avoid HDLC zero bit stuffing which could complicate the ground software.
At four watts RF output, you don't need the FEC, but it would be an interesting experiment, and easy to do as you only need to pre-calculate the FEC once and hardcode the BTEXT message.
73, Douglas KA2UPW/5
Wow Douglas,
sounds impressive and honestly I am glad you understand that. I am clueless :-)
Tx,
Stefan, VE4NSA
On Sat, Feb 21, 2015 at 7:03 PM, Douglas Quagliana dquagliana@aol.com wrote:
Bob asks:
I just cannot think of any neat must-do ideas for how to use the other bank settings. The settings in bank 0 are now:
BTEXT: USNA-W3ADO APRS Satellite every 2 minutes
I just cannot think of any use for a separate bank settings? If you have ideas of how to use the A/B settings let me know.
If you don't have any other ideas:
Set BTEXT to a short beacon message that includes a few sync bytes, your preferred text message and a few bytes of forward error correction. You would have to pre-compute these and manually enter the FEC bytes at the end of the BTEXT. All of this would be sent INSIDE the AX.25 packet as the BTEXT. That way standard TNCs would still see the BTEXT message and a few binary bytes (if they get a valid CRC) but we could write DSP software to ignore the HDLC flags, look for the sync bytes, and process the FEC too. Depending on your message you might want to 8b10b encode it to avoid HDLC zero bit stuffing which could complicate the ground software.
At four watts RF output, you don't need the FEC, but it would be an interesting experiment, and easy to do as you only need to pre-calculate the FEC once and hardcode the BTEXT message.
73, Douglas KA2UPW/5
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participants (3)
-
Douglas Quagliana -
Robert Bruninga -
Stefan Wagener