Tried today at 11:47 according to schedule and 25 minutes after 12:57 without any signal.
What exactly does “~” mean after a start time without a following end time?
If a message does not come for 2min, the APRS will end. There is no end time because it is not known when it will end.
I don’t understand that.
If there is no end time, why is there a start time?
Does that mean that APRS is always ready to digipeat?
If I understand it correctly I think it works like this…
- The transponder turns on at the scheduled start time for a pass and a 2min countdown timer starts.
- If a message is received within the 2 mins the scheduled message is sent and the countdown timer reset.
- This continues until 2 minutes elapse without an incoming message being received when the countdown timer hits 0 and the transponder turns off.
- The transponder is then off until the next scheduled start time on a different pass.
They can’t give an end time because it will depend on incoming messages being received in a 2 minute window. The transponder could be active for only 2 minutes if no message received in the first 2 periods, for 3 minutes if only a message received after 1 minute then none for 2 minutes, etc. It depends when the incoming messages are received. I guess theoretically if an incoming message was received every 1 minute 59 seconds after the start time the transponder would stay active indefinitely.
What it also means is that if a message isn’t received within the first 2 minutes of the start time the transponder will turn off and be unavailable for the rest of the pass so it needs somebody in the footprint of the satellite at the start time to send a message or people further along the pass won’t have a chance to work the satellite.
Of course I could be completely wrong but I think that is what they mean about the 2 minutes interval and why they are unable to give an end time.
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This is SAKURA’s weekly schedule from 9/30~10/06.
※Schedules are subject to change depending on operational conditions.
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That’s correct!
This is SAKURA’s weekly schedule from 10/07~10/13.
※Schedules are subject to change depending on operational conditions.
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Keep in mind that, as long as SAKURA sends the “si” beacon type, it cannot stick to the schedule because it has no accurate time.
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I want to ask about “User query” mode.
- Which “APRS query” will Sakura respond to?
- If a query does not come for 2min, 2m TRX will OFF?
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The APRS operating schedule will be changed.
The mode has changed from
“User query” to “User Message.”
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While at 09:1x UTC pass still on regular beacon pattern, SAKURA felt back to the si beacon at 10:4x UTC pass over Europe.
What the SI on the CW telemetry means? No accurate time? No APRS?
The SAKURA team doesn’t know it.
They said:
That comes from heritage program provided by different universities. We recognize it as just a symbol.
Anyway, if SAKURA transmits this beacon pattern, it has no accurate time. That means SAKURA cannot stick to the schedule.
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This is SAKURA’s weekly schedule from 10/14~10/20.
※Schedules are subject to change depending on operational conditions.
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For the Europe pass listed I was monitoring APRS on 145.825 and FM 437.375 but nothing heard.
Could someone confirm I read the schedule correctly and a transmission was expected at 06:46 UTC?
My Location is in the UK so max elevation of Sakura would only have been 10 degrees. Maybe the signal was too weak here?
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Hi Paul,
I’ve also expected user messages according to the schedule and therefore sent packets via JS1YNI from 06:46 on to activate these transmissions.
However, and although the CW beacon on 437.375 showed a regular pattern (no “si”), there was no signal on 145.825 to pick up.
It was only a 26° elevation pass for me, so perhaps SAKURA was not able to read me, but at least its CW beacon was as strong as usual for those passes.
73, Daniel
Hi Daniel,
Thanks for your reply.
With my current APRS setup I only have 5W TX and do not have a directional aerial. I’ve had success for ISS but only with high passes.
Please can you tell me if the 437.375 beacon is always transmitting? Or only on a schedule? I guess it stops while APRS operations are happening and then reverts to beacon after APRS is completed?
I’ll keep trying!
Many thanks again,
Paul
M1PWT
Well, there is no schedule for the UHF beacon.
But if it stops while transmissions on VHF are on schedule is a good question. Let us ask @gardens .
By the way, I put 50 watts into a 4 dBd directional.
Again no luck on today’s 07:1x pass with a max. elevation of 70°.
The CW beacon showed a regular pattern.
The data part’s last hex number a582b86c29a11024 indicates (expressed as binary) a “1” on its 3rd digit (0010 0100) which means “APRS Mission is running”.
By the way, I sent VIA JS1YNI what should be correct.