[amsat-bb] Delayed Telemetry Decoding

[Chris Thompson]

You can play back a Fox telemetry recording into FoxTelem at any time.  The
timestamps are written by the spacecraft into the header of the telemetry
frame. We slot the data into the data set filling any holes.

We do also store the time stamp from your computer when it was decoded and
another when it was received at the server.  We use those timestamps to
synchronize the clock on the spacecraft back to UTC, by working out what
time the on board computer last reset. But that algorithm uses data from a
small number of ground stations.  We make sure their clock is accurate and
they decoded the data real time.

73
Chris

On Wed, Oct 10, 2018 at 1:00 AM David Johnson <dave at g4dpz.me.uk> wrote:

> Hi
>
> FUNcube packets are accepted up to two days after they were received by
> the dashboard.
>
> We use the sequence number and frame type to determine the ‘satellite
> time’ since the epoch.
>
> We can use these packets to back fill any missing ones and ‘score’ them
> for the user.
>
> 73
>
> Dave, G4DPZ
>
> Sent from my iPhone
>
> > On 9 Oct 2018, at 06:57, Loren M. Lang <penguin359 at gmail.com> wrote:
> >
> > Normally, I decode telemetry live from the satellite and upload it
> > immediately. I have an RTL-SDR attached to my Android phone and use
> > SDRTouch to demodulate the FM signal feeding the headphone out to my
> laptop
> > running FoxTelem to decode the frames and upload it through my home's
> Wi-Fi.
> >
> > However, with the weather turning and the difficultly of getting
> everything
> > set up, I was wondering if there are any issues with recording the audio
> or
> > IQ signal on my phone during the pass and feeding it into FoxTelem from
> my
> > phone later. Does it use my computer's local time or expected to be the
> > live stream, or does it just rely on the time stamp in the decoded
> packets
> > for ordering the telemetry data whenever it's received?
> >
> > And on that, if I can decode later, is there a time limit I should follow
> > for decoding older data? If I captured a satellite pass in the morning
> > before leaving for work, but didn't feed it into FoxTelem for decode
> until
> > the evening when I get back home?
> >
> > And lastly, I know it's a different group operating it, but I'm curious
> if
> > it's a similar policy for AO-73, the first FUNcube sat for decoding
> packets
> > delayed from their capture time.
> >
> > Thanks for the info!
> > 73s,
> > Loren
> > AG7NC
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> _______________________________________________
> Sent via AMSAT-BB at amsat.org. AMSAT-NA makes this open forum available
> to all interested persons worldwide without requiring membership. Opinions
> expressed
> are solely those of the author, and do not reflect the official views of
> AMSAT-NA.
> Not an AMSAT-NA member? Join now to support the amateur satellite program!
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-- 
Chris E. Thompson
chrisethompson at gmail.com
g0kla at arrl.net