[amsat-bb] Need help decoding EO-79 packets.

[Edson W. R. Pereira]

A small correction:

When I wrote destination callsign, I meant source (or digipeater) callsign.

73, Edson PY2SDR

---
- We humans have the capability to do amazing things if we work together.
- Nós seres humanos temos a capacidade de fazer coisas incríveis se
trabalharmos juntos.

On Thu, Apr 21, 2016 at 9:51 PM, Edson W. R. Pereira <ewpereira at gmail.com>
wrote:

> The AX.25 implementations used in some cubesats do not implement the specs
> for AX.25 destination address field encoding correctly. The last bit of the
> last byte of the destination callsing (or digipeater) field should always
> be 1 in order to indicate the end of the destination field, but some
> implementations keep the bit as 0. This is the reason UZ7HO's soundmodem
> says NON-AX25 frame. Soundmodem does pass the frame to the KISS interface
> but any decoding software must be careful during the processing of the
> destination callsign (by assuming there are no digipeaters).
>
> Comparing the performance of the 1200 bps BPSK FUNcube-1 FEC encoding with
> cubesats using AX.25 1200 bps BPSK makes me wander why in this day and age
> we still use AX.25 for satellite links.
>
> 73, Edson PY2SDR
>
>
> ---
> - We humans have the capability to do amazing things if we work together.
> - Nós seres humanos temos a capacidade de fazer coisas incríveis se
> trabalharmos juntos.
>
> On Thu, Apr 21, 2016 at 7:56 PM, J. Boyd (JR2TTS) <
> the2belo at msd.biglobe.ne.jp> wrote:
>
>> On Thu, 21 Apr 2016 17:43:36 -0500, "JoAnne Maenpaa" <k9jkm at comcast.net>
>> wrote:
>>
>> > > There were some other things in my Soundmodem settings that did not
>> > > agree with the instructions for DeorbitSail, that may have messed it
>> up,
>> > > so I'll try again this morning during the next pass.
>> >
>> > I'm continuing to experiment by myself on this subject of receiving
>> > telemetry data using an SDR dongle and software. I've appreciated all
>> the
>> > bits of information offered by the stations who are already up and
>> running.
>> >
>> > One thing I'm finding with software packet reception is that the
>> software
>> > "modem" or software "TNC" (i.e.: soundmodem) seems to expect packets
>> with a
>> > good checksum. Just a single bit-flip and I don't have data.
>>
>> In soundmodem, I had "Bits Recovery" set to "SINGLE" initially, while
>> the DeorbitSail page seems to suggest it's more properly set to "NONE".
>> Not sure if that's significant, but your comment about flipped bits made
>> me suspect this. Anything's worth trying once.
>>
>>
>> --
>> J. Boyd, JR2TTS/NI3B
>> the2belo at msd.biglobe.ne.jp
>> http://www.flickr.com/photos/the2belo/
>> http://www.qrz.com/db/JR2TTS
>> Twitter: @Minus2_C
>>
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>
>