[amsat-bb] ISS ping box (now PBBS)

Edson W. R. Pereira ewpereira at gmail.com
Fri Sep 23 16:52:48 UTC 2016

Hi Dani,

I have been following with great interest the commissioning of BEESAT and
am looking forward to experiment with the digipeater onboard. Daniel,
EA4GPZ, has implemented a very nice modem for BEESAT in gnuradio (
https://github.com/daniestevez/gr-satellites). I have tested it with some
audio samples recorded by Jan, PE0SAT. It works very well.

It would be very nice if a similar type of experiment could replace the
ancient AX.25 digipeater onboard the ISS.

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 Fri, Sep 23, 2016 at 10:59 AM, Dani EA4GPZ <daniel at destevez.net> wrote:

> El 23/09/16 a las 14:22, Edson W. R. Pereira escribió:
> > What would be required (from the point of view of paper work, logistics,
> > approvals, etc.) to replace the current ISS packet radio TNC by a device
> > that would implement some more efficient digital communications? The
> device
> > could be a digipeater, but employing strong FEC and a more modern
> > modulation and framing structure and perhaps some better scheme for
> channel
> > access. Perhaps something similar to ngham.
> >
> > https://github.com/skagmo/ngham
> >
> > With FEC and higher speed, we could accommodate many more users on a
> single
> > pass. A dedicated software application on the ground would implement the
> > modem and process information -- separating different types of messages
> in
> > different screens, providing a chat like mode for real-time
> communications,
> > automatically forwarding APRS packets, etc.
> >
> > Am I day dreaming?
> Hi Edson,
> You're not daydreaming that much. The BEESAT satellites have a
> digipeater using the Mobitex-NX protocol, which has some form of FEC.
> Many other satellites on the Amateur bands transmit telemetry using
> strong FEC. For instance, AAUSAT-4 uses an r=1/2, k=7 convolutional code
> and (255,223) Reed-Solomon with CCSDS scrambling.
> Support and experimentation for these and many other protocols is very
> easy today using SDR.
> 73,
> Dani.
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