EA4GPZ: First tests of a narrowband data modem for QO-100

Thanks Achim, I just thought the same and was almost going to post it here...

G0MJW

I agree, DVB-S2X would indeed also be a perfect solution as partly discussed here:   IP over DVB-S2

Even ultra-low-bitrate would be possible, with only using an manually pointed LNB for reception..

Kinda SMS or APRS service, even from mobile shall be possible...

Unfortunately I miss the good old times where we had some international organizations like TAPR defining some common standards like AX.25. Or the AMSAT 400 Bit/s BPSK standard which was developed more than 40 Years ago for the first AMSAT P3 Satellites... and we still use it on QO-100 Or the famous PACSAT protocol (PB/PG) first used some 30 Years ago...

I see a lot of different protocols developed or proposed in the ham community, but none of them really optimized for satellite usage and optimized for efficiency in terms of bandwidth and S/N..

So I hope we will learn from Daniel's developments and get the right people together to add FEC and protocol layers to it,

F4DAV reports some further progress on Twitter:

Trying variable-MODCOD narrowband DVB-S2 on #qo100. 2400 bit/s of 8PSK 3/4 interleaved with 720 bit/s of QPSK 1/2, all in 2700 Hz. For beacons and other applications that can tolerate the latency of S2.

I test 13 dB below the PSD of the BPSK beacon. A stronger signal could carry QPSK 1/4, receivable with a bare LNB or a small horn if software demodulation can be made to work at low SNR and low symbol rate. Probably needs more pilots or better clocks.

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Now we need a protocol layer on top of it, which is optimized for satellite communication, for example PACSAT Broadcast (PB) protocol or similar with some narrow band low speed uplinks as a next generation beacon for QO-100 Uplink from Bochum...

Here is an excellent resource with all current documentation about the AMSAT PACSAT Broadcast Protocol and Ground Station Software (Client) from G0KLA: https://www.g0kla.com/pacsat/

Does anyone know an open source implementation for the PACSAT Server?

I will try to contact him, maybe he is interested.. it would be great on QO-100 I think..

Quote from St2nh

I think the (PACSAT software) which had been used by any/many PCASAT satellite, could be use as server .!! its ready and avalable ,for sure need some touches to sute ground station !!

Hi Nader,

For the "client" side on the ground exists WISP (also not open source), but the groundstation software PACSAT Suite from G0KLA is written in Java and available on GitHub. It runs on Linux and Windows..

Unfortunately the "server" side used on the PACSAT satellites never has been Open Source software as far as I know... But that's what we need and what is not part of the groundstation software! Someone needs to implement it...

73s Peter

Hallo Peter DB2OS

Chris Jackson, ZL2TPO, was the originator of the PacSat protocol. He studied at the Uni in Guildford and had a G0... call sign, you remember ? Eventually he can help you.

Quote from HB9SKA

Chris Jackson, ZL2TPO, was the originator of the PacSat protocol. He studied at the Uni in Guildford and had a G0... call sign, you remember ? Eventually he can help you.

Hi Thomas,

indeed I knew Chris very well, we meet many times at SSTL. But he never put his source code into public..

And again, I'm not talking about the PACSAT Suite for the groundstations.. it's the opposite part in the spacecraft what is needed.

It's not really rocket since.. everything is well documented, it only required some programmers willing to implement this..

73s Peter

Quote from DB2OS

And again, I'm not talking about the PACSAT Suite for the groundstations.. it's the opposite part in the spacecraft what is needed.

Yes, I understood it. If I remember me right, Chris implemented his protocol on the satellites and released WiSP thereafter.

Quote from HB9SKA

Yes, I understood it. If I remember me right, Chris implemented his protocol on the satellites and released WiSP thereafter.

Not really..

The PACSAT Protocol was developed by Jeff Ward G0SUL and Harold Price K8KA.

Jeff wrote the groundstation side of the PACSAT Broadcast Protocol: PB.EXE and PG.EXE which were running under DOS.

Chris Jackson, ZL2TPO/G7UPN later developed WiSP, an integrated groundstation suite for Windows. An amazing software which later became his door opener to move and work at SSTL in the UK.

None of the above is available in source code and probably never will be due to legal rights.

Ah OK, then my remembering was wrong. It's about 30 years ago the first PacSat's where active.

Quote from DB2OS

None of the above is available in source code and probably never will be due to legal rights.

Then I don't understand why you ask for this code.

Quote from HB9SKA

Then I don't understand why you ask for this code.

Hi Thomas,

Sorry if I was misunderstandable or if I was not clear enough,.

I'm not asking for this code..

I was asking if someone is aware of an server-side implementation of the PACSAT protocol (including open source) or if someone is willing to do an implementation...

Or is there no interest in a PACSAT style broadcast system on QO-100?