dsc

[alexandruy2k]

Hi,

I have a class M personal locator beacon and I want to have a look at what data exactly it's sending out.

With it I've managed to decode the AIS messages so I believe that my NESDR SMArt v5 is working ok. I've also been able to listen to VHF channels using the NFM Demodulator so that's my second proof the my hardware is working relatively well, so I suspect my issue with decoding DSC messages is something to do with an incorrect setting I have somewhere.

I have the DSC demodulator in the screenshot tuned to +400Hz and the RTL SDR tuned to 156.525 MHz. I know technically it's not correct, but I've tried various frequency shifts as it looks like my tuner has a small offset.

Any guidance as tp what sort of things I should try out or look at would be greatly appreciated

DSC call.PNG (340.36 KiB) Viewed 21895 times

Thank you very much

[srcejon]

VHF DSC doesn't currently work, as it uses a different modulation to HF.

[g0hdi]

Ah! That explains why I didn't receive anything on vhf. Nice to know the answer. Thanks for that 73 Brian

[alexandruy2k]

Looks like I wasn't subscribed to the thread so didn't realise that you replied the next day.

Are there any plans to implement DSC decoding for VHF?

If not any recommendations for alternative software in the meantime? I've read about a few but from what I've been able to tell a lot of the other software involves capturing the data with one bit of software and then piping it into different software for actual decoding.
I'm a fan of the integrated AIS decoding that SDRangel has implemented and would be hoping something similar for DSC over VHF

[srcejon]

I didn't try to get it working, but haven't been successful so far. Will come back to it, but have a few other things to look at first.

[andyrs]

Hi,

I've got some questions. 1st regarding size of flags displayed in DSC table. Is there a way to make them bigger, maybe even to fill whole cell? I've seen in source file there is a sizeHint set, but obviously is ignored somehow.
Right now I can barely recognize them, see:

20241207_145859.png (102.53 KiB) Viewed 20214 times

2nd question. If I understand correctly ship names are resolved online, yes? But there is no 'name resolving' for coast stations. Is it intended, or some error/bug?

[srcejon]

2nd question. If I understand correctly ship names are resolved online, yes? But there is no 'name resolving' for coast stations. Is it intended, or some error/bug?

It comes from aprs.fi, which doesn't seem to have data for coast stations. Could probably include a built in list for coast stations.

[srcejon]

Have added a list of coast station names: https://github.com/f4exb/sdrangel/pull/2355

[andyrs]

edit: wow that was fast! Thank you. All is working fine, I've also added for call initiator

Code: Select all

    if (CoastStations.contains(message.m_selfId)) {
        selfIdNameItem->setText(CoastStations.value(message.m_selfId));
    }

btw. some stations are still missing it seems. Maybe ITU list is incomplete? Yaddnet has them covered, as well as some ships that are not on aprs.fi.

Re my 1st question above: it turned out that tableWidget must have set its iconSize globbaly ie:

Code: Select all

ui->messages->setIconSize(QSize(36,16));

[srcejon]

btw. some stations are still missing it seems. Maybe ITU list is incomplete?

Do you have some examples? I only selected the DSC-WATCH category.