Newbie problems

[g4kzy]

Hello group,

I have just constructed my MiniTiouner v2 and it appears to be working. I am using it with the Minitioune software and I've tried V0.8 and V1.0.1.0r. I have a Rpi 4 with a touchscreen and a Pluto and I'm running Portsdown 4 Buster 202301141. To test it out I am sending using the Portsdown and receiving using the Mintioune software.

I'm not that familiar with ATV or DATV so I'm playing around with settings etc. to see what the impact of it all is. I have no antennas as such, just a paperclip pushed into the MiniTiouner F connector and a small wire hanging off the Pluto Tx SMA centre, and they are next to each other on the bench. When I can get the Tx and Rx working together I can get up to -30dBm shown on the RF power meter, or maybe -60dBm if I pull out the small wire from the Tx SMA. I see about -90dBm on the RF power meter when I'm not transmitting.

Most of the time I'm using a frequency of 2340 MHz, DVB-S2, QPSK, SR 333 and various FEC settings, which I don't much understand.

At various times I've had good reception on all sorts of frequency, with all sorts of SR, different modulation settings and various sources, including the Pi Cam, test cards, contest numbers, and at different resolutions. When it is working well I can get an MER of 35dB+.

What's puzzling me is that often the Minitioune software just refuses to lock up, as if the Tx is not on at all. At the moment I can't get it to work with the Pi Cam as a source even though it will lock within a few seconds if I select a test card or other "fixed" source, such as the contest screen. The Pi cam is clearly working because I can see it on the Rpi screen. A few days ago it would mostly work with the Pi Cam but not always with the test card, although that is more likely to have been caused by operator error.

I've tried power cycling the Portsdown, but this doens't seem to do much to improve things. What could I be doing wrong?

Thanks,

Paul G4KZY

[M5TXJ]

Hi Paul,

I suggest you wa\tch Dave G8GKQ's excellent presentation which explains everything DATV you really should know. The link below takes you to the explanation of FEC. You will find DATV very friendly and we're a helpful bunch when we can be, not so much of the cheque book willy waving as found in other aspects of the hobby. As for your issues, be aware there are combinations of equipment and settings that just don't work, Pluto and FEC5/6 for example.

https://youtu.be/oUoGvXYoY0Y?t=1151

73 Dave

[g4kzy]

Hi Dave,

Thank you for your reply. I'll certainly look at Dave's presentation this evening.

My (main) problem is quite simple really. If I select testcard as a source, I get a lock on the MiniTiune within a couple of seconds. Selecting Pi Camera without making any other changes and nothing ...

Before I went to bed (late) last night I thought to check the firmware on the Pluto, which I updated last week to v0.31-4-g9ceb-dirty (taken from FIRM2101RC.zip). There's a Portsdown menu option for the Pluto and checking the firmware is one option. The Portsdown seemed unable to read the Pluto firmware version. It said that the Pluto firmware was not compatible and that I need to update to v0.31-4-g9ceb-dirty.

Is there a possibility that the Pluto's firmware may have become corrupted? Plugging the Pluto into a PC and reading the html file from the disc definitely confirms that it has been updated with Evariste's firmware.

Or perhaps something else could be wrong? Do I need to add another USB power cable to the Pluto, for example?

Thanks,

Paul

[G8GKQ]

Paul

A few thoughts:

The Pi camera needs a USB audio dongle connected to operate. It also needs to be connected before boot. If you try to transmit with an unsupported configuration, the Pluto will lock up and need a reboot.

It also sounds like you have a Pluto connection problem. The Pluto seems unreliable if fed with more than 5.0 V. Aim for 4.9 V on the USB at the Pluto. You can improve the reliability by powering it using the separate USB power socket. If you can't read the Pluto firmware version, it means that the Pluto has disconnected - in hardware, by locking up or it has de-registered itself from the USB bus. Unlikely to be corrupted firmware.

I do all my testing at 437 MHz FEC 2/3, either with about 90 dB of attenuation between the Pluto and the MiniTiouner, or 70cm quarter-wave lengths of wire. You should aim to see between -70 and -30 on the MiniTioune power indication - see here: https://wiki.batc.org.uk/MiniTiouner_Po ... Indication.

It sounds like you're nearly there.

Dave

[G3YKI]

I am not the expert, but I noted that in my trials using a similar system:
1)the USB sound card is essential to transmit pictures from either Pi Cam or USB camera, though test card etc. work without it.
2)PiCam picture is displayed on the Pi screen when transmitting but Webcam picture is not.

You did not mention having the sound card connected.
If you have a spectrum analyser, RTL dongle or even diode detector it will give confidence that Pluto is actually transmitting.

Also Dave, G8GKQ advised me that:
"MiniTiouner is fussy about PIDs. The Portsdown and Ryde receivers have been designed to be more tolerant. The default Portsdown audio PID should be 257 - it may be that you have found a setting combination where it is undefined, and so gets set to 4096 either in the TX or in the RX software."
So I think this means if sound is not right, it may refuse to decode the picture.

SDR Angel software is an alternative means to decode the DVB-S signal through any standard SDR dongle (though I have seen reports that it is not so good on DVB-S2)

GL Ken

[g4kzy]

Hi Dave and Ken,

Thank you for your thoughts. You are correct that I didn't have the audio dongle plugged in. Since I moved house last year I've not seen it - it's in a box somewhere! I'll have to order another one from ebay.

I'm happy then, that the MiniTiouner seems to work and the Pluto mostly seems to work. Next job is to somehow find a suitable enclosure to build up my Portsdown / Langstone into a single unit. Things would be so much simpler.

Thanks again for the assistance.

Best wishes,

Paul