Transmitter Software Capabilities and Issues

Discussion about this major DATV Project. See also https://wiki.batc.tv/The_Portsdown_Transmitter
G8GKQ
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Re: Transmitter Software Capabilities and Issues

Post by G8GKQ » Fri Jan 12, 2018 4:31 pm

New Software Release

I've just issued a new release 201801061. The major changes are that it introduces the DATV Express as an output Device for the Signal Generator, and also allows the use of electronically-controlled attenuators on the Signal Generator. A future release will also allow the attenuator to be programmed to a set level for each band for the DATV Transmitter, so that you can adjust transmitter drive on a per-band basis.

The option is also introduced to apply 333KS QPSK modulation to the DATV Express Signal Generator or Portsdown Signal Generator Output. The level can then be adjusted whilst viewing the transmitted spectrum to allow the correct level to be set whilst monitoring spectrum regrowth.

The receive/signal monitor switching has been improved; only a single screen touch is now required to exit from receive, and the signal parameters are cleared from the screen after each receiving session.

Signal Generator details are here: https://wiki.batc.org.uk/Portsdown_Signal_Generator

Output Attenuator details are here: https://wiki.batc.org.uk/Output_Attenuator

Thanks to Ray M0DHP for writing the Attenuator control code and for testing and offering constructive comments.

Dave, G8GKQ

M5TXJ
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Re: Transmitter Software Capabilities and Issues

Post by M5TXJ » Tue Jan 16, 2018 3:17 pm

Hi Dave,
Yes me again! The build and testing continues and I've hit an issue, not sure if it's me. The Portsdown works great on all modes with the Pi camera but I've just acquired an ex CCTV camera and although all seems fine on H264 I'm getting the circular constellation if I try MPEG2. I've tried various frequencies and SR's but always the same. Software version 201801061
73 Dave

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Re: Transmitter Software Capabilities and Issues

Post by M0DHP » Tue Jan 16, 2018 5:14 pm

Hi Dave

Is the camera directly USB-connected to the Pi, like a webcam, not via EasyCap? If so, one thing to try is setting the Portsdown audio mode to “none” or “beeps”. I’m not sure if there’s a menu button to do this - you may need to use PuTTY to open a console session to set it - it’s under System Setup.

73
Ray

M5TXJ
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Re: Transmitter Software Capabilities and Issues

Post by M5TXJ » Tue Jan 16, 2018 5:42 pm

Thanks Ray but the camera is composite out into the easy-cap, and it works fine in H264 just not MPEG2.
73 Dave.
Attachments
0162018174037.jpg
H264 mode
0162018174037.jpg (314.45 KiB) Viewed 273 times
0162018173952.jpg
MPEG2 mode
0162018173952.jpg (270.06 KiB) Viewed 273 times

G8GKQ
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Re: Transmitter Software Capabilities and Issues

Post by G8GKQ » Tue Jan 16, 2018 10:35 pm

Hi Dave

Not a problem that I have seen before. However, please go into the console, go to System Setup, and then option 8 "Audio Input". Use the down arrows and then the space bar to select "no_audio" and press enter.

Then see if the problem is still there.

Supplementary questions:

Do you have anything else connected by USB? Mic dongle? RTL-SDR?
Do you still have a PiCam connected?
Does the MPEG-2 Test Card (selected on Menu 2) still work?

Dave

M5TXJ
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Re: Transmitter Software Capabilities and Issues

Post by M5TXJ » Wed Jan 17, 2018 3:33 pm

Hi Dave,

Went into console and selected no audio, still the same. H264 with both Pi cam and composite input both work, Pi cam MPEG2 and Card MPEG work just not composite MPEG2. As for USB devices, there's the Easy-cap and a usb sound card dongle, no RTL-SDR. Pi cam is still connected as it's built into the front panel of the Portsdown.

Dave.

G8GKQ
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Re: Transmitter Software Capabilities and Issues

Post by G8GKQ » Wed Jan 17, 2018 4:43 pm

Hi Dave

It could be a problem with the EasyCap. Do you have anybody local to you who you could do a trial swap with?

Dave

M5TXJ
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Re: Transmitter Software Capabilities and Issues

Post by M5TXJ » Wed Jan 17, 2018 4:53 pm

I've got another one here Dave, I may get chance to try it tomorrow but I'm off out now for another lovely 12hr night shift.

73 Dave

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Re: Transmitter Software Capabilities and Issues

Post by M5TXJ » Thu Jan 18, 2018 12:29 pm

We're not worthy!

Easy-cap changed and now have working MPEG2 composite. Beats me how it was working for H264 but not MPEG2 but now we're 100%. I can now concentrate on building a PA for 146.5MHz. One step closer...

73 Dave

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Re: Transmitter Software Capabilities and Issues

Post by G8GKQ » Thu Jan 18, 2018 4:07 pm

Hi Dave

Pleased that you have found a solution. The H264 coding uses a different software driver configuration to the MPEG-2, but I'm still surprised that it made a difference!

Dave

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