New Portsdown 2020 Software Update

Discussion about this major DATV Project. See https://wiki.batc.org.uk/The_Portsdown_Transmitter
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G8GKQ
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New Portsdown 2020 Software Update

Post by G8GKQ » Wed Feb 17, 2021 4:18 pm

I have just published a software update for the Portsdown 2020 (Raspberry Pi 3). This update (202102160) brings the System and LimeSDR software up-to-date and introduces an experimental DVB-T transmit capability using the LimeSDR Mini.

DVB-T transmit only works with the LimeSDR Mini loaded with firmware version 1.30. NOT the special DVB firmware. It is also limited to H264 encoding, not MPEG-2. The Guard interval is fixed at 1/32 and only QPSK is available. It has been tested at bandwidths between 250 and 1000 kHz. There is no DVB-T receive capability in this software (unlike Portsdown 4). Thanks to Charles G4GUO for providing this capability.

Note that (as with DVB-S/S2) there is a significant calibration power output spike that occurs a few seconds before the PTT line becomes active. However, it is more significant because the DVB-T power output is lower than that for DVB-S/S2.

The full list of updated features is:
  • New builds based on Raspios 2021-01-11
  • Update Limesuite Version to 20.10
  • Tidy LimeFPGA builds
  • Display Required TS Bitrate on Info Screen
  • Improve Jetson HDMI video quality
  • Initial LimeSDR Mini DVB-T transmit capability
As usual, you can update from Menu 3, Check for Update. The update will take a while as there are a lot of system upgrades to be applied. Just start it off and come back after a cup of tea/coffee.

Please report any bugs here.

Dave, G8GKQ

arthur21
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Joined: Fri Sep 02, 2016 9:04 am

Re: New Portsdown 2020 Software Update

Post by arthur21 » Mon Mar 01, 2021 8:16 pm

Hi Dave
Today I had fun viewing and controlling G8XTW's spectrum analyser over the internet my dvbt signal was produced with the Portsdown 2020 and a Lime mini into a CML class A amplifier at 437MHz producing 20w O/P. I have attached a screen grab from Phil's analyser.
We then decided to take a look at the dvbs signal from the same setup with a surprising result the dvbs signal appeared at about 1.1MHz low and with an unmodulated signal at 437MHz. Has anyone else observed this or is it something strange with my gear.
LIME MINI Test report reads Hardware V1.2 Firmware V6 Gateware V 1.30 and the last 4 tests show Failed

73 Arthur G4CPE
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arthur21
Posts: 26
Joined: Fri Sep 02, 2016 9:04 am

Re: New Portsdown 2020 Software Update

Post by arthur21 » Tue Mar 02, 2021 5:45 pm

Did a force update today and both dvbt and dvbs now working again.
73 Arthur
G4CPE

G8GKQ
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Re: New Portsdown 2020 Software Update

Post by G8GKQ » Wed Mar 03, 2021 10:22 pm

Hi Arthur

I was finally in a position to test and try to reproduce this problem today. I could not see anything amiss.

Please let me know if it happens again and we'll try to track down the cause.

The fact that the LimeSDR fails the last 4 tests is not unusual. It is normally caused by the gain of the TX and RX channels being slightly out of tolerance. You may find that it passes the tests when cold and with nothing connected to the SMAs.

Dave, G8GKQ

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keng8vdp
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Re: New Portsdown 2020 Software Update

Post by keng8vdp » Wed Apr 07, 2021 7:51 pm

After the update I find the reboot only works sometimes. Mostly reboot option causes shut down.
I did a forced update again but that didnt resolve the issue.
I also occasionaly see that the lime LED remains Green even though ive tapped TX to stop transmission.
Portsdown returns to main screen Looks normal but LED on lime-mini remains Green.
A reboot sorts it (until next time)
A change of "source" often results in NO TX unless I reboot.

I have a few issues now dont I, all since the update. Before that generally it worked very good most of the time.

As my old boss used to say "ploblems ploblems ploblems" hmmm.

Anone else seen these niggles ?

Ken G8VDP

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