Ryde Software Update with Corrected Search Width

Discussions about the Ryde "Set-top Box" Style Digital ATV Receiver. See https://wiki.batc.org.uk/Ryde_Receiver
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G8GKQ
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Ryde Software Update with Corrected Search Width

Post by G8GKQ » Wed Feb 23, 2022 4:34 pm

I have just issued a Ryde software update (202202230) with the following new features:
  • Reduce default frequency scan to +/- 0.5 SR
  • Use Raspberry Pi OS Lite Buster (Legacy) for new builds
  • Add SSH Menu Selected Composite Video Input Mode
The first feature corrects a bug that I inadvertently introduced in the last update. So now Ryde should not jump to signals on the adjacent channel. The change to the new-build OS will allow for faster initial builds (less updating of the build required).

The last feature is not a Ryde feature, but means that this build can easily be modified to be used as Composite Video to HDMI converter for the new BATC ATV Repeater project (more details in the next CQ-TV). Simply connect a Fushicai EasyCap (yes, I know that they are not available in the shop...) and then select option 8 on the settings menu in the SSH Console Menu, and then reboot. Note that his overwrites the Ryde functionality which can only then be restored from the SSH Console Menu. So do not use this facility if you want the build to function as a Ryde.

Please report any bugs here

Dave, G8GKQ

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Re: Ryde Software Update with Corrected Search Width

Post by G3GJA » Mon Feb 28, 2022 11:30 pm

Dave

This update seems to have fixed an issue that I've been chasing on GB3EY for sometime. Thinking back, it's its appearance might have coincided with a previous update.

It manifested itself as a brief random triggering of the logic by the Ryde indicating a valid input. No valid stream was detailed in the onscreen Ryde graphics and almost immediately it switched back to no signal, triggering the logic to send a K in video and CW.

It was reminiscent of the effect of desense in FM voice repeaters. I had spent sometime chasing this down and decided that as I couldn't reproduce the effect on the bench it had to be something to do with the NATS radar strength when on-site.

The radar is 20.5MHz LF of our input and there is over 100dB attenuation in the receive path the centre frequency. Radiomobile suggests that the radar will be putting at least -10dBm into the antenna.

Is it possible that the reduced scanning range has helped?

Thanks

Clive

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Re: Ryde Software Update with Corrected Search Width

Post by DL5BCA » Tue Mar 01, 2022 10:19 am

Hello Clive, hello Dave,

we had used the Ryde in our repeater DB0OV for quite a while.

We have an FM input at 2327MHz and the DVBS input (with the Ryde) at 2340MHz.
I noticed that the logic would sometimes trip when there was a strong signal on 2327MHZ.
As I'm currently testing the new Ryde update on my desk, I can't say if the behavior has changed.

Currently, the logic is triggered when a signal is present.
Is there a way to only trigger the logic when a video is detected?
Then you could also tune analog and digital receivers to the same frequency.

73 from north Germany
73 Thomas
DL5BCA

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Re: Ryde Software Update with Corrected Search Width

Post by G8GKQ » Tue Mar 01, 2022 11:48 am

For Clive:

Yes, the update may well have fixed this, as the receiver scans over a smaller bandwidth and would be less likely to be troubled by the radar that far LF.

For Thomas:

The logic only triggers when VLC detects that it has the precursors to valid video. After a lot of experimentation that seemed to be the best way to ensure the display of weak digital signals.

To operate both receivers on the same frequency, you could prioritise the Analog receiver over the digital receiver. That would mean that false triggers of the digital receiver would be hidden by the analog receiver. This logic is available in the new BATC ATV Repeater controller (to be described in the next CQ-TV).

If all your transmitting stations are close to frequency, you could further reduce the scan width. Line 227 of main.c in LongMynd. You would then need to recompile LongMynd - have a look in the update scropt for the code to do this.

Dave

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Re: Ryde Software Update with Corrected Search Width

Post by G3GJA » Tue Mar 01, 2022 12:39 pm

Hi Dave

Thanks for that. There seems to be another benefit too, which is a little harder to explain taking into account the changes you have made to the Ryde.

The overall sensitivity of the receiver has returned to what it was when we first installed the repeater. Prior to the latest update I could just get in using an FEC of 3/4, whereas now I can get in with 9/10 with at least 6dB in hand, all other variables being the same.

73

Clive

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Re: Ryde Software Update with Corrected Search Width

Post by G8GKQ » Tue Mar 01, 2022 2:13 pm

Hi Clive

That's interesting. Maybe the internal tuner software AGC was getting clobbered when the radar made it into the passband?

Useful to know!

Dave

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Re: Ryde Software Update with Corrected Search Width

Post by DL5BCA » Tue Mar 01, 2022 4:40 pm

Hi Dave,

thanks for the answer.
It's true, I hadn't thought about prioritizing...

Unfortunately I can't write or compile c.
For use in the repeater, the Ryde would not need to scan very far.

Maybe at some point you can implement a switch in the settings so that the logic in the Ryde sets the RX pin when an image is actually present...

But we will put the Ryde receiver back into the repeater this month and try...

Our repeater mostly sends analogue signals, because then there is no delay.
We use a quad splitter with a maximum of 9 images... But usually a maximum of 3 stations work on the repeater. With 2 players and a status display from the control Raspberry, we have 6 images that are sent to the transmitter or encoder, which is also analogue come.

73 from north Germany
73 Thomas
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Re: Ryde Software Update with Corrected Search Width

Post by DL5BCA » Tue Mar 01, 2022 4:46 pm

Hi Clive,

we also had a lot of interference from radar.
We have a seaport at our location and Bremerhaven is only 10 km away.

We switched an interdigital filter there and that helps a lot.
73 Thomas
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Re: Ryde Software Update with Corrected Search Width

Post by G3GJA » Wed Mar 02, 2022 11:35 am

Hi Thomas

I use the interdigital filters from Ewald, DK2DB.

GB3EY has a single antenna followed by a duplexer and two bandpass filters, one in the Tx leg and one in the Rx leg.
The Tx bandpass filter does not have notches but the Rx one has two, one set to the Tx frequency and the other on the radar frequency.

That arrangement gives over 104dB of attenuation of the air traffic radar at 1254 to 1255MHz and 1.8dB loss at the Rx frequency of 1275MHz. There's a DB6NT LNA between the duplexer and Rx bandpass filter.

The radar is 40km away and is line of sight; it runs 400MW (86dBW). That is a very big signal when it is only 20MHz from the input channel. I would think your radars are not in the 23cm band making it much easier to deal with.

73

Clive

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Re: Ryde Software Update with Corrected Search Width

Post by DL5BCA » Wed Mar 02, 2022 2:57 pm

Hello Clive,

the radar signals are also at 1250 Mhz here.
Because the signals come from ships, they are certainly not as strong as yours with 400MW (wow).

From time to time we still see spikes in our analog FM signals, but the filter has reduced that.

Have fun and success in the common hobby.

Thomas
73 Thomas
DL5BCA

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