Portsdown 4 Repeater TX and Stream

[G3GJA]

Hi Noel

I've come to much the same conclusion about the H264/H265 Chinese encoder box, although I've managed to get it to just about work with what is supposed to be a CBR of 1100kb/s.

The Pluto is set to produce 1MS/s with FEC of 3/4. I've had to reduce the video load by reducing the resolution to 1280 x 720 @ 25fps. Changing the GoP doesn't seem to affect it much.

The buffer analysis in the F5OEO Pluto firmware was helpful as was the pie chart in the Minitioune software. I have to leave more than 20% null packets for it to be usable, but it's not reliable or efficient.

I've been able to leave it running for 24 hours without falling over on the test card carousel, but it's very sensitive to lots of changing detail in the content causing the Pluto to underrun the buffer occasionally which kills the RF out.

I was disappointed that I couldn't get 1920 x 1080 @ 25fps reliably, however, it makes a good stand-alone streamer box.

Clive

[G8PUO]

From my own local experience regarding ATV and DATV, some users just want to display the repeater and learn. The cheap sat RX boxes provide an easier and more encouraging route into the hobby, without loosing the 'seed' and they move on elsewhere. Gaining new blood is not easy... and equally easily lost.

Now that FW is well on the way to coming online and the need to move JT's site, my thoughts are more on JT best route now the hardware is easier to access.

Depending on what route the NoV finds itself going, I could easily stay as is with the 24/7 trusted and working TX @ 4Ms/s, so the sat box users can continue, or reduce the bandwidth to a point that potentially disregards them (not ideal), so they will need to look at building the RX or move on.

Thus the pondering of a minimum 'standard' for repeater TX, as Duncan mentions, seems a happy balance?

[g8gtz]

Thus the pondering of a minimum 'standard' for repeater TX, as Duncan mentions, seems a happy balance?

I did do a lot of work looking at a new repeater standard as 4Ms (over 4MHz bandwidth) is a real waste of bandwidth and power given the quality we can now get in just 500 kHz.

We published the proposal for a new standard 2 years ago in CQ-TV 266 page 11 https://batc.org.uk/wp-content/uploads/cq-tv266.pdf

And guess what it said!

The ATV community has always been seen as developing and using the latest technologies. By adopting 1 MS DVB-S2 and H264 as the new repeater standard we will continue that approach and the BATC is keen to support our members to make that change.

73
Noel

[g8gtz]

I've come to much the same conclusion about the H264/H265 Chinese encoder box, although I've managed to get it to just about work with what is supposed to be a CBR of 1100kb/s.

Clive - I think we've ended up in the same place!

Unless Rob tells what the magic recipe (screen shots of the config page??) he uses at KM to get the Chinese box to produce 2 streams reliably, I think I will have to go for a separate encoder for on-air Tx but not yet decided which approach to take...

Noel

[M0DTS]

Here's some screenshots of the pluto/encoder settings i'm using for KM.
I've forced the second stream to 1280x720 manually hence it shows blank on the encoder status page.

Trick is to keep the sawtooth pattern in the pluto analysis page above zero - increase PCR/PTS if it's getting close.
It is always a battle against latency vs stability, i'm getting about 2seconds latency with the current setup when received on a STB, it's about 2.5-3 seconds when using minitioune or Ryde.

I would like to try the link-pi encoder but can't really warrant spending that money on yet another encoder that may sit on the shelf with the others!
I don't use the current Chinese boxes i have here now as PC encoding is far superior.
The PC does use WAY more electricity though!

Rob

[G3GJA]

Thanks for the settings, Rob.

It looks similar to what I ended up with but the further tweaks you have made may be what I need to make the ON-DMI-16E usable.

I too am reluctant to shell out another £125 on the LinKPi ENC1 encoder without substantial proof that performance is better.

Clive G3GJA

[M0DTS]

All my original testing was for 2Ms on 3.4GHz with 1080 res which worked well.
I may eventually to go to 8-psk to get the quality up to what i was seeing during testing compared to 1Ms... but that will be later down the line.

Now KM is really Digital in, Digital Out it's no where near as usable as it used to be unfortunately
Trying to have a full duplex conversation is just not coherent anymore with the extra delays... quite sad about that really.
We are not used to simplex through KM, until now everyone had look through and had proper 2-way chat without the need for talkback.

Analogue has it's benefits!

Rob

[radiogareth]

Interesting Rob, having managed my first FM qso on 5.6GHz the instant bit was a brief surprise.
Gareth

[Pa3fbx]

Hi,

I understand there are different Chinese Streaming boxes.

I have 2 the same (Link Pi ENC1) running standard 2x 2 MBit to 2 different internet services and running 1 Mbit to a pluto (never tested higher)
I can make a setup at home to portsdown IPTS but only pluto. (do not have lime)
The box runs on 100mBit network and normally around 40% cpu load.

I do not see any problem but than again i might be lucky.
Happy to do some bench tests (if i only can find some time.)

Benno

[G7VVF]

The Link Pi ENC1 seems to be quite a bit cheaper on AliExpress if you don't mind waiting a bit longer
https://www.aliexpress.com/i/1005001782244098.html
compared to Amazon
https://www.amazon.co.uk/LinkPi-encoder ... 1L43S?th=1

Duncan G7VVF