Repeater input bandwidths

Ideas, technical topics, help and discussion for ATV repeater builders
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g8gtz
Posts: 1176
Joined: Wed Apr 07, 2010 6:26 pm

Repeater input bandwidths

Post by g8gtz » Wed Jan 23, 2019 10:56 am

All,

With the significant improvement in video coding quality and the availability of MPEG-4 (H264) equipment (Portsdown) I think it's time we considered the specification of our repeater inputs - the current recommendations were made in 2002.

Most of us are running 4Ms (~4.5MHz) on 23cms and 2Ms (~2.25MHz on 70cms) and I think it's realistic to drop these to 2Ms on 23cms and 1Ms H264 on 70cms.

The instant benefit is a 3 dB gain - try getting that from improved antennas - and by using H264 there is no drop in video quality!

The reason for suggesting it now (and it is a suggestion) is that the new Portsdown 2019 with a LimeSDR Mini struggles to do MPEG2 above 1.5 Ms but will do H264 in 2Ms.

So the big question is can anyone recommend an H264 / MPEG-2 receiver which they have completed lock indicator mods on that we can all use?

73

Noel - G8GTZ

G8DKC
Posts: 243
Joined: Thu Jun 28, 2012 9:39 am

Re: Repeater input bandwidths

Post by G8DKC » Wed Jan 23, 2019 11:49 am

Hi All

GB3ZZ has MPEG-4 H264 receivers as an option, maybe others?

i would have thought adding an Rx or two might be a start,

and give users of MPEG-2 equipment, maybe only MPEG-2 a chance to accept the change,

Maybe we don't need another excuse not to come on :)

I'm sure Ivor and Shaun would show us how it's done.

Peter

G8DKC
Posts: 243
Joined: Thu Jun 28, 2012 9:39 am

Re: Repeater input bandwidths

Post by G8DKC » Wed Jan 30, 2019 10:14 pm

Found this article from 2013, shows what Noel was saying about the ""improvement in video coding quality"".

We have had several Batc talks over the years on this subject, but a useful read, regarding video standards.

https://wolfcrow.com/understanding-mpeg ... and-h-265/

Peter

G8DKC
Posts: 243
Joined: Thu Jun 28, 2012 9:39 am

Re: Repeater input bandwidths

Post by G8DKC » Sun Feb 10, 2019 2:41 pm

Re: LimeSDR-Mini Problems with DATV-Express Thread...

It's so easy to loop through another sat rx on 23 or 70, etc.

I've just ordered a HDMI switch to mod to work on lock light, as an experiment, just in-case needed.

Ivor and Shaun have done lots on GB3ZZ.

I say add not take away, put in extra receivers, then all are happy, well if only we could be :)

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