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Repeater input bandwidths

Posted: Wed Jan 23, 2019 10:56 am
by g8gtz

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?


Noel - G8GTZ

Re: Repeater input bandwidths

Posted: Wed Jan 23, 2019 11:49 am
by G8DKC
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.


Re: Repeater input bandwidths

Posted: Wed Jan 30, 2019 10:14 pm
by G8DKC
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. ... and-h-265/


Re: Repeater input bandwidths

Posted: Sun Feb 10, 2019 2:41 pm
by G8DKC
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 :)