2 channel DATV repeater output

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g7ntg
Posts: 94
Joined: Sat Feb 17, 2018 7:07 pm

2 channel DATV repeater output

Post by g7ntg » Sun Jun 28, 2020 10:15 am

How about DATV repeaters transmitting two simultaneous signals say, one at 1000s/r so that it can be received on a set top box and the other at 333 or 125 s/r for the fringe receivers like myself? The carriers can be very close together - I have done this on 23cms terrestrial TV and also via Es'Hail with very good results. I didn't see any application at the time - I just wanted to try it!

I used two portsdown transmitters fed into a 23cms splitter combiner via variable attenuators into one power amplifier.

I will do some more experiments here between myself here in Kettering and Arthur G4CPE in Luton next week.

This would hopefully make a big increase in DATV repeater useage and encourage more people into DATV

G6MNJ
Posts: 38
Joined: Mon Jun 09, 2014 6:25 pm

Re: 2 channel DATV repeater output

Post by G6MNJ » Tue Jan 30, 2024 10:54 am

Here in Cornwall we are about to do just that!

We have a 1080 HD service at 2Msym/s which if you can receive it is a superb service however there are areas where it does not cover so we will be installing a 2nd channel 2MHz up from the main output using a 2nd Adalm Pluto at 250Ksym then on to a mixer.

We did tests last summer on this with perfect results see attached

73 Paul G6MNJ

ps send my regards to Arthur!
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g8lce
Posts: 338
Joined: Sun Dec 06, 2015 10:26 am

Re: 2 channel DATV repeater output

Post by g8lce » Sat Feb 03, 2024 3:45 pm

There are several things that we will find out by having two channels on GB3NQ. We already know it works due to the test last year. We don't know for sure if it will make the repeater able to be received further away using the lower symbol rate channel. Can the power output of each channel be considered independantly? in which case the narrow channel could be stronger in that case the reaction between the signals may change. Then there is the type of encoding to experiment with - at the moment it will be H265.
In the future could there be a third channel with just data?
GB3NQ pushes onwards

Martin G8LCE

Pa3fbx
Posts: 168
Joined: Fri Oct 16, 2020 1:08 pm

Re: 2 channel DATV repeater output

Post by Pa3fbx » Mon Feb 05, 2024 11:26 am

Interesting Q.
I have installed a pluto dvb output next to an analog FMATV signal witch looks like an audio channel.
I do see some mixed signals out of the amplifier but both main signals work great.
I found smaller signals (250 and lower) are more interfered by windgenerators causing more flutter on 23cm.
So i will do some testing with higher Stream resolution to check if the flutter will reduce to a stable picture on 1000 or 2000Ks...

Benno

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