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Multiple DVB-T tuners

Added by Ahti Paju almost 11 years ago

I have question what could be wrong when I add 2 tuners, I loose signal quality for second tuner?
With 1 tuner I have excellent signal quality and soon if I add second tuner I got message that I have no signal.
I have tuned 3 different mux-es, mux1 is set for 1st tuner and mux2 and mux3 is set for 2nd tuner, so there is no frequency conflict.
Both tuner works well in single mode. Does anyone have experience with 2 tuners?

Thank you,


Replies (5)

RE: Multiple DVB-T tuners - Added by Prof Yaffle almost 11 years ago

Are they on the same cable, or different feeds from the antenna/aerial? I run multiple tuners with no problem, but they're on separate feeds... if I had a passive (unamplified) coax splitter in the way, though, I'd expect the current to split (Kirchoff's Law, if I remember correctly) and that could conceivably affect the signal.

That said, this is digital, so either the signal gets through or it doesn't - weak(er) signal doesn't mean a faint image, but might lead to some macroblocking if the image can't be decoded because of relative SNR.

RE: Multiple DVB-T tuners - Added by Ahti Paju almost 11 years ago

Thank you for your answer,
Yes, I have same source and 7,5 db spliter, I wanted to use multiple tuners because of the load balancing.
Currently I can't watch TV and record on same time if the both channels comes from same mux.

RE: Multiple DVB-T tuners - Added by Prof Yaffle almost 11 years ago

That would be my guess, then - your signal isn't strong enough to split, or your tuners aren't able to decode the resultant signal, anyway (not all tuners are equal, some are better than others).

You could try different tuners; you could try a dual tuner (so one input to the card, which can amplify on-board); you could try an in-line amplifier (masthead would be better - getting it closer to the source amplifies more signal, getting it closer to the tuners amplifies both signal and noise). I suspect that internal tuners are better than USB ones, but I have no proof of that - they just have more room for more chips.

Really, you'd need to do some testing, either with other kit or with something that would tell you the signal quality in a more sensible way. I don't think tvheadend's signal strength indicator is really useful, as I believe it's tuner-dependent, although it would tell you something if both tuners are the same.

RE: Multiple DVB-T tuners - Added by Ahti Paju almost 11 years ago

Thank you very much for advice, I will do some testing.

Ahti

RE: Multiple DVB-T tuners - Added by Hiro Protagonist almost 11 years ago

Ahti Paju wrote:

Yes, I have same source and 7,5 db spliter, I wanted to use multiple tuners because of the load balancing.
Currently I can't watch TV and record on same time if the both channels comes from same mux.

I'm currently running 3 DVB-T tuners connected to the antenna feed via a 1 -> 3 splitter. The antenna was originally going to a 1 -> 2 distribution amplifier, and each output going to a 1 -> 2 splitter, giving me 4 antenna feeds, but feeding one of those outputs into the 1 -> 3 splitter gave a pretty marginal signal.

I've now replaced that setup with a 1 -> 4 distribution amplifier, and feeding one output from that into the 1 -> 3 splitter for my tuners works much better.

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