HDTV High Bit Error Rate

HDTV High Bit Error Rate

8 posts
3 Sep 2012
Allinthemind
Photographer
Allinthemind
Nothing to do with photography really.  My HD channels (Freeview) were dropping out, so I checked and found that I have a 100% signal strength but the Bit Error Rate is fluctuating between 680 and 800 (about a third of the way along the measuring display bar (also it's red coloured whereas the signal strength is green)).
The non-HD channels are all perfect, no bit error rate at all.

I cast my mind back to my O-Levels and remembered that interference from other electrical sources used to cause problems on analogue signals, so I moved the other components out of the way so that the TV plugged straight into the aerial socket.  No change.

I thought that maybe the signal was too strong so I went to Maplins and bough an attenuater and a few ferrite chokes (just in case the TV power cable is transmitting EMI).

Again, no change.

Any ideas, what would be a normal Bit Error rate on a Freeview service?

It made me wonder if RF chokes would be useful in my office as I use a wireless landline 'phone and a wireless router as well as bluetooth keyboard and mouse and a mobile 'phone. Oh and two battery chargers all within a couple of feet of each other. One end of my desk looks like the Curry's clearance shelf.

So here's the question.. Would RF chokes perhaps improve performance to external HDD or Cable modems  (I'm thinking less retrys)?

All best

Si

And now for a randon picture..

Posted 3 Sep 2012
w4pictures
Photographer
w4pictures
You've done all the logical things, so have a look at the signal itself.

Has this just started happening? If so, has there been a change in transmitter quality, perhaps due to maintenance or even a change of transmitter?

Does the error rate vary with picture content? i.e. cartoons and still images need much lees bandwidth and compression than faster-moving frames, pans etc.

I suppose the usual old mularkey is to start with the signal and make sure everything in the resulting chain is as good as can be. So ideally, a class 1 aerial with a masthead anplifier and the best low-loss coax down to the receiver would maximise the signal quality and minimise interference. But its a lot of palaver if the thing has been working OK up till now.

Posted 3 Sep 2012
Allinthemind
Photographer
Allinthemind
I think it's been doing it since the switchover. We only got an HD tuner a few months ago, it's been doing it since then. It's only recently that I've noticed it as I now watch TV whereas before I was always doing something or watching films etc. We had a new fit-for-purpose aerial installed on our chimney, the coaxial cable looks like a good quality double shielded affair and I get 100% signal strength and 0 errors on normal digital tv. It's only on the HD channels I see the errors and dropouts. On my Samsung TV, I don't get drop outs, on the Samsung Freeview tuner/BD/HDD combo box plugged through to an LG TV I do get drop outs. Weird...

Si

I'm assuming that the BER is high and the problem. could it be some sort of incompatibility between an LG TV and the Samsung BD/HDD/Tuner gizmo?

Posted 3 Sep 2012
w4pictures
Photographer
w4pictures
If you can bear to plod through the process of elimination by moving the components around, then you should eventually get to the source of the problem.

If the Samsung TV is OK with the signal you have got, try it through the Freeview tuner/BD/HDD and see if that recreates the problem. Likewise, is the LG tv OK with a clean signal straight from the aerial?

One thought, its possible that the signal from the freeview/HDD box, rather than being a loop in and out, is being processed by the box to give you the "rewind live TV " facility but that the HD demands are a bit too high, thus the error generation. You can certainly check this by plugging the aerial straight into the TV.

Posted 3 Sep 2012
markchambers
Photographer
markchambers
I work for Currys/PC World (yes I know, I'm sorry) and we had a massive increase in people having trouble with LG equipment from Christmas through the spring. Particularly with one model of DVD Recorder and a couple of TVs
After many many rounds of the blame game between myself, other Managers, our Head Office and LG customer service (which is a poor joke) LG finally admitted that there was a problem and that the Freeview and Freeview HD tuners built into their products couldn't handle the signal strength post-switchover. Their solution? Any customers with issues should invest in some tech to reduce the signal strength as they couldn't be held accountable for the strength of the broadcast signal.
We ended up offering exchanges (to different brands) for all the customers that came to our store after that.

Posted 4 Sep 2012
grahamsphotography
Photographer
grahamsphotography


You never see Ferrite chokes on RF or BNC cables.



Posted 4 Sep 2012
alexcrawford
Photographer
alexcrawford

if its too high a signal strength(trouble caused by putting very high gain aerials up)then its possible to fit an in-line aerial attenuator for a few quid only.



Posted 4 Sep 2012
Allinthemind
Photographer
Allinthemind
Thanks for the help folks and the private messages.

Changing the LG set for a Samsung has resolved the immediate problem although the errors are still there, just being corrected by the TV.

Alex, I tried attenuating the signal but no difference there, also amplifying it.

Graham, the RF chokes ate interesting little beasts. they are fitted as standard to my battery chargers. As I understand it, you fit them to any cable that you want to stop EM transmissions from. Typically power leads. My External HDDs don't have them on their power leads although it could be there is one just inside the enclosure (which is where it should probably be anyway.

Si

Posted 4 Sep 2012
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