Odd problem this and I wonder if anyone can shed some light on it.
My new Philips freeview digibox makes a noise just like someone has not turned a tap off properly i.e a 'dripping' or 'chirruping' sound comes from the freeview channels. If I switch to the normal TV it goes away. Very irritating esp. after paying £120 for a new aerial.
Has anyone ever heard of a such a phenomenon??
TIA
Jb
Yep. Its faulty. Return it.
Probably got a dry jointed capacitor that slipped past final QA.
It is a common effect caused by low signal level or interference on a digital signal. You could ask in uk.tech.digital-tv for more advice particularly from the resident experts expert Bill Wright.
Peter Crosland
Thanks 'll go and ask Bill
Jb
Jb was thinking very hard :
If it is a fairly regular noise, take it back to the supplier as it is probably faulty. Much less regular, then that could be interference causing the signal drop out, or simply poor reception - check the signal level/quality.
That sounds to me like the noise that digital receivers make if the signal is weak or subject to interference. Such popping noises are the digital equivalent of hiss and distortion in analogue receivers. If the box has a signal strength display that's where I'd look first.
No signal strength meter and the noise is more of a 'plop plop' not a clicking, nor is it regular
It does sound like digital drop out. If the aerial is daisy chained through the box to the TV and it is a correct one and the analogue picture good I'd say the box is faulty.
I've got a Philips box that does show signal strength, though.
this is either radio frequency interference, poor signal from the aerial or interference coming from the mains. the latter should be eliminated by the unit's power supply, but in some cases this is not enough if your wiring is dodgy or you have bad load on the same mains. from what you are describing, it does not relate to switching inductive load on/off so the latter doesn't apply to you.
the sounds that you hear are results of erroneous decoding of the audio frames. if you watch close enough, you will see blocking and other artefacts in the picture as well (see last paragraph).
signal strength is not the only parameter when it comes to digital reception. error rate (BER) is not less important. DVB protocols can cope with some amount of errors, then glitches start to appear. check whether the aerial was installed and directed correctly, whether the cable/connectors are suitable. is it just one run of cable? some aerials are more sensitive to direction. maybe the installers checked for picture but did not care to direct properly. some aerials are plain unsuitable for DVB-T. I personally came across an aerial that worked fine for lower UHF channels but produced bad BERs for higher ones, which resulted in BBC channels showing up ok and SkyNews erroring all the time. with aerials made recently and certified this is unlikely.
all this has to be checked, unless, of course your freeview box is just faulty. try replacing it with a friend's and see if the problem persists. some boxes are more sensitive to bad signal.
/max
Thanks for that. I'll try moving the booster from the lounge to the loft and get it as close to the aerial as possible (as advised by others). We can rule out any and all mains borne interference including voltage step change, harmonic distortion and flicker. Power quality is my area of work so I know my supply is good. Someone suggested trying a different box so that's another option. Are the £20 variety as good as the £50 ones or do you get what you pay for?
Jb
you did not mention the signal booster. this could be the source of your problems. why do you need one? boosters often introduce too much noise noise, which could be fatal for digital reception. it is especially difficult to deal with them when there is no gain regulator. have you tried removing it altogether? I'd say that if, with the new high-gain aerial properly installed you still need a booster, then you're probably stuck without DVB. it is unlikely that in this case a signal booster can solve the problem. I'd advise to check the aerial installation, possibly move it around and lifting it higher. in BBC website you can find the coordinates of your nearest transmitter.
also, check whether the booster is suitable for digital reception.
if you or your friends have a laptop/PC with a DVB-T card, try it. these are more sensitive to poor signal and the software has signal power meter.
I had a good-quality on-digital philips box, a nokia box, then was thinking of buying a branded box and then got a 20-quid cheapo from a friend, called technika (AFAIK, tesco brand). out of three I had, the cheapo is the best when it comes to reception. the hardware is the same in almost all cheapos. I'd advise buying one in metal housing though. the prismatic one is different hardware but was positively reviewed.
I also have three PC tuners working 24/7. here you can't save much and should always buy a proven brand and good model.
/max
I've only tried one cheap one and it was rubbish. I returned it and swopped it for a better one. It also lacked the outputs I needed. I've got 5 assorted Freeview boxes here. The best performing (never any freezing etc) are my Topfield PVR and Sony STB. The others all have some issues or other - the worse being a Sagem I got for free with my TV.
Just to take this discussion a bit further - would you recommend buying a new TV with a built in digital tuner - or is it likely to fail? Is it better 'insurance' to have a separate set-top box? I would like to buy a TV with a built in one, but on reflection I have replaced my STB twice.
On Thu, 21 Jun 2007 08:52:00 GMT, "John" mused:
You'd be doing well to find a TV without tuner, and most tuners now are digital so for the price then it'd be cheaper to use a TV with built in digital tuner and then buy a cheap external box in the future if the one in the TV ends up being unrepairable.
One day, a TV with digital tuner will be the norm, like a TV with analogue tuner is now. Set top boxes will start to become rarer. I would imagine this will be in about 2020ish.
I dunno. I have all sony boxes and none of the display this sort of issue under poor signal. The audio is either there, or it break's up completely. If it does, the picture goes also, and you look at the analogue as an alternative, 90% of the time its of execrable quality due to multipath..I happen to be on the far side of several continental transmitters that are the other side of my local xmitter..in direct line of site.
Thats why I think the box is faulty.
The sound SOUNDS more like a nasty sort of LF instability in the power supply..
Beware that many of the bargain basement TVs sold by supermarkets etc don't have a FreeView tuner - I was looking at a 19" LCD widescreen set in Tesco for less than 200 quid which was analogue only. Not that it advertised that fact. Seems weird to me to sell a 16:9 set without FreeView since you can't get 16:9 off analogue.
On Thu, 21 Jun 2007 14:22:00 +0100, "Dave Plowman (News)" mused:
You can get it from another source connected to the AV socket that I would assume it would have though.
this is nature of DVB broadcasting. sound, video, subtitles, telext -- all go on the same frequency using the same modulation. this applies to a group of channels. another group will use a different frequency/modulation type. that's why BBC1 reception is usually more reliable and of better quality than, say, Sky Sports. if there are unrecoverable errors in the stream, both audio and video will suffer. if only sound is glitching and picture is ok, then most likely the signal is ok and the unit is faulty.
regarding separate/built-in receivers: it is unlikely that the built-in tuner will fail sooner than the TV itself. even if it does, you can still use an external one. just check in advance that you like the user interface. some of them are appalling, be that a built-in receiver or an external one.
/max
FWIW, this is deliberate (I was involved in designing some of the early OnDigital STBs). If the audio signal is corrupt, then it will be muted. This is because if you were to hear the audio equivalent of the sort of macroblock patterns you sometimes see with low signal stength etc., it would drive you mad!
It's kinda interesting that people seem to be able to cope with major distortion on vision more than sound. I guess one reason is that you can just turn your head away from the visuals, whereas the sound is more pervasive. One of the nice things about simple modulation schemes is that they tend to degrade more gracefully...
jon N
I have an Ondodgy box made by Philips. Characterised by the most amazing loud plops on sound if it looses signal. Near worried about the speakers if listening at reasonably high level - they were well over double the loudness of the prog material.
NICAM tends to stay rock solid after the picture has near disappeared in a snowstorm. Someone had their priorities right there.
My main Freeview source is now a Topfield PVR, and with exactly the same aerial and distribution system I can't remember seeing or hearing any transmission faults which were common with the Ondodgy box and a later (Sagem) FreeView one.
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