Digital Television

[Gingermick]

I went to a dealer the other day looking for a set top box. I found one I liked and executed a plan to purchase it. Plugged her in and executed some functions that got some channels and am generally very happy with the reception and quality.
However one channel has major problems with sound.
But the picture is excellant :confused: Makes no sense to me.

Anyone experienced this and fixed it without paying someone

[Iain]

More information on sound problem please....

[Gingermick]

crackle a bit like earthing a speaker cable and high pitched squeals and fizzes (and am not very good with onomatopoeia) then the machine must tell it that something's up and the sound stops.

[Iain]

That is a problem associated with weak signal or signal dropout, check your coax, all connectors and if you have any splitters replace them with F types if they are the old screw and saddle type.
With digital it likes a clean signal and all sorts of little bits of crap get in given a chance and cause all sorts of little problems.
Having said that it could be the antenna, is it cut for the digital channels or just the analogue, what transmitterare you pointing at.
For example with the analogue system you could be on channel 32-40 UHF and the digital could be 36-55 UHF, if your antenna is for the former and dedicated it will have problems with the new range of frequencies.
In Melb this is not a problem (except for some of the repeaters in the Dandenongs) as the configuration of channels is similar.
Also the antenna could be past its use by date (read stuffed).

[Iain]

As an afterthought, is SCB 10 the problem, if so it could be that it's not in full swing yet and still testing.
Have a look at this link
http://www.southerncrossbroadcasting...and/Mackay.pdf

[arose62]

I've heard that you need to be careful about the sound output from channels where you have less than good reception.

Apparently, as the STB cuts in-and-out, it can generate square edges on the audio signal, and this can blow the speakers.

I think I saw this on Whirlpool, and it was receiving some serious discussion.

Cheap insurance is to turn the volume down when visiting the dodgy channel.

Cheers,
Andrew

[Gingermick]

Our reception was lousy so we got a new antenna (from dick smith) and it didn't help. So I bought the set top box. It is channel 10 and sometimes ABC. SBS is good and so is 9 and 7.
But why would the picture quality remain?
There are some splitters on the cable in the ceiling somewhere. I'll take them out of the line and see if it helps.

(I'll have to study what you said earlier and keep switching back to analogue till I figure it out )
Cheers

[Iain]

Unfortunately Smiths Dick don't always have a great deal of knowledge on antennas, if it's big it must be good.
Try some electrical wholesalers in town and see if you can find a Log Periodic Band 3-4-5.
It is only just over one metre long but has considerably more gain than the combination antennas, and another bonus is there is no balun, the coax connects straight in.
It will probably have a part number like LP345 or similar, any good tech should know what you are talking about.
Cost is about $65-$70 and well worth it for the increase in gain.
They boast about 10db as opposed to about 3-5db on a combo that can be over 2 metres long with massive elements hanging everywhere, but do not be fooled by the lack of size.
Gain works on a logarithmic scale doubling every 3db, so 6db is double 3, 9db is double 6db and so on so it is an impressive figure.

[Groggy]

I agree with Iain. Forget DSE for this issue. I had similar problems and managed to fix them with a decent antenna. Initially I thought I was getting interference from somewhere and nearly went nuts trying to figure it out. Then I realised the signal meter was supposed to have a blue bar in the middle of it (it didn't). I got a new antenna and booster and now I have a solid blue bar and no noise or pixellation. Note that if your screen occasionally 'freezes', this is most likely just a reception problem.

[Gingermick]

So I have to spend some more money. darn it.
Thanks fella's

[Iain]

The other trap I have found with STB's is the 'strength meter', it (depending upon the box) can read signal strength 80%, but 80% of what???
It is a trap for the unwary and those who do not understand RF or the principles of digital recption.
You simply cannot have a bad picture, it cannot happen.
My STB work as low as 28db microvolts which is very low, some of the crappy ones will start to bomb out at around low 50's.
On analogue TV is pretty much unwatchable at about 55dbmv.
To make a digital analogy, imagine you are standing in a river and your mate is 100 metres downstream, he wants a beer, so you tip a can of beer in the river and he has to get it and seperate the beer from the water, thats analogue.
Digital, you put the can in the river and let him retrieve the can and open it himself.
No pollution, just the content of the can, its a bit more complex than that but essentially thats why you get such a clean image.
Digital arrives in coded blocks and the STB decodes that block of signal from the beer can, pull the antenna out of the wall and the transmission will continue for 2-3 seconds then freeze before going off.
That is because the STB has all the information and is still decoding what is on board and relaying to your TV until it runs out.
What can cause problems is a line of sight interuption like a tree in the wind, a large truck passing by etc.
Anyway, the more signal you have the better the chances of an uninterupted TV reception.
NB. Groggy and I went to the same school, as did Cliff Rogers and a few others here, albeit a few years apart.

[Termite]

The other trap I have found with STB's is the 'strength meter', it (depending upon the box) can read signal strength 80%, but 80% of what???
It is a trap for the unwary and those who do not understand RF or the principles of digital recption.
You simply cannot have a bad picture, it cannot happen.
My STB work as low as 28db microvolts which is very low, some of the crappy ones will start to bomb out at around low 50's.
On analogue TV is pretty much unwatchable at about 55dbmv.
To make a digital analogy, imagine you are standing in a river and your mate is 100 metres downstream, he wants a beer, so you tip a can of beer in the river and he has to get it and seperate the beer from the water, thats analogue.
Digital, you put the can in the river and let him retrieve the can and open it himself.
No pollution, just the content of the can, its a bit more complex than that but essentially thats why you get such a clean image.
Digital arrives in coded blocks and the STB decodes that block of signal from the beer can, pull the antenna out of the wall and the transmission will continue for 2-3 seconds then freeze before going off.
That is because the STB has all the information and is still decoding what is on board and relaying to your TV until it runs out.
What can cause problems is a line of sight interuption like a tree in the wind, a large truck passing by etc.
Anyway, the more signal you have the better the chances of an uninterupted TV reception.
NB. Groggy and I went to the same school, as did Cliff Rogers and a few others here, albeit a few years apart.

So basically if I put in a STB and go digital I can then pull free beer out of the river down the road.

[Gingermick]

Unless you have good clear line of sight to the river then the beer will be watered down a bit.

ps. Removed splitters and it didn't fix Ch10 or ABc too much. Looks like it's a new antenna. And I've just spent all my bonus. drat.

[knucklehead]

Mick,
You may be getting errors but they probably are affecting the picture.

One of the things with audio is it very unforgiving of errors, or rather our ears are unforgiving. A burst of errors will affect video and audio. The audio error may give a squeal or pop, which you cannot ignore (even if in another room). However the same error may cause a small pause or blocking in the picture which is much less likely to offend the senses.

But then again maybe you just need more time in the river of beer!

[Shedhand]

Unless you have good clear line of sight to the river then the beer will be watered down a bit.

ps. Removed splitters and it didn't fix Ch10 or ABc too much. Looks like it's a new antenna. And I've just spent all my bonus. drat.

g'day mick
Just came across this thread. I had the same problem you did. Luckily I got my new Loewe and STB from a reputable dealer who is famous for after sales service. I was assured I was getting the best bang for buck when I bought me new tele 12 months ago. As we have excellent line of site to our local transmitter we don't need an aerial for any channel. We get SCTV, Ten, 7even, WIN, SBS, ABC2 and ABCTV. We also get a number of Digital Radio Stations. Apart from those, the STB "auto-tuned" a few other station signals. They were SBSHDTV1, SBSHDTV2 and ABCHDTV. These stations were "broadcasting" stills and test patterns in HDTV and the audio reception was jerking, popping, squeaking while the video was pixilating all over the place like a mad woman on a trampoline. I don't know if those stations broadcast in HDTV mode anywhere else in the country (maybe only regional areas) but I just detuned the STB to get rid of all the HDTV stuff on the advice of the guru at the retailer and the other stations are fine. Are they HDTV signals you are pickingup?:eek: