How important is signal strength?

mattb001

Standard Member
Sorry if this is a stupid/common question:

How important is the signal strength on Freeview once you get past a certain level?

For example, if I have a signal strength of 70% but get no break up of picture, is the picture any worse quality than if it were 80%, 90% or higher?

I am under the impression that as the signal is digital, it either works or it doesn't (in which case the picture starts to break up). Is this correct?

Thanks
Matthew
 

HeadBanger

Well-known Member
If you don't suffer from any breakups and receive all mux's I wouldn't worry about signal strength as it is the quality of the signal that matters most. Some boxes even have meters indicating both signal strength and signal quality seperately.

A good clean quality signal with low bitrate errors will provide breakup free viewing even if the signal strength is low. However, when the strength is low (say, <50&#37;) then receivers can be more susceptable to interference from impulse noise. So strength can also be important if you are, for example, close to a road where passing mopeds emit electrical impulse 'noise'. A stronger signal will help a receiver reject impulse noise better as the noise doesn't swamp the signal so easily.
 

Chris Muriel

Distinguished Member
As long as the signal isn't too strong - in which case errors due to overload or saturation can occur (the solution being to introduce the right amount of attenuation to achieve linear operation).
In the above case, the quality should again degrade as the bit error rate will have risen.

Chris Muriel, Manchester
 

Steven

Senior Moderator
Small question..

Having probs with multiplex A which contains C5 and my US crime shows :p :( Live in a flat. Aerial cable split from living room; one for living room and 3 going to the bedroom's (with 3db gain splitter). I rearranged furniture in my room and having probs with C5. During day reception is OK but for some reason round about 8:45pm the signal goes

I use a usb dvb-t stick. Software says signal quality is 4/5 and strength is max. When C5 works signal quality is max. When I can't view C5 quality loses one bar. It has that much of an effect?! Not an option to move furniture back as I am lazy and I like how it is now

Do we reckon a set top box would be better?
 

SeanT

Distinguished Member
LFC_SL - it sounds like you are suffering from the digital equivalent of ghosting and are actually picking up two different things on the same frequency (eg. a different freeview mux or an analogue signal from a different transmitter very close to your signal you are trying to receive) - check pointing up of your aerial and the condition of it's cable - try a STB too
 

Chris Muriel

Distinguished Member
also..
See if you can borrow an STB from a neighbour for some tests - both at interference time and outside that time.

Chris Muriel, Manchester
 

Steven

Senior Moderator
Thanks guys

No STB to borrow. Flat mates have analogue TVs and neighbour is on holiday. For what it is worth I am next door to living room and analogue reception in there of C5 is perfect

I don't know much about the aerial - cable comes into the flat through skirting board

I am tempted to buy a STB regardless. I know it will be better than a usb stick anyhow
 

SeanT

Distinguished Member
Last time I had 25&#37;+ signal strength and a poor picture on one MUX, the guy had two aerials on the same mast, one pointing at Sutton Coldfield and the other at Waltham (was in Rugby)
 

SamRadford

Well-known Member
The Freeview signal increases slightly at dusk. Since this is when your problem starts, you may have too much signal. Especially since you say "strength is max". It should not be max. It should be under (say) 80&#37; to avoid analogue swamping (for one thing).
 

Steven

Senior Moderator
Standing at my bedroom doorway looking in... (to help with explanation below)

Just to clarify I did have my table with laptop by the top-left corner. That wall is next door to living room. Table now at top-right wall and reception of Mux A has been dodgy since. Distance across is 9ft left~right

Through testing with the laptop I have found I can move 5ft from the living room side wall and reception is OK. Further and reception goes. Literally a 4 ft black hole :p I have no idea why the right side of the room is a problem

Sorry to be a n00b, but when you're all talking about aerials and masts... erm rooftop of flat are we talking here? :blush:
 

Steven

Senior Moderator
This is all too much for this simpleton. Watching C5 Law&Order right now whilst I wait for MOTD

Saturday is the only day I can watch C5 in the evening. Other days I do not get a signal in the evening. No idea why

Any ideas? :D
 

Mr_Fantastic

Active Member
I would not use a PC TV Tuner to judge quality, they can be awful. Mine does not even show signal quality, it just shows a strength/quality amalgamation which is pretty much useless.

It might be worth getting a Freeview receiver from Argos, if you can find one that can be returned. I tried with a Philips but was told that it could not be returned if I purchased. Then try it out for a few days, preferably in different weather conditions (rain is a good test) and then return it before the 16 days is up. You might find you like it and want to keep it.
 

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