LCD TV picture quality

espresso

stevemcol wrote: »

OK, I've borrowed a sig strength meter. I have googled, honest, but I can't find what signal strength voltage I should expect. Anyone help?

What type of signal strength meter? A proper signal analyser for digital signals costs thousands! What strength/quality is displayed in the TV's set-up menus?

kwikbreaks

stevemcol wrote: »

OK, I've borrowed a sig strength meter. I have googled, honest, but I can't find what signal strength voltage I should expect. Anyone help?

I don't know for sure with modern sets and digital signals but back in the day when BBC2 colour came out a 1mv signal was reckoned to be pretty good and you'd get a picture of sorts with 100uv

What are you getting.

stevemcol

Just got hold of it now. It's a cheapo analogue needle unit, calibrated in dBu's.

Haven't checked my signal strength yet.

aliEnRIK

Im assuming you only see a problem when watching freeview?
Freeview is highly prone to poor picture quality

kwikbreaks

stevemcol wrote: »

Just got hold of it now. It's a cheapo analogue needle unit, calibrated in dBu's.

Haven't checked my signal strength yet.

From wikipedia...

dBμV or dBuV
dB(1 μVRMS) — voltage relative to 1 microvolt. Widely used in television and aerial amplifier specifications. 60 dBμV = 0 dBmV.

So the 60dB position is the same as the 1millivolt I remember from days of yore.

A quick search on google shopping shows loads of cheap meters which light up leds according to that scale and they suggest that 60 is poor 70-80 OK and 90 excellent.

stevemcol

Kwik B

I hate asking a question then arguing with the answer. But, if I'm reading wiki correctly then 0dBu is 0.775V, not 1 μV.
So if you agree, according to your earlier suggestion of 1mV being OK, that would be -57dBu?

(I'm relying on very rusty college work here and wiki)

AlienRik. I think you may have hit the nail on the head. I can feel a sky subscription in the offing!

So the switch over may, as I suspected, have been a retrograde step.

kwikbreaks

You are reading the wrong bit. look further down...
http://en.wikipedia.org/wiki/DBuV#Voltage

dBu or dBv
dB(0.775 VRMS) — voltage relative to 0.775 volts.[1] Originally dBv, it was changed to dBu to avoid confusion with dBV.[10] The "v" comes from "volt", while "u" comes from "unloaded". dBu can be used regardless of impedance, but is derived from a 600 Ω load dissipating 0 dBm (1 mW). Reference voltage dBmV
dB(1 mVRMS) — voltage relative to 1 millivolt, regardless of impedance. Widely used in cable television networks, where the nominal strength of a single TV signal at the receiver terminals is about 0 dBmV. Cable TV uses 75 Ω coaxial cable, so 0 dBmV corresponds to −78.75 dBW (-48.75 dBm) or ~13 nW.

dBμV or dBuV
dB(1 μVRMS) — voltage relative to 1 microvolt. Widely used in television and aerial amplifier specifications. 60 dBμV = 0 dBmV.

If you check one of the pictures of the meters with LEDs you will see that bigger numbers are rated better. If the dBs were really negative as you suggest then smaller numbers would be higher level signals.

fwor

stevemcol wrote: »

So the switch over may, as I suspected, have been a retrograde step.

Are you in an area that has already switched over (i.e. has analogue been switched off)? If not, you should see better signal strength after switch over, which may solve your problem.

If your area has switched, but you are near to an area that has not, your signal strength may still improve at a later date - they will probably have to keep the signal level down so that it doesn't interfere with the adjacent area. Once the whole region has switched they can turn the level up fully.

espresso

stevemcol wrote: »

Just got hold of it now. It's a cheapo analogue needle unit, calibrated in dBu's.

Haven't checked my signal strength yet.

Don't waste your time! Use the signal strength meter provided in the installation set-up menu on the TV.

You may be getting low signal strength on some of the MUX's affecting certain channels - your poxy meter won't show that will it.

kwikbreaks

It isn't even worth looking at that really. If the picture is poor then no amount of looking at meters will improve it - only improving the aerial/feeder can do that. 30 miles is a long way to get a freeview signal.