Quote:
Originally Posted by jrm01
A good signal level is determined by looking at the picture and being satisfied.
|
'Not true, especially with a digital signal. The nature of digital communications is such that the data (in this case a video signal) is essentially perfect until the signal degrades very near to the point where one receives nothing at all. Unlike analog video which degrades slowly and somewhat gracefully over a large range of signal levels by showing increasing amounts of snow with decreasing signal levels and increasing amounts of distortion with increasing signal levels, a digital stream will be nearly perfect until suddenly the consumer is faced with rapidly increasing numbers of artifacts for a change of only 2 or 3 dB.
Quote:
Originally Posted by jrm01
I've never quite trusted the TiVo signal strength numbers that they display. I've had good picture with low numbers and bad picture with high numbers.
|
That's because, in part, the quality of a broadband signal cannot be quantified with a single number.
Quote:
Originally Posted by jrm01
I think one of the better indicators is the RS Corrected and RS Uncorrected numbers shown on the diagnostic screen. Keeping these numbers at or near zero is a better measurement.
|
Except it isn't a very sensitive measurement. One could have signal levels which are dead bang on optimal, or only 1 dB away from starting to show artifacts in the picture and one would never know the difference. Unfortunately, a Signal Level Meter or Spectrum Analyzer is the only way to know for sure whether the signal leveks are close to optimal. Even worse, the signal level is not the only relevant measure of signal level, and while SLMs and SAs are far from cheap, the other devices used to determine signal quality are more expensive still.
The good news is, if you are a CATV or FIOS subscriber, they have the equipment and can determine whether your signals are good, or not. The bad news is, unless the signals are actually bad, the provider may charge you for the trouble call.
