8VALVE,
Here is some additional information that will help you.
When you are speaking of the signal level reading, you are reading multiple noise signals
and the actual satellite signal (
if aimed at a sat properly). The LNBF's amplifier section generates its own noise level - this is just inherent electronic noise. Background radiation from the earth, most solar activity and other terrestrial and non-terrestrial interference sources add into this noise level as well.
This signal level is important to you as it is an indication of system health, although it has less to do with the actual satellite signal reception. If you read zero or a near zero signal level, then you have a problem that will disallow you from reading any signal quality from the satellite signal.
These problems could be an open cable, a dead LNBF or a LNBF parameter that is set incorrectly.
The QUALITY level reading is very pertinent to the actual signal level from the satellite itself. It is basically the difference between all the extraneous noise signals and the actual satellite signal. The stronger the actual satellite signal is and the weaker the ambient or extraneous noise "floor" is, the greater the signal quality reading will be. However, both readings must be within the receivers operating range.
Check out some of the informational videos found here:
Applied Instruments - Educational Videos
RADAR