I have been sweeping for about 15 years now and no where and no one has ever just hit the test point with 15 dB of telemetry. I am not saying it isn't possible but every system I have been in from Ore. to Pa and Ak to Texas has hit it with 17 to 20 dB. Every one. And it works fine. I know what the modems do and you are right about that. They will adjust. But if it is hit too low then the noise is an issue. I have seen systems not wanting their modems to output less than 36 to 38 because they wanted to stay higher above the noise floor. The amps don't produce most of the noise in a return system........it is other outside influences related to cli. And with the amp cascades around 4 to 6 now it isn't as much a problem with amp contribution of noise. But what we may be missing here are the internal losses that probably get it to 15 and that has to be considered. There are diplexer losses and sometimes dc's internally like in older c-cor amps.......the starline series, SA amps and others. This will be the reason for hitting the test point with more than 15 after test point loss is considered.
You are right about the headroom on the 52 but systems won't do that because they want to run those levels because they want less amps and power supplys in the cascade........it's a money thing. Yes a better input can mean less noise but too much is distortion. Always an optimum there. The first amps out hit it with a little more for less noise and then a dB or 2 less in the last 5 for distortion control. But that was when cascades were 45 deep.
Re: What do you do to improve snr.
There is 1 reply to this message
