[mythtv-users] Channel Reception Issues

[Brian Wood]

On Feb 22, 2007, at 1:05 PM, ryanlists79 at gmail.com wrote:

>  Actually, I only experience the problem when recording on the  
> mythtv box, not on the TV.  With the mythtv box running, I can  
> disconnect the coax cable from the mythtv box and plug it into the  
> TV and everything displays perfectly.

That *probably* indicates the problem is in your machine, but not  
totally certainly. You could have third-order products in the  
incoming cable signal that are below the threshold of perception and  
are getting added to by products being created in the mixer in your   
PVR's tuner, the combination of which is enough to be visible,  
therefore if there was a cleaner incoming signal you would not see  
the problem, even though the tuner's mixer has not got any better.

Third order products and noise are cumulative, an amp with a better  
noise figure and CTB specs will make a lot more difference if put  
first in the chain than it would as the 15th in line for example

You really have to look at the entire system as a "system" that  
starts at the cable headend and ends at your PVR card, looking at  
individual pieces of the system is not really the best way to analyze  
the situation.

An example would be when your feet are cold in the winter. You think  
that since your feet are cold the answer is better boots, but  
actually you are losing heat in your legs such that by the time the  
blood gets to the feet it is too cold to keep them warm. The real  
answer is warmer pants even though your legs do not feel cold.  
Perhaps a bad example but I'm trying to put it in real-world terms.

So the MythTV user's list has devolved to a discussion of pants,  
what's the world coming to? But I hope you see the concept.

It would be interesting to know how far out on the cable system's  
cascade you are, but I think you'd have to know somebody to find that  
out.