Tuner problems / poor signal

G'day Guys

Just had a couple of new issues arise.

1st
Recoding 1 show on first tuner with a hashed picture - assumed poor signal and at digital drop-off.
Second tuner recorded following show on the same channel with a 10 minute overlap of the previous show.
However the second show recoded without any problems!! Same signal coming in but one tuner able to record OK but the other not?

2nd
Tuned to channel 10 to watch a program but the picture hashed (poor signal?)
Changed up one channel picture OK, then back down to 10, picture still hashed.
Changed down one channel picture OK, then back to 10, picture OK this time.
I could repeat this effect, going from channel 9 to 10 resulted in a good picture on 10 but going from 22 to 10 resulted in a hashed picture!!

I know both faults are due to a poor signal at the TiVo unit but at this time it is not often enough to go to the trouble of improving the antenna/cable. However I would like to know why one tuner was able to decode the signal and the other not and more interestingly why the same tuner was able to decode the signal when changing up one channel but not when changing down.
Anyone else had a similar situation or care to comment

This is the one problem with digital TV it is all or nothing and if the weather is bad a good signal can be degraded just enough to loose the picture all together.

Regards
Andrew

As you have said, unfortunately with digital signals there is a cliff effect between working perfectly and having problems.

If you are right on the boundary you may not get consistent results in your testing even if you try the same thing a minute apart.

Peter.