[mythtv-users] Low signal problem

Jan Schneider jan at horde.org
Tue Jan 27 18:25:37 UTC 2009


Thanks for the feedback.

Zitat von David Watkins <watkinshome at gmail.com>:

>> - I checked the ground connection. Antenna ground to power ground has a
>> resistance of 250 Ohm, no idea if that is a good or bad value.
>>
>> *Any* further ideas are highly appreciated.
>
> I fear I'm not going to be much help but since no-one else has
> replied, if nothing else I'll bump you back up the list.
>
> You probably have to face the fact you might have a defective card.
>> From the other ideas, a bad earth looks possible.
>
> If I was measuring the impedance between two earths I'd hope to see
> either a very low value (~1ohm), showing that they were well bonded
> together, or very high (hundreds of kOhm) indicating that they're
> completely isolated.  Your value looks a bit in the middle.

Yes, that's what I've read on another source too and which I found  
odd. I already wondered if the 1ohm was a typo, since my meter doesn't  
even measure milliohm. I guess the wiring in our house is pretty bad,  
the antenna cabling comes form analogue terrestrial times.

> It might be worth you mentioning what cable service you're trying to
> connect to, just to confirm that your DVB-C card is suitable.  You
> said your reception was flakey but in my experience of DVB (DVB-t)  I
> either get a channel or I don't.  I rarely get a poor quality picture.
> BTW  bit-error-rate, particularly uncorrected bit-error-rate is the
> best indicator of quality of DVB reception.  S/N can be misleading.

Not sure what you mean with cable service. Upon further reading I just  
learned that SNR is not really useful anyway.

But guess what, I just found out what the problem was: the C-2300  
seems to have some built-in brokenness in that you have to adjust the  
frequency down for it to properly receive the tuned in channels. I  
played with that, and indeed tuning the frequencies down by 125-500kHz  
gets me a crystal clear picture on the two channels I just tried.
Now I have to go through all transponders and find the optimal  
tune-down frequency and see if that helps with all stations.

In that regard, does anybody know how to tweak the frequency while  
showing the live picture? Is that possible at all with DVB, or does  
the card have to be locked to the frequency to show a station?

Jan.

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