[linux-dvb] nova-t 500 tuning problems

Patrick Boettcher patrick.boettcher at desy.de
Mon Nov 6 17:41:24 CET 2006


On Mon, 30 Oct 2006, Torgeir Veimo wrote:

> 
> On 29 Oct 2006, at 22:32, Jon Burgess wrote:
> 
> >
> >In your original post you mentioned that you had an older card which
> >worked fine with this same setup. Is this still correct that if you run
> >this same test with the other card then it will receive a signal OK?
> >
> >If this is the case, then your issue is that the new card doesn't like
> >the offset and can only tune using the non-offset 506MHz frequency?
> >
> >Or do both cards only work at 506MHz now that you've moved?
> 
> Only the old card works at 506MHz. I have a tiny antenna which I tried with
> force_lna_activation=1, and it seems to pick up at least one transponder at
> 522MHz, so it seems it can tune when the offset is correct (I don't have a
> proper outdoor antenna to test with..) I guess I need to wait until some
> offset issues are resolved in the nova-t 500 driver then..
> 
> I'm still baffled by why the in-wall signal doesn't have the correct offset
> though.

The signal cannot have an offset of 166kHz only because of a reflection of 
a wall. What will happen is that the receiver is going to receive the 
signal several times delays (echo). The channel-estimation is detecting 
that and discards the received echo (or is selecting the strongest). 

The broadcasters in France and UK (and maybe elsewhere also) are not using 
the center frequency to broadcast a channel but they are using it together 
with a small offset (usually +/-167kHz). Normally the demodulators are 
able to handle those offsets (at least of DiBx000 this is true and I guess 
for Philips and Zarlink as well).

The problem is the tuner maybe. Some silicon tuners are able to cut the 
signal depending on a given bandwidth (so is the mt2060). 

Maybe there is something wrong in the mt2060 calculation for offset 
frequencies.

Can you check that?

Patrick.

--
  Mail: patrick.boettcher at desy.de
  WWW:  http://www.wi-bw.tfh-wildau.de/~pboettch/



More information about the linux-dvb mailing list