[linux-dvb] Weak signal
chrismoll at chrismoll.homelinux.org
Wed Sep 7 13:47:19 CEST 2005
Le Mardi, 6 Septembre 2005 15:43, Damien Bally a écrit :
> I'm experiencing a rather weak signal when using tzap, though my dvb-t
> reception seems to be OK.
> Here are the figures :
> signal : 0043
> snr : fff
> ber: 0
> unc: 0
Of what I have read on this list, it seems these numbers can mean different
things depending on the driver and the dvb card. Values returned by the
hardware seems not to be very well documented (in most cases, I guess).
> As far as I'm not mistaken, the signal is an integer coded in hexa, so it
> means 67 out of 65535, which is very very low. The README indicates 0x800
> and above as a correct value.
> Is 0x0043 a reliable figure or a bug in tzap ?
Here are the values I get :
status 1f | signal 7676 | snr f2f2 | ber 00195000 | unc 00000000 | FE_HAS_LOCK
My card is a Terratec Cinergy 1200 DVB-C. With this card, the signal and snr
always give two identical bytes. For the signal value, lower means a better
signal. For the snr, the higher the better.
The ber acts a little crazy with this card. It can vary between the above
value and somthing like 20 with no apparent reason, but it only gets updated
like twice per minute, or so.
So I think the only really important value is unc, which are the number of
blocks that could not be corrected by error correction algorithms and thus
directly affect the quality of the output stream. For a perfect picture and
sound, you need 0 here.
So, IMHO, you shouldn't worry much about the other values as long as there are
no uncorrected blocks.
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