[linux-dvb] Signal, SNR, BER . .
wmichaels1 at earthlink.net
Sat Jul 9 06:56:54 CEST 2005
On Friday 08 July 2005 11:03 pm, stonewall at inebraska.com
> Working with szap on a satellite multicast application,
> does anyone have documentation to the meaning or value of
> the bits set on the frontend read for the SNR (or also
> known as EbN0) and BER?
> The values from szap only are relational, but the tuner
> on these PCI cards are calculating absolutes. For
> instance, a nominal SNR for the work I'm doing is around
> 15dB . . . but the report from szap, even if you convert
> to decimal, is 58,000 . . .
I think szap just returns whatever value the driver
The raw data for the lgdt3302 chip is noise. There is a
formula to convert it to SNR in dB in the specifications. I
coded that up but it produces a negative number when the
noise is greater than the signal and a small value around
15 dB for good signal. The DVB interface is an unsigned
integer so a weak signal results is a large positive value
and a good signal is a small positive value. Mythtv seems
to expect the opposite so I changed the driver to return
the raw data from the chip.
> And with BER, this is normally a double precision number
> . . . with a good status of around 10e-6 or so.
> Thanks in advance for any assistance
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