[linux-dvb] [Proposal] Meaningful reporting of SNR

Rusty Scott rustys at ieee.org
Fri Apr 14 04:14:49 CEST 2006

Having parsed through a number of the comments on this thread and feeling that
many of the responses have missed the mark.  Here is my bottom line:

1)  If the only thing the end user wants is signal strength and quality then why
doesn't the API only support these calls?  Let the driver developer decide how
these are measured for a given card.  Value is 0 to 100% for both strength and
quality.  (Sounds absurd when taken to extreme)

2)  Why not return BER or UCB in values from 0 to 100%?  The user is really only
concerned about if these are high or low.  They don't care about any absolute

3)  If SNR is useless in determining signal quality why have the capability in
the API at all?  If the capability is there to read SNR then it should be SNR
and since the driver is where chip specific information is stored, the driver
should know how to put that number into dB because it is different for
different chips.  If a card doesn't have the capability to actually determine
SNR then it shouldn't be returning one.  It should have other parameters to help
determine signal quality.

4)  Every parameter has its usefulness in different situations.  The application
developer should determine how her program is going to indicate good reception
versus poor reception.  More information is not a bad thing, it can be ignored
if it is not wanted but it cannot be generated where it is not provided.

There is no reason to limit the driver from producing accurate information,
according to manufacturer spec when possible, simply because that information
isn't available for every device in the driver space.

I'll climb down off my soap box now, I have a few patches to generate.


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