[linux-dvb] [RFC] SNR units in tuners

Steven Toth stoth at linuxtv.org
Fri Oct 17 20:13:40 CEST 2008

Devin Heitmueller wrote:
> Hello,
> In response to Steven Toth's suggestion regarding figuring out what
> the various units are across demodulators, I took a quick inventory


> and came up with the following list.  Note that this is just a first
> pass by taking a quick look at the source for each demodulator (I
> haven't looked for the datasheets for any of them yet or done sample
> captures to see what the reported ranges are).
> Could everybody who is responsible for a demod please take a look at
> the list and see if you can fill in the holes?

Some minor comments in line, basically confirming your assessment. When 
I can get some time I'll go back and do the cx22702.

> Having a definitive list of the current state is important to being
> able to provide unified reporting of SNR.

Indeed, good work, thanks.

> Thank you,
> Devin
> ===
> af9013.c        dB
> at76c651.c      unknown

Old code, being removed I think.

> au8522.c        0.1 dB


> bcm3510.c       unknown (vals > 1000)
> cx22700.c       unknown
> cx22702.c       unknown

I need to add dB support for this.

> cx24110.c       ESN0
> cx24116.c       percent scaled to 0-0xffff, support for ESN0
> cx24123.c       Inverted ESN0
> dib3000mb.c     unknown
> dib3000mc.c     always zero
> dib7000m.c      always zero
> dib7000p.c      always zero
> drx397xD.c      always zero
> dvb_dummy_fe.c  always zero
> l64781.c        unknown
> lgdt330x.c      dB scaled to 0-0xffff
> lgs8gl5.c       unknown
> mt312.c         unknown
> mt352.c         unknown
> nxt200x.c       dB
> nxt6000.c       unknown
> or51132.c       dB
> or51211.c       dB
> s5h1409.c       0.1 dB
> s5h1411.c       0.1 dB


> s5h1420.c       unsupported
> si21xx.c        unknown (scaled to 0-0xffff)
> sp8870.c        unsupported
> sp887x.c        unknown
> stv0288.c       unknown
> stv0297.c       unknown
> stv0299.c       unknown
> tda10021.c      unknown
> tda10023.c      unknown
> tda10048.c      unknown (looks like 0.1dB)


> tda1004x.c      unknown
> tda10086.c      unknown
> tda8083.c       unknown
> tda80xx.c       unknown

Old code, being removed I think.

> ves1820.c       unknown
> ves1x93.c       unknown
> zl10353.c       unknown

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