SNR always 0, but the values are reported 0-255 range by the driver.

Are all dvb drivers expected to report snr 0-65535? Mine seems to report 0-255.

I noticed that the snr for hvr-1600 (Name: "Samsung S5H1409 QAM/8VSB Frontend") is always 0 in the web-ui. The data that the web ui is getting from the backend is in the 220-240 range. Which matches what dvb snoop reports:

stephen@Dell-DM051:~$ dvbsnoop -s signal
dvbsnoop V1.4.50 -- http://dvbsnoop.sourceforge.net/

---------------------------------------------------------
Transponder/Frequency signal strength statistics...
---------------------------------------------------------
cycle: 1  d_time: 0.001 s  Sig: 42130  SNR: 225  BER: 0  UBLK: 0  Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 2  d_time: 0.005 s  Sig: 42130  SNR: 225  BER: 0  UBLK: 0  Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 3  d_time: 0.005 s  Sig: 42130  SNR: 230  BER: 0  UBLK: 0  Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 4  d_time: 0.004 s  Sig: 43066  SNR: 230  BER: 0  UBLK: 0  Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 5  d_time: 0.005 s  Sig: 43066  SNR: 230  BER: 0  UBLK: 0  Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 6  d_time: 0.005 s  Sig: 42130  SNR: 225  BER: 0  UBLK: 0  Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 7  d_time: 0.005 s  Sig: 42130  SNR: 225  BER: 0  UBLK: 0  Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 8  d_time: 0.004 s  Sig: 42130  SNR: 225  BER: 0  UBLK: 0  Stat: 0x1f [SIG CARR VIT SYNC LOCK ]
cycle: 9  d_time: 0.005 s  Sig: 43066  SNR: 230  BER: 0  UBLK: 0  Stat: 0x1f [SIG CARR VIT SYNC LOCK ]

Those seem like pretty good snr values if interpreted as single bytes:
225/255*100=88%
230/255*100=90%

The web-ui code seems to expect a value between 0-65535
https://github.com/tvheadend/tvheadend/blob/1c65e8b0f03384a5ca5b5fc7635ecad4fd85b415/src/webui/static/app/status.js#L491

femon reports 0% for the same range, so perhaps it is a driver issue?

stephen@Dell-DM051:~$ femon
FE: Samsung S5H1409 QAM/8VSB Frontend (ATSC)
status SCVYL | signal a492 | snr 00e1 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
status SCVYL | signal a83a | snr 00e6 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
status SCVYL | signal a83a | snr 00e6 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
status SCVYL | signal a83a | snr 00e6 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
status SCVYL | signal a83a | snr 00e6 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
^C
stephen@Dell-DM051:~$ femon -H
FE: Samsung S5H1409 QAM/8VSB Frontend (ATSC)
status SCVYL | signal  61% | snr   0% | ber 0 | unc 0 | FE_HAS_LOCK
status SCVYL | signal  64% | snr   0% | ber 0 | unc 0 | FE_HAS_LOCK
status SCVYL | signal  65% | snr   0% | ber 0 | unc 0 | FE_HAS_LOCK
^C

Replies (1)

RE: SNR always 0, but the values are reported 0-255 range by the driver. - Added by saen acro over 2 years ago

There is no specifications how signal values need to be reported,
and all do what they want.

In HEX

0-FF
0-FFFF
0-FFFFFF

On opposite side,
software need to have manual pattern set to read correct values.

(1-1/1)

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