[linux-dvb] Re: Newstruct and DVB-C with QAM_256

[Holger Waechtler <holger@convergence.de>]

Martin Neuditschko wrote:
> I have a Hauppauge DVB-c and I used the CVS-snapshot from
> 02.07.2002 (using:
> cvs -d :pserver:anonymous@linuxtv.org:/cvs/linuxtv checkout -rNEWSTRUCT DVB)
> 
> If I do "./czap RTL2", I get following output:
> status 00 | signal 9696 | snr d6d6 | ber 000fffff | unc 0000007f |
> status 00 | signal 8080 | snr d8d8 | ber 000fffff | unc 0000007f |
> status 00 | signal 7c7c | snr d7d7 | ber 000fffff | unc 0000007f |
> status 1f | signal ffff | snr eded | ber 000fffff | unc 0000007f | FE_HAS_LOCK
> status 1f | signal ffff | snr eeee | ber 0001f3df | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eeee | ber 0001f3df | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009efb | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009dea | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr ecec | ber 00009dea | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009d9c | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009d9c | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr ebeb | ber 00009d0b | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009d0b | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009c1d | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009e96 | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009e96 | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009f49 | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eaea | ber 00009f49 | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009ed4 | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009f2a | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eeee | ber 00009f2a | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr ecec | ber 00009d50 | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009d50 | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eded | ber 00009c07 | unc 00000000 | FE_HAS_LOCK
> status 1f | signal ffff | snr eeee | ber 00009eb3 | unc 00000000 | FE_HAS_LOCK
> 
> Are these values OK? What do the values mean?

yes, they look fine.

status: the lock bits. 0x1f means all circuits locked and working stable

signal: signal strength, usually evaluated by the inverse gain value
         of the AGC circuit. This is a 16bit unsigned integer, 0xffff
         means a saturated AGC circuit, if you run in troubles you might
         want to try to install a signal attentuator between your antenna
         cable and the DVB card

snr:    signal-to-noise ratio, a 16bit unsigned int. 0x0000 means a bad
         signal, 0xffff is too good to be real

ber:    bit error rate

unc:    uncorrected block count. The number of blocks that have not been
         corrected by the error correction circuit

FE_HAS_LOCK: the frontend circuits are locked and working, now an MPEG
         stream should be passed to the Demux


> Sometimes it is not able to switch to a channel:
> melchior:/usr/local/src/newstruct_020702/apps/szap # ./czap SRTL
> status 00 | signal 9595 | snr d4d4 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8989 | snr d2d2 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8c8c | snr d7d7 | ber 0000a2e8 | unc 0000007f |
> status 07 | signal 8a8a | snr d9d9 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8282 | snr d4d4 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 7b7b | snr d3d3 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 7b7b | snr d4d4 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8484 | snr d6d6 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8383 | snr d3d3 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8989 | snr c4c4 | ber 0000a2e8 | unc 0000007f |
> status 07 | signal 8d8d | snr cfcf | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8484 | snr d6d6 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8282 | snr d9d9 | ber 0000a2e8 | unc 0000007f |
> status 07 | signal 8c8c | snr d8d8 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 7c7c | snr d3d3 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8888 | snr d5d5 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 7a7a | snr d2d2 | ber 0000a2e8 | unc 0000007f |
> status 07 | signal 8383 | snr d4d4 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 7c7c | snr d1d1 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8585 | snr d7d7 | ber 0000a2e8 | unc 0000007f |
> status 07 | signal 8a8a | snr d8d8 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8383 | snr d9d9 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8282 | snr d4d4 | ber 0000a2e8 | unc 0000007f |
> status 07 | signal 8a8a | snr d4d4 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 7c7c | snr d5d5 | ber 0000a2e8 | unc 0000007f |
> status 00 | signal 8686 | snr d2d2 | ber 0000a2e8 | unc 0000007f |
> 
> Some suggestions to try something?

The 4th bit (FE_HAS_SYNC) is missing, this means that the frontend could 
not find the MPEG sync byte. This means that either your frontend 
parameters are not set correctly, the signal is ways too bad so that 
errors can't be corrected or that it is no DVB/MPEG transmission.



> My channels.conf:
> Sat1:378000000:INVERSION_OFF:6900000:FEC_AUTO:QAM_256:2176:2177
> Pro7:378000000:INVERSION_OFF:6900000:FEC_AUTO:QAM_256:2048:2049
> Kabel1:378000000:INVERSION_OFF:6900000:FEC_AUTO:QAM_256:2112:2113
> RTL2:378000000:INVERSION_OFF:6900000:FEC_AUTO:QAM_256:2304:2305
> ARD:314000000:INVERSION_OFF:6900000:FEC_AUTO:QAM_256:2176:2177
> ZDF:322000000:INVERSION_OFF:6900000:FEC_AUTO:QAM_256:2048:2049
> SRTL:570000000:INVERSION_OFF:6900000:FEC_AUTO:QAM_256:2048:2049
> VOX:810000000:INVERSION_OFF:6900000:FEC_AUTO:QAM_256:2112:2113
> 
> What is the difference betweed NVERSION_OFF and NVERSION_ON?

INVERSION_ON means that the transmitted signal is spectrum inverted, 
just try the opposite value to get a signal. Not all frontends support 
automatic inversion detection, so if the FE_CAN_INVERSION_AUTO flag in 
the FrontendCapabilities field is not set your scanning application has 
to try both values.


> What could I try to use instead of FEC_AUTO?

FEC_1_2 ... FEC_8_9.

Usually only FEC_1_2, FEC_2_3, FEC_3_4, FEC_5_6 and FEC_7_8 are used for 
DVB transmissions.

If somebody out there has the time to write a simple command line 
channel scan application to create channel lists please let me know, I'd 
like to include this in the DVB package, but here nobody has currently 
the time to do this.

Holger



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