[linux-dvb] Verifying that everything works with szap

Mike Barnard mike at bleeding-head.com
Wed Feb 21 04:20:07 CET 2007


    Hi, folks! I'm in the midst of trying to get my first Linux DVB-S 
setup working and I'm having a rather frustrating problem. I'm running 
Ubuntu Dapper, I think I have the necessary kernel modules loaded. My 
satellite dish is aimed correctly and the LNB works, as evidenced by the 
fact that my standalone receiver has no problem getting a good signal. 
Because I'm in North America, I wasn't able to use any stock DVB-S 
channels.conf files (at least not that are part of the Ubuntu dvb-utils 
package) so I hacked together a one-liner that looks like this:

ABC News Now:11953:v:1:19540:508:456

    I had no documentation on the format of the channels.conf file, so I 
guessed at what most of this means based on what I saw in the other 
example files. As far as I can tell, it's something like 
Name:Frequency:Polarization:satellite number:symbol rate:VPID:APID. I 
was also unable to figure out exactly what I needed to pass to szap to 
tell it I had a North American LNB with an LO frequency of 10750 MHz. I 
had seen other examples of szap usage on the net where people had passed 
the LO frequency to szap using -l, so I did that. But this is all I get:

$ szap -l 10750 -n 001
reading channels from file '/root/.szap/channels.conf'
zapping to 1 'ABC News Now':
sat 1, frequency = 11953 MHz V, symbolrate 19540000, vpid = 0x01fc, apid 
= 0x01c8
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
status 00 | signal 0000 | snr 0000 | ber fffffffe | unc fffffffe |
status 00 | signal 0000 | snr 0000 | ber fffffffe | unc fffffffe |
status 00 | signal 0000 | snr 0000 | ber fffffffe | unc fffffffe |

    That goes on forever. It looks like everything's working, but it's 
just not getting a proper signal. I'm guessing I'm somehow not 
specifying the LO frequency correctly, but I really don't know for sure. 
If anyone's curious about the drivers, the dmesg lines that appear 
relevant are:

bttv: driver version 0.9.16 loaded
bttv: using 8 buffers with 2080k (520 pages) each for capture
bttv: Bt8xx card found (0).
bttv0: Bt878 (rev 17) at 0000:00:0b.0, irq: 19, latency: 32, mmio: 
0xdfcff000
bttv0: detected: Twinhan VisionPlus DVB [card=113], PCI subsystem ID is 
1822:0001
bttv0: using: Twinhan DST + clones [card=113,autodetected]
bttv0: gpio: en=00000000, out=00000000 in=00f4ffff [init]
bttv0: using tuner=4
bttv0: add subdevice "dvb0"
bt878: AUDIO driver version 0.0.0 loaded
bt878: Bt878 AUDIO function found (0).
bt878_probe: card id=[0x11822],[ Twinhan VisionPlus DVB ] has DVB functions.
bt878(0): Bt878 (rev 17) at 00:0b.1, irq: 19, latency: 32, memory: 
0xdfcfe000
DVB: registering new adapter (bttv0).
dst(0) dst_get_device_id: Recognise [DST-03T]
dst(0) dst_check_stv0299: Found a STV0299 NIM
dst(0) dst_check_mb86a15: Found a MB86A15 NIM
dst(0) dst_get_device_id: [DST-03T] has a [MB 86A15]
dst(0) dst_get_device_id: [DST-03T] has a [MB 86A15]
DST type flags : 0x2 ts204 0x4 symdiv 0x10 firmware version = 2
dst(0) dst_get_mac: MAC Address=[00:08:ca:00:03:00]
DVB: registering frontend 0 (DST DVB-S)...




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