Thanks for the information Robert. Any tips on getting the full ts from my card. I am using a budget PCI card (Terratec Cinergy 1200 DVB-T SAA7146) And I used tzap -r to set up the dvr device. Then I just used cat to cat to the test.ts file ? Or any tips on sniffing PID 0x0015 directly from the card. /Simon. > From: "Simon G" <linuxtv@xxxxxxxxxx> >> http://simong.net/dvb/test.ts >> http://simong.net/dvb/test_small.ts > > Unfortunately neither is a full transport stream - both files only > contained PIDs 0x0418 and 0x0419, so it's useless for analysis :( > > Anyway, here's how the system works: > > In case of an SFN (single-frequency network), the multiplex is generated > at > one place and SFN MIPs (megaframe initialization packets) are inserted > which contain a GPS time synchronization offset and the transmission > parameters to use. The transmission towers will then transmit the signal > GPS time synchronized using the specified transmission parameters. In case > of an MFN (multi-frequency network) where only one transmission tower is > used, the transmission parameters are configured there. > > In any case, the DVB-T signal contains TPS (transmission parameter > signalling) which contains the modulation type, FEC rates, hierarchy > alpha, > guard interval and transmission mode. In effect, the receiver only needs > to > know the carrier frequency and the channel bandwidth, and can autodetect > all other parameters. So it does no harm if it is given a wrong FEC rate - > at worst, it will take a little longer to lock the channel as the receiver > first needs to receive the TPS, whereas it might be able to lock faster if > it is given all the right parameters. > > The transmission parameters given in the NIT are really only > informational - they SHOULD be correct but it doesn't harm if they aren't. > What actually affects the reception is the parameters given in the SFN MIP > (as it influences which parameters the transmission tower uses) and the > TPS > (as they influence what the receiver will use). Now it'd be interesting to > see what happens if the transmission tower puts incorrect values in the > TPS > bits, but I think that's quite unlikely to ever happen... > > Regards, > -- > Robert Schlabbach > e-mail: robert_s@xxxxxxx > Berlin, Germany > > > _______________________________________________ > linux-dvb mailing list > linux-dvb@xxxxxxxxxxx > http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb > _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
