On Tue, Feb 22, 2005 at 03:46:28PM +0100, Adam Egger wrote: > On Tue, 22 Feb 2005 22:48:28 +1100, Hamish Moffatt <[EMAIL PROTECTED]> wrote: > > On Mon, Feb 21, 2005 at 09:35:34PM +0000, Dan Robinson wrote: > > > cards (cx88 nova-t's): > > > [EMAIL PROTECTED] .tzap]# /usr/src/dvb-apps/util/szap/tzap "BBC ONE" > > > using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0' > > > status 01 | signal 0029 | snr c000 | ber 00003fff | unc 00000100 | > > > status 1f | signal 002a | snr ff3a | ber 000000c5 | unc 00000024 | > > > FE_HAS_LOCK > > > status 1f | signal 002a | snr ffff | ber 00000000 | unc 000000c6 | > > > FE_HAS_LOCK
> Thanks Hamish for so many good new information about the DVB stuff ;) > Could you just explain more about it? Which values are important in > the output of (tsc)zap? I've been always looking at the FE_HAS_LOCK > string only. Then I've ctrl-C tzap if the first line didn't have a > lock but the following ones. Is this ok? When you first tune a station (with tzap etc) the card may take a few seconds to lock. You might see a few lines without FE_HAS_LOCK and then it'll appear. No need to kill tzap and try again, just wait. The DVB transmissions include redundant data for error detection and correction (known as FEC - forward error correction). When your receiver card detects and corrects an error, it counts that in the 'ber' figure (ber meaning bit error rate). However if you get too many errors at once there is no way to correct that, which is an uncorrected error (unc number). Uncorrected errors mean that the MPEG2 stream will be corrupted, which may result in a visible glitch or pops in the audio etc. 'Signal' is a signal strength measurement. Higher is better. 'snr' is signal to noise ratio. Higher is better. The signal and snr figures are uncalibrated and can't be compared between different DVB cards currently. (Specifically cards that use different frontends, the actual VHF/UHF receiver part of the card.) Hamish -- Hamish Moffatt VK3SB <[EMAIL PROTECTED]> <[EMAIL PROTECTED]>
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