Re: How does bad reception influence quality of macroblocks?

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lynx.abraxas@xxxxxxxxxx wrote:

This  is  very valuable to know. Sadly I couldn't find any info on this in the
net.
What would You recon is ment with "signal strength" and  "signal  quality"  in
the  M$  windows  dvb-t  programme?  Would  it  be  SIG and SNR as reportet by
dvbsnoop or tzap? What do the other values discribe? SNR is never changing although it is reported. Here is some output of usbsnoop and tzap:

tzap ard
using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
reading channels from file '/home/lynx/.tzap/channels.conf'
tuning to 191500000 Hz
video pid 0x0201, audio pid 0x0202
status 03 | signal 8675 | snr 0000 | ber 001fffff | unc 00000000 |
status 1f | signal 8435 | snr 0000 | ber 00000000 | unc 00000013 | FE_HAS_LOCK
status 1f | signal 8455 | snr 0000 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
status 1f | signal 844e | snr 0000 | ber 00000000 | unc 00000000 | FE_HAS_LOCK

The crucial ones here are ber and unc.

Ideally both should be zero. BER is a measure of bit errors in the stream and up to a certain point, these errors are fully corrected with the original data able to be recovered by using the error correction code which is part of the encoding.

Once the number of errors exceeds the error correction capability, the picture/sound starts to show visible/audible artifacting and this will show up in the unc - uncorrected errors column.

I am a little puzzled as to why the second entry in your example is showing uncorrected errors and yet has a ber of 0.

The ber numbers can be quite useful for fine tuning your dish alignment, particularly LNB skew.

Regards,

Richard

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