On 12-04-24 06:42 PM, Andy Walls wrote:
> 
> Signal level varaition coupled with the HVR-1600's, at times, mediocre
> digital tuning side:

Ahh.  Pity.
 
> Run 'femon' on the cx18's dvb frontend when you have a live QAM capture
> ongoing.

OK.  Ran it all evening during the evening capture window.  Started it
at 20:30, sharp to coincide with the evening's recording from that card
also starting at 20:30 sharp.  Here's where it found anomalies:

$ nl /var/tmp/femon.out | grep -v "| ber 00000000 | unc 00000000 |"

So you can see, since femon prints an output line each second, the
number on the left is the seconds since 20:30 and we are looking
for any line showing a ber or unc that is non-zero:

     1  FE: Samsung S5H1409 QAM/8VSB Frontend (ATSC)
    67  status SCVYL | signal 013a | snr 013a | ber 00000198 | unc 00000198 | 
FE_HAS_LOCK
   313  status SCVYL | signal 013c | snr 013c | ber 0000026b | unc 0000026b | 
FE_HAS_LOCK
   457  status SCVYL | signal 013a | snr 013a | ber 0000026e | unc 0000026e | 
FE_HAS_LOCK
   802  status SCVYL | signal 013c | snr 013c | ber 00000265 | unc 00000265 | 
FE_HAS_LOCK
  1093  status SCVYL | signal 013a | snr 013a | ber 0000014b | unc 0000014b | 
FE_HAS_LOCK
  1184  status SCVYL | signal 013a | snr 013a | ber 000001ca | unc 000001ca | 
FE_HAS_LOCK
  1192  status SCVYL | signal 013a | snr 013a | ber 00000267 | unc 00000267 | 
FE_HAS_LOCK
  1385  status SCVYL | signal 013c | snr 013c | ber 0000025d | unc 0000025d | 
FE_HAS_LOCK
  1435  status SCVYL | signal 013c | snr 013c | ber 00000268 | unc 00000268 | 
FE_HAS_LOCK
  1511  status SCVYL | signal 013c | snr 013c | ber 0000026c | unc 0000026c | 
FE_HAS_LOCK
  1657  status SCVYL | signal 013a | snr 013a | ber 0000026a | unc 0000026a | 
FE_HAS_LOCK
  1693  status SCVYL | signal 013a | snr 013c | ber 0000026f | unc 0000026f | 
FE_HAS_LOCK
  1749  status SCVYL | signal 013c | snr 013c | ber 00000184 | unc 00000184 | 
FE_HAS_LOCK
  1796  status SCVYL | signal 013a | snr 013a | ber 00001a8b | unc 00001a8b | 
FE_HAS_LOCK
  1814  status SCVYL | signal 013c | snr 013c | ber 0000026d | unc 0000026d | 
FE_HAS_LOCK
  2028  status SCVYL | signal 013c | snr 013c | ber 00000275 | unc 00000275 | 
FE_HAS_LOCK
  2081  status SCVYL | signal 013c | snr 013c | ber 0000023a | unc 0000023a | 
FE_HAS_LOCK
  2261  status SCVYL | signal 013c | snr 013c | ber 00000264 | unc 00000264 | 
FE_HAS_LOCK
  2307  status SCVYL | signal 013c | snr 013c | ber 00000279 | unc 00000279 | 
FE_HAS_LOCK
  2318  status SCVYL | signal 013c | snr 013c | ber 0000026b | unc 0000026b | 
FE_HAS_LOCK
  2474  status SCVYL | signal 013a | snr 013a | ber 0000026f | unc 0000026f | 
FE_HAS_LOCK
  2533  status SCVYL | signal 013c | snr 013c | ber 00000098 | unc 00000098 | 
FE_HAS_LOCK
  2612  status SCVYL | signal 013a | snr 013a | ber 0000026a | unc 0000026a | 
FE_HAS_LOCK
  2627  status SCVYL | signal 013c | snr 013c | ber 00000108 | unc 00000108 | 
FE_HAS_LOCK
  2671  status SCVYL | signal 013c | snr 013c | ber 00000196 | unc 00000196 | 
FE_HAS_LOCK
  2870  status SCVYL | signal 013c | snr 013c | ber 00000264 | unc 00000264 | 
FE_HAS_LOCK
  3084  status SCVYL | signal 013c | snr 013c | ber 00000274 | unc 00000274 | 
FE_HAS_LOCK
  3220  status SCVYL | signal 013c | snr 013c | ber 00000275 | unc 00000275 | 
FE_HAS_LOCK
  3323  status SCVYL | signal 013c | snr 013c | ber 0000026b | unc 0000026b | 
FE_HAS_LOCK
  3406  status SCVYL | signal 013c | snr 013c | ber 0000024f | unc 0000024f | 
FE_HAS_LOCK
  3433  status SCVYL | signal 013c | snr 013a | ber 0000022a | unc 0000022a | 
FE_HAS_LOCK
  3946  status SCVYL | signal 013c | snr 013c | ber 00000270 | unc 00000270 | 
FE_HAS_LOCK
  4129  status SCVYL | signal 013c | snr 013c | ber 0000026d | unc 0000026d | 
FE_HAS_LOCK
  4275  status SCVYL | signal 013c | snr 013c | ber 00000273 | unc 00000273 | 
FE_HAS_LOCK
  4284  status SCVYL | signal 013c | snr 013c | ber 00000267 | unc 00000267 | 
FE_HAS_LOCK
  4411  status SCVYL | signal 013c | snr 013c | ber 00000270 | unc 00000270 | 
FE_HAS_LOCK
  4718  status SCVYL | signal 013c | snr 013c | ber 00000204 | unc 00000204 | 
FE_HAS_LOCK
  4779  status SCVYL | signal 013c | snr 013c | ber 00000181 | unc 00000181 | 
FE_HAS_LOCK
  4927  status SCVYL | signal 013c | snr 013c | ber 0000025e | unc 0000025e | 
FE_HAS_LOCK
  4973  status SCVYL | signal 013c | snr 013c | ber 00000157 | unc 00000157 | 
FE_HAS_LOCK
  5024  status SCVYL | signal 013c | snr 013c | ber 0000024c | unc 0000024c | 
FE_HAS_LOCK
  5310  status SCVYL | signal 013c | snr 013c | ber 00000190 | unc 00000190 | 
FE_HAS_LOCK
  5328  status SCVYL | signal 013c | snr 013c | ber 00000277 | unc 00000277 | 
FE_HAS_LOCK
  5439  status SCVYL | signal 013a | snr 013a | ber 0000026a | unc 0000026a | 
FE_HAS_LOCK
  5441  status SCVYL | signal 0138 | snr 0138 | ber 0000024f | unc 0000024f | 
FE_HAS_LOCK
  5447  status SCVYL | signal 0138 | snr 0138 | ber 00000266 | unc 00000266 | 
FE_HAS_LOCK
  5885  status SCVYL | signal 013a | snr 013a | ber 000000b3 | unc 000000b3 | 
FE_HAS_LOCK
  5928  status SCVYL | signal 013a | snr 013a | ber 0000020b | unc 0000020b | 
FE_HAS_LOCK
  5942  status SCVYL | signal 013a | snr 013a | ber 0000026b | unc 0000026b | 
FE_HAS_LOCK
  5966  status SCVYL | signal 013a | snr 013a | ber 000004d4 | unc 000004d4 | 
FE_HAS_LOCK
  6178  status SCVYL | signal 013a | snr 013a | ber 0000026c | unc 0000026c | 
FE_HAS_LOCK
  6657  status SCVYL | signal 0138 | snr 013a | ber 0000026e | unc 0000026e | 
FE_HAS_LOCK
  6761  status SCVYL | signal 013a | snr 013a | ber 00000268 | unc 00000268 | 
FE_HAS_LOCK
  6769  status SCVYL | signal 013a | snr 013a | ber 00000276 | unc 00000276 | 
FE_HAS_LOCK
  6777  status SCVYL | signal 013a | snr 013a | ber 00000277 | unc 00000277 | 
FE_HAS_LOCK
  6814  status SCVYL | signal 013a | snr 013a | ber 00000267 | unc 00000267 | 
FE_HAS_LOCK
  6868  status SCVYL | signal 0138 | snr 0138 | ber 00000171 | unc 00000171 | 
FE_HAS_LOCK
  6881  status SCVYL | signal 0138 | snr 0138 | ber 00000198 | unc 00000198 | 
FE_HAS_LOCK
  6891  status SCVYL | signal 0136 | snr 0138 | ber 00000249 | unc 00000249 | 
FE_HAS_LOCK
  6924  status SCVYL | signal 0138 | snr 0138 | ber 0000026b | unc 0000026b | 
FE_HAS_LOCK
  7116  status SCVYL | signal 0138 | snr 0138 | ber 00000150 | unc 00000150 | 
FE_HAS_LOCK
  7119  status SCVYL | signal 0138 | snr 0138 | ber 00000197 | unc 00000197 | 
FE_HAS_LOCK
  7140  status SCVYL | signal 0138 | snr 0138 | ber 00000270 | unc 00000270 | 
FE_HAS_LOCK
  7602  status SCVYL | signal 0138 | snr 0138 | ber 00000264 | unc 00000264 | 
FE_HAS_LOCK
  7716  status SCVYL | signal 0138 | snr 0138 | ber 00000194 | unc 00000194 | 
FE_HAS_LOCK
  7732  status SCVYL | signal 0138 | snr 0138 | ber 00000272 | unc 00000272 | 
FE_HAS_LOCK
  7751  status SCVYL | signal 013a | snr 0138 | ber 00000181 | unc 00000181 | 
FE_HAS_LOCK
  7770  status SCVYL | signal 013a | snr 013a | ber 00000270 | unc 00000270 | 
FE_HAS_LOCK
  7781  status SCVYL | signal 0138 | snr 0138 | ber 0000026f | unc 0000026f | 
FE_HAS_LOCK
  7796  status SCVYL | signal 0138 | snr 0138 | ber 00000275 | unc 00000275 | 
FE_HAS_LOCK
  7808  status SCVYL | signal 0138 | snr 0138 | ber 0000022f | unc 0000022f | 
FE_HAS_LOCK
  7816  status SCVYL | signal 013a | snr 0138 | ber 0000024e | unc 0000024e | 
FE_HAS_LOCK
  7822  status SCVYL | signal 013a | snr 013a | ber 00000270 | unc 00000270 | 
FE_HAS_LOCK
  7956  status SCVYL | signal 0138 | snr 0138 | ber 00000268 | unc 00000268 | 
FE_HAS_LOCK
  8008  status SCVYL | signal 0138 | snr 0138 | ber 0000026d | unc 0000026d | 
FE_HAS_LOCK
  8011  status SCVYL | signal 0138 | snr 0138 | ber 00000260 | unc 00000260 | 
FE_HAS_LOCK
  8232  status SCVYL | signal 013a | snr 013a | ber 0000024b | unc 0000024b | 
FE_HAS_LOCK
  8235  status SCVYL | signal 013a | snr 013a | ber 00000073 | unc 00000073 | 
FE_HAS_LOCK
  8255  status SCVYL | signal 0138 | snr 0138 | ber 00000254 | unc 00000254 | 
FE_HAS_LOCK
  8274  status SCVYL | signal 0138 | snr 0138 | ber 0000024e | unc 0000024e | 
FE_HAS_LOCK
  8303  status SCVYL | signal 0138 | snr 0138 | ber 0000017f | unc 0000017f | 
FE_HAS_LOCK
  8305  status SCVYL | signal 0138 | snr 0138 | ber 00000184 | unc 00000184 | 
FE_HAS_LOCK
  8354  status SCVYL | signal 013a | snr 0138 | ber 00000270 | unc 00000270 | 
FE_HAS_LOCK
  8442  status SCVYL | signal 0138 | snr 0138 | ber 0000024b | unc 0000024b | 
FE_HAS_LOCK
  8473  status SCVYL | signal 0138 | snr 0138 | ber 0000014b | unc 0000014b | 
FE_HAS_LOCK
  8510  status SCVYL | signal 0138 | snr 0138 | ber 00000253 | unc 00000253 | 
FE_HAS_LOCK
  8557  status SCVYL | signal 013a | snr 013a | ber 00000260 | unc 00000260 | 
FE_HAS_LOCK
  8578  status SCVYL | signal 013a | snr 013a | ber 00000259 | unc 00000259 | 
FE_HAS_LOCK
  8639  status SCVYL | signal 0138 | snr 0138 | ber 00000151 | unc 00000151 | 
FE_HAS_LOCK
  8742  status SCVYL | signal 013a | snr 0138 | ber 0000018c | unc 0000018c | 
FE_HAS_LOCK
  8820  status SCVYL | signal 0138 | snr 0138 | ber 00000265 | unc 00000265 | 
FE_HAS_LOCK

First recording of the evening shows "glitches" at the following
intervals:

4
130
157
396
742
790
1035
1035
1035
1071
1134
1146
1203
1256
1328
1338
1378
1602
1638
1694

Not sure if that's a close enough correlation or not.  Not even sure
what those ber and unc values even mean.
 
> Watch for the BER or UNCorrectable block count to increase at about the
> same time you view a glitch in the video.  If this is the case, there is
> something about the signal the HVR-1600 is having trouble with.  (The
> older models don't have the best digital tuner and digital demod
> combination out there.)

So just sucky hardware in general?

> If the signal shown in femon is at a relatively high level most of the
> time, then the cable signal probably has an instantaneous signal that
> sometimes overdrives the frontend.  An inline attenuator might make the
> problem go away.
> If the signal is at a low level, it may drop below threshold
> occasionally.  An in line amplifier, installed as close to where the
> signal comes into you home as possible, might help.

Not sure if those signal and snr values represent normal, low or high
levels.  The values displayed above are fairly representative of the
rest of the samples for the period in terms of signal and snr.
 
> If it's not signal level related and not DMA related, then it is a
> problem with the cx18 driver feeding things to the DVB core, or a
> problem with the DVB core itself.

I guess I will have to leave that up to the expert(s).  :-)

b.


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