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Author Topic: Odd shaped SNR-vs-tone graph - line #4 fault again  (Read 3656 times)

burakkucat

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #60 on: July 28, 2020, 08:21:42 PM »

Iím thinking that the evidence of the SNRM-vs-tones graph with the hollow bowl where the hilltop should be means thereís an enhanced pickup of rf interference in those frequencies. Non linearity, poor balance I donít know. What do our sages think?

I am unsure. To be honest, I have never seen such an effect prior to your line(s) displaying such peculiar behaviour.

Also I can't think of any way to mimic such behaviour in my test set-up.
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #61 on: July 28, 2020, 08:38:08 PM »

I think something really odd is going on. "Line 3" is now down and line 4 is back up to full speed and itís SNR vs tones graph looks normal. That says to me that Janet switched modems 3 and 4 over when asked by AA and hasnít switched them back, but why "line 3" really line 4 was then down is a mystery. The test program that I write which queries the firebrick and gets the status of all the lines says that line 4 is the correct BBEU ID now though - it has a table of expected values and checks them off to detect modems plugged into the wrong wall sockets. So Iím totally confused. I asked Janet to put the modems back to the way they should be when AAís test session had had a while to complete. It looks like iím seeing line 3 into modem 4 - good SNRM vs tones curve and high speed and dead modem 3 line - presumed line 4, so they havenít been swapped over, but then how can the BBEU check now be succeeding? The program has been tested and it has detected cross connected modems successfully before.
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #62 on: July 28, 2020, 09:32:55 PM »

Janet admits she knocked the power off on modem 3. now line 4 is all good - SNRM curve back to normal shape and sync rate high at 2.9Mbps d/s. What on earth?
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burakkucat

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #63 on: July 28, 2020, 10:21:21 PM »

Totally puzzled and confused.  ???
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #64 on: July 29, 2020, 12:45:57 AM »

The tones vs SNRM curve looks beautiful, and the speed is very good. I wonder if there is anything that AA might have unwittingly or otherwise done remotely, giving the line a tweak as part of a diagnostic procedure or some other procedure that can serve as a temporary bandaid and cure a fault for a while. (Thinks of wetting current making faults go away or at least covering them up - as the basis for an analogy, not literally.) But to cure a fault so completely Ö ?  ???   ???   ???
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Weaver

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Re: Odd shaped SNR-vs-tone graph - line #4 fault again
« Reply #65 on: August 01, 2020, 03:15:51 AM »

Thereís that slight hollow back again now in the SNR vs tones graph. A couple of noise spikes sent the downstream target SNRM right up to 6dB and so it going fairly slowly downstream just now. It just seems to be susceptible to big spikes at the moment and every few days somethings happening with this line.
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