[time-nuts] 60 Hz line quirks, anybody recognize this stuff?

[Chuck Forsberg WA7KGX N2469R]

On 09/01/2012 02:17 PM, Magnus Danielson wrote:
> On 09/01/2012 08:35 AM, Hal Murray wrote:
>> The context is using the 60 Hz line for timing.
>>
>> I'm feeding 60 Hz from a wall wart transformer into a modem control 
>> signal
>> that the kernel PPS stuff watches.  Mostly, it works as expected, but
>> occasionally, it picks or drops a cycle.
>>
>> In order to understand what was going on, I fed the same signal into the
>> audio input and setup a job to capture the audio.  Here is an example 
>> of a
>> pick:
>> http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Aug-09-a-pick.png 
>>
>> http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Aug-09-a0.png
>> http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Aug-09-a1.png
>>
>> OK, that somewhat makes sense.
>>
>>
>> Something happened several days ago.  I used to get picks/drops 
>> rarely, say
>> ballpark of 1 a month.  Now I'm getting 10 or 20 per day.  So I started
>> looking closer.
>>
>> I'm now seeing stuff like this.  I've got lots and lots of examples.  
>> I added
>> a second PC with different hardware.  It sees the same stuff.
>>
>> Does anybody recognize this?
>>
>> http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-01-a0.png
>> http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-01-b0.png
>> http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-01-c0.png
>> http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-01-d0.png
>> http://www.megapathdsl.net/~hmurray/time-nuts/line/2012-Sep-01-e0.png
>>
>>
>
> It's interesting to notice that you have about the same distance from 
> the middle in all 5 examples. It's like you trigger a diode drop for a 
> while. Notice that there is a small slope towards zero.
>
> Cheers,
> Magnus
>
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I have noticed many stalls in Windows lately, possibly the result of 
Flash and Firefox not getting along.
The first plot suggests a multitasking related problem.

-- 
Chuck Forsberg WA7KGX N2469R     caf at omen.com   www.omen.com
Developer of Industrial ZMODEM(Tm) for Embedded Applications
   Omen Technology Inc      "The High Reliability Software"
10255 NW Old Cornelius Pass Portland OR 97231   503-614-0430