[time-nuts] question about multi-way measurement

[Jerry Hancock]

It looks like the image I sent got trimmed off.  Did I do something wrong?

Regards,

Jerry


> On Dec 26, 2018, at 4:21 PM, Jerry Hancock <jerry at hanler.com> wrote:
> 
> The other issue is application priority in windows.  Here’s an example.  I have a timer running at .75 seconds in Visual Basic.  To the left is normal priority and to the right I set the application to real time priority in device manager.
> 
> I then calculated the time between timer interrupts.  I was having a problem reading my 3457a over GPIB using Visual basic at a consistent rate.  I still can’t figure out why every 4 or 5 reads, the time increases by about .05 seconds.  It’s not in the 3457a, could be in the Keysight VISA code. What I need is a way to read GPIB with an STM32F7 board.
> 
> After setting the priority to real time, the standard deviation improved by a factor of 7.  By the way, I thought it was interesting that my PC counts ticks to .1us.  
> 
> 
> 
> Regards,
> 
> Jerry
> 
> 
>> On Dec 26, 2018, at 3:42 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
>> 
>> 
>> tvb at LeapSecond.com said:
>>> But most people have only one counter (one internal or external timebase
>>> reference) and one clock to be measured. So the measurements are one-to-one.
>>> If you have more references or more clocks, you're welcome to combine 2, or
>>> 3, or as many as you want. It gets complicated but in some cases this
>>> complexity is justified. 
>> 
>> Lots of people have several PCs, each with their own clock.  If you have your 
>> time-nut hat on, they are crappy clocks with lots of common mode errors 
>> (temperature, network delays).  I think the techniques should apply.
>> 
>> 
>> -- 
>> These are my opinions.  I hate spam.
>> 
>> 
>> 
>> 
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