[time-nuts] Scopes and 1 PPS signals?

Brooke Clarke brooke at pacific.net
Tue Oct 23 20:14:00 EDT 2007


Hi Alan:

It's not the delay that's limited, it's the sweep speed, or maybe that's saying 
the same thing.

I do have a SR DG535 that can be used to generate the needed delay per Dave's 
suggestion, but I'm already short of 50 Ohm coax cables.  Tried to get them at 
Radio shack but they no longer carry any 50 Ohm cables or bulk cable.

Any recommendations for good value coax that's on line?

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.precisionclock.com
http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam


Alan Melia wrote:
> Hi Brooke, ah well its probably a case of "not the right instrument for the
> job...." but that's a bit tough if its all you got, maybe the extra delay
> mentioned by others is what's called for. My old analogue scopes will do it
> :-)) Im surprised you can only get 10 screens worth delay. Some scopes will
> allow delay and sweep on different ranges of the TB.
> 
> Alan
> 
> ----- Original Message -----
> From: "Brooke Clarke" <brooke at pacific.net>
> To: "Discussion of precise time and frequency measurement"
> <time-nuts at febo.com>
> Sent: Wednesday, October 24, 2007 12:20 AM
> Subject: Re: [time-nuts] Scopes and 1 PPS signals?
> 
> 
> 
>>Hi Alan:
>>
>>I tried.  At 100 ms/sq the second pulse would be just off screen to the
> 
> right.
> 
>>  At 200 ms/sq the second pulse should be at center screen.  Using the
> 
> window
> 
>>function the window time base can be no more than 10X faster than the main
>>trace which would be 20 ms/sq, way too slow to see the pulse.
>>
>>Have Fun,
>>
>>Brooke Clarke
>>http://www.PRC68.com
>>http://www.precisionclock.com
>>http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam
>>
>>
>>Alan Melia wrote:
>>
>>>); SAEximRunCond expanded to false
>>>Errors-To: time-nuts-bounces+brooke=pacific.net at febo.com RETRY
>>>
>>>I presume it has a calibrated delayed TB how about using that ??
>>>Alan G3NYK
>>>
>>>----- Original Message -----
>>>From: "Brooke Clarke" <brooke at pacific.net>
>>>To: "Discussion of precise time and frequency measurement"
>>><time-nuts at febo.com>
>>>Sent: Tuesday, October 23, 2007 11:05 PM
>>>Subject: [time-nuts] Scopes and 1 PPS signals?
>>>
>>>
>>>
>>>
>>>>Hi:
>>>>
>>>>While trying to figure out the O-1814 Rb source I found a 1 PPS signal
>>>
>>>that's
>>>
>>>
>>>>less than 10 us wide.  But using an HP 54501A DSO it's almost impossible
>>>
>>>to
>>>
>>>
>>>>determine the period.  http://www.prc68.com/I/O1814.shtml
>>>>
>>>>If the display is 1,000 dots wide:
>>>>at 2 us/sq the trace takes up about 4.5 squares or 450 dots,
>>>>at 200 us/sq the trace takes up about 0.045 squares or 4 dots but the
>>>
>>>second
>>>
>>>
>>>>pulse is way off screen.  At slower sweep speeds you can't see the
> 
> pulse.
> 
>>>>Are there scopes that allow the period of a narrow pulse to be measured
>>>
>>>that
>>>
>>>
>>>>don't cost an arm and leg?
>>>>
>>>>--
>>>>Have Fun,
>>>>
>>>>Brooke Clarke
>>>>http://www.PRC68.com
>>>>http://www.precisionclock.com
>>>>http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Cam
>>>>
>>>>_______________________________________________
>>>>time-nuts mailing list -- time-nuts at febo.com
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>>>
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>>>
>>>
>>>>and follow the instructions there.
>>>
>>>
>>>
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>>
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