[time-nuts] Scopes and 1 PPS signals?

Brooke Clarke brooke at pacific.net
Tue Oct 23 23:19:42 EDT 2007

Hi Dider:

I'll give that a try tomorrow.  What does your camera setup look like?
Digital SLR on tripod?  Does that mean the TDS-210 can not do a screen dump to 

I've been looking at the Rigol DS1102CD mixed signal scope.  The 100 MHz 2 
analog channel & 16 digital channels is very reasonably priced.  But after 3 
emails I still have not been able to see a programming manual for it.  Although 
they do have a software package.

Have Fun,

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

Didier Juges wrote:
> ); SAEximRunCond expanded to false
> Errors-To: time-nuts-bounces+brooke=pacific.net at febo.com RETRY
> I took some pictures of my Thunderbolt's PPS output. While it's pulse is not
> quite as narrow as what you report, it's 10uS, way too narrow for the scope
> to display it in normal ("Sample") mode at 250mS/div (the fastest setting
> that will allow to measure the period of a PPS signal) on my TDS-210 digital
> storage scope.
> There are at http://www.ko4bb.com/Test_Equipment/Thunderbolt/PulseStretching
> The names are self explanatory, but just in case :-)
> 1_PPS_10xProbe is the PPS measured at the end of a 3 foot cable with a 10x
> probe
> 2_PPS_Sample Mode is the PPS signal in normal (sample) mode, as you probably
> would see it on any DSO without any special mode. It's fair to say it would
> be hard to make sure what you are seing or measuring. Please note that some
> of the time, the scope triggers, but the trace is flat. I had to wait to
> make this shot, which was the best I saw in about 30 seconds.
> 3_PPS_PeakDetect_Mode is the same signal, with the scope in Peak-Detect
> mode. It is easy to check the period (if not very acurate). In this mode,
> all sweeps look the same.
> 4_PPS_Diode is with a 1N4148 between the PPS output and the scope probe. See
> how the 10uS pulse is now a solid 250uS at 1/3 the height. It would be much
> easier to see on any scope, I need to pull the old trusty Tek 2245A and see
> what it does on it.
> 5_PPS_Diode_5.6nF is the same diode with a 5600pF capacitor across the
> probe. The pulse is now strecthed to ~10mS.
> 6_PPS_Diode_5.6nF is the same signal at the 250mS/div sweep rate.
> That's a heck of a lot cheaper than $45. Does not even need a power supply
> :-)
> Didier KO4BB
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