another small breakthrough on our NERD technology.

[picowatt]

@PW:

Excellent example using the horizontal scale to determine the very slow frequency shown. But there is also a much higher frequency shown on the scope's display. Big "M" means megaHertz, and little "m" means milliHertz, right?

At the bottom of the LeCroy shot above, in the grey stripe that contains the "LeCroy" name, the sample rate and the RTC reading,  there is a figure given as   "  f=2.34324MHz  ".

What does this figure represent? 

(Note where the scope's trigger is set: on the top Yellow CVR channel, right smack dab in the middle of an oscillation burst.)

TK,

I was indeed warned...

What is this, 'scope 101?  I have spent way too much time on this already, but yes, trigger source ch1, DC, and on a rising edge, trigger level is at +320 millivolts, and trigger frequency, that is, CH1, 2.34 MHz.  Because of the nature of the duty cycle, I would want confirmation of that freq.  I can't give you a visual read of the feq at this time base, as the osc's are too close together.  But you already knew all this.

Note where the trigger settings are in FIG 4, which explains why the 'scope is reading f:0.00000 Hz.

Thank-you for the "quiet time" but I see, as you warned, it was entirely in vain.  Possibly the info I provided may assist other readers in reading 'scope shots in general, otherwise my time was completely wasted.

PW 

[picowatt]

MH,

A visual read of FIG 4 indicates the osc freq is about 1.56MHz.  The trigger is set poorly for that capture, and as well, the osc freq may not be all that stable.  The trigger frequency in that shot is f:0.00000 Hz, which means at these trigger settings, the 'scope can''t provide a frequency.  Also, the mean for CH3 is stating the frequency as 1.431MHz, but as noisey as that channel's indicated signal is, I would rather trust my visual read of 1.56MHz.

In FIG 3, the trigger frequency calculations the scope is doing related to channel 1 are being interrupted for 15 seconds during each of the overall time periods of the FG waveform and therefore the scope is likely providing an inaccurate read of the CH1 frequency.  One might be able to adjust the indicated freq using a bit of math versus the duty cycle, but I wouldn't. 

If no settings were changed as to the FG offset, etc, that would affect osc freq between the captures of FIG3 and FIG 4, I would trust the visual read from FIG4 of the osc freq I made, and use the 1.56MHz as the best determination of the osc frequency.

PW

[MileHigh]

Ah ha!  The sampling frequency is 2.34 MHz.  I can grok that.  Perhaps someone else can try to get into the grokin' groove.

I was suspicious about that 6.17 MHz stuff also.

It's only grok'n'roll but I like it.....

[picowatt]

Ah ha!  The sampling frequency is 2.34 MHz.  I can grok that.  Perhaps someone else can try to get into the grokin' groove.

I was suspicious about that 6.17 MHz stuff also.

It's only grok'n'roll but I like it.....

MH,

The sampling frequency for FIG. 3 is 1K samples per second.  The 2.34MHz is the 'scope "guessing" at the channel 1 trigger frequency.  The trigger frequency (osc on CH1) is being interrupted for 15 seconds every FG period.  The scope is having to deal with that as best it can at this time base/sample rate and the 2.34MHz number is really not usable for anything.  See my previous post.

PW

[picowatt]

MH,

A more accurate visual ("optical", as I use glasses!) read of the osc freq in the FIG 4 capture (I zoomed in) is closer to 1.515MHz.

PW