3.Osciloscope measured frequency is flawed / wrong when Acqu Mode is set to "Peak detect"
How to test:
(Use Mode to switch to activate oscilloscope).
In HOR menu check that Acqu Mode is set to "Sample".
In Measure menu activate Frequency for the channel that you are using.
Connect oscilloscope probe to calibration port.
Check the measured frequncy on display ( it should be 1KHz).
Use HOR menu and set Acqu Mode is set to "Peak detect".
Check the measured frequency on display (on my units 2.2 Khz instead of 1KHz).
4.In Trigger menu: The line that represents Trigger level is shown if Coupling option is set to "DC" but is NOT shown if Coupling option is set to "AC".
How to test:
Press Trig button.
Set Coupling to "DC".
User arrows to set a level.
(Note that trigger level is shown on display like a popup message and a line).
Set Coupling to "AC".
User arrows to set a level.
(Note that trigger level is shown on display the line that represents the level is not shown)
I doubt that Owon will pay much attention to the last two "defects". Dave did a very informative video on AC trigger mode and it's use.
His video #685 addresses the missing trigger level indicator. The whole video is good but the specific info is at 16:57 to 18:01 on the timeline.
The peak detect acquisition mode is really meant to capture glitches/events that might otherwise be missed in the standard sample acquisition mode, and that appears to be working as it should. In this mode there
IS additional information being captured and the freq display is telling us what it sees.
On the FW version 4.1.0 (and 5.4.0, my only points of reference) Owon also included a "counter" on page-2 of the HORZ menu. That counter displays the correct frequency when the measure freq display doesn't. I have no idea where it gets it's information.
One easy way of displaying the additional information captured in peak detect mode is to zoom in on the
paused waveform.
How to test:
Oscilloscope probe on CHAN-1, CHAN-2 OFF.
Set CHAN-1 coupling to AC (just to keep everything centered on the screen)
Set HORZ to 200us, refresh rate to LOW, PEAK DETECT acquisition.
Set TRIGGER to DC, Falling Edge.
Attach probe to scope compensation signal to display a signal
-- (At this point the frequency display should be displaying something other than 1KHz)--
Pause the display using the RUN/STOP button
Set HORZ timebase to 1.0us to zoom in on wave form
Note the extra pulse on the waveform being counted on the frequency display.
If you dont see an extra pulse, un-pause the display, switch HORZ to SAMPLE acquisition mode and then back to Peak Detect (verify that freq display is displaying something other than 1KHz), then do the above pause and zoom. On occasion, the extra pulse is on the rising edge so you may have to scroll the horizontal over to see it.
IMO the erroneous frequency display is not really a bug, it interprets/displays what has been captured. Perhaps it's one of the things that comes with the lower price point of the scope (ie memory depth, sample rate, etc). If a situation requires the peak detect mode be used in order to catch the glitches, the cursors (time) will let the user zero in on what ever period of interest is needed.
Maybe the "counter" in the HORZ menu that they placed on the later versions of the firmware was meant to address situations like this.
I'd be curious to know how the Hantek 2D72 responds to the same setup.
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