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Testing Issues

Posted: Tue Dec 26, 2017 3:07 pm
by danadak
Just bought and received DSO112A.

Some observations -

1) Using your test signal at 100 Khz, time base 1 uS or 2 uS or 5uS display will not be stable.
Only when selected 10 uS or higher will I get a stable display. Waveform 7 divisions high,
vert at .5 Vdc, Normal triggering

2) Using your test signal at 100 Khz, time base 1 uS, trying to see leading edge of test signal,
I should see 5 Mhz sample rate / 100 Khz signal = 50 samples. I see no stable display.

3) Using test signal at 1 Mhz, Tektronix 1 GS/sec scope TDS754A, 10X probe compensated
on Tek scope, I see not a square wave but a severely distorted RC rise and fall waveform.
Why is this not a high drive CMOS output on the processor ? So thats its square ?


4) Using your 1 Mhz test signal the DSO112A will not trigger at any timebase setting ? It has
5 Mhz sample rate, why is it not triggering at all.

5) How do I tell what version of firmware I have ? What DSO112A screen is it stated on ?

6) Any plans to upgrade with signal averaging, envelope mode, and FFT ? Signal averaging (noise reduction)
the most important, followed by envelope (jitter measurements) followed by FFT for spectrum studies.

Regards, Dana.

Re: Testing Issues

Posted: Tue Dec 26, 2017 10:39 pm
by cuppieinc
It is stated in the manual :

Note: Trigger is ignored when timebase is set to 5us/Div or
faster. This is because MCU is too busy to handle
trigger at these timebase settings.

Meaning that at 5us or below triggering is ignored so no stable output at these timebases

Re: Testing Issues

Posted: Wed Dec 27, 2017 1:14 am
by danadak
Makes me wonder if interupts are being used and variables are not
being referenced by pointers, which will increase amount of stack push
required and lower effective trigger rate. And simply setting a flag and
exiting, to service flag in main. That's the way fast ISR response occurs.
Also if DMA is being used.

If 1 uS and 5 uS horizontal rate not working, how can JYE Tech claim its has
a BW of 2 Mhz. Unless of course thats analog BW that no one can see or use,
because screen is full of way too many cycles.

In this case triggering at 10 uS to get it to work lookiing at 1 Mhz means
one cannot see detail of 1-2 cycles of waveform filling the screen.

And it seems menu-ing 1,2 , 5 uS of time base that does not work very misleading.

Regards, Dana.