Products > Test Equipment

SainSmart DDS120 & DDS140 USB Oscilloscope

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ganzuul:
Glad I could help! I learned a lot in the process, and I don't think I'm done. =)

By the way, I just noticed that the DDS 120's File > Record an Review function actually does work! It's much more usable than the Single trigger. It will record up to 450 frames to disk.

psynapse:
A little off topic. I have the DDS140 (BM104) which uses

ad9288
cy7C68013
altera max II.

The altera gives a lot of extra I/O pins for logic analyser / sig.gen.  I have not traced the circuit to see whether it plays any major part in analogue acquisition

However I note that the (awful) software is the same for both scopes, so I am guessing the protocol to the cy 7C68013 is the same.

Somebody mentioned an API to the device, where can I find that please.

Like one of the other folk here, I brought this thing to record single shot events, but triggering is almost non existent. And the faster the sample rate, the less likely the trigger is to happen.  A quick calculation on USB2 transfer rates suggests that the device goes blind whilst it transfers the next 40k bytes of samples.  Another person noted that the record function works  ...... and it does ..... but seems to have the same problem ...... ie grab 40k bytes, transfer it to the PC, store it on hdd, get the next 40k ..... which would mean that the data is actually full of holes.  All that said, if I could get true triggering, 20kx2 samples would be fine

Postscript:

Just opened mine up to take a photograph ...... to my horror I find the AD is a 40Msps certified part and the crystal to the logic array is 80Mhz   ....... This would be fine, except that this device is meant to be 100M samples per second per channel  .... So I shall try and send it back

donut6:
I also have the DDS140, advertised on amazon.co.uk as a 40MHz 200M/S Oscilloscope.

But, the analogue front end is identical to the DDS120?

Too lazy to return it. Might try my hand at writing an OpenGL scope app!

gambit58:
Hello
I just received the SainSmart DDS-120. The device drivers installed properly for Windows 7/64 Ult. When I run the scope software that is included I receive an error message (See attached). Suggestions for a fix?
Thank you

ganzuul:

--- Quote from: psynapse on October 09, 2014, 12:07:43 am ---Just opened mine up to take a photograph ...... to my horror I find the AD is a 40Msps certified part and the crystal to the logic array is 80Mhz   ....... This would be fine, except that this device is meant to be 100M samples per second per channel  .... So I shall try and send it back

--- End quote ---

That's an amazing thing to hear!  :wtf:

I wonder if the AD is actually a genuine part? I can imagine an off-brand higher spec device would cost less than a brand-name one.

Perhaps it can be overclocked in the DDS 120, like doc suggested?


--- Quote from: donut6 on October 09, 2014, 06:18:43 pm ---I also have the DDS140, advertised on amazon.co.uk as a 40MHz 200M/S Oscilloscope.

But, the analogue front end is identical to the DDS120?

Too lazy to return it. Might try my hand at writing an OpenGL scope app!

--- End quote ---
Are the probes identical too?

I'll gladly collaborate with you on the scope app. =D

Attached is a capture I made with a trial version of a program called USBlyzer. I was not able to capture any of the control signals which are obviously sent back to the uC, or any of the traffic in that direction, to my frustration. However, the data it sends should be trivial to plot. I'll next try USB Hound, which I found through links on this site: http://janaxelson.com/development_tools.htm

I wonder if the easiest way to make a pretty graph would not be to use "poor man's anti-aliasing" and simply downscale a large bitmap. A further degree of averaging/smoothing could be to use a fading effect. Ideally, this would make the visual equivalent of; sort 5 or so samples, drop the highest and lowest, take average value, and display it. - This very simple signal conditioning procedure has high noise immunity. There is no need to decimate the signal rate; one can just shift in the next sample in the sequence.

A much more advanced, experimental idea could be to see if http://en.wikipedia.org/wiki/Karplus%E2%80%93Strong_string_synthesis can't be used for a kind of triggering... Wave form stabilization, to be exact. The theory is just extremely interesting.

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