General > General Technical Chat
Review: Hantek DDS 3X25. Anyone own one?
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Mechatrommer:
a picture will worth 1K of word. the trigger output (or should it be input? shouldnt it?) is something never been reviewed. and pls dont blame anybody (incl me) if you found out this unit is not for you. you've made the decision and all the good and bad that we have found already stated in this thread. and praise to master saturation for bringing us in here :P will be looking forward for your point of view (review) Cheers ;)
Lunat1c:
I just stumbled upon this thread while searching for a signal generator to start up my lab and I must say that this couldn't have happened at a better time!

You guys are awesome! Working together and with the help of Mecha you made this little baby worth owning :) Thanks a lot for your efforts!

I have gone through the thread and just to make sure, in a nutshell we could say that the upgrades that Mechatrommer has performed are through the software that one uses to interface with the signal generator, right?

From what I've been reading on DDSs, this piece of hardware seems to be the best bang for the buck AWG. The Instek SFG1003 provides signals up to 3MHz while this one has more features and has a higher frequency range for the same price. Please correct if I'm wrong as I'm a beginner when it comes to this stuff and wouldn't wanna be disappointed if i purchase this :)

Thanks
Mechatrommer:
1 thing to add. if you rely on sweep function, then dds is not much of a wonder. there will be signal distortion when you try to change the signal (shape/amplitude OR frequency OR both, during transition only). i'm not sure whether it is a DDS weakness, or a "Cheapo" DDS weakness.
Lunat1c:
oh. If the problem is during transition only I can't see it affecting me that much at this point. At least I hope not :)

One question, what's the maximum frequency of all waveforms with the latest modifications you have posted?
Mechatrommer:

--- Quote from: Lunat1c on May 12, 2011, 08:25:26 am ---One question, what's the maximum frequency of all waveforms with the latest modifications you have posted?

--- End quote ---
if you are talking about all waveforms, the device's DAC sampling rate/clock need to be observed closely = 200MSa/s. lets take the worst case waveform ie square (max rise time), 2 adjacent samples from lo to hi will need 5ns to rise (ideally), so about how long it has to stay at that hi level (pulse width) will depend on your definition of what good a square signal is, i'm not sure the real figure/standard, but for me, maybe like... 1 portion rise, 8 portion hi, 1 portion fall and another 10 portion (fall,lo,rise). so altogether 20 points needed to generate 1 cycle of acceptable square (my standard). so calculate it 200MSAPS / 20SA = 10MHz. if you need higher quality square, you need to lower that figure. higher and higher frequency signal, they will all converge to resemble sine signal, ie poor square, poor triangle, poor arbitrary etc. But as for sine, it is usable up to 100MHz (2 points per cycle), but no accurate noise level has been figured at that highest frequency. the most accurate so far i think, is presented by seattle above, with his 10bits scope.
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