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Review: Hantek DDS 3X25. Anyone own one?

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Mechatrommer:
i'm working on a new UI for it. but its been halted for sometime now. i only finished the GUI, no code yet. thats going to be a hell for me :P

marmad:

--- Quote ---The Velleman is 2 MHz, the Hantek is at 20 MHz.  See rf-loop post on the 'flatness' of the spectrum, suggests there are minimal sine harmonics to 3 MHz to be on par with the Velleman for say, audio work, to compare with Velleman, were a tests has it it clean to ~ -90dB.
--- End quote ---

@saturation

Just a note: even though I'm tipping towards buying the Hantek (for the raw speed and wealth of other hardware that they jammed into their device), the comparison above is not quite fair.  From what I've read, Velleman is being conservative with their specs, applying them equally to all waveform outputs, including arbitrary - while it appears Hantek is being slightly optimistic in theirs.  The Velleman does clean simple waves (like the sine) to 5MHz and can do perfect sine sweeps up to 25MHz (half the 50MHz clock speed) from their delivered software.  So from what I gather, the Hantek has perhaps a 4-fold advantage in real speed comparisons with clean sine waves (5MHz to 20MHz), but less with complex waveforms since it has half the sample size (4KSa vs 8KSa in the Velleman).  The Velleman also has a switchable low-pass filter on the output which the Hantek is lacking - but I'm hoping to rectify that.

BTW, not trying to dis the DDS-3X25 - I'm on the path to buying it myself - but I just thought the Velleman deserved a more accurate comparison  :)

saturation:
Hello marmad,

Yes, no worries, a critical eye always helps to identify more things to fix or exploit.  I was using their advertised frequency capability to compare both.  I agree with your comments.  Clearly both have pros and cons the more you dig into it.   For example, you could play with the sweep capacity to output long durations of a single frequencies far above 2 MHz to overcome its limit.

More info on the forums:

http://forum.velleman.eu/viewtopic.php?f=11&t=3267

http://forum.velleman.eu/viewtopic.php?f=11&t=6079




--- Quote from: marmad on July 09, 2011, 08:04:48 pm ---
--- Quote ---The Velleman is 2 MHz, the Hantek is at 20 MHz.  See rf-loop post on the 'flatness' of the spectrum, suggests there are minimal sine harmonics to 3 MHz to be on par with the Velleman for say, audio work, to compare with Velleman, were a tests has it it clean to ~ -90dB.
--- End quote ---

@saturation

Just a note: even though I'm tipping towards buying the Hantek (for the raw speed and wealth of other hardware that they jammed into their device), the comparison above is not quite fair.  From what I've read, Velleman is being conservative with their specs, applying them equally to all waveform outputs, including arbitrary - while it appears Hantek is being slightly optimistic in theirs.  The Velleman does clean simple waves (like the sine) to 5MHz and can do perfect sine sweeps up to 25MHz (half the 50MHz clock speed) from their delivered software.  So from what I gather, the Hantek has perhaps a 4-fold advantage in real speed comparisons with clean sine waves (5MHz to 20MHz), but less with complex waveforms since it has half the sample size (4KSa vs 8KSa in the Velleman).  The Velleman also has a switchable low-pass filter on the output which the Hantek is lacking - but I'm hoping to rectify that.

BTW, not trying to dis the DDS-3X25 - I'm on the path to buying it myself - but I just thought the Velleman deserved a more accurate comparison  :)

--- End quote ---

Mechatrommer:

--- Quote from: marmad on July 09, 2011, 08:04:48 pm ---...but less with complex waveforms since it has half the sample size (4KSa vs 8KSa in the Velleman)...
--- End quote ---
i still dont have a need for complex arbitrary wave, sine is still the mostly i used. and i still dont have a clear clue on what application of deep memory for complex arbitrary is really essential, except maybe in a very specific (but seldom) app like medical device that read heartbeat or simulating sensor output etc. but i guess that will be seldom for me. anyway, the IO output (12bit) the 3x25 provided, i'm thinking a way if we can output digital data like out of it. my current imagination is an arbitrary (analog) wave editor and at the same time we can see the equivalent digital data, or vice versa, we specify the digital data (serial or parallel) and we can see the equivalent analog wave. well, thats something for me to play later.

marmad:

--- Quote --- the IO output (12bit) the 3x25 provided, i'm thinking a way if we can output digital data like out of it.
--- End quote ---

You can use Digital Output pin 11 (in generator mode it would reflect the the MSB of the DAC) as the Sync out.  If you generate full-scale simple waves (sine, square, triangle or saw) DO11 will be the same as a sync pulse out - although it is still just another unbuffered pin of the FPGA - although it might not suffer crosstalk problems with the Output since it's laid out farther away on the PCB.

Sample generator output image - 10 bits in image, but it's the same with 12 bits.

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