Poll

What is your interest in the Hantek DDS 3x25?

I own one
36 (27.1%)
I am considering getting one
40 (30.1%)
Curious about the hack
16 (12%)
Just passing through
41 (30.8%)

Total Members Voted: 111

Author Topic: Review: Hantek DDS 3X25. Anyone own one?  (Read 289889 times)

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Offline asbokid

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #400 on: October 29, 2012, 05:57:34 pm »
We need an AWG for generation of Gaussian white noise.   Are these any good for that?  Is there an in-built white noise function?   The sample size is just 4KSa, so for white noise injection for our minimum test period (1 second), the samples would have be transparently looped.  If that's possible.  Also, for this project, bandwidth is needed up to 20MHz really.   Not sure whether it would be suitable for our special needs  :P  which is adding background noise to a transmission channel to test comms transceivers.  If it is good, I will write a Linux driver, if no one has already done/doing so?

Any special deals available?    Saelig sold out long ago at US$100. Though today there are plenty vendors on fleabay charging US$145 shipped.   Taobao (China merchant site) has the DDS 3X25 listed for US$116 plus shipping.

There is also the DDS-3005 at US$230, with a higher bit depth than the DDS-3x25 - (14 bits instead of 12), higher sample size (256 KSa instead of 4KSa) but a lower maximum frequency (5 MHz instead of 25MHz).

Any thoughts?  What about other manufacturers of budget USB-based AWG/FGs?

cheers, a

« Last Edit: October 29, 2012, 06:06:34 pm by asbokid »
 

Offline torch

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #401 on: October 29, 2012, 08:13:28 pm »
Yes, both the supplied software and Mechatrommer's "Goltek" software have noise generators. The supplied software actually has two: gaussian noise and white noise. They both run continuously.  You can run either Hantek or Goltek without the DDS 3x25 physically present in a demo mode to see if that meets your needs.
 

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #402 on: October 29, 2012, 09:25:57 pm »
As far as I know the DDS-3x25 is not very flat across its spectrum, so the white noise may not be so white. The limited sample size may also limited the low frequency power unless the software can update the sample memory fast enough.
 

Offline asbokid

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #403 on: October 29, 2012, 10:17:54 pm »
Way-dee-day!   Thanks guys for your insights.  I shall give it some thought.  Dunno how pure white the noise really has to be. It's complex with a (DSL) transmission channel when it undergoes so many transformations to understand the final effect of the noise  :o

I will go and make some f****ing noise with the demo programs!

cheers, a

« Last Edit: October 29, 2012, 10:21:03 pm by asbokid »
 

Offline Mechatrommer

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #404 on: October 29, 2012, 10:40:28 pm »
goltek will not be able to create white noise for you, its only to send arb signal to dds3x25, try using tektroniks ArbExpress to create white noise. if you really serious about white noise, the 3x25 memory might not be enough for you. do you mean your white noise requirement really maxed to 20MHz?
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline torch

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #405 on: October 29, 2012, 11:31:07 pm »
The following were taken controlling the output with the Hantek supplied software then the Goltek version. Frequency set to 20Mhz, voltage output set to 3.5v.  Input set to 1x. and the DDS 3x25 connected to a modded Rigol scope with a BNC cable and 50 ohm terminator tee.  "Auto" setting used then persistence turned on to show overall effect.

Hantek software, "white noise":



Hantek software, "gaussian noise":



Goltek software, "noise":



Goltek definitely seems less random at those frequencies. Hope this helps.
 

Offline asbokid

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #406 on: October 30, 2012, 02:22:54 am »
goltek will not be able to create white noise for you, its only to send arb signal to dds3x25, try using tektroniks ArbExpress to create white noise. if you really serious about white noise, the 3x25 memory might not be enough for you. do you mean your white noise requirement really maxed to 20MHz?

Well it's for VDSL2 CPE modems which in the UK use sub-carriers up to 17.5MHz, iirc.  The ITU G.992 training period during which the background noise is tested lasts for a minimum of one second (but the test is usually repeated at least once).  So, as you point out, the DDS 3X25 Sample Memory which can hold just 4KSa isn't big enough. And however random that sample set is made to be, it will still end up being repeated many times over during that one second or more of testing.

The alternative, sfaics, is a US$5000+ piece of equipment, with 256MBytes of fast RAM.  A price that is way beyond the budget for a project that is being funded by, erm, me!   :'(

I don't understand why this equipment is so expensive.  The Application Note accompanying the Maxim series of high-speed DACs [1] describes the functional architecture of an Arbitrary Waveform Generator.  It doesn't look that expensive.  The DAC itself costs at most US$30.


Though, presumably a high-end MCU would be needed to clock in 14-bit samples at 200Ms/s or more. Over at dangerousprototypes, they started chatting about building an AWG, but the initial enthusiasm fizzled out and nothing materialised.  Is it within scope of the hoi polloi?!

cheers, a

[1] http://para.maximintegrated.com/en/search.mvp?fam=hsdacs&tree=master
« Last Edit: October 30, 2012, 02:28:42 am by asbokid »
 

Offline torch

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #407 on: October 30, 2012, 03:16:55 am »
Is it important that the noise is completely random? Noise usually covers a wide range of frequencies, right? Two thoughts:

1. utilize Goltek's sweep function to cover, say 1KHz to 25MHz with a 1ms step interval and the "noise" (or a custom) waveform.

2. write some software to feed the DDS 3x25 with a constant stream of new waveforms from the computer to get around the memory limitations.
 

Offline asbokid

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #408 on: October 30, 2012, 03:20:59 am »
heh, Torch!

Thank you very much for going to the trouble of posting these.  You've made the device all the more tempting!

cheers, a
 

Offline Mechatrommer

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #409 on: October 30, 2012, 05:47:47 am »
for random data like this it will boil down to memory size and clock speed. as far as 3x25 is concerned it has 4096 bytes memory and 200M sample/sec thats the limit when you put in your calculation. at that clock rate, you can put in some 100MHz harmonics (not random) and then add up lower freq harmonics etc and so on. if you calculate 4096 samples at 200MSps, that is a 48KHz repetition. from there you'll decide whether 3x25 can do the job or not.

as for goltek, it will "normalized" and "centered" the input data so you may get somehow sometime attenuated signal. agree with torch you may want the original hantek software to produce random data and send to 3x25 to see the difference.

tell you what, if you are sceptic about 3x25 buy, you may send us (or me?) the ArbExpress data to be produced in the 3x25, we'll (or me? whioever comes first) provide signal output capture just tell us which portion you are interested in or we may capture the portion we're interested in ;) bear in mind 3x25 only maxed to ±3.5V magnitude (mind is modded to ±10V) take that into consideration when normalizing or generating your data (i can renormalized your data to suit).
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline asbokid

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #410 on: October 31, 2012, 08:54:20 pm »
That's a very generous offer, Mechatrommer! Thank you!  You've opened up another issue.  I don't even know what sort of amplitude of noise is required.   I'm basically replicating for VDSL2 some earlier tests done on ADSL2+ CPE.    All sorts of issues to tackle yet - matching the impedance of the noise injector with the transmission line, while limiting the attenuation, removing or adding the -48v DC bias on the line, etc.

How did you mod yours for +/- 10v ?

cheers, a
« Last Edit: November 03, 2012, 11:14:32 am by asbokid »
 

Offline Mechatrommer

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #411 on: November 01, 2012, 08:04:50 am »
most of us are not expert in your VDSL area so we cant help on that and what kind of noise requirement you need, that one you need to figure out your self. we use 3x25 for different purposes from one person to the other.
Quote
How did you mod yours for +/- 10v ?
put gain amplifier at the output, i hacked the trace and put it in between, that will invalidate the warranty ;). gain opamp info is everywhere you may find so i will not elaborate and claim to be an expert... here may help... http://www.soasystem.com/eng/goltek/amplifier.htm except i embedded it into the 3x25 already so its now permanent.
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline saturationTopic starter

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #412 on: December 03, 2012, 07:20:47 pm »
Having access to an ovenized 1996 Racal Dana counter stable to .001 ppm I retested the 3x25 frequency stability and was surprised that it easily did 0.1ppm over 6 hours.  By comparison, in the same period the more reputable SFG1003 Instek generator was 1ppm until after 1 hour warm up, then they were on par.  Another plus for this el-cheapo.
« Last Edit: December 15, 2012, 05:15:31 pm by saturation »
Best Wishes,

 Saturation
 

Offline zibadun

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Review: Hantek DDS 3X25. Anyone own one?
« Reply #413 on: December 13, 2012, 07:25:57 pm »
Finally wrapped my head around using the hantek DLL from a python script. I need to generate a sweep with a step of about 25 kHz  from 1 to 30 MHz. The exact phase and frequency of each step is not important but I need the amplitude to stay as constant as possible through the entire range (into a 50ohm load). Can somebody please point to a post that I need to pay attention to implement this sweep?
 

Offline marmad

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #414 on: December 13, 2012, 07:47:17 pm »
Finally wrapped my head around using the hantek DLL from a python script. I need to generate a sweep with a step of about 25 kHz  from 1 to 30 MHz. The exact phase and frequency of each step is not important but I need the amplitude to stay as constant as possible through the entire range (into a 50ohm load). Can somebody please point to a post that I need to pay attention to implement this sweep?

I was again playing around with coding sweeps on the Hantek just the other day (after Dave's Bode plot post) and I have to say, it's difficult to get perfectly smooth ones. The problem is that there is no published or documented way to change frequencies exactly at zero crossings - so the frequency might step anywhere along the waveform (the number of possible commands in the DLL is really rather abysmal.). Somehow Hantek manages to do them smoothly from the DDS-3X25 control software (although not logarithmically), but I haven't been able to figure out how - perhaps it's time to try a USB protocol sniffer and figure out what that software is sending to the device for certain commands. I was incorrect - the Hantek doesn't do smooth sweeps either.
« Last Edit: December 18, 2012, 12:06:41 am by marmad »
 

Offline Mechatrommer

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #415 on: December 14, 2012, 02:20:07 am »
try to sniff at dll level. i made a dummy DDS3X25Dll.dll and dump anything the hantek software is sending to it. the app layer will be like App->DDS3X25Dll.dll->USB driver. YMMV. freq change at zero crossing is one thing, signal sweep "flatness" is another, that can be a challenge since ds3x25 is not flat at >5MHz. i cant find the post or file in my HDD showing the flatness respond for my ds3x25. my Goltek provides option for flatness control, by carefully tuning and profiling your ds3x25 output curve. i also have not been able to solve the zero crossing freq change (or at least changing freq without changing signal phase or voltage level, i need to study back on this when i have time. i'm counting on marmad and other brilliant members on this.

as for dave's video for bode plot, 1st it cant show phase shift 2nd is not a log scale vertically and horizontally. and 3rd it needs super flat FG. as someone posted in the thread, its a poor man "pocket" method after buying an DSO and FG at premium price.
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline marmad

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #416 on: December 14, 2012, 02:51:52 am »
i also have not been able to solve the zero crossing freq change (or at least changing freq without changing signal phase or voltage level, i need to study back on this when i have time. i'm counting on marmad and other brilliant members on this.

I think I'm done sinking hours into this device - let's face it, it's a pain in the ass to work with - and I've pretty much given up on the Hantek company. Their software is crappy; they don't release needed documentation on interfacing (as evidenced by the fact that their software can do zero crossing changes - but they've never explained how); and they won't release the source code even though they're hardly supporting their own products. And now there's the Rigol DG4062 2-channel AWG for €650 - a much greater value for the money - and I hear that it can be hacked to 160 or 200MHz  :D  It seems more economical in the long run to put the time into something that earns money towards one of the new Rigols  ;)

Quote
as for dave's video for bode plot, 1st it cant show phase shift 2nd is not a log scale vertically and horizontally. and 3rd it needs super flat FG. as someone posted in the thread, its a poor man "pocket" method after buying an DSO and FG at premium price.

But I don't think anyone was suggesting that it was anything more than a simple method for getting a simple picture when you don't have another method immediately at hand.
« Last Edit: December 14, 2012, 11:42:40 am by marmad »
 

Offline T4P

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #417 on: December 14, 2012, 05:33:32 pm »
Of course, it's good as a 150$ AWG  ;) No 150$ gen can come even close. in fact there isn't a 150$ AWG apart from hantek but hey.
Crap but it works for 150$ fantastic as a "First AWG"  :P If one is quite broke ATM
 

Offline marmad

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #418 on: December 14, 2012, 05:49:40 pm »
Of course, it's good as a 150$ AWG  ;) No 150$ gen can come even close. in fact there isn't a 150$ AWG apart from hantek but hey.
Crap but it works for 150$ fantastic as a "First AWG"  :P If one is quite broke ATM

Absolutely! No disagreement at all. It's just that I (and Mecha and others here, of course) have devoted dozens of hours of time trying to 'iron out' the annoying kinks - and add missing functionality - which keep it from being great. Speaking only for myself, I need to consider investing my time elsewhere and upgrade my AWG  ;)  But it certainly got me through some work I had to do with an AWG in the meanwhile.
 

Offline zibadun

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #419 on: December 15, 2012, 03:30:42 pm »
ds3x25 is not flat at >5MHz. i cant find the post or file in my HDD showing the flatness respond for my ds3x25. my Goltek provides option for flatness control, by carefully tuning and profiling your ds3x25 output curve.

I've tried GOLTEK generator and out of the box it generates a fairly flat sine.  Unlike the Hantek software!  Very good job!  The problem is I need to do some extra things during the sweep every N steps (i.e. retune the LO of an SDR).  Is it possible control the goltek via an API? If I can tell GOLTEK to output Freq X at amplitude Y via a DLL or something - that would solve my problem too, and save a lot of time banging the head against the wall ;)
 

Offline Mechatrommer

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #420 on: December 15, 2012, 04:46:44 pm »
Is it possible control the goltek via an API?
no, goltek is a simple app its not designed to provide pipeline for other app. you can code your own by calling ds3x25 api. make your own profile, do some back arithmetic for flat output and call the ds3x25 api. but i believe you wont get nice transition between frequencies, if you can then let us know ;) i did a "quick slap" write up on how to get the flat output... http://www.soasystem.com/eng/goltek/flat.htm i'm not sure though if you can understand the broken english. and there's the my ds3x25 output profile in bitmapped format. fwiw.
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 

Offline zibadun

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #421 on: December 15, 2012, 04:56:17 pm »
Is it possible control the goltek via an API?
no, goltek is a simple app its not designed to provide pipeline for other app. you can code your own by calling ds3x25 api. make your own profile, do some back arithmetic for flat output and call the ds3x25 api. but i believe you wont get nice transition between frequencies, if you can then let us know ;) i did a "quick slap" write up on how to get the flat output... http://www.soasystem.com/eng/goltek/flat.htm i'm not sure though if you can understand the broken english. and there's the my ds3x25 output profile in bitmapped format. fwiw.

Yep, I've read your flatness page Mech.   No problem with writing my own, all it takes it time (of which there is a slight shortage :).  Don't really care about transitions between frequencies for now.  But here is an idea for your GOLTEK - add a simple TCP server that will listen on a port and accept commands which are equivalent of key presses in the GUI and would call the same functions as the "buttons" in your generator.  This would make your software easily controllable from the "outside" programs.   Anyway now back to fighting with 3x25 API .. :)
 

Offline torch

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #422 on: December 15, 2012, 09:46:23 pm »
Of course, it's good as a 150$ AWG  ;) No 150$ gen can come even close. in fact there isn't a 150$ AWG apart from hantek but hey.
Crap but it works for 150$ fantastic as a "First AWG"  :P If one is quite broke ATM

Absolutely! No disagreement at all. It's just that I (and Mecha and others here, of course) have devoted dozens of hours of time trying to 'iron out' the annoying kinks - and add missing functionality - which keep it from being great. Speaking only for myself, I need to consider investing my time elsewhere and upgrade my AWG  ;)  But it certainly got me through some work I had to do with an AWG in the meanwhile.

As a dilettante just getting into this field, I have to thank you and Mecha for your efforts. I couldn't justify an expensive full-featured AWG, but I could afford the Hantek. In point of fact I'm still scratching the surface of what one can do with one of these but have found it to be an almost essential compliment to the oscilloscope in many cases. And the improvements you guys have achieved just add even more value. I can't understand why Hantek seems to have orphaned the DDS 3X25.

I think they dropped it just as it was at the cusp of greatness to rival the popularity of the Rigol 1052 with amateurs like me. All they really have to do is give talented people like you the source code and/or specs and they could be selling these like hotcakes.  I point to the Linksys example: They wanted to keep their corporate secrets until they were forced to release the source code (because they borrowed from Linux). Once the firmware was open, fans took over writing customizable firmware and sales of the WRT54G took off, leading to a whole family of similar routers that are still highly sought. So Linksys was selling lots of product without the cost of developing firmware. Why can't Hantek understand the benefits of that sales model is beyond me.
 

Offline marmad

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #423 on: December 15, 2012, 09:55:13 pm »
I can't understand why Hantek seems to have orphaned the DDS 3X25.
Well, as mentioned in the other thread I recently started, they are producing more of them - just putting them in a slicker-looking container - and asking a lot more money for them ($231 at AliExpress).  So they are trying to cash in on the success of the DDS-3X25 - but without any real extra effort on their part.
« Last Edit: December 15, 2012, 09:58:00 pm by marmad »
 

Offline Mechatrommer

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Re: Review: Hantek DDS 3X25. Anyone own one?
« Reply #424 on: December 16, 2012, 02:37:42 am »
without any real extra effort on their part, without any real effort to OSHW it, nothing. i guess their business model (most low end brand chinese i guess) is... they build a product that caught their eye, produce and distribute it and dissapear, and then go to the next product that caught their eye and do again, hell with customers let them figure out themselves. the poorest model i can imagine as far as professionalism is concerned. what keep them going is that, nobody can beat their price and probably sales of only few percent from what they produced already give them some profit for their next project, thats their "magic". if you ebay, there still some d3x25 unit available. so you see, they dont really give a damn about these unsold products, they already on the "next phase" of their development.
Nature: Evolution and the Illusion of Randomness (Stephen L. Talbott): Its now indisputable that... organisms “expertise” contextualizes its genome, and its nonsense to say that these powers are under the control of the genome being contextualized - Barbara McClintock
 


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