Author Topic: Hantek - Tekway - DSO hack - get 200MHz bw for free  (Read 1657706 times)

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Offline tinhead

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #550 on: May 11, 2011, 10:26:59 am »
yep, the current fw version have some bugs. Hantek got a long list with bug description and "promised" to fix it within 2 weeks :)
The current version (well, the last whcih was av. on Hantek website) is crashing only once a day instead of few per day,
but still not sufficient. Some measuring ugly bugs are fixed, but others not.

In pirnciple evey version since 2.6.0 have some bugs, the best is still 2.5.x which was developed by Tekway before they got bought by Hantek and (probably) before the developer got replaced - bit less functions but very stable. However, 2.5.x have hard coded english and chinese, 2.6.x not (languages module based) - that's alreay one of the error sources, additionaly the new menu functions are not clean implemented, seems that the return path is lost sometimes producing of course crash.
FPGA/CPLD and Linux are still working, just the GUI crashing, so "only" some part need to be fixed.



I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 

Offline colinbeeforth

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #551 on: May 13, 2011, 06:02:40 am »
Interesting, I've been checking what sample rate is in operation at different timebase settings and found some oddness with my Hantek DSO5102B 100MHz DSO.

In all the DSOs I've ever seen, the rules are straightforward, if not exactly simple.  Since the amount of acquisition memory is the limiting factor at low timebase settings and the maximum sample rate is the main limiting factor at high timebase settings, the links between these things is as follows:

Number of sample points = time/div x number of divisions (16 in Hantek/Tekway) / time between sample points (or 1/sample rate)

So what normally happens is at low timebase settings, the acquisition memory is filled full or near enough (as the maths don't always work out to exactly fill the available memory).  As you increase each step in timebase setting, the digitiser gets one step faster and the acquisition memory is filled again or near enough.  Eventually, you reach a timbase setting where the sample rate is it its maximum.  The next timebase setting upwards will cause the acquisition memory to not be filled as much, because the sample rate must remain the same, but you will acquire sample over a shorter amount of time.  Eventually, you have to stop at the highest timebase setting when the total amount of memory sampled isn't too low to show across the screen.  For example on a 16 division screen, showing only 16 points would not be very useful, so you have to decide what upper setting to use as a maximum.

What I have found with my Hantek, in single channel 4k memory mode, is this rule is followed at various timebase settings until it reaches 2 uS, when the sample rate is 100MS/S, and the total memory acquired in each 'sweep' is 3200 points.  See what I mean, (2 uS x 16)/10 nS = 3200 (at 100MS/S, the time between points is 10nS)  It doesn't always work out to give 4000.  This is quite normal in all DSOs and just their basic internal mechanics at work.

On my Hantek DSO5102B, at every timebase setting up to and including 2uS, the sample rate is a 1, 2.5 , 5 sequence, like 1MS/S, 2.5MS/s, 5MS/S.

At timebase setting of 800nS, the sample rate switches to 200MS/s, and breaks the pattern of the 23 timebase settings below.
At timebase setting of 400nS, the sample rate switches to 400MS/S.
At timebase setting of 200nS, the sample rate switches to 800MS/S.

From 200nS.div up to 8nS/div, the sample rate stays stuck at 800MS/S.
Finally, at the top timebase setting of 4uS per div, (100MHz model limit) the sample rate jumps to 1GS/S.

Now, this is where it is quite odd and hard to understand.  At 800nS/div, it should be using 250MS/S and at 400nS/div it should be 500MS/S, then for all settings above 200nS it should be 1GS/S.

Strangely for a DSO specced at 1GS/S, you only actually get it at one timebase setting, with many more high speed timebase settings being 800MS/S.

When I first saw a Tekway  scope, I only saw the max sample rate of 800MS/S, so I suspected the manufacturer of cheating on their spec sheet.  I obviously missed trying it at the top 4nS timebase setting.  However, this was a lot of the reason why I didn't buy one six months ago when I saw a demo.  I thought if they would fudge the spec, they would not be trustworthy in other ways.

Now I am beginning to understand, with the help of tinhead's reports on the background of the development group, what has been happening.  It looks to me like they may have lots of software and maybe electronics engineering talent, but somehow have missed to have anyone with strong experience using scopes and test equipment, or with experience of how many other makers work their hardware.  By being different, it upsets customer's expectations.  I used to sell LeCroy DSO against HP and Tek, so I know how many difficult questions customers ask.  They don't just shrug and buy for cheapest price, they really want to know how they work, so they can make a good comparison between different offerings on the market.  Mind you, I am talking about technical and engineer customers.

While I understand that my experience probably isn't the average DSO buyer, and the Hantek will still seem ok to a non-critical or inexperienced user, there are many many experienced technicians and engineers, who will find this scope a bit weird.

I have some guesses as to why the timebase shifts like it does, but without any real information, they remain guesses.  I don't see why the time base gets stuck at 800MS/S.  It should go straight to 1GS/S only limited by the amount of acquisition memory selected.

I'm sure all these modern cheaper DSOs have limitations with memory at fast digitising speed.  4K shows up because it is likely the maximum of fast RAM available in the FPGA chip.  We are talking about very fast data, 1GS/S means an 8 bit data word every 1 nanosecond.  Light travels 30cm in that time, no RAM in the world can cope with 1 nanosecond write times!  All sorts of engineering cleverness is needed to get this to work.  But this means memory size limits, you can't use big cheap DRAM, it's not fast enough at all.  My LeCroy will acquire 50k per channel at fastest time base setting.  It took a lot of demultiplexing to achieve that with static RAM.  At 1GS/S, eight ADCs will deliver an 8 bit word every 8 nanoseconds each.  Even 8 nanoseconds is faster than the fastest silicon SRAM I've seen and far faster than cheaper DRAM.  This little scope is going like blazes to do what it does, so that is very impressive, but no doubt needs tricks to get it to work, and those tricks means some limitations.  Limitations that we have to live with.  I far prefer it when a manufacturers are open and honest about their products' limitations, you feel like you can trust them for taking you into their confidence.

I have sent all this information to Hantek and had helpful replies for them, they know there are some difficulties but seem keen to sort them out.  So I agree with tinhead, they are trying, and maybe a little patience will get us a better result.  It does show you how difficult the world market is though for Chinese manufacturers.  By comparision, Agilent would never send a scope out the door without being totally sure it was up to the standard of an experienced engineer -  But they charge 5 or 10 times as much and Hantek/Tekway is far cheaper.  It reminds me of the old engineer's saying, you can have good, fast, and cheap, pick any two!

Many people underestimate how logn good software takes, but What amazes me is this:  I recently looked at Geoff Graham's website:  http://geoffg.net/  He has done a brilliant job of creating a neat small computer for many different jobs, it was in Silicon Chip recently.  He devised a complete Basic command line interpreter in 8 days!!!  There was about 3 weeks of study behind that plus a lifetime of software experience, but it does make you think.  Software seems to be hard to me, but to some people, it isn't so difficult.  Trying to get the complex programmable hardware in the Hantek DSO to work effectively would be more tricky I'm sure, but you've got a 400MHz ARM processor to help do it with, that is a serious resource.  My LeCroy runs rings around the Hantek with a 20MHz 68020 for maths capability - granted it gets some hardware help for some tasks, but it's 20 times slower, both are 32 bit, and ARM has inbuilt support for LCD displays if I remember correctly.  It should be capable of getting near to LeCroy's signal processing capability!  My Hantek crashes twice a day, my LeCroy maybe once per year, I can't actually remember the last time it crashed.

Maybe Hantek should offer a basic system software and sell an optional maths processing addition, like LeCroy used to sell their scopes.  That would pay for the extra development costs.  Then again, I like the idea of them offering an SDK, there are enough open source smart engineers out there who will happily create a magnificent operating system, and it won't cost Hantek anything.  Building a user community around a product will create it's own success.  It would be first choice over all the other competing Chinese products then.  I can hope.
 

Offline rf-loop

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #552 on: May 13, 2011, 06:38:20 am »
Quote
From 200nS.div up to 8nS/div, the sample rate stays stuck at 800MS/S.
Finally, at the top timebase setting of 4uS per div, (100MHz model limit) the sample rate jumps to 1GS/S.

AFAIK to 20ns/div it use 100MHz clock.
8, 4 (and2) ns/div it use 125MHz clock for ADC's

I have measured it directly from  ADC's clock lines. (FPGA produce these 8 (4) interleaved clock signals with PLL from 100MHz base time base.)

so, not only 4ns/div.
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
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Offline tinhead

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #553 on: May 13, 2011, 10:58:29 am »

Number of sample points = time/div x number of divisions (16 in Hantek/Tekway) / time between sample points (or 1/sample rate)...
What I have found with my Hantek, in single channel 4k memory mode, is this rule is followed at various timebase settings until it reaches 2 uS,
when the sample rate is 100MS/S, and the total memory acquired in each 'sweep' is 3200 points. 
See what I mean, (2 uS x 16)/10 nS = 3200 (at 100MS/S, the time between points is 10nS)  It doesn't always work out to give 4000. 
This is quite normal in all DSOs and just their basic internal mechanics at work.


if you count like that, you should count what behind the menu, the scope is always using this area, menu is only overlay displayed (click F0 to hide it).




I'm sure all these modern cheaper DSOs have limitations with memory at fast digitising speed.  4K shows up because it is likely the maximum of fast RAM available in the FPGA chip.  We are talking about very fast data, 1GS/S means an 8 bit data word every 1 nanosecond.  Light travels 30cm in that time, no RAM in the world can cope with 1 nanosecond write times!  All sorts of engineering cleverness is needed to get this to work.  But this means memory size limits, you can't use big cheap DRAM, it's not fast enough at all. 


Generally spoken this didn't matter because of ADC hold function, the waveform per seconds time (up to 2500 wfrm/s) is describing how fast the data will get collected and processed,
the dead time between can be used for whatever (haven't analyzed how this actuall design works) - the DSO can continuously sample until 4k are full or it can sample/hold every 1ns
The FPGA can handle both, that's only 8 x 8bit data, refreshed every 125MHz on each ADC where the FPGA can sample i/o with 250MHz.


I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 

Offline carloscuev

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #554 on: May 13, 2011, 12:37:04 pm »
Hello everyone, I've made the recommended PSU update from tinhead (thanks a lot again for your dedication), well half of it because I didn't had all components in hand and didn't got component needs to spend 40 bucks at mouser to get free shipping (In my country $40.00 USD is the minimum for free shipping)

I didn't had electrolytic caps, so no upgrade there.
The DC-DC Converter capacitors I used are tantalum Low-ESR TPSA106K010R1800
Yes, I know 10uF is not the recommended 47uF, but I think it's enough if the converter is not going to be used at full 3A rated current.
I think I've made a really nice dead-bug soldered module ;)



Module's trimmer is fine tuned to get 3.300v (if my meter is well calibrated, which I think so)
Unfortunately I didn't took screenshots of the same signal before and after the mod (after the mod I executed a self-calibration)
Maybe it's my imagination, but I really see the waveforms (of the current project I'm working on) with less noise and they look better!

Happy hacks everyone !!
 

Offline tinhead

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #555 on: May 13, 2011, 12:40:49 pm »
Some ppl asked how the DSOs will get manufacturer calibrated, so i decided to look inside the fw.

What i found is nice feature allowing to extend the analog bw. As already said before these DSOs are using variable gain amplifier in
the input stage in combination with digital filter to cut the bw. Each model is having then two kind of settings within the firmware,
the vag opamp settings and digital filter max corner frequency. We can't (easily) manipulate vag settings, but we can use
something what will be afaik used for test and calibration to change the max bw.

How it works:
simply create a file "tst" in root directory of the DSO OS (/tst), edit this file like following

[filter] x

where x is the digital filter max corner frequency (it will be normally read from model, where for example DST1102B
is setting the x to 10 (x10) = 100MHz. This "tst" file is overwritting (temporairy in the memory, so no change to firmware)
the model based settings, so you can use higher values. Of course the VAG opamp will not allow to have flat frequency
response but you will be able to do e.g. FFT or avg. sampling up to 450MHz.

Everything above 450MHz didn't really matter, the overclocked ADCs can not handle much more.
With such setting ( [filter] 45 ) in the tst file my DSO is allowing to capture 400MHz singnals (with -15db attenuation )
and 300MHz signals (with -9db attenuation).

The best rise time with such mod is about 1.05ns (pulse generator), giving 333MHz bw which seems to be
good but in principle we have still -3db on 220MHz, -6db on 250MHz, -9db 300MHz, -15db 400MHz and falling (instead of digital
filter and vag based brick wall on 300MHz). I did used it for example to control 433MHz carrier signal,
which worked beautiful.

So it is not a true bw hack, but at least something. If you don't have another high bw scope and wish to measure/control
higher freq. this solution is good enough. The hadrware freq. counter (in the bottom status line) is anyway working
stable up to 410MHz.

Btw, the /tst file will be used after reboot - so create it and reboot to enable it. Other values works too, for example
if you wish to cut the bw for some reason. Afaik there are other interessting options like disabling of single
ADCs (might be usefull for those who have no warranty ...) or skew time calibration, more later.
« Last Edit: May 13, 2011, 01:00:18 pm by tinhead »
I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 

Offline Mechatrommer

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #556 on: May 13, 2011, 02:25:29 pm »
What i found is nice feature allowing to extend the analog bw. As already said before these DSOs are using variable gain amplifier in
the input stage in combination with digital filter to cut the bw...

where x is the digital filter max corner frequency (it will be normally read from model, where for example DST1102B
is setting the x to 10 (x10) = 100MHz. This "tst" file is overwritting (temporairy in the memory, so no change to firmware)
the model based settings, so you can use higher values. Of course the VAG opamp will not allow to have flat frequency
response but you will be able to do e.g. FFT or avg. sampling up to 450MHz.

Everything above 450MHz didn't really matter, the overclocked ADCs can not handle much more.
With such setting ( [filter] 45 ) in the tst file my DSO is allowing to capture 400MHz singnals (with -15db attenuation )
and 300MHz signals (with -9db attenuation).

The best rise time with such mod is about 1.05ns (pulse generator), giving 333MHz bw which seems to be
good but in principle we have still -3db on 220MHz, -6db on 250MHz, -9db 300MHz, -15db 400MHz and falling (instead of digital
filter and vag based brick wall on 300MHz). I did used it for example to control 433MHz carrier signal,
which worked beautiful....
let me repeat this post. this is interesting stuff and have been in my dream. so tinhead, is that means if the x setting is default to x10, then 400++MHz signal will not be able to be detected? ie low amplifier gain? badly attenuated by firm/software?
« Last Edit: May 13, 2011, 02:28:54 pm by Mechatrommer »
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline tinhead

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #557 on: May 13, 2011, 03:55:33 pm »
let me repeat this post. this is interesting stuff and have been in my dream. so tinhead, is that means if the x setting is default to x10, then 400++MHz signal will not be able to be detected? ie low amplifier gain? badly attenuated by firm/software?


100Mhz DSO don't have to detect 400Mhz signals :) Sure, depends on scope and design you might see higher freq. signals,
for Hantek/Tekway 200MHz model the signal disapear from display by about 310Mhz, and actually you can't really trust
in what you see for signals above 250Mhz.

So for the "/tst" file:
x is equal to model bw/10, so for 60MHz models 06, for 100MHz models 10, for 150MHz models 15 and finally for 200MHz models 20.

The firmware is doing exact the same calculations (however tst file is overriding them). These settings are for digital filter (implemented in FPGA),
and such filter will be used by Rigol/Hantek/Tekway/Instek (together with VAG opamp) to realize the brick wall filter to reduce bw.

So in principle, during hack from 100 to 200Mhz the model name changes and as the filter is model name based it will be then set to a
specific corner freq. Unfortunately the VAG opamp settings are not easy to change (except bin patching), so to have flat freq. response
we can maximal set that what the firmware know as highest model (200Mhz for Hantek/Tekway, or 150MHz for Rigol/Instek).
No idea is there is a way for something similar like the /tst file on Hantek for Rigol/Instek scpes, they probably have to be bin patched.

On Hantek/Tekway we have Linux, and the manufacturer luckily implemented easy way to override the filter settings by the /tst file.
Maybe is not something for every day use, but i think it is nice to have. Sure it does work only for 4k short memory,
and for best waveform view avg. mode should be enabled (however 400Mhz signal doesn't looks worse than 200Mhz, only attenuated of course)
and yes it does only work for single chanel (as we need to sample 1GSs to capture 400Mhz) but for those who don't have sampling
scopes or fast analog scopes it might be useful. Even the auto settings works for 400Mhz signals. Sure, measurments results need
to be recalculated, but that's not a big deal (knowing the attenuation values for 250, 300 and 400Mhz).

For a full "300 or 400MHz hack" the VAG opamp part of the firmware should to be changed, therefore i will not call it "hack",
it is just a feature.
I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 

Offline Mechatrommer

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #558 on: May 13, 2011, 04:29:37 pm »
100Mhz DSO don't have to detect 400Mhz signals :)
you are right. but 1Gs/s should be able to detect 400MHz according to Nyquist.

For a full "300 or 400MHz hack" the VAG opamp part of the firmware should to be changed, therefore i will not call it "hack",
it is just a feature.
for me , it is a hack... that not everybody can do. last question pls. by enabling 400MHz "feature" (ie disabling brick wall filter), will the lower frequency <=200MHz distorted, affected, contaminated? (or whatever you want to call it). edit: ok i just read about the why "dso bw limit", is to avoid noise, but how about flatness, is it affected?

if the answer is no, then i think this is the most stupidiest effort that the manufacturer did. even if the answer is yes, then they still the same by not giving access to user to enable/disable it. my 2cnts.
« Last Edit: May 13, 2011, 04:35:14 pm by Mechatrommer »
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline tinhead

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #559 on: May 13, 2011, 05:25:56 pm »
100Mhz DSO don't have to detect 400Mhz signals :)
you are right. but 1Gs/s should be able to detect 400MHz according to Nyquist.

sure, 1GSs scope can do it, even more than this (however the waveform reconstruction will be not the best)
but 100MHz don't have to do it.

for me , it is a hack... that not everybody can do. last question pls. by enabling 400MHz "feature" (ie disabling brick wall filter), will the lower frequency <=200MHz distorted, affected, contaminated? (or whatever you want to call it). edit: ok i just read about the why "dso bw limit", is to avoid noise, but how about flatness, is it affected?

if the answer is no, then i think this is the most stupidiest effort that the manufacturer did. even if the answer is yes, then they still the same by not giving access to user to enable/disable it. my 2cnts.


well, a blue led instead of red is also hack, so you right.

It can be done by everybody who did hacked via UART, because all you need is to connect to the DSO, killall dso.exe,
create the tst file in root dir with [filter] 45, save it and restart dso application by /dso.exe.
You should then see status message "get corner freq ID =45 from filetst ok"
If this works, you can reboot DSO and enjoy the additional (attenuated) bandwidth.

Sure, there is some additional disortion coming from the higher freq., it have to be there anyway,
therefore the avg. mode or equi. sampling should be used for such measurments.

If you don't have necessary equipment to measure for example 400MHz signal this solution will help you,
it is maybe not a every day situation anyway.

The manufacturer have impelmented user selectable digital filter, but the max freq. is on Hantek/Tekway 247Mhz
and it is an additional filter and not the real bw filter. With the custom SDK, which i hope will
be released soon by the forum user "censored for now" everybody would have a chance to implement
for example a simple shell script to enable/disable the /tst file.

As i have my DSO on the network a quick remote execute is good enough for me for now.
I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 

Offline Mechatrommer

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #560 on: May 13, 2011, 05:38:35 pm »
If you don't have necessary equipment to measure for example 400MHz signal this solution will help you,
yes sure, very sure! it will help alot! -15db is better than nothing. and as you have indicated in earlier post, it did help you.

it is maybe not a every day situation anyway.
yes sure it will not be everyday. but could be a saviour on one particular project in a month.
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline saturation

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #561 on: May 13, 2011, 07:08:53 pm »
A great discussion!  @colinbeeforth: your posts do get people thinking a lot.
Best Wishes,

 Saturation
 

Offline Mechatrommer

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #562 on: May 15, 2011, 12:51:39 pm »
if the answer is no, then i think this is the most stupidiest effort that the manufacturer did. even if the answer is yes, then they still the same by not giving access to user to enable/disable it. my 2cnts.
i'm sorry. there was a misunderstanding. i was in emotional state that i thought my dso is the same as the discussed hantek. it turned out they are different. but my previous points still stand.

edit: tried to find hantek dso user manual in google but unsuccessful. instead i found this thread is mentioned in hackaday (i did search if its mentioned here, but no) http://hackaday.com/2010/11/24/double-the-hertz-double-the-pleasure/ i havent read all the lengthty replies there.
« Last Edit: May 15, 2011, 01:50:16 pm by Mechatrommer »
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline tinhead

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #563 on: May 15, 2011, 02:32:11 pm »
if the answer is no, then i think this is the most stupidiest effort that the manufacturer did. even if the answer is yes, then they still the same by not giving access to user to enable/disable it. my 2cnts.
i'm sorry. there was a misunderstanding. i was in emotional state that i thought my dso is the same as the discussed hantek. it turned out they are different. but my previous points still stand.

edit: tried to find hantek dso user manual in google but unsuccessful. instead i found this thread is mentioned in hackaday (i did search if its mentioned here, but no) http://hackaday.com/2010/11/24/double-the-hertz-double-the-pleasure/ i havent read all the lengthty replies there.


different ? now i'm lost :)

Hantek user manual is here
http://www.hantek.com.cn/Manual/DSO5000Series/DST%20B%20Series%20Digital%20Storage%20Oscilloscope%20User%20Manual(Ver0.9).pdf

Tekway user manual
http://www.tekwayins.net/pic/DST%20B%20Series%20DSO%20User%20Manual(Ver0.9).pdf

both have exact the same erros, like wfrm/s (2000 but in real 2500, mentioned in product prospects, review and on the website)
and are of course not updated since 2yrs ... which of course sucks, on the other side why they should update manual if the firmware is chaning weekly.
I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 

Offline Mechatrommer

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #564 on: May 15, 2011, 02:43:38 pm »
different ? now i'm lost :)
coz mine is rigol :P i thought they come from the same root. i should have check the feature earlier. thanx i got the manual already. i was searching dst1102b keyword earlier.
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline tinhead

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #565 on: May 15, 2011, 02:49:30 pm »
different ? now i'm lost :)
coz mine is rigol :P i thought they come from the same root.

ahh, ok. In principle the digital filter and vag opamp are used in exact same way on Rigol, the stupid thing is that
it is hard to change anything there due the DSP bios (instead of Linux like on HanTekway).
I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 

Offline drieg

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #566 on: May 15, 2011, 08:07:08 pm »
"Take it apart!"  ;)

Tekway DST1062B, PCB Ver1.00.5 2010/11/30...
« Last Edit: May 15, 2011, 08:09:32 pm by drieg »
Bricked Rigol? This thread might be of any help.
 

Offline flolic

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #567 on: May 15, 2011, 08:23:48 pm »
Drieg, a little explanation?
You removed BGA package, why?  ;D
 

Offline drieg

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #568 on: May 15, 2011, 08:44:45 pm »
...because I like to know how things work and it's easier like this unless you have x-ray eyes ;D
Bricked Rigol? This thread might be of any help.
 

Offline Mechatrommer

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #569 on: May 15, 2011, 08:55:56 pm »
You removed BGA package, why?  ;D
look at the avatar.
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline flolic

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #570 on: May 15, 2011, 09:13:36 pm »
look at the avatar.

Mecha, I know Drieg is our scope doctor  ;)
But I expected more specific answer from him, like "I removed that chip because...."  :)
 

Offline tinhead

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #571 on: May 15, 2011, 10:52:07 pm »
Everything above 450MHz didn't really matter, the overclocked ADCs can not handle much more.
With such setting ( [filter] 45 ) in the tst file my DSO is allowing to capture 400MHz singnals (with -15db attenuation )
and 300MHz signals (with -9db attenuation).

The best rise time with such mod is about 1.05ns (pulse generator), giving 333MHz bw which seems to be
good but in principle we have still -3db on 220MHz, -6db on 250MHz, -9db 300MHz, -15db 400MHz and falling (instead of digital
filter and vag based brick wall on 300MHz).

The "tst" file hack:

i did measured it again, this time with active x10 500MHz probe terminated on 50Ohm instead of direct connection from
signal gen to dso (of course terminated) as in the results above.

As the probe is x10 the DSO internal compensation will be not used, giving a bit better response (filter = 45),

100MHz = 0db
150MHz = 0db
200MHz = 0db
250MHz = -3db
300MHz = -6db
350MHz = -9db
400MHz = -12db

which is really nice (easy to calculate measured vs. real values). I did measured with sinus and square waves, there is about ±0.5db
between both which is fair enough.

The scope internal compensation didn't really work proper above 250Mhz giving fancy results, so it make no sense to
use x1 probes with this hack (above 200mv/div) which i think is good enough for 99.99% applications.
I think the compensation circuit could be adapted to work properly, but honestly i don't see any reason to do this.

So in principle, with proper probes, it is a 250MHz bw hack. For me, as already mentioned was not the extra 50MHz
important but the chance to measure 400MHz signals.


"Take it apart!"  ;)

Tekway DST1062B, PCB Ver1.00.5 2010/11/30...

heh, great, thanks for this picture.
I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 

Offline colinbeeforth

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #572 on: May 16, 2011, 08:22:16 am »

Hi tinhead, and all,

Quote
if you count like that, you should count what behind the menu, the scope is always using this area, menu is only overlay displayed (click F0 to hide it).

Ah, thank you!  I had not noticed this.  When you remove the menu display, the trigger point on the screen moves, and I had assumed that it was simply scaling the 16 divisions to fit across the larger screen.  I am totally amazed, now it has 19.5 divisions!  What a strange number, although I can see why, they stick with 40 pixels wide per division.  Whoever devised this system originally must have been taking LSD - 19.5 divisions is so weird. *laughs*  Why supply expensive hardware and acquire waveform in memory, and then cover some of it up most of the time?  I use menus all the time, and so will most users.  I hardly ever switch them off, so the extra 3.5 divisions is a waste of design effort and complexity for no gain.

This gets back to a fundamental aspect of design philosophy.  Call is Colin's law of DSOs if you like!!! *laughs*   However, it is a common principle in many fields, particularly aerospace.  All instruments and DSOs should work so that if the customer is inexperienced, and reacts by doing nothing, he/she will get the best result anyway.  How this would work with the Hantek/Tekway scope would be to remove the 'menu off' F0 button, and leave menus always on.  The software would be simpler, as there is no exception mode.  Show the whole acquired waveform on the available space at all times.  That way, you never have to know anything about the DSO to get it to work at its best.  Why even have a non-menu-shown expanded mode?  It doesn't really contribute much, apart from 2 cm of extra screen space.  Simpler all round and no animals would be harmed!! ;D

This is one thing that intrigues me about the Hantek/Tekway design; 16 divisions (in menu mode), the 2, 4, 8 sequence of timebase settings, all look like it was designed by a programmer used to binary and software, not by a scope engineer.  Partly, I like the fact that it breaks old concepts and shows a willingness to try new things, but also, there are quite a few aspects of this scope that are odd or don't work very well.  It makes me think that the designer didn't have a lot of experience with other DSOs, so wasn't sure of the best way to do many things.  *shrugs* Like you said, we will probably never know.

Quote
Generally spoken this didn't matter because of ADC hold function, the waveform per seconds time (up to 2500 wfrm/s) is describing how fast the data will get collected and processed, the dead time between can be used for whatever (haven't analyzed how this actuall design works) - the DSO can continuously sample until 4k are full or it can sample/hold every 1ns The FPGA can handle both, that's only 8 x 8bit data, refreshed every 125MHz on each ADC where the FPGA can sample i/o with 250MHz.

Not sure what you are trying to say here?  The waveform update rate isn't very important to digital scopes, despite the fact that some mainstream DSO makers try to get you to think it is the only number that matters - it is in their interest to promote their banner spec and get you to ignore so many important things that affect the usefulness of a DSO.  They appeal to our natural desire for simplicity, but it is always a mistake to accept at face value what a salesman is telling you!!  I know, I was one!!  I try very hard to get people to think about DSO operation and specs.  There are many factors, DSOs are not simple!  They cannot be, and they are not an equivalent of an analogue scope.  I think they should be called something else, because they do not work like an analogue scope, but I also realise that this is hoping for too much, the name DSO - we are stuck with it now.   A buyer must know quite a lot to be able to make an informed choice.  This is even more important now since low cost models are becoming available with many built in compromises.  Before, you could trust the big makers to not screw it up too badly, although there were big name DSOs that really weren't very good during the early days of DSOs.  Any DSO will work for a school teacher to show a sine wave.  But to use it, even in hobby deign or repair work, it won't do the important things you really badly need.  Why spend money on a DSO when a cheap analogue scope will do as well and be much easier to use??!!

As another thought about update rate... what is the response time of the LCD display, and how fast are its pixels updated?  I don't have a model number or spec on the display LCD used int he Hantek/Tekway DSOs.  If it is typically around 5mS pixel response time, the fastest update rate that can be seen is limited by the LCD response rate.  1/5mS =2000 changes black to white per second = 1000 hertz of a waveform.  So, the fastest that any pixel can turn on and off, is 1000 times per second.  It makes the very high waveform update rates that Tek and HP have been quoting pretty pointless I think.

I'm not saying update rate is unimportant, just that there are other factors, and some of them are more important.  Update rate does become irrelevant, if the DSO triggers on the feature you want to see.  The real banner spec that differentiates digital scopes from analogue is storage and single shot use.  Update rate is irrelevant to single shot use.  If update rate matters so much to a DSO user, they'll get much better results from an analogue scope.  It only becomes an issue if you have no analogue scope and are stuck with a digital scope as your only tool.  That's another reason why it would be more rational to call digital scopes something else, then inexperienced users wouldn't be fooled into thinking that a DSO is a replacement for an analogue scope.

The Hantek/Tekway screen is 800 x 480, which is enough to be useful, at a reasonable cost.  More vertical resolution would have given the designer more flexibility/  A vertical acquisition is 8 bits, so there are 256 steps, and that can be fitted into the 480 vertical with one_pixel = one_step plus borders etc, quite nicely.  Scopes with vertical resolution less than 256 pixels have a difficult job showing a smooth waveform like a sine wave nicely without showing jaggies.  This does bring up another issue, screen alias.  The actual DSO sample rate while very important for some things isn't relevant for this discussion, if you decimate acquired_memory to fit into a limited number of horizontal pixels, that is a form of sampling also, so alias can occur at the pixel level of the screen, unless some tricks are used like memory_to_display_compression_algorithms.  So alias can happen even just showing things on a screen - it's sampling after all!  That's another reason for my opinion that the Hantek/Tekway screen of 800 horizontal pixels is a reasonable decision.  My LeCroy is 810 lines, with vertical raster scanning!! Yes, it's quite unusual, but it achieves 810 x 696 on a common CRT using cheap raster scan and cheap TV monitor components.  The earlier models used full vector display with no raster scan at all, and gave superb displays, but at an impractical cost.  Having seen and used the earlier LeCroy 94XX series, the 93XX was a reasonable compromise, but it was clearly a compromise, the 94XX screens were beautiful to see and being true vector, made lovely waveforms.  It took a large board chock full of expensive ICs to do it though.  Raster scan wasn't as nice, but it was adequate, so long as the resolution was high enough.  Likewise, I reckon the Hantek/Tekway at 800 x 480 is a reasonable compromise and the addition of colour does help with contrast and waveform identification.  With the earlier LeCroys, the eye saving orange phosphor was ok to use long term, but the lack of colour to identify waveforms could occasionally be a nuisance.  Being able to split the screen vertically into 2 or 4 separate graticules was a big help and largely avoided the need for colour.  Hantek/Tekway are perhaps limited there, since they have fewer vertical pixels, although I would have thought the LeCroy way of doing 2 sets of graticules on one screen would be acceptable on the Hantek/Tekway display.  Again, it's like the original designer of the Hantek/Tekway system didn't know much about what other scope makers had found effective in the past.

On a related subject:  I have an older HP54601A, it was given to me by a very kind colleague, although it had a few faults at the time.  I fixed the faults although that took time and special effort to get an IC that was obsolete, so it shows how even big manufacturers get hit by obsolete chips.  Seems to me that many pieces of equipment are having longer lives than the chip makers would have guessed, as many ICs are made obsolete well before the equipment is gone.

I use the HP DSO it for certain jobs.  It was a major step in the early development of DSOs, when HP were able to produce a low price point DSO that sold heaps of them to schools.  It had a really big green CRT screen, and that is why I use it, my eyes are getting older and big screens with good contrast help.  It has only a very short acquisition memory, so it is quite limited for many jobs.  I use my LeCroy 9310 for any serious work though, and using the HP for simpler jobs and that saves the LeCroy.  The LeCroy is a much larger box and eats up my bench space quickly.  Also, if the LeCroy has a failure, I won't be able to afford a LeCroy replacement or even to fix my 9310 - parts are becoming very expensive for them now, and parts obsolescence is a big problem.  Anyway, this explains why I have some experience with other DSOs.  Also, I had to do serious spec comparison in DSO sales situations, I also have experience with using different DSO designer's concepts.  I don't have any experience with using the most recent models of DSO from the bigger makers, but from some long discussions on this forum with other users I am led to believe that the newer range of HP/Agilent scopes are attractive.  I've also used Tek over the years, and have respect for their fast analogue designs, but I'm afraid I don't like their lunchbox DSO designs.  Even the expensive models (over $3k Australian) don't have any sort of acquisition_memory_to_display_compression_algorithm.  I have an email from Tek support in the USA confirming this, I didn't just dream it.  In other words, if you acquire more than about 320 data points, it must be compressed somehow to get it onto a small number of horizontal pixels of an LCD display.  Most of the earlier LCD displays are 320 wide by 240 (234) high.  So how do Tek get the larger memory to display on the limited number of LCD pixels?  They decimate the available memory data and only show a small percentage of the data on the screen.  For example, if they had (imaginary numbers) 3200 data points, they could show 320, so only 1 in every 10 points is actually displayed.  If there was a glitch, 3 data points wide, and it fell into the 9 out of 10 that didn't get shown, you won't see it on the display.  When I asked the Tek sales-guy in Australia about this, he almost shouted the mantra "but the data isn't lost, it's in the memory and you can see it any time by using waveform zoom".  Now, that is quite true, but why would I go through the often tedious process of winding the zoom pot many turns to perhaps see something that <might> be there, but I saw no evidence of in the first immediate view?  In reality, you will get sick of doing this <for every single acquisition you make>!!  In practice, decimating acquired_memory to fit it onto a small low resolution display is not a good idea.  It is easy on your hardware, so convincing your customer to accept it, saves you cost on hardware so you make more profit.  I prefer engineering the equipment not the customer...  The problem becomes far worse the bigger the acquired memory becomes, yet long memory is incredibly useful for tracing data on serial lines like USB, RS232, I2C...  LeCroy 94XX and 93XX series have always used a proper acquired_memory_to_display_compression_algorithm, which I suspect is why some makers have made such a <big thing> of waveform update rate.  LeCroy take a complete data acquisition run, then break the memory into bins, if the display is say 600 horizontal pixels there are 300 bins.  In each bin they sort out the highest voltage and lowest voltage, and display them on two pixels.  That way, if any amplitude deviation, even one memory bit wide is a high or low flyer, you will see it on the screen.  It won't be a fully accurate representation on the low res screen, but you will see something that will grab your interest, and then you can zoom to see exactly what it it.  That's why the "waveform update rate" is lower on older LeCroy DSOs, because they are taking the time to show you everything you need to know.  That's why I have never owned a Tek DSO.  I can't stand the thought of a glitch being there in the memory and not seeing it immediately, the concept frustrates me just thinking about it, you actually captured the event you want, but can't see it...

I have it confirmed from Rigol, that they decimate their data for display the say way Tek do.  When did a designer ever get sacked for copying Tek?  I still don't think it is a best_practice concept though.  I have it confirmed from GWInstek that they have an acquisition_memory_to_display_compression_algorithm in at least the GDS1000A series DSOs and perhaps other models.  I have seen a demonstration of a Tekway DSO that proves there is some sort of compression algorithm being used - although I have no idea how it works, but it does show very small features in a long memory acquisition on a much reduced number of horizontal display pixels.  I'd love to know how such a system works.

OK, so maybe that is enough for now.  Like I said, the true usability of DSOs is not simple, so the Chinese makers are doing the users a dis-service by not explaining in more detail how their scopes work.  I can understand why they would be concerned about telling their competitors what they are doing, but if they don't tell their customers how good they are, maybe the customers will go elsewhere also.  It all comes down to users becoming better informed and choosing wisely.  For many end users, I can understand why this won't happen, since their applications are undemanding and they don't care to understand a lot of complex details.  At least one well know manufacturer has made a fortune selling scopes that in my personal opinion aren't very clever at all.  Many manufacturers have copied them.  There's no doubt in my mind, that making a lot of noise and shouting about a couple of banner specs wins the day for their sales ledgers.  It all depends on what you are using a scope for.  Final test instruments for an electronics manufacturer, or for a field service technician following a "set this, set this, read waveform" sort of handbook, a cheap poorly designed DSO will do enough to complete the job.  When you don't know what will drop on your workbench tomorrow, or what you are going to be building next month, or working in a research lab, it is a different matter.  Even computer monitors use data speeds that were dreams only a few years ago.  DSOs need a set of design features that makes the scope as flexible as possible, so it earns its price and never leaves that nasty feeling when you simply can't see what you need to see to solve a problem.  In the end, it's the tricky problems that cause you grief, and that's what you spent your money to solve, what's the point in having spent money on a DSO that can show you nice sine waves, which you already understand, but won't show you the spike that is really what is causing the unexplained behaviour of a micro you are working on?  You didn't spend the money to show sine waves, but to show you the things that weren't expected...  LeCroy's early scopes excelled at this, finding things that weren't expected.  They were builders of high energy physics instrumentation first, and I think that motivated a lot of their early work.  I'm not sure the market is the same now, but end users are.

We still need to know that what's on the screen of a  DSO screen is true, and know it will earn its keep in the future when it gets thrown jobs that no-one anticipated.

The Hantek/Tekway is the first cheap DSO I've considered worth spending money on, but the operating software is disappointing in quite a few areas.  It could be so much better!

Cheers, Colin
 

Offline Mechatrommer

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #573 on: May 16, 2011, 09:02:59 am »
i think it boils down to performance vs cost. as you say it yourself...
It reminds me of the old engineer's saying, you can have good, fast, and cheap, pick any two!
dso maker (hardware and software) can struggle to maximize and perfect the performance. but later they will charge exponential. or they (engineers and management) can ignore it, and let it flow/blend/balance with the market (profit vs cost). its called business, a "contaminated engineering", imho.

you can buy a perfect scope, or buy hantek and get involved in this thread. pick one.
« Last Edit: May 16, 2011, 09:08:15 am by Mechatrommer »
if something can select, how cant it be intelligent? if something is intelligent, how cant it exist?
 

Offline tinhead

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Re: Hantek - Tekway - DSO hack - get 200MHz bw for free
« Reply #574 on: May 16, 2011, 12:34:28 pm »
Colin,

there are only 19 divs, you miscounted it. We have also 760x400 effective points on the display.
Why ? Probably easier to divide. Of course it could be fixed view area with a bit larger display,
like on Agilent DSOX but on the other side the F0 Menu On/Off marking is big enough to see it :)

To understand why Tekway chose 800x480 display (or why some things are like this and not different) we have to look back.
They new on the market, so probably they started DSO development from business point of view:
- take µC/DSP platform which is wide available and cheap
(Samsung SoC instead of TI DSP - to be different/better and cheaper than competitors)
- create something "known" but at lower price
(like Tektronix clone)
- chose nice company name assiociated with something ppl know.
(like Tek-way ...)

So Tekway was born, and of course the first product was Tektronix clone. They even made some advertisement
like "our Tektronix clone - but cheaper". I do have such Tekway DST1102 too, you can blind navigate through
menu if you know Tektronix TDS2012 - but of course exact the same disadvantages - slow display update rate,
crap display and 2500 points memory. You can still buy some of these DSOs - designed for chinese market (only chinese fw).

However Tekway realized that ppl don't need another one Tektronix clone - to have a chance on DSO market you have
to develop something better than (chinese) competitors. So the actuall series was born.

To not start from scratch they decided to continue work and improve their DST1000 platfrom.
So instead of Samsung S3C2410 (266MHz) like on DST1000 then chose S3C2440 (400Mhz), added external SRAM and CPLD,
faster and bigger FPGA and bigger display. If you look on the Samsung SoC dev. board market you wil find out
the common biggest display at that time was Innolux AT070TN83 - they wide available, good quality and cheap displays.

All these steps are typical for someone who just started on DSO market, they will need some time (or well, with the Hantek
merger they actually got a "good" name, or at least known name) to be real DSO developers/manufacturers.
However, if i do compare to comeptitors they already better than all of them together (uni-t, atten, rigol) - at least on the paper.

Sure, these firmware bugs are not nice - but the platform is good, so it is easier to fix firmware bugs instead of "fix the platform".
I know that earilier firmwares were working much better, sure with some small bugs around F7 button but everything else was ok.
The "disaster" started as they decided to implement more features, more languages, more menu options and tried to
fix alread known small bugs ... i do undertood why they did it:
- missing features vs. chinese competitors products
- Hantek ruled multilanguage product policy
but honestly don't know why they decided to use not stable firmware version for end user products.

Anyway, maybe they learned from Microsoft ("field evaluation" engineering) and as you said
"designed by a programmer used to binary and software, not by a scope engineer" - so if you don't knwo what
ppl really need develop "something you think it might work" , let end user test it and decide later based on feedback.

If you look on competitors - e.g. UNI-T - they realized very fast "we need bigger display", but instead of display with
biger resolution they chosed bigger display with small resolution, removing all informations from website ... as ppl realized
they got cheatted uni-t promissed to fix the firmware. One year later and after 4 firmware updates no changes on the
display - and probably they will never fix it - the platform is not good enough for better resultion.
Rigol/Atten - they have to start from scratch too - the DSP/display controller platform is not good enough to
handle bigger resolutions, Rigol decided (at least until now) to not cheat customers and is still producing DSOs with 320x240
and "small" display, ATTEN/Siglent did same as UNI-T - big display with small resolution (yhear, the typical buyer will not even recognize it).
The worse part of the story is that many ebay/china shops are selling these Atten/Siglent/UNI-T DSOs under
"big resolution 800x480 DSO" - which isn't truth. As we can see "fix the platform" is not easy step.

Back to "topic" - of course is Tekway/Hantek not a real DSO manufacturer, they doing great job and let's hope they will
fix firmware issues. I know them and i know they doing everything necessary to fix it - however i can't vouch for.

I don't know why all chinese manufacturers hiding details of their products, there is nothing to shame about.
If a product does not have something implemented, well who cares, the truth is better than "cheatting".
Probably they learned from the wester-world competitors - if you need to know something "bad" about
Tektronix - don't ask them, ask Agilent - and vice versa of course. I remember these nice LeCroy
presentations - "refresh rate didn't matter, do single shot and you can find the spike with our software".
Sure, i would probably said the same if my product is slow refreshing. Of course the actuall HanTekway 2500 wrfm/s
are not much, but better than 800. It was not all that long ago that Tektronix prodeuced DPOs with similar refresh rate,
even current low range models are not much better at all. Or look on Hameg - no single word about refresh rate,
but copmetitors know it of course, and yeah it is on Tekway/Hantek level. If you look on my first post in this thread you
will see i was looking for "replacement" for my broken TDS754D. To be very i bough the older Tekway model and was
disapointed (currently using it as DIY Spectrum Analyzer), then bought Tektronix DST2012 - again very
disapointed (luckily i bough it very cheap, with broken front and display). Then i started again to look around chinese product,
tested some and finaly decided to use Tekway. It can't repalce my old TDS754D, but is a good enough.
Today i would probably buy 70Mhz Agilent DSOX2000 (and hack it to higher bw) or Tekway - even with these firmware bugs -
because of the potential within this hardware/software platform.

It is all about the price vs. features. On the other side there is no warranty that high end scope will have perfect firmware,
actually you can buy one of the R&S scopes and you will see how perfectly they freezing every two days, there
are other DSOs with known issues too, nobody is perfect.

So what, good value for money ? Sure, and it does have potential, but jesus, some of the firmware issues need to fixed asap.
I don't want to be human! I want to see gamma rays, I want to hear X-rays, and I want to smell dark matter ...
I want to reach out with something other than these prehensile paws and feel the solar wind of a supernova flowing over me.
 


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