First of all the 200us/div and 1M was not working from the beginning. Right after i recognized it on a very
first firmware i send it as bug report - i don't know when exactly but one on next firmwares was able
to enable 1M in 200us/div but zoom was not working. So i asked again and got answer
that the way how the DSO is designed they can't enable 200us/DIV and 1M - the next fw version then was
not capable again of doing 200us/div and 1M. I thought, what a bummer, but anyway,
it works below and above 200us/div, or just with 512k while in 200us/div.
Now the answer i got was send by Tekway long before they got bought, feel free to send Jonas
an email and ask him why this is like it is, maybe Hantek engineers can do more that Tekway org.
designer was capable of (i doubt that, but let's try).
This is only one and small example:
Set display dots
400us/div
1M memory
capture.
push Utility
look SysRunParam it show 100MS/s, 800000 sample dots, 800000display dots
Stop
Cursors
Turn sec/div 20ns/div ok you see dots but not 10ns distance, they are 8ns,
ok turn 8ns/div oh well now dots are 6.4ns and only left half of screen
try horizontal position: can not move
turn 4ns/div all disappears
Ok same agen but 200us/div
oh, can not select 1M, only 512k
push Utility
look SysRunParam it show 100MS/s, 400000 sample dots, 400000display dots
cursors
Stop
Sec/div to 20ns
measure 10 dot interval = 107ns
turn 8ns/div measure dot interval 12.8ns
turn 4ns/div now dots only left half of display
measure dits interval = 6.4ns
Mode dots, 200us/div 1Mpoints, 10MHz signal from Rubidium standard to scope. Capture.. Stop, change to 8ns/div
measure freq on the screen. 11.7MHz so use 0.855 but specs do not tell that need use this constant for multiply.
all 3 examples are with zoom higher than 10 000, if you stay within x10 000 everything will be fine (for dots, vectors see below)
Out of curiosity, with which version you saw this working? Becasue none of the firmwares i have here is or was ever
capable of doing properly zoom > 10 000/20 000, not even the first pre-production firmware from Dec 2009.
Btw, display vectors have not this problem. So how they make vectors if they do not use these sampled dots, or is it so that display dots are not sampled true dots at all? What is meaning if displayed dots are not sampled datapoints?
If they can scale vector display why not these dots?
no, vector have same problem, due the better interpolation you can use up to 20 000 zoom.
So for example 400us/div zoomed to 20ns/div (x20 000) will still work, but 200us/div zoomed to 8ns/div
not anymore. when you don' t believe (luckily there is fine timebase now, no need to patch timebase table to see it)
change the timebase to 10ns/div and you will see the sampled 10MHz signal (with 512k, 200us/div, 20000 zoom)
have length of 100ns. Now when you do the sample for dots sampled you will see 10ns/div is not working
anymore - that's because it can only 10 000 zoom.
Of course this is kind of bug, but actually hard to restrict the timebase, so this is one
of these things where the user have to think a bit about. When you select 2ns/div you
will immediatelly not wonder why you see only one or two dots or just a ine between 2 dots -
because you reached already the smpling / screen size limit.
Now in dual window mode it is easy to restrict zoom in firmware - there is 1000 max, in single
window due better resolution 10 000 for dots and 20 000 for verctors ut you have
only one timebase, so the conditioning is bit more complex (when limit zoom, how limit zoom,
why limit zoom, why just not display "warning, zoom out of accuracy").
I don't know, maybe Hantek is smart enough and can fix that, but knowing that they
never did it (and i'm sure at least the org. Tekway engineer was knowing this restriction) i doubt
they can do it. Again, make a snapshots and ask Jonas. I can work with that, restrictions
are there to be followed.
200us/div, zoom to 20ns/div, measure 10 dot interval = 107ns
sure, you have 10 dots, sampled with some jitter, multiply by 10 the jitter and you will get something between
104ns (103.5ns) and 106.5ns (well, 107ns are next to 106.5ns). You can actually see the jitter, when you exactly measure
the time between each dot you will see sometimes the difference, sometimes positive, sometimes negative,
sometimes exact time. There is nothign wrong with that (well, maybe the 500ps trigger accuracy on
paper but 350ps to 650ps in the reality, sure avg 500ns but it should be always below 500ps to
follow western standards of datasheets).
I actually don't give a f** what ppl think about Hantek and the way how they work.
I do know Tekway was different - sure more complex to communicate, but that was typical for small company
(well, actually departement of a big company working on own costs with own company name).
But the product which i chose, bought, tested and later announced here is not bad, actually one of the
best you can get for money - the firmware is (when you forget here and there some small things)
really good one - imagine Owon with this firmare, there will be no competitor on market for
long time.
On the other side these small things in the firmware which we can't change, they could be
implemented better with no cost. Everybody would accept that there is max zoom 1000/10000/20000,
when the manufacturer will not hide this fact but clearly show to user a small warninng (nothing else,
i still wish to see more than 1000/10 000/20 000 zoom !!! even if the accuracy is gone)
- "
zoom limit reached, out of accuracy", there is nothing to shame about,
1000/10 000/20 000 zoom are acceptable values.
What not acceptable that the manufacturer is not clearly talking about, this remains me on these
faked sample rate things on Rigol. Of course most chinese manufacturers hiding informations,
not only because of competitors but also because they don't know that in western countrys
a good manufacturer is telling everything about the product .... ups, actually not, actually
every manufacturer is trying to cheat a bit
EDIT: you know what, i add it into the bug list from page 60 even if i don't see it as a real bug,
but it should be not that complex for them to add just a small warning.
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Topic: Hantek - Tekway - DSO hack - get 200MHz bw for free (Read 2198960 times)