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owon budget scope rebadges and firmware updates - is it a dealbreaker?

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ebastler:

--- Quote from: kokodin on November 09, 2024, 01:13:49 pm ---there is one oryginal 2 channel owon that is set to be 200mhz bandwidth. but it is still 1gs/s and still only 10k samples buffer. i wonder how a triangular wave would look on it at those conditions, and if it's firmware could hack lower spec models because they limit the number of samples in scopes with bandwidth lower than 50mhz quite drastically.

--- End quote ---

(a) 200 MHz bandwidth in a two-channel scope with 1GSa/s is alright. You get 500 MSa/s in dual-channel operations, so the Nyquist criterion is still met -- although it's a bit marginal. If you feed a 200 MHz triangular wave into a scope with 200 MHz bandwidth, it will look like a 200 MHz sine wave, because none of the higher harmonics make it though the low-pass filter. That's actually just determined by the input bandwidth, not the sampling rate.

(b) Not sure I fully understand your idea with the firmware hack. But if OWON sells a lower-spec model with lower sampling rate, it is very unlikely that its ADC and acquisition hardware (probably an FPGA) can be run at 1 GSa/s. Again, fast ADCs cost actual money. OWON would use a cheaper, slower ADC in the cheaper scope.

It is quite common for scope manufacturers to offer a few related models with different bandwidth specifications which are based on the same hardware. But I have not come across a family of scopes with different sampling rate specifications while being based on the same hardware.

kokodin:
(a) I know what you mean, i was just wondering if that 200 is just a gimmiky label you pay extra and , the front end tapers in analog bandwidth the same as 100mhz version but they unintentionally overbuild it and capitalizing on that by "making new model" or is that different hardware in the same case.
I know what sampling rate is, i am just bad at expressing my thoughts in a language i technically never learned past 3 years in highschool :].
Triangle wave would be a good test if the analog  bandwidth or the sampling give up first.

(b)
Model No.   Channel   Bandwidth   Sample Rate   Record Length
SDS1022      2             20MHz      100MS/s     10K
SDS1052      2             50MHz      500MS/s     10K
SDS1102      2            100MHz       1GS/s           10K
SDS1202      2            200MHz       1GS/s           10K

Basically i was wondering how did they cut down the bandwidth and sampling rate in the lower 2 removing one adc if 1gs have 2, underclocking them or putting pin compatybile lower grade parts. the absolute cheapest owon rebadge i can buy is something like sds1102 model only with 110mhz bandwidth.
Can it be made 200mhz or is the front end tuned to be barely 110mhz for the rebadge, would they make so much effort to spin separate batch of mainboards or just flash different firmware. Since they make multitude supermarket brands i don't think they care too much to tune every single one to indyvidual specs. but who know, maybe every factory batch of mainboards is a different revision.

Aldo22:

--- Quote from: kokodin on November 09, 2024, 02:29:33 pm ---(a) I know what you mean, i was just wondering if that 200 is just a gimmiky label you pay extra and ,

--- End quote ---
With the Hantek DSO2000, this is only a question of the probes that are supplied.
There is only one scope hardware, as far as I know.
The bandwidth... well.
The important thing is the sampling rate.
I bought a 100MHz DSO2000.
I trust the amplitude up to about 20MHz sine, because I can verify it up to that.
But It can also measure 200MHz with both channels enabled.
The screenshot shows 1s persistence so that you can judge the jitter.
I don't think it's too bad for a $150 scope. The Fnirsi 1014D doesn't manage that.
But yes, that is the limit and the VPkPk/VRMS measurement means nothing there.

ebastler:

--- Quote from: kokodin on November 09, 2024, 02:29:33 pm ---Model No.   Channel   Bandwidth   Sample Rate   Record Length
SDS1022      2             20MHz      100MS/s     10K
SDS1052      2             50MHz      500MS/s     10K
SDS1102      2            100MHz       1GS/s           10K
SDS1202      2            200MHz       1GS/s           10K

--- End quote ---

Oops, there goes my statement "I have not come across a family of scopes with different sampling rate specifications while being based on the same hardware". I guess I have come across one now... It seems very likely that these scopes are indeed based on the same acquisition hardware. OWON apparently considered it a good idea to artificially limit the sampling rate for market segmentation reasons.

The scopes from Siglent and Rigol can be "upgraded" to higher bandwidth via a software key only. The front-end amplifier has a switchable lowpass filter already built-in. It is somewhat likely that the OWONs are built the same, but I guess we don't know for sure.

Whether OWON has taken further precautions to disable cross-model firmware updates, we don't know either. They could easily do that via a model ID stored in flash ROM somewhere, or encoded on the PCB via a few resistors or jumpers which get populated differently depending on the model number. 

So unless you find specific "hacking" info somewhere, it's a bit of a gamble to buy a lower-spec'd model in hope of upgradability.

kokodin:
Yes i was kind of hoping i find that info here, or leave it if someone kind read my thread and dump the firmware somehow for comparacy or database building. The idea of multicolor multi brand gathering just trigger something in me, like rebadged fiat 600/ zastava 750/ seat 750, or my collection of mini sewing machines.

Aldo22 Fnirsi 1014D seems to be a joke compared to the other two alternatives. I seen test video where bandwidth tapered drastically at 4mhz, so either the guy didn't terminated the signal properly, used 1x probe or the 100mhz is a case print with no much corelation to reality. To do my investigation with my hantek i had to limit both probes to 20mhz :P but i see your test to be impressive showcase of what can be done with the scope. I don't think i will ever use it that way. I need a scope mostly when adjusting analog tv's from my colection or for arduino project, now i needed to test if microcontroller in 30 years old amplifier runing at 4mhz was alive. And it was, only talking in bursts of data then being silent. Fault was elsewhere, now everything works. But i wouldn't find the fault with my analog junk.
It would be even better if i had 3 channels but oh well, so far i am happy. Owon would probably work too even with very limited sampling in 4 channel mode.

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