oscilloscope memory depth  - Page 1
Forum section: electronics / beginners

author: stern0m1
author_rank: Contributor
timestamp: January 31, 2018, 10:50:45 pm
content: Hi,Does the memory depth of an oscilloscope make a difference if I plug in a usb drive or connect to a computer?Thanks

author: ataradov
author_rank: Super Contributor
timestamp: January 31, 2018, 11:01:30 pm
content: Yes, it does.

author: stern0m1
author_rank: Contributor
timestamp: January 31, 2018, 11:08:12 pm
content: Thanks.Another question,For the Hantek DSO5202P I see the specs say 1GSa/s sample rate and 40k memory depth.Does that mean it can properly record 40 seconds? 1000 samples a second x 40? Just trying to see if I understand this right.Thanks.

author: ataradov
author_rank: Super Contributor
timestamp: January 31, 2018, 11:11:19 pm
content: 1000 samples per second is 1 kSa/s.1 GSa/s is 1 billion samples per second. So with 40k sample memory ts can record 40 microseconds of real-time data.Basically 40K buffers is barely useful for just on-screen observation. Don't think you can record traces of any usable duration.Useful memory sizes start at 10-20 Msamples.Also note that you can reduce sampling rate, so memory will last a bit longer at the expense of sampling rate. But 40K samples are still not useful for long term observations.

author: stern0m1
author_rank: Contributor
timestamp: January 31, 2018, 11:22:05 pm
content: my bad, I should have understood that.The scope is listed as 200Mhz and 40k memory. Roughly speaking up to what frequency can I properly measure with relying on usb storage or usb to computer?Thanks

author: ataradov
author_rank: Super Contributor
timestamp: January 31, 2018, 11:27:38 pm
content: EDIT: Nonsense answer removed.With 1 GS/s you can do full 200 MHz square waves.And this has nothing to do withe the memory size. You only need as much memory as many there are horizontal pixels on the display.Memory will limit how much you will be able to capture in a single trigger event. For repetitive signals it does not matter.

author: stern0m1
author_rank: Contributor
timestamp: January 31, 2018, 11:31:41 pm
content: for non repetitive signals I assume what kind of memory makes a difference. If it cant be saved fast enough to the memory then the accuracy is being degraded?

author: ataradov
author_rank: Super Contributor
timestamp: January 31, 2018, 11:35:20 pm
content: You can't save fast enough to the computer over USB. USB 2.0 HS maximum bandwidth is 52 MBytes/s. Your ADC will generate 1 GB/s.So all scopes save sampled data into a buffer, and then transfer it into computer at a much slower rate.What sort of memory is sufficient for you depends on the application. I personally would not consider a general-purpose scope with less than 12 MSamples of memory. I would actually gladly trade sampling rate for memory in most cases, within the reason, of course.

author: myf
author_rank: Regular Contributor
timestamp: February 01, 2018, 06:04:13 pm
content: Hi,Maybe I shall buy the rigol ds1054z with its 12MB data but I have never used it.So can I use it as a 1kHz data logger for one 10seconds shoot at 1kSa/s ?more is better, but I only need about this 20kB data (for 2 channels)Has this scope other data-logger limits ?or can I record at any xx-samples per second for yy-seconds when the product xx * yy * n channels <= 10 MB ?Can I zoom and unzoom on the screen, and shift before and after inside this delay ?I read that siglent sds1104x has a better data-logger but I don't what can be better.Maybe you might describe such examples...Thank you very much for your answers.Have a nice day !François (from France)

author: ataradov
author_rank: Super Contributor
timestamp: February 01, 2018, 06:11:10 pm
content: Quote from: myf on February 01, 2018, 06:04:13 pm24 MS with unlock codes. But whether you should buy it or not - it is up to you. DS1054Z has one very annoying issue - saving 12 MS buffer to external flash drive takes 15-20 minutes. I have not tried to connect it to PC, so I have no idea hoe that goes.Quote from: myf on February 01, 2018, 06:04:13 pmThat depends if settings will allow you to go that slow.Quote from: myf on February 01, 2018, 06:04:13 pmIf you are talking about DS1054Z, then yes, once captured, you can look at any part of the buffer.Quote from: myf on February 01, 2018, 06:04:13 pmI have no idea how any scopes perform as data loggers. Never used them in that capacity.

author: tautech
author_rank: Super Contributor
timestamp: February 01, 2018, 07:05:09 pm
content: Quote from: ataradov on February 01, 2018, 06:11:10 pmAlexI think the OP is referring to the work being done by lundmar using LXI connection for Linux.Indeed the new 4ch Siglent is very fast a getting data back from SCPI commands.https://www.eevblog.com/forum/testgear/open-source-lxi-tools-and-liblxi-v1-0-released-for-gnulinux/msg1415397/#msg1415397