Question about Picoscope 4245 specs buffer memory - Page 1
Forum section: electronics / testgear

author: newbieswe
author_rank: Newbie
timestamp: September 01, 2020, 07:45:14 pm
content: When reading about Pico 4245 specs one key feature that are supposedly good is the buffer memory 250m for longer recording samples.Earlier I wanted to buy a Siglent SDS 1104 and use it on the car instead of a usb scope.Is there any way I can find how big buffer memory sds 1104 have?And I am a Newbie in this field so go easy on me.

author: Andreas
author_rank: Super Contributor
timestamp: September 01, 2020, 09:14:05 pm
content: Hellofor the Siglent:Memory depth: 14 Mpts on the 2 Channel model (shared between both channels)and obviously 2*14 Mpts (per ADC) on the 4 channel model (shared per ADC)I think you mean PS 4425 instead of 4245?Note that the 256 Mpts with 12 Bit resolution each are shared by the active channels.And the PicoScope 6 software has a limit of 100 Mpts per channel.But with slow aquisition (< some MS/s) you can get up to 100 Mpts per channel.with best regardsAndreas

author: newbieswe
author_rank: Newbie
timestamp: September 01, 2020, 09:39:02 pm
content: Sorry I meant 4225How big advantage does the Pico with a larger memory buffer against siglents 1104 for capturing intermittent failure in sensors and other automotive components. Or is the Siglent a good scope for automotive?https://www.picoauto.com/products/automotive-oscilloscope-kit/picoscope-4000-series-specifications

author: tautech
author_rank: Super Contributor
timestamp: September 01, 2020, 10:27:33 pm
content: What we need understand when the topic of scope memory depth arises is the differences in 'capture' memory management strategies between manufacturers.There are 2 main philosophies, a fixed amount of memory and an amount that varies with timebase settings.We can argue forever which is best however that's not the point, the point is understanding how each strategy works and how we might use each to the best advantage.LeCroy,PicoTestPicoTech and Siglent use the same strategy and it allows for large amounts of memory for captures when certain usage styles are implemented.Typically to have the maximum memory available it must first be selected and then a timebase where the maximum is available used then for closer inspection Zoom mode is selected where a dual timebase is available to examine the capture in greater detail.Typically this is NOT how we use a DSO everyday however like a History or Sequential mode it's there if we need it or know we will need it but for the Siglent the History memory buffer is always running invisibly in the background.A screenshot using the Zoom mode FYI:Quote from: newbieswe on September 01, 2020, 09:39:02 pmA scopes suitability for a job is defined by its feature set and for decoding busses the decoding protocols that it offers.

author: newbieswe
author_rank: Newbie
timestamp: September 02, 2020, 06:25:01 am
content: tautech thank you for the explanation

author: Andreas
author_rank: Super Contributor
timestamp: September 02, 2020, 06:54:08 am
content: Quote from: tautech on September 01, 2020, 10:27:33 pmPlease dont mix up PicoTest with PicoTech.Quote from: newbieswe on September 01, 2020, 09:39:02 pmThe main advantage of a large buffer is for measuring single shot events which occur e.g. during cranking of engine start.Zooming and panning is usually faster on a laptop/PC screen than with the dials on a scope.Finding intermittend failures in sensors is a demanding task with every scope because you usually do not know how the sampling and filtering of the signal within the ECU is done. If you know the filter time constants you can use the filter options on the PicoScope to see the signal the same way as it is seen by the ECU.But in many cases reading the fault code memory with a diagnostic tool is the better option for intermittend faults.with best regardsAndreas