Faster acquisition rate

Applications, development tools, FPGA, C, WEB
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max paper
Posts: 7
Joined: Mon Mar 13, 2017 5:39 am

Faster acquisition rate

Post by max paper » Tue May 16, 2017 9:13 am

I'm acquiring sequences of ultrasound pulses using SCPI with Matlab.
I utilized for this a modified version of an example code (http://redpitaya.readthedocs.io/en/late ... -exm1.html)

It works well, but it is quite slow (around 0.5 s/acquisition).
It appears that the time-consuming commands are the reading of the buffer :
signal_str=query(tcpipObj,'ACQ:SOUR1:DATA?'); % 0.3s
and the conversion in numbers:
signal_num=str2num(signal_str(1,2:length(signal_str)-3)); %0.1s

Is there something I can do to faster the process or will I have to forget the SCPI/Matlab option? The acquisition speed I am aiming for would be in the 1-5 ms range (I'm using a decimation of 8).

Thank you for your help

Jerome_LMA
Posts: 1
Joined: Tue Apr 12, 2016 11:23 am

Re: Faster acquisition rate

Post by Jerome_LMA » Mon May 29, 2017 1:05 pm

I found the same issue. Curious to know what is the bottleneck (time-wise) for fast sampling using TCP/IP query.

redpitaya
Site Admin
Posts: 238
Joined: Wed Mar 26, 2014 7:04 pm

Re: Faster acquisition rate

Post by redpitaya » Wed Jul 12, 2017 12:14 pm

Sorry, but there is not much you can do to speed it up, this is the limitation of the current SCPI server.

However we are working on a better implementation that should be ready in the beginning of October.

albert.ruiz
Posts: 12
Joined: Fri Jul 17, 2015 6:43 am

Re: Faster acquisition rate

Post by albert.ruiz » Fri Jul 14, 2017 1:37 pm

I had the same problem when I was reading the full buffer, what I did to speed up the process was to run the signal processing in the microprocessor from RedPitaya and send just a few data through that way I did not have to send a full buffer which takes a lot of time (you are right).

max paper
Posts: 7
Joined: Mon Mar 13, 2017 5:39 am

Re: Faster acquisition rate

Post by max paper » Wed Jul 19, 2017 9:21 am

Thanks for the answers.

As I am doing all the signal processing afterward I am not sure I could speed it up this way.
The time-consuming operation is "signal_str=query(tcpipObj,'ACQ:SOUR1:DATA?'); % 0.3s" and I am not sure there is a way to reduce this one...

bryan.hayes
Posts: 5
Joined: Mon May 15, 2017 6:05 pm

Re: Faster acquisition rate

Post by bryan.hayes » Wed Jul 19, 2017 5:31 pm

max paper wrote:I'm acquiring sequences of ultrasound pulses using SCPI with Matlab.
I utilized for this a modified version of an example code (http://redpitaya.readthedocs.io/en/late ... -exm1.html)

It works well, but it is quite slow (around 0.5 s/acquisition).
I also found a maximum of about 2Hz. Not suitable at all for my needs. I ended up learning C and writing my own program. Now I get several thousand Hz. Seems SCPI is very easy to work with, but also slow.

Pineapple
Posts: 7
Joined: Fri Oct 26, 2018 11:20 am

Re: Faster acquisition rate

Post by Pineapple » Mon Oct 29, 2018 11:29 am

redpitaya wrote:
Wed Jul 12, 2017 12:14 pm
However we are working on a better implementation that should be ready in the beginning of October.
Any news about that? Is the solution already integrated in the new software?

uwe_f
Posts: 3
Joined: Fri Jan 04, 2019 10:53 am

Re: Faster acquisition rate

Post by uwe_f » Tue Feb 05, 2019 10:29 am

Hi,

in the manual you find some options, like raw or volts for the scale and float and ASCII for the format. Does it make a difference for transferring the buffer through SCPI ?

BR
Uwe

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