RedPitaya Data Acquisition

Introduction

This tool was written as part of the "Information Barrier eXperimental" project (Repository), Description. The Red Pitaya is a signal processing device with fast capture capabilities. The hardware together with this software is used in the IBX to provide a Gamma Spectrometer.

The software makes use of the FPGA module oscilloscope that is shipped with the RedPitaya OS. It can be used for any triggered data acquisition task using a Red Pitaya. It was greatly inspired by this project, thanks to Grozomah for that!

Installation

On RedPitaya itself

This should be very straightforward. If you have a C++ compiler (g++) and cmake installed, it just boils down to:

git clone <repoaddress>
mkdir build_acquisition
cd build_acquisition
cmake ../ibx-acquisition/
make

After that, you can either run the file from the directory you build in (./acquisition), or put it in any folder that is included in your $PATH variable. No make install rules are included so far.

Cross Compiling

This is rather complicated, but possible.

Usage

The following examples assume that the binary is in a directory that is included in your $PATH variable.

All options can be seen using

acquisition -h

Usually, you might need many options for a run. A good example is

acquisition -t 3 -v -150 -o 4 -p 32 -l 384 -r 90 110 30 200 -f best_measurement_ever 60

The line above will do the following:

• Trigger for Input on Channel A, negative edge (-t 3)
• Trigger when input voltage is recorde in ADC channel below -150 (-v -150)
• Use output mode 4 (-o 4), output mode 4 is specifically useful for gamma spectroscopy. It integrates the incoming signal, and stores only! the integral in the output file. A simple method is implemented to reject traces that would contain two or more gamma peaks. -r 90 110 30 200 are the rejection settings. For more details see notes on rejections.
• The output of each event will include 32 datapoints that were recorded before the trigger triggered -p 32
• Each event will be output as a set of 384 datapoints -l 384
• Output will be written to file best_measurement_ever.txt, the suffix is added automatically (-f best_measurement_ever)
• Measurement will take about 60 seconds (stops at first event after 60s are over)

For more info refer to the acquisition -h.

Some notes on rejection algorithm

A very simple rejection has been implemented (only for output type 4). For this output, the -r <min> <max> <s> <e> option should be specified. For each trace, the code calculates the integral and finds a peak between channel <s> and <e>. The code will reject detected traces if either one of the following conditions is true:

• integral < peak *
• integral > peak * (or accept traces only if the negation of both is true together)