Pulsar post processing tools 3pt-calc.exe, and 3pt.cfg

This software tool can be used to extract pulsar signals from 8bit unsigned IQ data captured with a RTL dongle or equivalent.

First the data has to be captured with the tool rtl_sdr.exe as described in
example; rtl_sdr -s 2e6 -f 419.0e6 -n 2e8 dump.bin, meaning;
-s 2e6; sample rate 2MS/s
-f 419.0e6; frequency 419MHz
-n 2e8; number of samples to process
dump.bin; name of the file

Next the pulsar has to be extracted from that dump.bin and that can be tricky.
From the tools available we have chosen to write our own.

Short description:
3pt.exe chops the IQ file into pulsar periods, performs FFT and writes them as 10 spectrum files to disk.
The python script reads the spectrum files and folds them to one file and plots it in a multi plot graph.

User instructions
-Put the 3pt.exe, the IQ file the 3pt.cnf and the python plot script in one directory.
-Open the config file, edit it, and save it.
-Run 3pt.exe. One processor core of your PC will be occupied completely.
-When finished a number of period spectra files will be written:
--spectrum files containing 10 spectrum rows and 1 sum row each.
--1 band pass file; FYI.
--1 band pass correction file; FYI.
The spectrum files can be examen with a spread sheet program or with the python plot script.

The config file
0.------first part calculation------------
1.pulsar name = B0329+54
2.pulsar period time [s]= 0.71448358541
3.Sample rate [Sps]= 2000000.0 optimal sr(+) or pt(-) [ppm] (default step:+-0.005, 0:off)=0
5.DM= 26.78 freq [MHz]= 404.0
7.IQ input file name =da3.bin
8.number of output bins= 108
9.output file name without extension= abcd
10.process period from= 0
11.process period to (0:all)= 1118
12.clipping and RFI filtering (0:no,1:yes)= 0
13.clipping and RFI filtering level [%]=0
14--------second part folding, plotting----------
15.plot period from = 0
16.plot period to (0:all)= 95
17.fold period from =2
18.fold period to (0:all)=1118
19.exclude channels (0:None else 1..10 csv)=0, time=12345,5432
21.observatory location=abcde

You can download the 3pt tool here 3pt-version 105

You can download the extended user instructions here 3pt-user instructions 08



Fig.1 - B0329+45 DWRT


Fig.2 - B0329+45 SGRT


Fig.3 - B0833-45 GGAR


Fig.4 - J0437-47 GGAR

Here are two extra IQ files to work with. These files were captured by Guillermo Gancio, member of the IAR.

Two other IQ files ( and can be found here

0437-47 IQ data and info

vela1 IQ data and info

Michiel Klaassen july 2020