Skip to content


Subversion checkout URL

You can clone with
Download ZIP
Sudden ionospheric disturbance collector (sidc)
C Shell
branch: master
Failed to load latest commit information.
init_scripts Init script fix, added init script for red hat distros
.gitignore Add gitignore file
LICENSE Don't strip debuginfo
README.rst Whitespace cleanup Add Update Version bump
sidc.conf Remove trailing slash for data directory
sidc.spec Updated specfile
sidc.sysconf Add sysconf file


Sudden ionospheric disturbance collector (sidc)

Note: This is the fork of the original sidc with various improvements and bugfixes.

1. Introduction

sidc is a simple C program to monitor and record VLF signal for sudden ionospheric disturbances. It is forked from sidd program wirrten by Paul Nicholson <>

2. Installation

  • First install FFTW3 dependency from or use your favorite package manager to install fftw-devel package.

  • Install alsa-lib-devel package if you want to use alsa (optional).

  • Configure and compile the source




  • Install the source (if appliable)

    make install

  • Edit sidc.conf to suit your requirements. Select an output policy from the three available.

  • Start sidc in verbose foreground mode with the command

    ./sidc -vvf

  • The program will output peak and rms readings in the range 0.0 to 1.0 Adjust your mixer gain settings to leave a little headroom on the peak reading.

  • Plot the utility spectrum file

  • Check the data file columns are the ones you want.

  • Set your PC clock and activate your favourite time synchronisation software. Make sure it slews the clock rather than stepping the time.

  • Restart sidc in background with

    ./sidc -v

  • After a period of time, plot some of the data from the output file.

  • After a midnight crossing, make sure sidc has switched to the next output file.

3. Command line options

There are just a few command line options - most controls are in the config file.

-v Be a little more verbose with log messages. Use several -v for more detail.
-f Run in foreground. By default, sidc detaches from the process group and terminal and becomes a daemon. In foreground mode, log messages are duplicated to stderr.
-c config_file Run with a specified config file. By default, sidc looks for /etc/sidc.conf
-p pid_file Override default PID file location which is /var/run/ Pid file is created everytime this process becomes a daemon. Creation is skipped if file is not writable.

4 Miscellaneous notes

  • sidc will set the soundcard to the nearest available sample rate to that specified in sidc.conf
  • 24 bit soundcards may return data in 32 bit words. Try setting 'bits 24' and if sidc reports the mode unavailable, use 'bits 32'.
  • Make sure you have enough disk space. The example sidc.conf with 8 bands generates files of about 100Mbytes per day, which compress down to about 30Mbytes. Arrange scripts for plotting. Arrange scripts for compressing and archiving files that are a few days old.
  • Simple init scripts provided. Check the readme in init_scripts directory.
Something went wrong with that request. Please try again.