Spectrel: Process, Explore and Capture Transient Radio Emissions (Lite)

Getting started

Spectrel is (yet another) SDR-agnostic program for recording radio signals and spectrograms. It offers a lightweight alternative to Spectre written in pure C. Powered by SoapySDR and the FFTW library.

⚠️ We're in pre-alpha - please expect some instability.

Supported Platforms

Spectrel is expected to be compatible with most Linux distributions.

Prerequisites

• FFTW3
• SoapySDR
• The drivers for the hardware you want to have support for.

Installation

1. Clone the repository

   git clone https://github.com/jcfitzpatrick12/spectrel.git && cd spectrel

2. Build the binary
   Assuming you are in the root directory for this repository:

   sudo make install

3. Good to go!
   You can now run Spectrel using:

   spectrel -r <receiver> -f <frequency> -s <sample_rate> -b <bandwidth> -g <gain> -T <duration> [-d directory]  [-w window_size] [-h window_hop] [-B buffer_size]

   The spectrograms are streamed to a file named <timestamp>_<receiver>.cf64, where <time_stamp> is the current system time formatted in the ISO 8601 standard and <receiver> is the SDR driver name. Each sample corresponds to a complex DFT amplitude (64 bits per component), stored in column (spectrum) major ordering.

   OPTIONS

   -r receiver
   The SDR driver name. Examples: "rtlsdr", "hackrf"

   -f frequency
   Center frequency in Hz

   -s sample_rate
   Sample rate in Hz

   -b bandwidth
   Bandwidth in Hz

   -g gain
   Gain setting in dB

   -T duration
   Recording duration in seconds

   -d directory
   Output directory (default: current working directory)

   -w window_size
   FFT window size (default: 1024 samples)

   -h window_hop
   FFT window hop size (default: 512 samples)

   -B buffer_size
   Buffer size (default: 16384 samples)

Examples

Record spectrograms for 20 seconds at 95.8MHz using an RTL-SDR:

spectrel -r rtlsdr -f 95800000 -s 250000 -b 250000 -g 30 -T 20

Record spectrograms for 10 seconds at 445MHz, at the maximum sample rate for a Hack RF One (20MHz) into a custom directory:

spectrel -r hackrf -f 445000000 -s 20000000 -b 20000000 -g 20 -T 10 -d ./recordings