sdr-modem

Modem based on software defined radios.

Design

Features

• TCP-based
• Custom binary protocol based on protobuf messages.
• Supported modulation/demodulation:
  • GMSK
• Supported SDRs:
  • sdr-server
  • plutosdr
  • file
• Misc:
  • Doppler's correction for satellites using SGP4 model
  • Save intermittent data onto disk for future analysis/replay

API

• Defined in the api.h
• And in the api.proto

Configuration

Sample configuration with reasonable defaults:

https://github.com/dernasherbrezon/sdr-modem/blob/main/src/resources/config.conf

Dependencies

sdr-modem depends on several libraries:

• libvolk. It is recommended to use the latest version (Currently it is 2.x). After libvolk installed or built, it needs to detect optimal kernels. Run the command volk_profile to generate and save profile.
• libconfig
• libprotobuf-c
• libz. Should be installed in every operational system
• libm. Same
• libiio for plutosdr SDR (Optional)
• libcheck for tests (Optional)

All dependencies can be easily installed from r2cloud APT repository:

sudo apt-get install curl lsb-release
curl -fsSL https://leosatdata.com/r2cloud.gpg.key | sudo gpg --dearmor -o /usr/share/keyrings/r2cloud.gpg
sudo bash -c "echo \"deb [signed-by=/usr/share/keyrings/r2cloud.gpg] http://apt.leosatdata.com $(lsb_release --codename --short) main\" > /etc/apt/sources.list.d/r2cloud.list"
sudo bash -c "echo \"deb [signed-by=/usr/share/keyrings/r2cloud.gpg] http://apt.leosatdata.com/cpu-generic $(lsb_release --codename --short) main\" > /etc/apt/sources.list.d/r2cloud-generic.list"
sudo apt-get update
sudo apt-get install libvolk2-dev libprotobuf-c-dev libconfig-dev check libiio

Build

mkdir build
cd build
cmake ..
make