PortSDR: Interfacing with SDR devices

PortSDR is a C++ library for interfacing with SDR devices. It is designed to be simple and easy to use. The library is designed to support many SDR vendors.

Why not use SoapySDR instead?

SoapySDR is a great library for interfacing with SDR devices. However, it is not very easy to use:

• it's a plugin based system.
• It requires compiling/installing a plugin for each vendor you want to use.

PortSDR is meant to be a lot easier to use

Supported Devices

• RTL-SDR (with librtlsdr)
• AIRSPY Mini / R2 (with libairspy)

Building

Dependencies

• CMake
• libusb
• librtlsdr
• libairspy (builds from source if not found)

Building

Ubuntu

sudo apt-get install cmake librtlsdr-dev
git clone 
cd portsdr
mkdir build
cd build
cmake ..
make
sudo make install

API Usage

Opening the first device

#include <iostream>
#include <portsdr/portsdr.h>

int main()
{
    PortSDR::PortSDR sdr;

    // Get the first available SDR device
    const std::shared_ptr<PortSDR::Device> device = sdr.GetFirstAvailableSDR();
    if (!device)
    {
        std::cerr << "There are no devices" << std::endl;
        return 1;
    }
    
    std::cout << "Device: " << device->name << std::endl;
    std::cout << "Serial: " << device->serial << std::endl;
    
    // Open the stream from the device
    std::unique_ptr<PortSDR::Stream> stream;
    
    int ret = device->CreateStream(stream);
    if (ret != 0)
    {
        std::cerr << "Failed to open the device" << std::endl;
        return 1;
    }
    
    return 0;
}

Listing the capabilities of the stream

The stream object allows you to get the capabilities of the device.

GetGainModes is used to get the available gain modes.

GetGainRanges function returns a vector of all gain stages which can be used by SetGain.

GetSampleRates returns a vector of all available sample rates.

GetSampleFormats returns a vector of all available sample formats.

Example usage of the capabilities

int main()
{
    PortSDR::PortSDR sdr;
    
    // Get the first available SDR device
    const std::shared_ptr<PortSDR::Device> device = sdr.GetFirstAvailableSDR();
    if (!device)
    {
        std::cerr << "There are no devices" << std::endl;
        return 1;
    }
    
    // Open the device
    std::unique_ptr<PortSDR::Stream> stream;
    
    int ret = device->CreateStream(stream);
    if (ret != 0)
    {
        std::cerr << "Failed to open the device" << std::endl;
        return 1;
    }
    
    // Print the capabilities
    std::cout << "Sample rates: ";
    for (auto rate : stream->GetSampleRates())
    {
        std::cout << rate << " ";
    }
    std::cout << std::endl;
    
    std::cout << "Gains: ";
    for (const auto& gain : stream->GetGainRanges())
    {
        std::cout << gain.stage << " ";
        std::cout << gain.range.min() << " ";
        std::cout << gain.range.max() << " ";
    }
    std::cout << std::endl;
}

Gain Control

There are two ways to control the gain:

• SetGain(int) which allows you to set the gain of all stages at once.
• SetGain(int, std::string_view) which allows you to freely control gain given a gain stage.

Depending on the device, there are also different gain modes for SetGain(int)

For AirSpy Mini/R2 devices gain modes:

• Linearity
• Sensitivity

SetGainMode is used to set the gain mode.

Example usage of PortSDR::Stream

#include <iostream>
#include <portsdr/portsdr.h>

int main()
{
    // Open the device
    std::unique_ptr<PortSDR::Stream> stream = device->CreateStream();
    
    // Set callback
    stream->SetCallback([](const void *buffer, std::size_t elements)
    {
        // Do something with the samples
    });
    
    // Set the sample rate
    stream->SetSampleRate(2.4e6);
    
    // Set the center frequency
    stream->SetCenterFrequency(100e6);
    
    // Set the gain
    stream->SetGain(20);
    
    // Start the stream
    stream->Start(); 
    
    // End the stream
    stream->Stop();
    return 0;
}

Converters

Some SDR libraries support different sample formats. Some don't. This library contains automatic converters to convert the samples to any format you want.

Automatic conversion

// ... Get the device 

// Open the device
std::unique_ptr<PortSDR::Stream> stream = device->CreateStream();

// Set the sample format to 16-bit
stream->SetSampleFormat(PortSDR::SAMPLE_FORMAT_INT16);

Currently supported formats from SDR vendors:

• RTLSDR: 8-bit (uint8_t), 16-bit (with automatic conversion)
• AIRSPY: 16-bit (int16_t), 32-bit (float)

Goals

• Add more automatic type converters for different SDR devices.
• Maybe use libvolk optionally for SIMD optimizations of automatic converters.
• Add more SDR vendors support.

Remarks

This library was created to be used in my projects.

If the API design has flaws, please let me know. I am open to suggestions.