Using a Red Pitaya as an SDR: Boards, Software, and Setup

Yes—a supported Red Pitaya can act as an SDR. Its analog input feeds an ADC, FPGA logic converts sampled signals into I/Q data, and host software such as GNU Radio, SDR#, or HDSDR handles the radio functions. The exact board and application matter: Red Pitaya documents a 0–60 MHz tunable range for its SDR transceiver, but a separate receiver application is documented for 0–50 MHz. Check your model against the official compatibility table before setting up a system.

How a Red Pitaya works as an SDR

On receive, connect an antenna to a Red Pitaya analog input. The ADC digitizes the signal; FPGA logic performs digital I/Q down-conversion; and the board sends I/Q samples to software running on a computer. The host application then displays or processes the received signal.

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In the documented SDR transceiver application, the receive path uses an FPGA I/Q down-converter and the transmit path uses an I/Q up-converter. The application supports two receivers and two transmitters. Those are application capabilities, not a guarantee of a particular receiver sensitivity, transmit power, or performance across the entire tuning span.

Check whether your Red Pitaya model supports SDR

Compatibility depends on the board model and generation. Red Pitaya’s supported features and apps by model table distinguishes between models that support SDR, those where it is unavailable, and those marked unsupported.

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Converter sampling rate and bit depth describe digitization, not measured sensitivity, linearity, dynamic range, spurious-free range, safe RF input level, or transmit output power. The cited documentation does not provide comparable bench measurements for those properties.

Choose the software path for your use

GNU Radio Companion

Red Pitaya’s SDR transceiver documentation provides a GNU Radio starting point using an AM transceiver flowgraph. Its documented sequence is:

1. Connect an antenna to the board’s IN1 input.
2. Open the SDR Transceiver application on the Red Pitaya.
3. Install GNU Radio on the host computer.
4. Clone Pavel Demin’s Red Pitaya Notes repository and open the AM transceiver flowgraph in GNU Radio Companion.

Use the repository and flowgraph identified in the Red Pitaya SDR applications guide; the guide is a starting configuration, not evidence that every operating-system and software combination will work unchanged.

SDR# or HDSDR with ExtIO

The same guide describes using SDR# or HDSDR with a pre-built ExtIO plug-in. Install the host program and plug-in, select Red Pitaya as the source, enter the board’s IP address, and start the stream. The guide gives a 122.88 MSPS setting in that client procedure; treat it as specific to the documented configuration rather than a universal setting for every board or application.

HPSDR-compatible applications

The official OS also documents HPSDR-compatible transceiver and receiver applications. The receiver mode emulates one Hermes module with eight receivers on STEMlab 125-14, and two Hermes modules with eight receivers each on SDRlab 122-16. Compatible clients belong to third-party HPSDR/Metis software families. Red Pitaya says it does not maintain these programs and warns that their developers may no longer maintain them, so confirm a client’s compatibility and status before building a workflow around it.

Know which frequency range and sample rates apply

Red Pitaya’s SDR transceiver documentation gives a tunable range of 0–60 MHz. It lists these I/Q data-rate choices:

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A separate Red Pitaya Learn page for the SDR Receiver describes a 0–50 MHz tunable range and I/Q rates of 50, 100, 250, and 500 kSPS. These figures belong to that receiver application; they should not be combined with the transceiver specifications as if they were one shared configuration.

Account for the analog interface and RF setup

Board-level analog characteristics can affect the frequencies you can acquire or generate. Red Pitaya’s data acquisition and generation introduction specifically notes AC-coupled inputs and outputs on SDRlab 122-16, which can limit acquisition and generation frequency range. Check the documentation for your exact board and the requirements of the signal you intend to receive or transmit.

The documented setup calls for an antenna connected to an analog input, but the cited sources do not prescribe a universal antenna, connector, band filter, attenuator, or protection network. Choose the RF interface for your frequency band and signal conditions rather than assuming the board input can be connected safely to any antenna or RF source.

What the published specifications do—and do not—tell you

The stated tuning spans and converter figures are useful for deciding whether a board and application are a plausible fit. They do not establish equal practical performance throughout the range or a performance advantage over a dedicated SDR. In particular, the cited specifications do not establish receiver sensitivity, RF input limits, transmit power, or the authorization required to transmit. Do not infer those from ADC or DAC resolution.

A Red Pitaya-hosted paper describes a low-cost prototype with a nominal 50 MHz RF input/output bandwidth, but reports that only part of the transmit chain was implemented and demonstrated. That is a research prototype, not a requirement or performance guarantee for the standard SDR transceiver application. See Red Pitaya based low-cost SDR platform.

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