Thank you to Sarah Rose Giddings for submitting news about the release of one of her latest software programs called "rtl_tcp_echo". This “man-in-the-middle” application enables you to simultaneously monitor and record signals of interest, then replay the captured IQ data at a later time using software compatible with rtl_tcp.

The software is compatible with Linux, and Sarah notes that a Windows build will be available soon.

RTL_TCP_ECHO is a Go application that acts as a proxy between an rtl_tcp server and its client. It transparently passes control commands (such as frequency, gain, and sample rate), forwards IQ data, and records the IQ stream to a file. Later, you can run the application in playback mode, serving the recorded IQ data as a fake rtl_tcp server—allowing SDR software to connect and replay the IQ stream.

Features

• Proxy Mode:
  Forwards all rtl_tcp commands (including frequency and gain) and IQ data between client and server. Simultaneously records IQ data to a file.
• Playback Mode:
  Serves a previously recorded IQ file as an rtl_tcp-compatible server for SDR software to connect and decode.
• Transparent Command Handling:
  All client commands (frequency, gain, sample rate, etc.) are passed through with optional logging.
• Simple Configuration:
  Easily specify listen/forward addresses and recording/playback file paths via command-line flags.