This repository contains source code for hl2_tcp, a rtl_tcp server for Hermes Lite 2 SDR radio.

The Hermes-Lite is a low-cost direct conversion software defined amateur radio HF transceiver based on the AD9866 broadband modem chip, an Altera Cyclone IV EP4CE22 FPGA, and the HPSDR/Hermes SDR project.

The hl2_tcp server can connect to a Hermes Lite 2 SDR via UDP over ethernet, transcode received RF IQ samples, and then serve that data via the rtl_tcp protocol.

rtl_tcp is a command-line tool developed by OsmoCom and others, for various Realtek RTL2832-based DVB-T USB peripherals, to serve IQ samples from those USB devices over TCP. There are multiple SDR applications, available for Linux, macOS, or Wintel systems, that can connect to a local or remote SDR radio peripheral via the rtl_tcp protocol. This server allows using those SDR applications with a Hermes Lite 2 SDR, but only if the application supports the HL2 sample rates (48k, 96k, 192k, and 384k). Among the SDR applications supporting those sample rates are the iOS and macOS apps: rtl_tcp SDR and SDR Receiver, allowing HL2 SDR reception an iPhone, iPad, or Mac.

Usage:

hl2_tcp -d

Discovers Hermes Lite 2 IP Address. Prints random diagnostics.

hl2_tcp -a Hermes_IP_Addr [-p tcp_server_port] [-b 8/16]

Starts a server for the rtl_tcp protocol on a local TCP server port (default rtl_tcp port 1234) and waits for a TCP connection. Upon opening an rcp_tcp TCP connection, starts a UDP connection to the Hermes Lite 2 at Hermes_IP_Addr on UDP port 1024, and transcodes OpenHPSDR/Metis UDP data to rtl_tcp TCP data. Also prints more random diagnostics.

Important note: Under macOS Catalina 10.15.7 or later, or macOS Big Sur, this server may need to be installed and run from an Admin account, due to new macOS firewall security/privacy features.

More information on the Hermes Lite 2 can be found on this web sites: Hermes-Lite2 wiki

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rhn@nicholson.com
N6YWU
http://www.nicholson.com/rhn/

License: MPL 2.0 with exhibit B
No warrantees implied.

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