My repeater projects fall into five categories:

  1. FPGA based hardware, state machines and additions
  2. 900MHz repeaters.
  3. USRP based dynamic digital linking.
  4. Telemetry configuration, gathering and automation.
  5. Messaging

FPGA Based hardware and state machines

The basic FPGA control hardware has been realized on three platforms: the first using an off the shelf FPGA evaluation board for prototyping, and the second using a custom HAT board for the Single Board Computers (SBC) adopting the raspberry Pi HAT standard.

Sadly the second platform had to be abandoned as FPGA has shot up in price and is virtually unavailable and so is the raspberry Pi. Instead, we are adopting the Odroid C4, which outperforms it and the FPGA has also been replaced with one more reasonably priced and available. There is no A/D on chip so that has functionality has been replaced by the standalone PUTSI project.

A unique ‘topHAT’ architecture was designed that enabled a second addition of other modules such as:

  • C4FM transceiver
  • 900/2400 MHz transceiver with programmable I/Q
  • Second Analog port
  • Quad Analog port
  • Buffered Digital I/O

900 MHz Repeaters

The prototype hardware was deployed on one repeater, VE6NHM on the 900 MHz band. It executed the basic state machine for PTT control, timeouts and CW identification, but required an external device for remote updates and programming, this was accomplished using a Raspberry Pi 2 and cable to the JTAG interface on the board.

The Pi HAT phase 1 integrated all the software and hardware together into a single HAT board, and added an 8-channel interface to the on-chip analog to digital converter on the FPGA. This was deployed on VE6NHM and VE6CQM.

The Pi HAT phase 2 implemented the AllstarLink software on the Raspberry Pi, with a custom channel driver for the Pi HAT hardware. This added more feature to the platform and ability to link other systems using the web-based liking platform.

Phase 3 is in development adding a second port and dabbling more in the Asterisk and MMDVM world. Yet to be deployed.

USRP based Dynamic Digital Linking

The digital repeater linking project has four aspects:

  1. Drivers. A custom channel driver for AllstarLink that implement a full implementation of the USRP protocol, with programmable talk groups for remote steering.
  2. Configuration. Web-based software for configuring bridges and adding peers to them. This was written in the java language and deployed on the Apache Tomcat platform.
  3. Hubs. Hub software that makes the connections and performs the traffic routing.
  4. Format Conversion. Software available from other projects to convert to formats such as DMR, YSF and M17.

Telemetry

The telemetry project also has five aspects:

  1. USB-based interface board realized on a PIC microcontroller (PUTSI).
  2. Interface to Allstar to replace extinct chameleon device.
  3. Web based software for configuration and display.
  4. Alarm monitoring and reporting.
  5. Automation to respond to alarm conditions.

Messaging

Messaging is a future project that will extend the ability to send alarms, SMS messages and other data to a mobile station, as well as report GPS coordinates using an ESP8266 interface platform and a TK981 transceiver. The interface has been built and tested, but not yet deployed to a repeater.