A PIC-Based Repeater Controller

GB3GD is controlled by a custom-built module designed by GD4HOZ.

The design was originally created for the GB3LD repeater operated by the South Lakeland Repeater Group.

Features:

• CTCSS TX tone generation
• DTMF remote control of various parameters
• 1750Hz tone detection
• In-Band tone generation (CW, cue beeps etc)
• Talkthrough audio gating
• Raynet (Carrier access) mode
• Various test modes

And all in the space of 3 (Yes, three) IC's.

The heart of the system is a PIC16C74 microcontroller. Peripheral to this are a DTMF decoder and a CML FX828 CTCSS/Selcall CODEC. Status information is provided on an intelligent LCD module

This design makes the FX828 do things for which it was never intended, but it does them rather well!