Digital Modes

The goal of the QCDC is to bring all current digital modes used on FM to the Springfield metro area and give operators the opportunity to experiment and compare different modes side by side.

We are using a receive antenna at 350' AGL and a transmit antenna at 330' AGL at the 147.015 site. Since all five repeaters will share the same transmit antenna, receive antenna, coax, and location, this creates a true apples-to-apples comparison environment.

To further level the playing field, we sourced five Motorola MTR-2000 100W repeaters aligned to identical power outputs and receive sensitivity. Since Motorola doesn't natively support Fusion, D-STAR, and NXDN, we installed MTR2K MMDVM boards (Multi-Mode Digital Voice Modems) into each chassis — giving every mode identical hardware and the flexibility to switch modes if needed.

A Celwave 8-Port receive multicoupler with a pre-amp and bandpass filter is tuned to the receive antenna. It provides up to eight receive outputs with the filtering needed to prevent transmitter interference, and just enough gain to overcome splitter and filter losses — all five repeater receivers connect to it.