ONTRACK, the Government organisation responsible for managing New Zealand’s rail network, owns and operates a nationwide radio system to facilitate safe movement of trains and track workers around the country. The system, which was installed in the early 1980’s, has had no major upgrades and consists of 148 hilltop and tunnel VHF repeaters, interlinked by a series-connected narrowband UHF network to a National Train Control Centre (NTCC) in Wellington.
In a bold move to improve system reliability and flexibility whilst at the same time providing a platform for mobile data capability, ONTRACK have embarked upon a major upgrade to this system. VHF analogue radio is to be retained for voice and data communication from the hilltop to the train due to its excellent coverage properties, however in a radical side step from tradition, the existing UHF linking infrastructure is to be replaced with an IP network. This will require installation of radio over IP (RoIP) conversion equipment at each repeater site throughout the North and South Islands.
ONTRACK considered several RoIP solutions from around the world before selecting Xworks to develop a custom solution for them. The result of this development effort is the ORC400 four-channel RoIP device. The ORC400 provides many functions specifically required by ONTRACK, including:
- Bandwidth efficient G.729A audio compression
- Integrated Selcall and CTCSS encode/decode
- Mobile radio data interface
- Serial control and diagnostics of Spectra Engineering MX800 base station radios (Channel, Forward/Reverse Power, RSSI, Temperature etc)
- Local I/O for site monitoring, control and diagnostics
- Integrated gigabit Ethernet switch
- Extensive front panel diagnostic capabilities
- Remote management via SNMP and web browser
The result is a fully integrated, vendor neutral RoIP solution that can be managed and controlled remotely from the NTCC. The benefits of the system include:
- Ability to remotely monitor the entire radio network
- Ability to remotely reconfigure the radio sites (including radio channel and power settings)
- Automatic diagnostic reporting for both the radio and IP network systems
After rigorous on-site testing, ONTRACK Chief Radio Engineer Trevor Pollock says “The ORC is loaded with every conceivable feature for operating a mobile radio system over an IP network. The voice quality is amazing and it’s a real miser on IP bandwidth.”