MCA1000 VHF System

Minecom Leaky Feeder

Pyott-Boone Electronics, as the master U.S. distributor for Minecom, products offers the MCA1000 VHF leaky feeder system providing Full Duplex Voice and Data communications. The MCA1000 operates in the 150 to 174 MHz frequency range with 2.5Mhz of TX bandwidth and 2.5Mhz of RX bandwidth. The system is available as MSHA approved under # 23-A090003-0 for operation in hazardous or explosive mine environments.

The Minecom system is flexible for adaptation to any mining or non-mining application. The down line distribution system is easily changed, expanded, or adapted by the customers trained electrical staff as the operation grows. Minecom leaky feeder communication systems are also capable of providing ‘mine - wide’ radio communications in excess of 60 miles of underground mine entries. In fact, wherever you run Minecom’s leaky feeder cable to our specifications, we guarantee voice and data coverage. Multiple systems can be networked to cover hundreds of miles or multiple sites.

HEAD END

The Head End can be located either on the surface (required in U.S. Coal mining) or underground, however it is recommended that the Head End be centrally located if underground for increased survivability. The ‘Heart and Brains’ of the system is the ‘Head End’ (VHE) and along with the voice and data radio repeaters; optional components such as video distribution units, telephone interface, PBE Page Phone Coupler, etc.; rack power supply; and stand-by batteries is mounted in a standard 19” rack cabinet. The Head End supports up to four leaky feeder output ports for redundancy and economy; a fault in one leaky feeder leg will have no effect on the other legs. Front panel switches are provided to enable mine staff to switch the DC power on/off to each leaky feeder cable leg to assist with fault finding and allow staff to log voltage levels & current drain etc. Additionally the rack includes a circuit breaker panel with breakers for all major devices located inside the rack.

LEAKY FEEDER DEVICE CONNECTIONS

All Minecom devices offer standard N type RF connectors or Minecom’s proprietary leaky feeder electrical style terminal & saddle connections depending on the type of leaky feeder cable used. The Minecom cable connection method allows for easy assembly underground, without the need for specialized training, tools or skills.

AMPLIFIERS

Minecom offers a wide range of Bi-Directional Amplifiers in various voltage ranges for standard and intrisincally safe applications to carry both Voice & Data. The amplifiers are necessary to overcome signal losses incurred as the radio frequencies progress along the leaky feeder cable, pass through a branch, etc. The normal distance between amplifiers is an entire roll of cable or 1640FT (500m) unless there is a branch, voltage barrier or power coupler in-line between that distance. If those devices exist the amplifier spacing is reduced to compensate. Amplifiers are down line powered by 48 VDC (non-coal mining only) with MSHA approved units using 24VDC for normal operation and a 96 hour, 12 VDC battery pack called the Model 1955 to supply intrinsically safe power.

DIAGNOSTICS

All MineCom amplifiers have ultra bright diagnostic LED’s that can be easily seen from a distance. Drive-By- Diagnostics® amplifiers indicate ALC operation, DC voltage level and operating status. Minecom amplifiers were specifically designed for the transmission of high speed Data. They feature ALC (Automatic Level Control) circuits to overcome signal level changes, as well as over coming variances in the distance between amplifiers. They also offer a high level of sideband immunity, as well as a high level of immunity from external noise.

OTHER DEVICES

In line devices like single or dual branch units are used to provide coverage off the main line with a single branch for ‘T junctions’ and a dual branch for ‘X junctions’. Other components such as termination boxes ensure the correct standing-wave-ratio (VSWR) along the cable at each, joiner boxes are used to reconnect cable breaks, and the power coupler works in conjunction with any PBE power supply.

VOICE COMMUNICATIONS

There is a large variety of third party two-way voice communications equipment including Talk-Through-Repeaters, Base Stations, Handheld Portables, Vehicle radios, Fresh Air Base radios and Desktop radios that work with the Minecom leaky feeder system. Additionally radio to telephone and radio to pager phone interfaces for one or more voice channels can be connected in the rack. The PBX interconnect unit provides the interface between a base station radio and standard PBX extensions in the mine, telephone calls can be made to offsite PSTN or GSM telephone numbers if enabled from radios that feature numeric keypads. Third party audio bridges are useful for connecting multiple repeaters or interfaces together either for day to day use and often enhance our systems as an emergency situation feature.

DATA COMMUNICATIONS

Once the basic leaky feeder infrastructure is installed it is easy to add data to the system to provide telemetry for monitoring and control including pumps, fans, sub stations, etc. Third party data radio modems can be used to transfer data at baud rates of up to 28.8 Kbps and generally connected to any piece of equipment that has an RS232 / 485 port as either half duplex or full duplex communications.