Electrical Engineering/Mobile Phone Signal Reception from Underground Areas.
Dear Prof Cleggsan
1. Are there limitations for Mobile Phone Signal Transmission/ Reception from Underground Areas viz Tunnels, Coal, Oil Mines, Wells etc ?.
i.e. 20 feet, 50 feet, 125 feet, 150 feet below etc
2. Can there be any methods to boost the Mobile Phone Signal reception so that the underground worker/s may be able to communicate with their wireless devices ?.
3. What are the communication channels modes for underground manpower viz to communicate with office workers on ground level ?.
Using the elevator/lift to travel up and down the ground level
could be the only solution for communication ?.
4. Can Walkie - Talkie (two way radio communication) device work
in Underground areas ?.
Awaiting your reply,
Thanks & Regards,
Prashant S Akerkar
1. It is much depending on frequency of service, distance from main transponders, repeaters or transmission equipment as well as the receiver sensitivity. Some are operating up to 1/2 mile some only a few feet.
2. Yes, repeaters are used in places like long tunnels; i.e., New York City Lincoln tunnel.
3. There are certain radio frequencies for fire, police, emergency, etc. for use in tunnels, bridges and tall buildings.
4. Two way radios answers are similar; function of the frequencies being employed, power level, location of transceivers, etc. etc. Each country has its own authorization for commercial usage where police, government authorities, construction workers, emergency vehicles, etc. must have reliable communications in protected and controlled areas.
There are many places for you to research these frequency assignments, equipment, authorizations and so forth but it is country specific and region specific in large part.
Happy hunting; a rich area for you to explore.