Signal Post Telephone System
For Magneto Telephones
The Home Signal Telephone System is a reliable and convenient wired link for the station master to communicate with outdoor crew and drivers of arriving trains. It also enables the station master to monitor the sounds of running trains and activity at the outdoor location.
The system consists of two devices; an outdoor unit known as a Signal Post Telephone or SPTand it's indoor pair called the Station Master's Console or SMC.
Handsets are not used at either unit. Voice is conveyed by loud-speaker - microphone. The communication system is semi-duplex.
A single pair of dedicated wires between the two units suffices for all functions of the system and power supply of 12 Volts DC is required only at the SMC.
The SMC is a robust and ergonomic desk-top or wallhanging set. It provides push-button controls for calling, monitoring and speaking.
The SPT is housed in a thick powder-coated steel tube that mimics the tube of the signal post on which it is mounted at a height of about two meters. It is vandal resistant and can be exposed to a wide temperature range, heavy rain and dusty wind. All openings are situated below the unit to prevent the ingress of rainwater .Insects are kept out by a stainless steel wire mesh.
The outdoor user, such as the train driver or maintenance crew can stand next to it and converse with the station master by speaking into the funnel shaped opening below the unit. Speech from the station master emerges from a loud-speaker through the same opening.
A push button mounted below the set operates a micro-switch to CALL the SMC. This is the only control on SPT the and all it’s other functions are commanded remotely by the SMC.
Conversation through the SPT is entirely hands-free and it does not require any local power supply. .
Calling: When the train driver presses the CALL button below his SPT, the SMC will begin to ring, alerting the station master. Simultaneously, the SMCwill send back a tone to the SPT, assuring the driver that ringing is taking place at the other end. Similarly, if the CALL button on the SMC is pressed, a loud tone radiates from the SPT.
Monitoring: A Press-To-Talk or PTT button is provided on the SMC. With this control the station master can talk to or listen to the driver. The driver has no control. He can walk away after conversation without operating any switch or control.
Speech: If his SMC is left in the ON condition, the station master can listen to sounds from the vicinity of the SPT. Movement of trains, personnel and attacks by vandals can easily be identified.