Communications system

A telemetry system including at least a single remote station capable of responding to controls originating at mutually independent locations, said remote station including a receiver and an out ut module controlled by said receiver for making received data available for controlling utilization apparatus,

• said output module including a tri-level gate operable to three distinctive conditions,
• said output module having two inputs for controlling said tri-level gate,
• a first input connected to be responsive to said receiver, said tri-level gate operative to two of said three distinctive conditions depending on said first input, and
• a second input for controlling said tri-level gate to its third distinctive condition.

A telemetry and control system including a plurality of field stations responsive to data respresenting control signals transmitted over a transmission channel which is adapted to selectively provide constant control signals or control signals or predetermined duration comprising,

• a receiver connected to said transmission channel, first and second memory means each with a plurality of locations and transferring means
• controlled by said receiver, said first memory means connected to said receiver for storing data received thereby,
• said transferring means transferring said data from said first memory means to said second memory means a first predetermined time after receipt of said data,
• and means for clearing selected locations of said second memory means a second predetermined time after operation of said transferring means,
• whereby said selected locations may provide outputs of second predetermined time duration and unselected locations may provide constant outputs.

A telemetry and control system including a master station and a plurality of field stations interconnected by a single duplex communication link in which field stations transmit to said master station in response to reception of messages from said master station, an improvement for disabling a transmitter at a field station to prevent such transmitter's failure from preventing transmissions by other field stations comprising:

• a master station with a transmitter and receiver,
• a plurality of field stations each with a transmitter and receiver,
• said master station transmitter coupled to field station receivers and said field station transmitters coupled to said master station receiver over said single duplex communication link,
• means at each field station, responsive to reception of a transmission directed to it, to enable said field station's transmitter,
• timing means at each said field station coupled to said means for enabling and reset by said means for enabling, said timing means timing out a predetermined period and thereafter becoming set in absence of a resetting signal within said predetermined period, and
• alarm means at each said field station, energized by said timing means, when set to disable said field station's transmitter,
• whereby failure of a field station transmitter in a transmitting condition is cured, after said predetermined period by disabling said failed transmitter.