Multipoint data communication with a supervisory system for detecting a malfunctioning remote station

Claim 2

A random access multipoint data communication system having a central station, a plurality of remote stations and means for establishing a multiple access channel from each of said remote stations to said central station and a broadcast channel from said central station to said remote stations, wherein said central station comprises means for generating a timing signal for causing each of said remote stations to define commonly shared time slots on said multiple access channel, and wherein each of said remote stations comprises means for transmitting data on a randomly determined time slot of said multiple access channel, said central station comprising means for periodically and sequentially transmitting an interrogating signal to said remote stations to cause each of the remote stations to return an acknowledgment signal to said central station and means for processing the received acknowledgment signal to determine the presence of a trouble in any one of said remote stations, each of said remote stations comprising means for transmitting said acknowledgment signal in response to said interrogating signal.

Claim 3

A random access multipoint data communication system as claimed in claim 1, wherein said central station includes means for specifying one of said time slots and transmitting a signal indicative of the specified time slot together with said interrogating signal to said remote stations and wherein each of said remote stations includes means for transmitting said acknowledgment on said specified time slot.

Claim 4

A random access multipoint data communication system having a central station, a plurality of remote stations and means for establishing a broadcast channel from said central station to said remote stations and a multiple access channel from said remote stations to said central station: said central station comprising means for transmitting on said broadcast channel a series of frames each containing information on the status of time slots on said multiple access channel and a series of data slots, and means for inserting a message destination address and a message signal into said data slots and inserting a supervisory destination address and a supervisory polling signal into said data slots at periodic frame intervals; and each of said remote stations comprising means for defining said time slots on said multiple access channel in accordance with a timing signal contained in said transmitted frames, means for randomly selecting one of said defined time slots in accordance with said status information when there is a need to transmit a message signal, means for transmitting a message signal on said selected time slot, means for detecting a coincidence between said message and supervisory destination addresses and the address of the own remote station, means for processing the message signal if the message destination address coincides with the address of the own remote station, means for detecting said supervisory polling signal if the supervisory destination address coincides with the address of the own remote station and means for inserting a supervisory acknowledgment signal into one of said time slots in response to the detection of said supervisory polling signal, said central station including means for processing the transmitted supervisory acknowledgment signal to determine the presence of a trouble in any one of said remote stations.

Claim 5

A random access multipoint data communication system having a central station, a plurality of remote stations and means for establishing a broadcast channel from said central station to said remote stations and a multiple access channel from said remote stations to said central station: said central station comprising means for transmitting on said broadcast channel a series of frames each containing information on the status of time slots on said multiple access channel and a series of data slots, and means for inserting a message destination address and a message signal into said data slots and inserting a supervisory destination address and a supervisory polling signal into said data slots at periodic frame intervals; and each of said remote stations comprising means for defining said time slots on said multiple access channel in accordance with a timing signal contained in said transmitted frames, means for randomly selecting one of said defined time slots in accordance with said status information when there is a need to transmit a message signal, means for transmitting a message signal on said selected time slot, means for detecting a coincidence between said message and supervisory destination addresses and the address of the own remote station, means for processing the message signal if the message destination address coincides with the address of the own remote station, means for detecting said supervisory polling signal if the supervisory destination address coincides with the address of the own remote station and means for inserting a supervisory acknowledgment signal into one of said time slots in response to the detection of said supervisory polling signal, said central station including means for processing the transmitted supervisory acknowledgment signal to determine the presence of a trouble in any one of said remote stations.

Claim 6

A random access multipoint data communication system as claimed in claim 3, wherein said central station comprises means for specifying one of said time slots on said multiple access channel and inserting the identifier of the specified time slot into said data slots together with said supervisory polling signal, and wherein each of said remote stations comprises means for inserting said supervisory acknowledgment signal into said specified time slot.