Centralized data communications system incorporating a plurality of remote stations (11), each having a plurality of information channels (10) associated therewith. A selected remote station and its associated information channels are tone addressed by a central station (23) communicating with a group of remote stations over a respective communications channel (12). The remote stations (11) may have a current sensor (210) connected to one of the information channels for sending data corresponding to the amount of current sensed in an electrical path (212) back to the central station (23) upon being properly addressed. This data, together with data representative of the voltage on the monitored electrical path, is used by the central station to calculate energy consuption. The calculated energy consumption is retained at the central station (23) and used for information and billing purposes. The central station may also send data to an addressed information channel (10) at a remote station for controlling an operation thereat. The central station (23) can also receive data from various parameter measuring sensors (47) at a remote station, e.g. sensors measuring temperature, humidity, fluid flow, etc. which may be connected to other information channels (10) and thus the system may be used as a general purpose data gathering or distributing communications system.

Computer controlled energy monitoring system

In an exemplary communications system a multiplicity of mobile terminals are to share a communications link with a primary processor. The primary processor may transmit a multiterminal polling signal defining a series of successive response time slots which the terminals may randomly select. A terminal wishing to send a message transmits a brief response burst in the selected time slot giving its identification. The primary processor may then sequentially poll specific individual terminals having messages to send. The primary processor may maintain a record of currently active terminals and/or of collisions (where more than one terminal seeks to transmit in the same response time slot), and as needed may automatically send e.g. with its multiterminal poll, a time slot number change, creating a greater or lesser number of time slots for future use by the active terminals. The system is thus highly adaptable on a dynamic basis during operation so as to readily maintain optimum throughput under changing conditions. As a consequence additional terminals may become active simply by transmitting their respective identifications in randomly selected response time slots. The multiterminal poll may include a listing of one or more terminals for which the primary processor has a message so that the primary processor may be assured that such terminal is available (as indicated by its response in a random time slot) before a lengthy message is sent.

Multiterminal communication system and method

Tis method provides high utilization collision free access to a digital pulse communications medium with priority provided by message class and/or terminal type, regardless of network topology. This is accomplished by utilizing a controller which broadcasts a series of polling frames to all terminals, the response to each of which is a single bit (pulse) from any terminal remaining eligible to respond. All responses to a poll are logically OR'ed by the network to provide a combined response frame at the controller, thus making the process ambivalent to collisions. A polling frame and associated response frame, called a polling cycle, determines one digit of a selected address. A terminal not selected in a given cycle is blocked from responding further, until its high order digit(s) are again selected. Each polling cycle is therefore context sensitive, thus maximizing the information flow per poll and minimizing data flow and network travel time per terminal selection. Each polling frame specifies the value of the address digit being tested, thereby giving the controller complete control of priority of network addresses to receive service. To provide priority by message class, the additional message class bits are prefixed to each terminal address, providing a unique address for each terminal/message class combination. Each terminal is then free to modify the prefix of its own address to specify message priority.

Method of polling to determine service needs and the like

A downlink between a communications dispatch console and a digitally trunked radio repeater system site controller efficiently transfers message data between the site controller and the console over a standard 9.2 kilobit per second landline. A downlink trunking card identical in structure to trunking cards used in the preferred embodiment system for RF channel signal processing interfaces the site controller with the landline link. A similar trunking card on the other side of the landline link interfaces the dispatch console processor with the landline link. Message protocol and format is translated between the site controller and the landline link and between the landline link and the dispatch console. Data buffering at each end of the landline link maximizes data transfer rate over the landline, and in addition, a priority scheme insures that more important messages are transmitted over the downlink before less important messages. Retransmit-until-acknowledged protocol is used to insure reliable message transfer--and also to permit receiving units along the downlink to slow down transmitting units in order to avoid message traffic blockage.

Processor-to-processor communications protocol for a public service trunking system

Channel efficiency in a communications link between a controller and multiple portable units is increased by polling the active units and a set number of inactive units in a sequence where a "poll" consists of sending the binary coded address of the portable unit. The stream of transmitted data bits is only interrupted by a response from the portable unit, then resumed at the end of the response or a given portion of the response. During the reception of the response, certain other types of messages can be sent out by the controller. Portable responses can be automatic responses as to status, etc., or can be data initiated by the operator of the portable unit keyboard and stored in the portable unit memory until "armed" by the operator, then automatically transmitted to the controller when the portable unit address is received.

Polling system for a duplex communications link

MULTIPOINT POLLING TECHNIQUE Abstract of the Disclosure A multipoint polling system wherein a multipoint switch selectively connects a plurality of remote terminals to a central station in response to remote terminal addresses transmitted on a signaling path to the multipoint switch. Polling apparatus stores portions of a remote terminal address list provided by the central station and transmits individual ones of the stored remote terminal addresses on to the signaling path. The polling apparatus periodically requests different portions of the remote terminal address list and replaces the stored remote terminal address portion with the requested remote terminal address portion. The multipoint switch is advantageously comprised of a plurality of sections with each section of the switch responsive to a portion of the address list for establishing a signaling path between the central station and selected ones of the remote terminals defined by the address list portions. The failure of a multipoint switch section to respond to remote terminal addresses results in the address list portion normally transmitted to the failed section and the address list portion normally transmitted to a remaining active section being transmitted to the active section whereby the active section polls the remote terminals previously polled by both the failed and active sections.

Multipoint polling technique

Clocking signals are recovered from an incoming signal train by a master clock oscillator phase locked to the incoming signals and, in the event of failure of the master clock, by a standby clock similarly phase locked to the incoming signals. When an outage of the incoming signal is detected, or when it is presumed that the incoming signals are being improperly received, both clocks are unlocked from the incoming signals and the standby clock is phase locked to the output of the master. If there is subsequent phase slippage of the standby, it is unlocked from the master and both clocks run free. In one operational sequence, both clocks are again phase locked to the incoming signals if signal reception is restored.

Protection scheme for clock signal recovery arrangement

Clocking signals are recovered from an incoming signal train by a master clock oscillator phase locked to the incoming signals, and, in the event of a failure or malfunction involving the master clock, by a standby clock similarly phase locked to the incoming signals. One of the malfunctions occurs when the phase of the clock output slips a cycle with respect to the phase of the signal train. It is determined that a cycle slippage condition exists when phase comparisons of the signals indicate the clock output is passing from a phase lag error to a phase lead error, or vice versa, without passing through a region of no phase error.

Orlando Napolitano

Papers

Multipoint polling technique

Protection scheme for clock signal recovery arrangement

Detection of cycle slippage between two signals