Abstract: A detonator roll call method wherein each detonator is assigned a unique identifier and, at each detonator, in response to an enquiry signal to all the detonators a count is incremented and compared to the roll call identifier and, if the comparison is positive, a reply is sent by the detonator.

Abstract: The present invention provides a method and apparatus for monitoring a trunked radio communications system by using some type of radio scanning receiver that is not designed for that purpose. In addition, the invention provides a method for automatically determining the polarity of the received control channel data. Further, the invention provides a method for automatically determining the type of trunked radio communications system. In addition the invention provides a method for automatically determining the channels in a trunked radio system and a method for automatically determining the bit rate of transmitted digital signals over a control channel of a trunked radio communications system.

Abstract: An apparatus and method for coupling an automated attendant to a telecommunications system. The apparatus includes a switching device which establishes connection between a plurality of trunk lines of an existing telecommunications system and a plurality of ports of an automated attendant. A switching device of the apparatus is controllable to establish communication between any of the trunk lines and any of a plurality of station line ports that are adapted to be coupled to a plurality of telephone stations, respectively. The apparatus substantially isolates either the switching network or the automated attendant from the AC audio portion of a telecommunications signal based on whether the automated attendant or the switching network is handling the telecommunications signal, and is capable of monitoring the status of the trunk and stations lines to detect for an on-hook condition.

Abstract: A method of detecting and recovering from an out-of-band signaling failure in a telecommunications network involves the reprogramming of switching centers to utilize existent inband signaling capabilities to temporarily replace the failed out-of-band capability. A processor of an originating switching center recognizes the loss of out-of-band signaling capability, determines impacted trunks and switches to in-band signaling from out-of-band signaling. In an alternative embodiment, the switch may use maintenance data bits of impacted trunks to initiate a call. The terminating switching center is programmed to receive and recognize the change in bit value of the signaling data and initiates well known processes to seize the trunk in memory, check continuity and receive dialed number data, preferably in the form of tones, over the seized trunk. The terminal switching center for the trunk then attempts to complete the call in accordance with the received dialed number data.

Abstract: On-hook VF transmission through a channel unit to a subscriber telephone instrument is provided by a control unit which generates control signals for the channel unit. The control unit responds to receipt of an "idle" code by creating commands which establish a VF path through the channel unit regardless of whether the subscriber instrument is on-hook or off-hook.

Abstract: The no balance duplex signalling circuit eliminates the need for setting balance resistors and capacitors to match or be proportional to cable resistance and capacitance as was required of previous duplex signalling circuit designs. A microcomputer is also used to evaluate the output of a simple loop current and voltage sensing circuit to dynamically determine the signalling state of the far end of the trunk conductors. The microcomputer stores a plurality of data which indicate signalling thresholds for all possible duplex signalling states. The microcomputer can then compare the measured voltage and current on the trunk conductors to automatically make a determination of the signalling state based on the stored data indicative of permissible signalling states.

Abstract: Detector for telephone charging signalling in the form of periodic pulses derived from alternating current signals at specific frequencies transmitted in analog form by means of a line (2) comprising two wires (A, B), for example to a central office line interface circuit of a private telephone installation connected to an analog network subscriber line. The detector comprises an input filter (4) centered on the frequency (Ft) of the expected signalling, a sample and hold circuit (6) connected to the output of the input filter (4) and to the output of a clock (7) supplying a signal (HE) whose frequency (FE) is close to the value (Ft), a lowpass filter (8) within the band of which the characteristic signal from the sample and hold circuit is included, and a level detector (9) adapted to supply a presence signal for a characteristic signal at a level above a predetermined threshold at the output of the lowpass filter (8).

Abstract: A DC signalling Detector (DCSD) circuit 10 for processing DC signalling information from a telephony loop. In accordance with the invention the DC signals are processed to indicate, during a first time interval, a tip lead at ground potential, a tip lead at battery potential, and a tip lead disconnected from any potential. During a second interval of time DC signals are processed to indicate a forward loop current, a reverse loop current and the absence of loop current. These six conditions are resolved by the DCSD circuit into two output status lines. The two output status lines are amenable for being input to a controller 2, such as a local microprocessor. The DCSD circuit of the invention thus advantageously combines within one circuit the functionality of a tip voltage detector and a loop current detector.

Abstract: Real-time conversion between two different A/B signal coding schemes based on the DS1 time division multiplex format is achieved by time sharing a programmable state machine. The time sharing is accomplished synchronously with the DS1 superframe such that each of the 24 DS1 channels have signalling translated once every superframe. Programmability of the state machine is facilitated by the use of an EPROM. A RAM is used for real-time storage of signal states, machine states and processor provisioning for each channel, thereby facilitating time sharing of the state machines. Flexibility is provided through the unique use of an EPROM, which can be modified to directly change the signalling translation response depending on the type of telephony service being provided and the coding scheme used for the signalling. Processor provisioning of the RAM selects a service type translation for each of the 24 DS1 channels.

Abstract: An improved DX circuit may be connected to signaling and reference leads of a DX signaling link, without need to balance the internal impedance of the DX circuit against that of the external DX signaling link. The DX circuit senses the magnitude and direction of current flow on the leads, and operates on the principle that when a near end signaling circuit is on-hook, a positive current flow indicates that a far end signaling circuit is off-hook and a current flow of zero indicates that it is on-hook, while if the near end signaling circuit is off-hook, a negative current flow indicates that the far end signaling circuit is on-hook and a current flow of zero indicates that it is off-hook. The arrangement allows the DX circuit to properly function irrespective of the resistive load presented by the DX signaling link.

Abstract: A communication system having remotely controllable signal receiving means for automatically setting the receive function for a start-signal transmitted from a terminal device and for changing the receive function when the terminal device is changed. At start-up, a main processor reads start-signal type information for each of the terminal devices from a main memory. The line circuits associated with the respective terminal devices are then set with a start-signal receive function according to the start-signal type information. When a terminal device is added or changed, the start-signal receive function is changed by merely updating the start-signal type information stored in the main memory.