A differential transceiver transmission line integrity detector detects both open and short circuits in the transmission lines (12,14). The two transmission lines are terminated at both ends by selected impedances. A driver (30, 32) coupled to each of the transmission lines drives the lines with data signals. Signal levels on the lines are detected and compared with expected levels to generate line integrity indications. Both open and short conditions are detected and indicated by the line integrity indications.

Differential transceiver with line integrity detection

A line powering system for a multi-channel communication system is disclosed having a central office or primary communication terminal configured to communicate with one or more remote locations via two or more communication lines. Line powering, from the primary location to the remote location, is provided by a power supply, which is selectively connected to one or more of the lines via a switching module. Line monitoring and switch control may occur automatically or by a controller. A ground fault detector is provided to monitor for excessive ground fault current and selectively disconnect the faulted line. A rapid line voltage discharge module is provided to discharge line voltage to meet specification.

Line powering in a multi-line environment

An apparatus for testing a data multiplex transmission system by providing simulated source and sink of data for the multiplex transmission system that is compatible with the multiplex system and complies with the protocol of the Input/Output modules of the multiplex system. A programmable read only memory is programmable by means of toggle and thumbwheel switches to selectively and variably control the protocol, the length, the rate, the destination and the content of the data message. A status display is connected to the programmable read only memory to indicate the current point of progression of its programmable sequence. An error detector is connected to the programmable read only memory for determining whether the memory has stalled at a point of progression and an error display is also connected to the programmable read only memory to indicate and identify the error when this stall condition has occurred. A random access memory is included in the apparatus for storing the data received by it and a display is provided for displaying the contents of the random access memory.

Multiplex system tester

Drop-outs in a data read channel having one or more controllable elements are managed A data read channel derives a signal having at least one drop-out characterising parameter from which data are to be recovered The signal from the data read channel is tapped and compared with at least one drop-out characterising parameter of the tapped signal with two or more thresholds to categorise the drop-out One or more elements of the data read channel is controlled in response to the category of the drop-out

Drop-out management system and method

The method involves evaluating the regular, sequential sequence of null symbols (2) as synchronization information on receiving the digital radio signal (DAB signal). The digital radio signal is sampled at twice the rate as the synchronization information. The energy of the sampling signal resulting from the null symbols is used as a measure of transmission quality.

Method of detecting the transmission quality of digital radio signals consisting of a regular sequence of data symbols separated by null symbols

In a multipoint data communications system in which a central processing unit communicates with a plurality of remote terminals over a shared two-way communications facility, an automatic fault isolation circuit is provided to monitor energy levels originating at the several remote terminals. One or more energy level thresholds are incorporated into bridging locations through which incoming and outgoing address and message signals are distributed to, and collected from, remote terminals by way of the shared facility for the purposes of detecting noise buildups and isolating trouble conditions automatically without human intervention.

Michael Gordon Taylor

Papers

Fault isolation in communications circuits