Abstract: An approach is provided for monitoring of the activity in production computer systems. During a first period of time, substantially all of a first plurality of dispatches sent to a CPU are recorded. Each dispatch of the first plurality of dispatches indicates an initial instruction of a stream of instructions that is executed without interruption by the CPU. Based on the first plurality of dispatches, a baseline profile that indicates a normal execution flow in the system is generated. During a second period of time, substantially all of a second plurality of dispatches sent to the CPU are monitored. Based on the baseline profile and on at least one of the second plurality of dispatches, a determination is made whether an abnormal execution flow exists in the system during the second period of time. One or more actions are performed in response to determining that the abnormal execution flow exists in the system during the second period of time.

Abstract: A supervisory channel is provided on a digital transmission system by frequency modulation of the data signal transmitted along a transmission link which includes repeaters. The frequency modulation can be carried out using an elastic store. Each repeater includes means for demodulating the frequency modulation so that each repeater can be addressed and interrogated. Each repeater can also phase modulate the data signals on the return link to a terminal station so that signals indicative of an interrogated condition can be transmitted to the terminal station.

Abstract: To transmit a number of individual speech channels over a smaller number of transmission channels, the frequency range of each speech channel is broken into sub-channels and each of these is considered separately for operational activity. Composite speech signals are then formed from the active frequency sub-channels of the individual speech channels and these are transmitted with coding signals indicative of their composition.

Abstract: A method and apparatus for testing for forward echoes produced by signal transmission through a length of transmission line in which a succession of 1 ns pulses are applied to the line and the outward signals are multiplied by pulses delayed by a succession of discrete delay times. The products resulting from 65,500 pulses subjected to the same delay are integrated to eliminate the effects of thermal noise and the results for different delay times plotted against the delay time to produce a correlation curve in which the echoes appear as perturbations on the curve.