Abstract: Echo suppressor break-in circuitry must be able to distinguish between double-talking speech on one path of a transmission channel and echos on that one path due to speech on the other path in order that suppression can be removed when both parties are talking. The present disclosure relates to an improved method and arrangement for approximating the echo that may result on an echo return path from speech on another path, which approximation may then be compared with the actual signals on the return path to determine the presence of double-talking speech. In an illustrative embodiment, a first memory store arrangement follows increasing magnitude signals and, during decreasing magnitude signals, provides an output signal corresponding to a predetermined decay rate. A second memory store arrangement follows increasing signals, less a predetermined loss, and holds the magnitude of the last peak while the signal is decreasing.

Abstract: During echo suppression in a system utilizing a full echo suppressor, noise is typically inserted in the receive line of the near-end party to assure him that the line has not "gone dead". The need for a separate noise source for this purpose is eliminated in a digital system by using the existing coded incoming signals on the line. Thus, during echo suppression the bits of the coded incoming signal are altered to provide a random noise signal of normal background amplitude which is then inserted on the receive line. In an illustrative companded sign magnitude code embodiment, the sign bit is replaced by the least significant bit, the least and next-to-least significant bits are interchanged and the remaining bits are zeroed, thereby producing an unintelligible background noise signal of appropriate amplitude.

Abstract: An analog-to-digital counting encoder or a digital-to-analog counting decoder for a pulse code modulation signal typically requires a function generator using precision components to generate a piecewise linear comparison signal corresponding to a segment companding law. As a result, nonproportional component change introduces nonlinear distortion in the encoded or decoded signal. To mitigate nonlinear distortion and to provide a less expensive digital signal processing arrangement, the invention resides in an improved nonprecision component function generator. The function generator includes two serially connected integrators which are advantageously switched in a complementary fashion to provide the comparison signal.

Abstract: A traffic data gathering apparatus with a local memory having a control word per data gathering input provides highly flexible, remotely modifiable determination of various data gathering features associated with each individual input. Thus, the effective data gathering rate for each input is determinable on a per input basis to accommodate data from different types of equipment; and the data from selected pluralities of the inputs can be grouped, and grouping changes made, with considerable ease and flexibility. The data gathering rates are determined by scaling the scanning rate or, for greater resolution, by scaling data obtained at the scanning rate.

Abstract: During echo suppression in a system utilizing a split echo suppressor, suppression is removed when the near-end party breaks in (i.e., during double talking) and is typically replaced with a small fixed loss inserted in the receive line. To minimize loud echoes without unduly penalizing soft talkers at the far end, the loss inserted in the receive line can be varied advantageously according to the incoming signal level by using a compression circuit. The present disclosure relates to a simple arrangement for providing instantaneous compression loss in a digital system by modifying the incoming encoded signal in a predetermined manner. In an illustrative embodiment, one-half the value of the input signal is added to one-half of a selected value when the input signal level equals or exceeds the selected value.