Signal/quantizing-distortion ratio (SQDR) was measured as a function of input level at a sampling frequency of 64 kHz with a phase- and amplitude-modulated sine wave of 800 Hz as input signal for different adaptive delta modulation systems. The parameters are: the number of bits taken into account in deciding step-size changes (bit-memory length); the ratio between the number of successive identical bit repetitions after which the step size is increased and the number of consecutive bit alternations after which the step size is decreased (up/down ratio); the step-size change factor a; and the use of single or double integration. Only one parameter is changed at a time resulting in a total of 54 measurement curves of SQDR as a function of input level. An analysis of the measurements is presented in terms of an averaged SQDR and its systematic spread as a function of the parameters.

To be economically attractive, all-electronic spacedivision multiplex (SDM) networks must have a minimum of wiring and interconnection joints, take maximum advantage of IC-type matrix modules, offer inexpensive control (including checking, fault location and traffic supervision) and still satisfy transmission requirements. A means to meet all these demands is presented. It is based on a special p-n-p-n triode crosspoint featuring negligible crosstalk and signal current losses and a very low level of switching noise. Spurious triggering (rate effect) can be eliminated without any special requirements regarding the slope of any signal or the properties of the p-n-p-n device. When such crosspoints are used in unbalanced networks with single-wire through-switching and common return, the added application of the "high-low" principle ensures effective suppression of wiring crosstalk and noise pickup. The resultant signal transfer properties depend practically solely on the interfaces of the network as if these interfaces were directly interconnected. Wiring is minimized by suitable integration of control circuitry into the matrix module and by using the transmission wiring additionally for control without disturbing transmission paths in use. IC modules withn \times mcrosspoints can be made with onlyn + m + 1terminals for transmission and control in addition to supply terminals.