Test system for mark to space ratio of telephone dialling pulses - gives reading for individual pulses using gated counters controlled by oscillator

摘要

Telephone-type dialling pulses (NS) at the input of the tester are counted (Z) and displayed (a1), (a9). The pulses are also routed to a gate (T) whose outputs feed an impulse counter (JZ) and period counter (PZ). An oscillator controls the gate. Intermediate registers (JS), (PS) are connected to a divider network (R) whose outputs operate display devices via drivers (AS1), (AS9). The counter output also operates a comparator (V) which indicates if the pulse waveform is within the required tolerance. If the pulse counter (JZ) is a count-up circuit and the dwell counter (PZ) is a countdown type, the arithmetic unit (r) operates as an add-subtract circuit.