Abstract: The bit error ratio of digital data transmission equipment is measured by applying a bit error ratio test data stream to a signal path through the equipment, and coupling an interfering signal source into the signal path. Measurements of the bit error ratio of the equipment are acquired for different levels of interfering signal, and the gain error introduced by coupling the interfering signal source into the signal path is determined. The bit error ratio of the equipment in the absence of the interfering signal is estimated from the measurements of the bit error ratio and the gain error.

Abstract: The invention is primarily concerned with measuring the frequency response of a regenerator in a digital transmission system. The method and apparatus provide for a variable pulse to be inserted in a sequence of pulses representative of normal traffic through the system and superimposition of a sinusoidal signal on the variable pulse. Results can be plotted from passing a number of sequences through the regenerator and varying the amplitude and/or frequency of the sinusoidal signal and varying the pulse.

Abstract: This invention relates to method and apparatus for measuring noise margins in digital transmission systems. The method requires the introduction of a variable pulse into a sequence of pulses which represents normal traffic, varying a parameter of the pulse, detecting the pulse, and accumulating information concerning the variations to determine probability distribution of the deviations produced by measuring the variations relative to a standard. The apparatus includes means for introducing the variable pulse into a sequence of pulses and for observing and recording detection of the variable pulse in each sequence to compile a probability distribution of the aforementioned deviations.