Abstract: A capture scheme detects repetitive occurrences of finite-length bit patterns within an applied data signal to provide trigger events for equivalent time sampling of the data signal. The capture scheme enables acquisition of samples within designated bit patterns of the data signal, independent of whether the data signal is random in nature, since the designated finite-length bit patterns occur repetitively within the data signal. In an apparatus implementation of the capture scheme, a bit pattern detector detects a designated bit pattern within the applied data signal and generates trigger events responsive to the occurrences of the bit pattern. An equivalent time sampler receives the data signal and trigger events to acquire samples of the data signal within the designated bit pattern.

Abstract: An internally triggered equivalent-time sampling system characterizes high-speed data signals having a predetermined nominal data rate by using an internal oscillator that runs independent of a synchronous trigger signal. The sampling system acquires samples of the data signal at a strobe rate, set by the oscillator, which is lower than the nominal data rate of the data signal. The samples, the strobe rate, and the nominal data rate are communicated to a quality optimizer which compensates for static rate deviations between the nominal data rate and the actual data rate of the data signal to establish timing correspondence between the acquired samples. The timing correspondence establishes the time placement of the acquired samples when characterizing the data signal on a display or other output device. When the oscillator has high timing stability relative to the data signal, jitter and other attributes of the data signal are accurately characterized.

Abstract: An apparatus and method are provided based directly on measurement of power to enable an accurate and repeatable determination of extinction ratio. One implementation includes an optical-to-electrical (O/E) converter responsive to a modulated optical signal, a multimeter connected to the O/E converter for measuring a voltage corresponding to average optical power, a power meter connected to the O/E converter for measuring a voltage corresponding to the optical power in the modulation signal, and a microprocessor for determining the extinction ratio from the measured signals corresponding to average optical power and optical power in the modulation signal.