Apparatus and method for displaying multiple sample spacing waveform segments

Claim 1

An optical time domain reflectometer for launching optical pulses into a fiber under test for generating an optical return signal from the test fiber for acquiring and displaying waveform data as a waveform trace on a display device having a display area defined by a number of horizontal pixels and a number of vertical pixels and a viewport defined by a start distance and an end distance and min and max amplitudes comprising: an acquisition system for acquiring at least two waveform segments having data points representative of the optical return signal with each waveform data point having an amplitude value related by time to a distance and each waveform segment being acquired using a different pulsewidth optical pulse, a different sample spacing and a different staring distance; a processor for receiving and storing the data points of the waveform segments in an array, for determining the starting distances of the waveform segments, for generating a waveform data segment table containing the start distances, the sample spacing and an index into the array of waveform data points related to distance for each waveform segment, and for generating a bit map array representative of the waveform trace by establishing a horizontal pixel skip value, establishing a horizontal distance skip value, calculating a horizontal distance per pixel skip value for the display area as a function of dividing the distance between the viewport start distance and the viewport end distance by the number of horizontal pixels in the display area, mapping the horizontal pixels to distances by setting an initial pixel count to zero and an initial horizontal distance value to the viewport start distance and sequentially adding the horizontal pixel skip value to the pervious pixel count and adding the horizontal distance skip value to the previous horizontal distance value, correlating the distance values for the horizontal pixels to the amplitude values of the data points of the waveform segment using the indexes of the data points related to distance and mapping the amplitude values to the appropriate vertical pixels associated with the horizontal pixels; a memory for storing the amplitude value of each data point of the respective waveform segments, the waveform segment table, and the bit map array representative of the waveform trace; and a display means including a display controller coupled to the display device for receiving and displaying the bit map representation of the waveform trace on the display device.