Multimode optical time domain reflectometer having improved resolution

A method of generating waveform data for displaying as a waveform trace on a display device in a multimode optical time domain reflectometer launching optical pulses into a fiber under test for generating optical return signals from the test fiber comprising the steps of:

• a) acquiring waveform data representative of the optical return signals using first and second multimode optical transmitters operating at first and second wavelengths for launching optical pulses into the fiber under test to generate optical return signals corresponding to the first and second wavelengths of the launched optical pulses and converting the respective optical return signals into electrical signals representative of the optical return signals using first and second optical receivers responsive to the respective wavelengths of the launched optical pulses;
• and
• b) processing the waveform data representative of the optical return signals at the first and second wavelengths for determining a difference in fiber slope between the optical return signals at the first and second wavelength and modifying the fiber slope of the second optical return signal by adding the difference between the fiber slopes to the waveform data of the second optical return signal for producing composite waveform data having waveform data acquired at both the first and second wavelengths.