Abstract: A method and apparatus for transmitting data descriptive of an electromagnetic waveform wherein a constant amplitude signal is frequency modulated and transmitted to a remote site where digital signals are generated in response to zero crossings of the fm analog signal. Interrupt signals are generated in response to zero crossings for storing time differences between successive digital signals corresponding to the zero crossing which are then averaged at the Nyquist sampling rate to display and analyze a constructed waveform simulating the original signal.