Patent ID: 7251577

Claim:
An instrument for acquiring digital data representing an input signal in response to a realtime power mask trigger signal comprising: an input processor for receiving the input signal and producing a stream of seamless blocks of digital data; a realtime power mask trigger signal generator for generating a trigger signal on the occurrence of a trigger event; an acquisition memory for storing a predefined number of blocks of digital data about the trigger event in response to the trigger signal; and a digital signal processor for processing either the digital data from the input processor, or the digital data stored in the acquisition memory to produce a processed signal; the realtime power mask trigger signal generator comprising: a circulating buffer for receiving the blocks of digital data; a windowing function which produces windowed blocks of digital data from the blocks of digital data in the circulating buffer; a discrete Fourier transform for converting the windowed blocks of digital data into frequency spectra, each frequency spectrum having a plurality of frequency bins, and each frequency bin having a power amplitude; an integrator for integrating the power amplitudes of a frequency spectrum over a defined bandwidth to produce an integrated power for the defined bandwidth; and a comparator for generating the trigger signal when the integrated power of the defined bandwidth violates a specified power level for the defined bandwidth; the realtime power mask trigger signal generator being fast enough to keep up with the stream of digital data.