Patent ID: 7418357

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 time-to-frequency 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 specified number of frequency spectra over a defined bandwidth, and if the specified number of frequency spectra is greater than one, averaging the integrated power amplitudes of the frequency spectra with an averaging function, 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.