Patent ID: 8233569

Claim:
A realtime spectrum trigger generator for use in a realtime oscilloscope, comprising: said realtime oscilloscope including acquisition circuitry, said acquisition circuitry acquiring time domain input signal under test, and including means for converting said input signal under test to a frequency domain signal having quadrature components as a function of a given frequency; and means for generating a trigger from the quadrature components as a function of a given threshold and a given phase; wherein said oscilloscope further comprises: a recirculating memory for receiving samples of the input signal under test at a first input; a trigger circuit having the trigger as an input and providing a trigger position signal as a first output and a stop command as a second output, the stop command being coupled to a second input of the recirculating memory to stop receipt of the samples; and a processor having a first input for receiving the samples from the recirculating memory, a second input for receiving the trigger position and a third input for receiving the given phase, the processor providing the samples to an acquisition memory at an output adjusted for time alignment as a function of the given phase.