Tailpulse signal generator
View Patent ↗A tailpulse signal generating/simulating apparatus, system, and method designed to produce electronic pulses which simulate tailpulses produced by a gamma radiation detector, including the pileup effect caused by the characteristic exponential decay of the detector pulses, and the random Poisson distribution pulse timing for radioactive materials. A digital signal process (DSP) is programmed and configured to produce digital values corresponding to pseudo-randomly selected pulse amplitudes and pseudo-randomly selected Poisson timing intervals of the tailpulses. Pulse amplitude values are exponentially decayed while outputting the digital value to a digital to analog converter (DAC). And pulse amplitudes of new pulses are added to decaying pulses to simulate the pileup effect for enhanced realism in the simulation.
1. A tailpulse signal generator comprising:
digital signal processor (DSP) for generating digital tailpulse signals from gamma energy spectrum data, said DSP adapted to: pseudo-randomly select energy values from the spectrum data and pseudo-randomly select pulse time intervals; produce digital pulse amplitude values corresponding to the number of events at the selected energy values and at the selected time intervals; exponentially decay the pulse amplitude values in time; at each selected time interval, add a new pulse amplitude value to an old exponentially decaying amplitude pulse value; and exponentially decay the resulting pulse amplitude value in time to simulate the pileup effect;
a digital-to-analog converter (DAC) operably connected to receive said digital tailpulse signals from said DSP and produce analog voltage signals therefrom to simulate tailpulses characteristic of the gamma energy spectrum; and
means for supplying power to said tailpulse signal generator.
2. The tailpulse signal generator of claim 1 ,
wherein the computer processor means comprises an FPCA module.
3. The tailpulse signal generator of claim 1 ,
wherein said DSP is adapted to: receive gamma energy spectrum data including two numeric arrays characterizing the gamma energy spectrum and a Poisson timing array comprising natural logarithms of an independent pseudo-random variable; and generate pseudo random variables for selecting the energy values and the pulse timing intervals.
4. The tailpulse signal generator of claim 3 ,
wherein said DSP is adapted to receive command messages and process said spectrum data according to said command messages.
5. The tailpulse signal generator of claim 4 ,
wherein said DSP is adapted to receive the spectrum data from an offboard spectrum analyzer.
6. The tailpulse signal generator of claim 1 ,
further comprising: a spectrum analyzer adapted to analyze an energy spectrum of a radioactive material to produce the spectrum data; and a user input/control interface for controlling said spectrum analyzer and said tailpulse signal generator.
7. The tailpulse signal generator of claim 1 ,
further comprising: a data storage unit having spectrum data of at least one radioactive material stored thereon and accessible by said DSP; and a user input/control interface for controlling said DSP and said tailpulse signal generator.
8. A method of generating tailpulse signals comprising:
controlling a digital signal processor (DSP) to pseudo-randomly select an energy value from energy spectrum data;
controlling the DSP to pseudo-randomly select a pulse time interval;
controlling the DSP to produce a pulse amplitude value corresponding to the number of events at the selected energy value;
controlling the DSP to exponentially decay the pulse amplitude value in time;
at the selected time interval, controlling the DSP to add a new pseudo-randomly selected pulse amplitude value to the exponentially decaying amplitude pulse value to produce a resulting pulse amplitude value;
controlling the DSP to exponentially decay the resulting pulse amplitude value in time to simulate the pileup effect; and
controlling a digital-to-analog converter (DAC) to produce analog voltage signals from the pulse amplitude values.