Eg&g Instruments, Inc.

Perkinelmer Instruments LLC

Advanced Measurement Technology, Inc.

Jeffrey V Peck

Russell D Bingham

Dale A Gedcke

Rex C Trammell

A method and apparatus for precision time interval measurement in a time-of-flight mass spectrometer (TOF-MS). The method and apparatus produces an instrument capable of measuring bursts of data occurring at rates much higher than the average data rate. An asynchronous serial stream of data, consisting of a start pulse followed by an arbitrary number of stop pulses, repeated an arbitrary number of times, is converted into a digital stream of data synchronized to a precision master clock. Conversion of the asynchronous, analog data to synchronous digital data simplifies the measurement task by allowing the use of powerful, low-cost digital logic in the measurement.

Method and apparatus for precision time interval measurement

A digital signal averager for averaging data collected by an analog detector is provided. The digital signal averager includes an analog-to-digital converter for converting the analog detector output to a digital signal for processing, a timing device for generating delayed timing pulses for sequencing operation of the digital signal averager, an averaging device for summing and storing data. The delayed timing pulses allow data to be acquired by the ADC at a series of variably offset timing sequences relative to a trigger pulse. Offsetting the data acquisition timing sequences by time slices smaller than the actual sample rate of the ADC allows data to be acquired at a higher effective sampling rate. One complete series of offset timing sequences provides a data set containing all the information which would be acquired by a ADC having a faster sampling rate. Accuracy of the data is further enhanced by a series of parallel averaging devices, including one processing device and multiple memory devices, which perform real-time averaging of data. A digital signal processor applies a method for data compression to the averaged data to reduce data transfer rate and storage capacity requirement for transferring the averaged data to an analysis and storage device for long-term storage.

High-performance digital signal averager

A method for improving the speed of convergence to sub-least-significant-bit accuracy and precision in a digital signal averager when the measurements are averaged over many samples where the noise inherent in the signal is not large compared to 1 LSB. A slider offset circuit implements the method which adds offsets to an analog input signal acquired from an analog sensor. The slider offset circuit compensates for limitations in the resolution of an analog-to-digital converter by adding a sub-least-significant-bit offset to the input signal. Similarly, the slider offset circuit compensates for the differential non-linearity using a Gatti offset which are whole number multiples of the average voltage bin width. Speed of convergence to sub-LSB accuracy is further improved by employing non-consecutive increments in the two sliders.

Apparatus for improvement of the speed of convergence to

A time analyzer having an improved interpolator with temperature compensation. The time analyzer of the present invention can be operated in a wide range of temperatures without need of recalibration in the field. The device includes hardware for making a coarse time measurement. A fine time measurement is obtained by interpolating within a cycle of the master clock. A temperature correction look up table is produced which incorporates information unique to each analyzer. Information stored in the look up table of each instrument is used to correct time measurement for enhanced precision.

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Knoxville, TN, United States of America

Jeffrey V Peck