Self-calibration of an oscilloscope using a square-wave test signal
AssigneeLeCroy Corporation
InventorsJoseph M. Schachner, Viktor Hungerbuehler
Life of this patent
Estimating the term…
Abstract
Self-calibration of a digitizer is carried out by using a square-wave test signal which is digitized by the digitizer, and temporal positions of the digitized values output by the digitizer are compared to respective reference periods of the test signal. The results of the comparison operations are then used by a microprocessor to calculate a time delay for adjusting a clock signal supplied to the digitizer.
Claims14
Apparatus for performing calibration, comprising:
- a signal generator for generating a reference signal having a preselected period;
- a digitizer for digitizing said reference signal to produce a plurality of digitized values having respective amplitudes;
- and
- a programmable controller for obtaining, in each respective period, a temporal position of a digitized value with respect to a corresponding period of said reference signal, said programmable controller determining, based on the obtained temporal positions, a period, slope and delay corresponding to an approximate median value of the amplitudes such that sampling times of said digitizer are adjusted on the basis of the determined period, slope and delay.
A digital oscilloscope with a self-calibration operation, comprising:
- an input port for receiving an input signal;
- a signal generator for generating a reference signal having a preselected period;
- a front end circuit for selecting one of said input and reference signals;
- a digitizer for selectively digitizing said input signal or said reference signal to produce a plurality of digitized values having respective amplitudes;
- and
- a programmable controller for obtaining, in each respective period, a temporal position of a digitized value of said reference signal with respect to a corresponding period of said reference signal, said programmable controller determining, based on the obtained temporal positions, a period, slope and delay corresponding to an approximate median value of the amplitudes such that sampling times of said digitizer are adjusted on the basis of the determined delay.
A method for performing calibration in a digital oscilloscope, comprising the steps of:
- receiving an input signal;
- generating a reference signal having a preselected period;
- selecting one of said input and reference signals;
- selectively digitizing said input signal or said reference signal to produce a plurality of digitized values having respective amplitudes;
- obtaining, in each respective period, a temporal position of a digitized value with respect to a corresponding period of said reference signal;
- and
- determining, based on the obtained temporal positions, a period, slope and delay corresponding to an approximate median value of the amplitudes such that sampling times in said oscilloscope are adjusted on the basis of the determined period, slope and delay.
Dependencies are inferred from the claim text.