US 6,660,991 B2 · Method and apparatus for measuring a low power signal

Abstract

Low intensity light is incident upon a photodiode whose output is coupled to an integrator. The output of the integrator is coupled to an input of an A/D converter, whose output is coupled to a microprocessor, whose output is coupled to a filter. A second output of the microprocessor is coupled to a gate electrode of a FET to provide a reset signal to the FET to reset the integrator. The microprocessor compares the digital samples of the integrated signal from the A/D converter and, firstly, generates the reset signal if a sample is beyond a set limit, and, secondly, calculates delta values between adjacent samples and interpolates the delta values for the reset periods so as to provide a continuous data stream which can be filtered by a filter matched to the form of the original signal.

Claims11

Dependent claims

A method of measuring a low power signal, comprising:

receiving a low power signal from a signal source;
integrating the received low power signal over controllable integration periods to provide an integration signal;
sampling the integration signal at a frequency substantially higher than a frequency of the integration periods to provide digital samples of the integration signal;
determining differences between digital samples to provide a stream of delta values;
and
filtering the stream of delta values to provide a filtered signal substantially matching the received low power signal.

3 more elements

Dependencies are inferred from the claim text.

Method and apparatus for measuring a low power signal

Life of this patent

Method and apparatus for measuring a low power signal

Life of this patent

Abstract

Claims11