Method and apparatus for measurement of wide dynamic range signals

An apparatus for measuring a varying average magnitude over time of signals having a wide dynamic range, the apparatus comprising:

• a single transducer for sensing a physical parameter having a magnitude and converting the physical parameter to an electrical signal indicative of the magnitude of the physical parameter,
• a first signal channel operatively connected to the transducer and having a first gain, the first signal channel having a first detector responsive to the electrical signal for providing a first output signal, the first output signal being indicative of an average magnitude of the physical parameter in a first magnitude range, the first magnitude range corresponding to the first gain, the first signal channel using an averaging process having a first time constant;
• a second signal channel operatively connected to the transducer and having a second gain, the second signal channel having a second detector responsive to the electrical signal for providing a second output signal, the second output signal being indicative of an average magnitude of the physical parameter in a second magnitude range, the second magnitude range corresponding to the second gain, the second signal channel using the averaging process having the first time constant;
• a third signal channel operatively connected to the transducer and having a third gain, the third signal channel having a third detector responsive to the electrical signal for providing a third output signal, the third output signal being indicative of an average magnitude of the physical parameter in a third magnitude range, the third magnitude range corresponding to the third gain, the third signal channel using the averaging process having the first time constant;
• and
• control circuitry for selecting only one of the first, second and third output signals during each of a plurality of time periods, generating from the selected output signals a magnitude signal, and averaging the magnitude signal using a second time constant greater than the first time constant to provide an average output magnitude signal indicative of the average magnitude of the physical parameter.