Tracking percent overload signal as indicator of output signal magnitude
First Claim
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1. Apparatus for providing an indication of the magnitude of an electrical signal, comprising:
- an envelope detector connected to an input signal and providing an envelope signal corresponding to the envelope of the input signal;
a voltage source providing threshold voltage of a selected value;
a circuit connected to the envelope signal and the threshold voltage and being operable to provide a binary output signal when the envelope signal exceeds the threshold voltage; and
an output circuit connected to the binary output signal for providing an indication of the percentage of time the binary output signal is high during a predetermined time period or window thereby providing an indication of the magnitude of the input signal.
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Abstract
Tracking percent overload signal as an indicator of output signal magnitude is achieved by measuring the percent of time the envelope of a varying modulated signal is above a predetermined programmable threshold. The technique is implemented by a level detector including an envelope detector along with circuitry for detecting when the envelope has exceeded the programmable threshold. The output of the level detector is sampled and fed to a counter which provides a digital output which indicates the percentage of time the envelope exceeds the set threshold.
21 Citations
16 Claims
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1. Apparatus for providing an indication of the magnitude of an electrical signal, comprising:
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an envelope detector connected to an input signal and providing an envelope signal corresponding to the envelope of the input signal;
a voltage source providing threshold voltage of a selected value;
a circuit connected to the envelope signal and the threshold voltage and being operable to provide a binary output signal when the envelope signal exceeds the threshold voltage; and
an output circuit connected to the binary output signal for providing an indication of the percentage of time the binary output signal is high during a predetermined time period or window thereby providing an indication of the magnitude of the input signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
a second envelope detector circuit connected to the input signal, a second voltage source providing a second threshold voltage of a selected value, a second circuit for providing a second binary output signal when the envelope signal exceeds said second threshold voltage, and, a second output circuit connected to said second binary output signal for providing an indication of the percentage of time said second binary output signal is high and thereby providing a further indication of the magnitude of the input signal. -
9. The apparatus as defined by claim 8 and additionally including an amplifier circuit having a predetermined gain connecting said input signal to the second envelope detector circuit.
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10. The apparatus as defined by claim 1 wherein the envelope detector circuit includes a first transistor element for providing said envelope signal, the circuit connected to the threshold voltage includes a second transistor element for preventing the envelope signal from falling below a predetermined level, and wherein the circuit providing the binary output signal comprises an active load circuit connected to the first and second transistor elements.
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11. The apparatus as defined by claim 10 wherein the envelope detector circuit includes a third transistor element coupled to said first transistor element in a differential amplifier configuration for connection to a differential input signal.
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12. The apparatus as defined by claim 11 and additionally including a clipping circuit connected to the active load circuit.
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13. The apparatus as defined by claim 12 wherein the clipping circuit comprises an inverter.
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14. A method of determining the level of an electrical input signal comprising the steps of:
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detecting the envelope of the input signal and generating an envelope signal thereof;
generating a binary output signal only when the amplitude of the envelope signal exceeds a predetermined threshold level;
sampling the binary output signal for a predetermined time period; and
determining the portion of time the binary output signal is high during said time period for providing a measure of the amplitude of the input signal. - View Dependent Claims (15, 16)
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Specification