Digital AGC for a CDMA radiotelephone
First Claim
1. A method for generating a gain control signal for a transceiver, comprising the steps of:
- integrating the power of a received and sampled signal;
calculating a logarithm of the received integrated power;
subtracting a predetermined reference value from the logarithm of the received integrated power to generate a first error signal;
filtering the first error signal;
comparing the filtered first error signal to a predetermined first threshold;
incrementing or decrementing a first counter value and resetting a filter accumulator as a function of the result of the step of comparing; and
converting the first counter value to an analog voltage for controlling the gain of a receiver;
where the logarithm is the second logarithm of the power, and wherein the step of calculating includes the steps of;
inputting a digital word that represents a value of the received integrated power to a priority encoder to determine a position of the most significant set bit of the digital word; and
using the determined position as the second logarithm.
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Accused Products
Abstract
Disclosed herein are methods and apparatus for generating digital receiver and transmitter AGC values for a spread spectrum transceiver. A method includes the steps of (a) integrating the power of a received and sampled signal; (b) calculating a logarithm of the received integrated power; (c) subtracting a predetermined reference value from the logarithm of the power to generate a first error signal; (d) filtering the first error signal; (e) comparing the filtered first error signal to a predetermined first threshold; (f) incrementing or decrementing a first counter value and resetting a filter accumulator as a function of the result of the step of comparing; and (g) converting the first counter value to an analog voltage for controlling the gain of a spread spectrum receiver amplifier. The logarithm is preferably the second logarithm of the power. The method further includes generating a transmitter AGC value.
76 Citations
26 Claims
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1. A method for generating a gain control signal for a transceiver, comprising the steps of:
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integrating the power of a received and sampled signal; calculating a logarithm of the received integrated power; subtracting a predetermined reference value from the logarithm of the received integrated power to generate a first error signal; filtering the first error signal; comparing the filtered first error signal to a predetermined first threshold; incrementing or decrementing a first counter value and resetting a filter accumulator as a function of the result of the step of comparing; and converting the first counter value to an analog voltage for controlling the gain of a receiver; where the logarithm is the second logarithm of the power, and wherein the step of calculating includes the steps of; inputting a digital word that represents a value of the received integrated power to a priority encoder to determine a position of the most significant set bit of the digital word; and using the determined position as the second logarithm.
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2. A method for generating a gain control signal for a transceiver, comprising the steps of:
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integrating the power of a received and sampled signal; calculating a logarithm of the received integrated power; subtracting a predetermined logarithmic power reference value from the logarithm of the received integrated power to generate a first error signal; filtering the first error signal; comparing the filtered first error signal to a predetermined first threshold range; incrementing or decrementing a first counter value and resetting a filter accumulator as a function of the result of the step of comparing; and converting the first counter value to an analog voltage for controlling the gain of a receiver. - View Dependent Claims (3, 4, 5, 6)
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7. Apparatus for generating a gain control signal for a transceiver, comprising:
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means for integrating the power of a received and sampled signal; means for calculating a logarithm of the received integrated power; means for subtracting a predetermined reference value from the logarithm of the power to generate a first error signal; means for filtering the first error signal; means for comparing the filtered first error signal to a predetermined first threshold; means for incrementing or decrementing a first counter value and resetting a filter accumulator as a function of an operation of said comparing means; and means for converting the first counter value to an analog voltage for controlling the gain of a receiver; where the logarithm is the second logarithm of the power, and wherein the calculating means includes; priority encoder means for inputting a digital word that represents a value of the received integrated power for determining a position of the most significant set bit of the digital word;
wherein the determined position is designated as the second logarithm.
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8. Apparatus for generating a gain control signal for a transceiver, comprising:
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means for integrating the power of a received and sampled signal; means for calculating a logarithm of the received integrated power; means for subtracting a predetermined logarithmic power reference value from the logarithm of the power to generate a first error signal; means for filtering the first error signal; means for comparing the filtered first error signal to a predetermined first threshold range; means for incrementing or decrementing a first counter value and resetting a filter accumulator as a function of an operation of said comparing means; and means for converting the first counter value to an analog voltage for controlling the gain of a receiver. - View Dependent Claims (9, 10, 11, 12)
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13. A method for operating a spread spectrum radiotelephone, comprising the steps of:
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receiving a spread spectrum RF signal and amplifying the received signal with at least one receiver amplifier; demodulating the amplified RF signal to derive in-phase I and quadrature Q signals; repetitively squaring a magnitude of the I and Q signals and integrating the squared magnitudes over a period to derive an indication of the power of the received signal over the period; obtaining a logarithm of the derived power indication; obtaining a first error signal that indicates a difference between the logarithm of the power indication and a predetermined power; filtering the first error signal; comparing the filtered first error signal to a first bipolar threshold signal and incrementing or decrementing a first counter value and resetting a filter accumulator in accordance with the comparison; and generating a gain control signal for the at least one receiver amplifier in accordance with the first counter value. - View Dependent Claims (14, 15, 16)
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17. A spread spectrum transceiver, comprising:
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a transmitter for transmitting a spread spectrum RF signal through at least one transmitter amplifier; a receiver for receiving a spread spectrum RF signal and for amplifying the received signal with at least one receiver amplifier; a demodulator for demodulating the amplified RF signal to derive in-phase I and quadrature Q signals; means for deriving from the I and Q signals an indication of the power of the received signal over a period; means for obtaining a first error signal that indicates a difference between the power indication and a predetermined power; a first filter for filtering the first error signal; means for comparing the filtered first error signal to a first threshold signal and for incrementing or decrementing a first value and for resetting a filter accumulator in accordance with the comparison; means for generating a gain control signal for the at least one receiver amplifier in accordance with the first value; means for generating a second value; means for subtracting the second value from the first value and for subtracting the derived indication of the power of the received signal over the period from a reference value to form a second error signal; a second filter for filtering the second error signal; means for comparing the filtered second error signal to a second threshold signal and for incrementing or decrementing the second value and for resetting a filter accumulator in accordance with the comparison to form an open loop transmitter power control value; means for combining the open loop power control value with a closed loop power control value to form a combined power control value; and means for generating a gain control signal for said at least one transmitter amplifier in accordance with the combined power control value. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26)
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Specification