AGC circuit for burst signal
First Claim
1. An AGC circuit for burst signal comprising a quasi-synchronization demodulator for receiving an intermittently transmitted burst modulation signal and demodulating said burst modulation signal to a baseband signal, two analog-to-digital converters for converting the output signal of said quasi-synchronization demodulator to a digital signal, a first multiplier for receiving the output signals of said analog-to-digital converters and an integrator and executing a multiplying operation, two square circuits for squaring the output signal of said first multiplier, an adder circuit for adding the output signal of said square circuits, a digital subtractor for subtracting a predetermined reference signal from the output of said adder circuit, an area decision unit for deciding three different areas defined by comparing a first and a second reference predetermined values with the level of said subtractor output signal, a selector for selecting one of predetermined three different loop constants K1, K2 and K3 based upon the output signal of said area decision unit, a second multiplier for multiplying the output signals of said selector and said subtractor, and the integrator for integrating the output signal of said second multiplier to drive said first multiplier thereby, said loop constants K1, K2 and K3 being related as K1>
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K2≧
K3, said first reference value being set to be greater than said second reference value, said selector selecting said loop constant K1 when the output signal of said subtractor is greater than said first reference value, selecting said loop constant K3 when the output signal of said subtractor is less than said second reference value and selecting said loop constant K2 when the output signal of said subtractor has an intermediate value between said first and second reference values.
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Abstract
An intermittently transmitted burst modulation signal is demodulated to a baseband signal and multiplied with a variable gain coefficient. A range where a difference signal of a power signal of the multiplied signal from a reference power level is included, in a plurality of level ranges, is decided. A loop constant is determined in accordance with the decided range and is multiplied with the difference signal. An integrated multiplied difference signal with the loop constant is used for changing the variable gain constant.
16 Citations
8 Claims
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1. An AGC circuit for burst signal comprising a quasi-synchronization demodulator for receiving an intermittently transmitted burst modulation signal and demodulating said burst modulation signal to a baseband signal, two analog-to-digital converters for converting the output signal of said quasi-synchronization demodulator to a digital signal, a first multiplier for receiving the output signals of said analog-to-digital converters and an integrator and executing a multiplying operation, two square circuits for squaring the output signal of said first multiplier, an adder circuit for adding the output signal of said square circuits, a digital subtractor for subtracting a predetermined reference signal from the output of said adder circuit, an area decision unit for deciding three different areas defined by comparing a first and a second reference predetermined values with the level of said subtractor output signal, a selector for selecting one of predetermined three different loop constants K1, K2 and K3 based upon the output signal of said area decision unit, a second multiplier for multiplying the output signals of said selector and said subtractor, and the integrator for integrating the output signal of said second multiplier to drive said first multiplier thereby, said loop constants K1, K2 and K3 being related as K1>
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K2≧
K3, said first reference value being set to be greater than said second reference value, said selector selecting said loop constant K1 when the output signal of said subtractor is greater than said first reference value, selecting said loop constant K3 when the output signal of said subtractor is less than said second reference value and selecting said loop constant K2 when the output signal of said subtractor has an intermediate value between said first and second reference values. - View Dependent Claims (2, 6)
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3. An AGC circuit for burst signal comprising a quasi-synchronization demodulator for receiving an intermittently transmitted burst modulation signal and quasi-demodulating said burst modulation signal to a baseband signal, an analog-to-digital converter for converting the output signal of said quasi-synchronization demodulator to a digital signal, a first multiplier for receiving the output signals of said analog-to-digital converter and an integrator and executing a multiplying operation, two square circuits for squaring the output signal of said first multiplier, an adder circuit for adding the output signals of said square circuits, a digital subtractor for subtracting a predetermined reference signal from the output of said adder circuit, a digital polarity detection circuit for detecting a polarity of the output signal of said subtractor, a selector for selecting a loop constant K1 when it is detected by said polarity detection circuit that the output signal of said subtractor is positive and selecting a loop constant K2 (K1>
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1K2) when the output signal of said subtractor is negative, a second multiplier for multiplying the output signals of said selector and said subtractor, and the integrator for integrating the output signal of said second multiplier to drive said first multiplier thereby. - View Dependent Claims (4)
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5. An AGC system for burst signal comprising steps of;
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a first step for quasi-demodulating an intermittently transmitted burst modulation wave signal to a baseband signal; a second step for multiplying the baseband signal with a variable gain coefficient; a third step for obtaining a received signal level by using the multiplied signal; a fourth step for deciding a range, where a difference signal of the received signal level from a reference level is included, in a plurality of level ranges; a fifth step for determining a loop constant in accordance with the decision range; a sixth step for multiplying said difference signal with the determined loop constant; a seventh step for integrating the multiplied difference signal with the loop constant; and an eighth step for changing said variable gain constant in said second step. - View Dependent Claims (7, 8)
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Specification