Dual threshold demodulation in an amplitude modulation radio receiver
First Claim
1. A radio receiver, comprising:
- a) an amplifier configured to receive a radio frequency (RF) input signal and a gain control signal, and provide an amplified signal;
b) a mixer, configured to combine said amplified signal and a local oscillation signal and provide a mixed output;
c) a first threshold comparator configured to compare a baseband signal with a first comparator threshold level, and provide a first comparator output, said baseband signal being derived from said mixed output;
d) a second threshold comparator configured to compare said baseband signal with a second comparator threshold level, and provide a second comparator output coupled to an output of said radio receiver, said second comparator threshold level being of lower magnitude than said first comparator threshold level;
e) an automatic gain control (AGC) circuit, configured to receive said first comparator output and provide said gain control signal.
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Accused Products
Abstract
A method, algorithm, circuits, and/or systems for demodulation in an amplitude modulated (AM) radio receiver are disclosed. In one embodiment, a radio receiver can include an amplifier configured to receive a radio frequency (RF) input signal and a gain control signal, and provide an amplified signal, an automatic gain control (AGC) circuit configured to receive a high threshold comparator output and provide the gain control signal, a mixer configured to combine the amplified signal and a local oscillation signal and provide a mixed output, a high threshold comparator configured to compare the mixed output with a reference level and provide the high threshold comparator output, and a low threshold comparator configured to compare the mixed output with the reference level and provide an output of the radio receiver.
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Citations
20 Claims
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1. A radio receiver, comprising:
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a) an amplifier configured to receive a radio frequency (RF) input signal and a gain control signal, and provide an amplified signal; b) a mixer, configured to combine said amplified signal and a local oscillation signal and provide a mixed output; c) a first threshold comparator configured to compare a baseband signal with a first comparator threshold level, and provide a first comparator output, said baseband signal being derived from said mixed output; d) a second threshold comparator configured to compare said baseband signal with a second comparator threshold level, and provide a second comparator output coupled to an output of said radio receiver, said second comparator threshold level being of lower magnitude than said first comparator threshold level; e) an automatic gain control (AGC) circuit, configured to receive said first comparator output and provide said gain control signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An automatic gain control (AGC) loop circuit, comprising:
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a) an amplifier configured to receive a radio frequency (RF) input signal and a gain control signal, and provide an amplified signal; b) a mixer, configured to combine said amplified signal and a local oscillation signal and provide a mixed output; c) a filter configured to receive said mixed output and provide a baseband signal therefrom, said baseband signal being converted into a digital, recovered, baseband signal by a comparison of said baseband signal with a first threshold level; d) a threshold comparator configured to compare said baseband signal with a second threshold level higher than said first threshold level, and to provide a threshold comparator output; e) an AGC block configured to receive said threshold comparator output and generate said gain control signal therefrom. - View Dependent Claims (9, 10, 11)
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12. A method of demodulating a radio frequency (RF) input signal, comprising the steps of:
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a) receiving said RF input signal in an amplifier of a radio receiver; b) mixing an output of said amplifier with a local oscillation signal to form a mixed signal; c) obtaining a recovered signal from said mixed signal; d) performing a first comparison of said recovered signal with a first reference threshold level to provide a first signal, said first signal providing gain control for said amplifier; and e) performing a second comparison of said recovered signal with a second reference threshold level to provide a digital, recovered, baseband signal, wherein said first reference threshold level is higher than said second reference threshold level. - View Dependent Claims (13, 14)
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15. A radio receiver, comprising:
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a) a first amplifier configured to receive a radio frequency (RF) input signal and provide an amplified signal; b) a mixer configured to combine said amplified signal and a local oscillation signal and provide a mixed output; c) a second amplifier configured to receive said mixed output and provide an intermediate frequency (IF) signal; d) a first threshold comparator configured to compare said IF signal with a first reference threshold level, and provide a first comparator output; and e) a second threshold comparator configured to compare said IF signal with a second reference threshold level, and provide a second comparator output coupled to an output of said radio receiver. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification