Direct-coupled signaling receiver with PL/DPL detector
First Claim
1. A detector circuit for selecting signaling information transmitted with a radio frequency (RF) signal for interpretation by a radio receiver comprising:
- at least one filter circuit for filtering demodulated audio signals direct current (DC) coupled thereto;
a signaling decoder DC coupled with the at least one filter circuit for determining a frequency and/or bit code of signaling information from the at least one filter circuit; and
wherein the signaling decoder includes a first signaling path and a second signaling path where the first signaling path provides signaling information and direct current (DC) offset information to a switched capacitator subtracting circuit and the second signaling path provides only Dc offset information to the subtracting circuit.
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Accused Products
Abstract
A detector circuit (100) for detecting signaling information transmitted with a radio frequency (RF) signal for interpretation by a radio receiver includes a first low pass filter (105) for filtering demodulated audio signals that are directly coupled thereto and for providing a first filtered signal. A second low pass filter (109) is directly coupled with the first low pass filter (105) for filtering the first filtered signal and providing a second filtered signal. A signaling detector (111) is then directly coupled with the second low pass filter (109) for determining the frequency and/or bit code of signaling information included in the second filtered signal.
35 Citations
26 Claims
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1. A detector circuit for selecting signaling information transmitted with a radio frequency (RF) signal for interpretation by a radio receiver comprising:
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at least one filter circuit for filtering demodulated audio signals direct current (DC) coupled thereto; a signaling decoder DC coupled with the at least one filter circuit for determining a frequency and/or bit code of signaling information from the at least one filter circuit; and wherein the signaling decoder includes a first signaling path and a second signaling path where the first signaling path provides signaling information and direct current (DC) offset information to a switched capacitator subtracting circuit and the second signaling path provides only Dc offset information to the subtracting circuit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A signaling receiver for decoding analog and digital signaling information identifying a specific user among a plurality of users on a radio frequency (RF) channel comprising:
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a first low pass switched capacitator filter direct current (DC) coupled to a demodulator for providing an audio signal and DC offset signaling information by a predetermined amount; a second low pass switched capacitator filter DC coupled to the first low pass switched capacitator filter for filtering the audio signal and providing only the DC offset signaling information; a detector DC coupled second low pass switched capacitor filter, the detector comprising a continuous time low pass filter and a discrete time comparator for providing a digital representation of the signaling information; and wherein the detector includes a first signaling path and second signaling path where the first signaling path provides signaling information and direct current (DC) offset information to a switched capacitator subtracting circuit and the second signaling path provides only DC offset information to the subtracting circuit. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A method for providing a digital representation of signaling information received in a radio receiver comprising the steps of:
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receiving a demodulated signal including an audio signal, direct current (DC) offset signaling information and extraneous information from a demodulator located within the radio receiver; DC coupling the demodulated signal from the demodulator to a first filter; filtering the demodulated signal in the first filter such that the extraneous information is eliminated and the audio signal and DC offset signaling information is amplified; DC coupling the audio signal and DC offset signaling information directly to a second filter; filtering the audio signal and DC offset signaling information in the second filter such that the audio signal is eliminated; DC coupling the DC offset signaling information directly to a detector having a first signaling path and second signaling path where the first signaling path provides signaling information and direct current (DC) offset information to a switched capacitor subtracting circuit and the second signaling path provides only DC offset information to the switched capacitor subtracting circuit; detecting the DC offset signaling information such that DC offset of the signaling information is cancelled providing a resultant signaling information; and converting the resultant signaling information into a digital format for interpretation by the radio receiver. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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Specification