Data limiter for a radio pager
First Claim
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1. A data limiter, comprising:
- comparison means having a first input for receiving a first signal and a second input for receiving a reference signal;
first and second transconductance amplifiers, each having a first input coupled to receive said first signal, a second input coupled to receive said reference signal, and an output, each amplifier having a respective predetermined input offset voltage; and
an integrator having an input coupled to the outputs of said first and second transconductance amplifiers and an output coupled to the second input of said comparison means and to the second inputs of each of said first and second amplifiers to provide said reference signal.
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Abstract
A data limiter for a radio pager is described in which an analog input signal including a data signal is compared in a comparator with a threshold voltage which is adjusted by means of a feedback network. The network consists of transconductance amplifiers having predetermined input offset voltages related to the amplitude of the analog signal which monitor the departure of the analog signal from a reference voltage to provide output currents which are integrated by an integrator and applied as the threshold voltage to the comparator and as the reference voltage to the transconductance amplifiers.
39 Citations
25 Claims
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1. A data limiter, comprising:
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comparison means having a first input for receiving a first signal and a second input for receiving a reference signal; first and second transconductance amplifiers, each having a first input coupled to receive said first signal, a second input coupled to receive said reference signal, and an output, each amplifier having a respective predetermined input offset voltage; and an integrator having an input coupled to the outputs of said first and second transconductance amplifiers and an output coupled to the second input of said comparison means and to the second inputs of each of said first and second amplifiers to provide said reference signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A data limiter, comprising:
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a voltage comparator having a first input for receiving an analog signal including a data signal and a second input for receiving a reference voltage; first and second transconductance amplifiers, each having a first input coupled to receive said analog signal, a second input coupled to receive said reference voltage, and an output, each amplifier having a respective predetermined input offset voltage, wherein the input offset voltages of the first and second transconductance amplifiers are opposite polarity and are approximately equal to one half of the peak-to-peak amplitude of the analog signal, and wherein said first amplifier sources a current to its output when the amplitude of the analog signal exceeds the reference voltage by the amount of its input offset voltage, and the second amplifier sinks current from its output when the amplitude of the analog signal is less than the reference voltage by the amount of its input offset voltage; and an integrator having an input coupled to the outputs of said first and second transconductance amplifiers and an output coupled to the second input of said voltage comparator and to the second inputs of each of said first and second amplifiers to provide said reference voltage. - View Dependent Claims (11)
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12. A data limiter, comprising;
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a voltage comparator having a first input for receiving an analog signal including a data signal and a second input for receiving a reference voltage; first and second transconductance amplifiers, each having a first input coupled to receive said analog signal, a second input coupled to receive said reference voltage, and an output, each amplifier having a respective predetermined input offset voltage, wherein the input offset voltages of the first and second transconductance amplifiers are opposite polarity and are approximately equal to one half of the peak-to-peak amplitude of the analog signal; and a digital integrator having an input coupled to the outputs of said first and second transconductance amplifiers and an output coupled to the second input of said voltage comparator and to the second inputs of each of said first and second amplifiers to provide said reference voltage. - View Dependent Claims (13)
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14. A method of comparing an audio signal with a threshold voltage comprising the steps of:
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comparing said audio signal and said threshold voltage in first and second transconductance amplifiers each having a predetermined input offset voltage; and integrating the outputs of said first and second amplifiers to alter said threshold voltage.
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15. A data limiter, comprising:
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comparison means having a first input for receiving a first signal and a second input for receiving a reference signal; first and second transconductance amplifiers, each having a first input coupled to receive said fist signal, a second input coupled to receive said reference signals, and an output connected to a node, each amplifier having a respective predetermined input offset voltage; and an integrator having an input coupled to the node and an output coupled to the second input of said comparison means and to the second inputs of each of said first and second amplifiers to provide said reference signal. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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Specification