Dual mode radiotelephone terminal selectively operable for frequency modulated or phase modulated operation
First Claim
1. A mobile radiotelephone, comprising:
- control means for generating a first state of a control signal when operating the radiotelephone in a first mode of operation and for generating a second state of the control signal when operating the radiotelephone in a second mode of operation;
means, responsive to said control signal, for generating a first electrical representation of an audio input signal when operating in the first mode of operation and for generating a second electrical representation of the audio input signal when operating in the second mode of operation;
means, responsive to the first electrical representation, for generating a first phase modulation control signal and a second phase modulation control signal;
means, responsive to the second electrical representation, for frequency modulating a transmitter injection frequency signal in accordance therewith; and
modulator means for generating a transmission frequency signal that is modulated, in the first mode of operation, in accordance with said first electrical representation and that is modulated, in the second mode of operation, in accordance with said second electrical representation, said modulator means comprising,means for receiving said transmitter injection frequency signal and for regenerating the transmitter injection frequency signal to provide at a first output a first injection frequency signal and at a second output a second injection frequency signal, said first injection frequency signal having a non-zero phase shift with respect to said second injection frequency signal;
first mixer means having a first input coupled to said first injection frequency signal and a second input coupled to said first modulation control signal, said first mixer means having an output for providing a first output frequency signal that is phase modulated in accordance with said first modulation control signal;
second mixer means having a first input coupled to said second injection frequency signal and a second input coupled to said second modulation control signal, said second mixer means having an output for providing a second output frequency signal that is phase modulated in accordance with said second modulation control signal;
combining means, having a first input coupled to said output of said first mixer means and a second input coupled to said output of said second mixer means, for combining said first and second mixer means outputs into a modulator output signal; and
biasing means having a control input for receiving said control signal and an output, said output of said biasing means being coupled to at least said first mixer means for selectively enabling said first mixer means, during the first mode of operation as indicated by the state of said control signal, to output said phase modulated first output frequency signal, said output of said biasing means selectively enabling said first mixer means, during the second mode of operation as indicated by the state of said control signal, to output a frequency signal that is substantially identical to said first injection frequency signal.
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Accused Products
Abstract
A dual-mode radiotelephone terminal includes a π/4-shift DQPSK modulator (11). A dual-mode modulation is achieved by mixing an output of a transmitter oscillator (16) with an output of an offset oscillator (18) to form an injection signal (LO) at a final transmitter frequency, the injection signal being further modulated with a quadrature modulator in a digital mode of operation. In an analog mode of operation the transmitter oscillator or the offset oscillator is frequency modulated and the quadrature modulator is disabled, thereby passing the frequency modulated injection signal without substantial attenuation. The LO signal is regenerated and also phase shifted with a circuit (35) having a frequency multiplier (30) and a frequency divider (34). The circuit outputs two local oscillator (LO) signals (LOA and LOB), each of which directly drives an associated quadrature mixer (36, 38) of the modulator. In another embodiment the dual-mode radiotelephone terminal includes a VHF synthesizer (23), a UHF synthesizer (21), and a local oscillator (4C) that provides a signal only when operating in the analog receiving mode. The local oscillator signal is mixed with a first IF signal for providing a second IF signal when operating in the analog receiving mode or in a standby mode. A control signal is employed for selectively enabling and disabling various of these components as a function of the operating mode, thereby conserving power.
61 Citations
14 Claims
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1. A mobile radiotelephone, comprising:
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control means for generating a first state of a control signal when operating the radiotelephone in a first mode of operation and for generating a second state of the control signal when operating the radiotelephone in a second mode of operation; means, responsive to said control signal, for generating a first electrical representation of an audio input signal when operating in the first mode of operation and for generating a second electrical representation of the audio input signal when operating in the second mode of operation; means, responsive to the first electrical representation, for generating a first phase modulation control signal and a second phase modulation control signal; means, responsive to the second electrical representation, for frequency modulating a transmitter injection frequency signal in accordance therewith; and modulator means for generating a transmission frequency signal that is modulated, in the first mode of operation, in accordance with said first electrical representation and that is modulated, in the second mode of operation, in accordance with said second electrical representation, said modulator means comprising, means for receiving said transmitter injection frequency signal and for regenerating the transmitter injection frequency signal to provide at a first output a first injection frequency signal and at a second output a second injection frequency signal, said first injection frequency signal having a non-zero phase shift with respect to said second injection frequency signal; first mixer means having a first input coupled to said first injection frequency signal and a second input coupled to said first modulation control signal, said first mixer means having an output for providing a first output frequency signal that is phase modulated in accordance with said first modulation control signal; second mixer means having a first input coupled to said second injection frequency signal and a second input coupled to said second modulation control signal, said second mixer means having an output for providing a second output frequency signal that is phase modulated in accordance with said second modulation control signal; combining means, having a first input coupled to said output of said first mixer means and a second input coupled to said output of said second mixer means, for combining said first and second mixer means outputs into a modulator output signal; and biasing means having a control input for receiving said control signal and an output, said output of said biasing means being coupled to at least said first mixer means for selectively enabling said first mixer means, during the first mode of operation as indicated by the state of said control signal, to output said phase modulated first output frequency signal, said output of said biasing means selectively enabling said first mixer means, during the second mode of operation as indicated by the state of said control signal, to output a frequency signal that is substantially identical to said first injection frequency signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A mobile radiotelephone, comprising:
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control means for generating a first state of a control signal when operating the radiotelephone in a first mode of operation and for generating a second state of the control signal when operating the radiotelephone in a second mode of operation, wherein in said first mode of operation said radiotelephone is operable for transmitting and receiving a frequency modulated signal, and in said second mode of operation said radiotelephone is operable for transmitting and receiving a phase modulated signal; a Very High Frequency VHF frequency synthesizer means having an output for providing a frequency signal FVHF ; frequency divider means having an input coupled to an output of said VHF frequency synthesizer means and an output for providing a frequency signal equal to FVHF /N; an Ultra High Frequency UHF frequency synthesizer means having an output for providing a frequency signal FUHF ; first frequency mixer means for mixing FUFH with a received frequency signal; first Intermediate Frequency IF filter means having an input coupled to an output of said first mixer means and an output for providing a first IF signal; second mixer means having a first input coupled to said first IF signal and a second input, said second mixer means having an output for outputting a second IF signal; local oscillator means responsive to said control signal for generating a local oscillator frequency signal when operating in said first mode of operation, said local oscillator frequency signal being coupled to said second input of said second mixer means; means, having an input coupled to said second IF signal output by said second mixer means, for generating a signal in response to a frequency modulation of said received frequency signal; third mixer means having an input coupled to said first IF signal and a second input coupled to said output of said frequency divider means, said third mixer means having an output for outputting a second IF signal; and means, having an input coupled to said second IF signal output by said second mixer means, and being responsive to said control signal, for generating an output signal when operating in said second mode. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification