Phase based vector modulator
First Claim
1. In a vector modulation system in which a vector modulated output signal is produced by summing component signals produced by first and second circuits in response to first and second input modulation signals, an improvement wherein the first and second circuits comprise continuously variable phase modulators, so that any form of amplitude, phase or frequency modulation can be generated.
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Abstract
Vector modulation is effected by summing output signals from two phase modulators. The lack of amplitude modulation on the signals when summed permits non-linear processing of the signals, such as PLL frequency translation. In one embodiment, the phase modulators comprise fractional-N phase locked loops modulated with digital data words. In another, the phase modulators comprise direct digital synthesizers.
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Citations
17 Claims
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1. In a vector modulation system in which a vector modulated output signal is produced by summing component signals produced by first and second circuits in response to first and second input modulation signals, an improvement wherein the first and second circuits comprise continuously variable phase modulators, so that any form of amplitude, phase or frequency modulation can be generated.
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2. In a vector modulation system in which a vector modulated output signal is produced by summing component signals produced by first and second circuits in response to first and second input modulation signals, an improvement wherein the first and second circuits comprise phase modulators and each of the phase modulators comprises a phase locked loop.
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3. In a vector modulation system in which a vector modulated output signal is produced by summing component signals produced by first and second circuits in response to first and second input modulation signals, an improvement wherein the first and second circuits comprise phase modulators and each of the phase modulators comprises a direct digital synthesizer.
- 4. In a vector modulation system in which a vector modulated output signal is produced by summing component signals produced by first and second circuits in response to first and second input modulation signals, an improvement wherein the first and second circuits comprise phase modulators and each of the phase modulators comprises a fractional-N phase locked loop.
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6. A vector modulator capable of generating any form of amplitude, phase or frequency modulation, the modulator comprising:
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a source of local oscillator signals; a summing network having first and second inputs and an output; and a first continuously variable phase modulator having a first input coupled to the source of local oscillator signals, a second input for receiving a first modulation signal, and an output coupled to the first input of the summing network; a second continuously variable phase modulator having a first input coupled to the source of local oscillator signals, a second input for receiving a second modulation signal, and an output coupled to the second input of the summing network; input means for receiving vector signals; and a processor for altering said vector signals and producing the first and second modulation signals therefrom.
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7. A vector modulator comprising:
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a source of local oscillator signals; a summing network having first and second inputs and an output; and a first phase modulator having a first input coupled to the source of local oscillator signals, a second input for receiving a first modulation signal, and an output coupled to the first input of the summing network; a second phase modulator having a first input coupled to the source of local oscillator signals, a second input for receiving a second modulation signal, and an output coupled to the second input of the summing network; input means for receiving quadrature I and Q signals; and a processor for altering said quadrature I and Q signals and producing the first and second modulation signals therefrom, said processor producing said first and second modulation signals (X and Y) by altering the quadrature I and Q signals according to the following formulas;
space="preserve" listing-type="equation">X=tan.sup.-1 (Q/I)-cos.sup.-1 (SQRT(I.sup.2 +Q.sup.2)/2)
space="preserve" listing-type="equation">Y=tan.sup.-1 (Q/I)-A+cos.sup.-1 (SQRT(I.sup.2 +Q.sup.2)/2)where A is an arbitrary phase term reflecting a phase offset.
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8. A vector modulator comprising:
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a source of local oscillator signals; a summing network having first and second inputs and an output; and a first phase modulator having a first input coupled to the source of local oscillator signals, a second input for receiving a first modulation signal, and an output coupled to the first input of the summing network; a second phase modulator having a first input coupled to the source of local oscillator signals, a second input for receiving a second modulation signal, and an output coupled to the second input of the summing network; input means for receiving vector signals; and a processor for altering said vector signals and producing the first and second modulation signals therefrom, said processor including a memory responsive to vector signals applied thereto to produce corresponding first and second modulation data signals.
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9. A vector modulation apparatus capable of generating any form of amplitude, phase or frequency modulation comprising:
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first means for receiving first and second vector signals; second means coupled to the first means for producing first and second output signals (X and Y) corresponding to the first and second vector signals; a local oscillator; a first continuously variable phase modulator responsive to the first output signal (X) from the second means and responsive to the local oscillator, for producing a first phase modulated output signal; a second continuously variable phase modulator responsive to the second output signal (Y) from the second means and responsive to the local oscillator, for producing a second phase modulated output signal; and a combiner having first and second inputs coupled to outputs of the first and second phase modulators, and having an output for outputting a summed output signal. - View Dependent Claims (10, 11, 12, 13)
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14. A method of using phase modulation to generate a signal with any amplitude, phase or frequency characteristics, the method comprising the steps:
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providing vector signals; determining X and Y signals corresponding to said vector signals; continuously phase modulating a first local oscillator signal with the X signal to produce a first output signal; continuously phase modulating a second local oscillator signal with the Y signal to produce a second output signal, said second local oscillator signal having the same frequency as the first local oscillator signal; and summing the first and second output signals. - View Dependent Claims (15, 16, 17)
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Specification