Baseband phase modulator apparatus employing digital techniques
First Claim
1. A Zero IF modulator apparatus for modulating RF carrier signals with baseband signals and operative to perform phase or frequency modulation, comprising:
- first and second analog-to-digital converters each having a separate input adapted to receive an analog baseband signal and each having a separate output for providing a digital signal indicative of the analog baseband signal applied to said input,a weighting function generator means having an input coupled to the output of said first analog-to-digital converter and operative to provide at an output said digital signal at the output of said first analog-to-digital converter as multiplied by a given weighting function,a digital sine/cosine amplitude converter means having an input and operative to provide at a first output a first digital quadrature baseband signal and to provide at a second output a second digital quadrature baseband signal,adding means having one input coupled to the output of said weighting function generator means and another input coupled to the output of said second analog-to-digital converter with the output of said adding means coupled to the input of said sine/cosine amplitude converter means wherein said sine/cosine converter can receive a digital baseband signal from either said first or second converters,a first digital-to-analog converter coupled to said first output of said sine/cosine converter means to provide at an output a first analog quadrature signal,a second digital-to-analog converter coupled to said second output of said sine/cosine converter means to provide at an output a second analog quadrature signal, andmodulation translation means including a carrier oscillator operating at a given frequency, said modulation translation means responsive to said first and second analog quadrature signals for translating said signals to a given carrier frequency.
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Abstract
There is disclosed a Zero IF modulator apparatus for modulating carrier signals with baseband signals, the modulator includes digital logic circuitry including a sine/cosine amplitude converter which is responsive to the baseband signals for providing first and second digital quadrature baseband signals. These digital quadrature baseband signals are then employed by coupling the same to digital-to-analog converters where the outputs of each converter is indicative of a first and second quadrature signal. These signals can then be translated to a given carrier signal for transmission over a desired communication channel.
118 Citations
24 Claims
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1. A Zero IF modulator apparatus for modulating RF carrier signals with baseband signals and operative to perform phase or frequency modulation, comprising:
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first and second analog-to-digital converters each having a separate input adapted to receive an analog baseband signal and each having a separate output for providing a digital signal indicative of the analog baseband signal applied to said input, a weighting function generator means having an input coupled to the output of said first analog-to-digital converter and operative to provide at an output said digital signal at the output of said first analog-to-digital converter as multiplied by a given weighting function, a digital sine/cosine amplitude converter means having an input and operative to provide at a first output a first digital quadrature baseband signal and to provide at a second output a second digital quadrature baseband signal, adding means having one input coupled to the output of said weighting function generator means and another input coupled to the output of said second analog-to-digital converter with the output of said adding means coupled to the input of said sine/cosine amplitude converter means wherein said sine/cosine converter can receive a digital baseband signal from either said first or second converters, a first digital-to-analog converter coupled to said first output of said sine/cosine converter means to provide at an output a first analog quadrature signal, a second digital-to-analog converter coupled to said second output of said sine/cosine converter means to provide at an output a second analog quadrature signal, and modulation translation means including a carrier oscillator operating at a given frequency, said modulation translation means responsive to said first and second analog quadrature signals for translating said signals to a given carrier frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A Zero IF modulator apparatus for modulating RF carrier signals with baseband signals and operative to perform phase or frequency modulation, comprising:
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first and second analog-to-digital converters, each having a separate input adapted to receive an analog baseband signal, and each having a separate output for providing a digital signal indicative of the analog baseband signal applied to said input, a weighting function generator means having an input coupled to said output of said first analog-to-digital converter and operative to provide at an output a said digital signal at the output of said first analog-to-digital converter as multiplied by a given weighting function, digital accumulator means having an input coupled to the output of said weighting function generator means and operative to provide at an output an integrated digital signal, first adding means having one input coupled to the output of said digital accumulator means and another input coupled to the output of said second analog-to-digital converter, said adding means having an output, sine/cosine converter means having an input coupled to the output of said adding means and operative to provide at a first output a first digital quadrature signal and at a second output a second digital quadrature signal, a first digital-to-analog converter coupled to said first output of said sine/cosine converter means to provide at an output a first analog quadrature signal, a second digital-to-analog converter coupled to said second output of said sine/cosine converter means to provide a second analog quadrature signal, first mixing means having a first input responsive to said first analog quadrature signal and having a second input and an output, second mixing means having a first input responsive to said second analog quadrature signal, and having a second input and an output, means for applying a source of carrier signals to said second inputs of said first and second mixers to provide at said outputs first and a second modulated signals and, means coupled to said outputs of said mixers to combine said first and second modulated signals to provide an output modulated signal for transmission over a communications link, said modulated signal being modulated according to which analog-to-digital converter receives said baseband signal. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A Zero IF modulator apparatus for modulating carrier signals with baseband signals, comprising:
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a first analog-to-digital converter for converting a baseband signal at an input to a digital signal, accumulator means including a first adder coupled to the output of said first analog-to-digital converter to provide at an output an integrated digital signal, with said first adder having one input adapted to receive a digital word signal for selecting a mode of modulation operation, means including a second adder having one input coupled to the output of said accumulator means and another input adapted to be coupled to a digital signal source and adapted to convert said integrated digital signal to first and second quadrature signals. - View Dependent Claims (21, 22, 23, 24)
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Specification