Baseband differentially phase encoded radio signal detector
First Claim
1. An apparatus for detecting differentially phase encoded radio signals, comprising:
- a quadrature downconverter means for downconverting said differentially phase encoded radio signal to a first and second baseband signal in phase quadrature with each other;
first and second sampling means, each for providing on its output, a stream of pulses representative of an analog signal on its input;
means for applying said first baseband signal to said first sampling means;
means for applying said second baseband signal to said second sampling means;
first and second matched filter means,means for connecting said first sampling means to said first matched filter means;
means for connecting said second sampling means to said second matched filter means;
timing means for periodically enabling said first and second sampling means and said first and second matched filter means; and
arithmetic means connected to said first and second matched filter means for subtracting the output of said second matched filter means from said first matched filter means whereby said differentially phase encoded ratio signal is detected.
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Abstract
A radio signal is applied to an in phase detector channel and a quadrature phase detector channel. Each detector channel includes, in cascade arrangement; an in phase downconverter means for downconverting the received radio signal to a baseband signal; a sampling means for sampling the baseband signal at a predetermined rate; and a matched filter means matched to the symbol waveform and wherein the sample pulses are stored over a predetermined period of time that corresponds to two data symbols. The sum of the pulses for the first data symbol and the sum of the pulses for the second data symbol are compared to determine if there has been a phase reversal between the two data symbols. The outputs of the in phase and quadrature phase channels are summed, which results in demodulation of the encoded data.
169 Citations
18 Claims
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1. An apparatus for detecting differentially phase encoded radio signals, comprising:
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a quadrature downconverter means for downconverting said differentially phase encoded radio signal to a first and second baseband signal in phase quadrature with each other; first and second sampling means, each for providing on its output, a stream of pulses representative of an analog signal on its input; means for applying said first baseband signal to said first sampling means; means for applying said second baseband signal to said second sampling means; first and second matched filter means, means for connecting said first sampling means to said first matched filter means; means for connecting said second sampling means to said second matched filter means; timing means for periodically enabling said first and second sampling means and said first and second matched filter means; and arithmetic means connected to said first and second matched filter means for subtracting the output of said second matched filter means from said first matched filter means whereby said differentially phase encoded ratio signal is detected. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. The method of detecting a differentially phase encoded radio signal comprising the steps of:
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quadrature downconverting a differentially phase encoded radio signal to a first and second baseband signal in phase quadrature with each other; sampling said first and second baseband signal at a predetermined rate; passing said sampled first baseband signal through a first matched filter device; passing said sampled second baseband signal through a second matched filter device; and combining the correlated output of said first matched filter device and said second matched filter device. - View Dependent Claims (17, 18)
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Specification