Log-polar signal processing
First Claim
1. A method for processing radio signals, that vary over a wide dynamic range, which comprises the steps of:
- amplifying the radio signals in a plurality of serial stages;
detecting the output of each amplifying stage;
summing the detected outputs of each amplifying stage together to provide a signal proportional to the logarithm of the amplitudes of the radio signals;
generating signals proportional to the phase of the radio signals from the output of the last amplifying stage; and
processing the signals proportional to the logarithm of the amplitudes and the signals proportional to the phase of the radio signals, in order to generate restored digital signals representative of the radio signals.
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Abstract
The invention relates to a method and an arrangement intended for radio communication systems and effective in digitalizing and subsequently processing numerically arbitrary radio signals. The signals are represented by composite (complex) vectors which have been subjected to disturbances in the system, such that information in the signals has been lost. This information is restored in its entirety when practising the present invention. For the purpose of solving this problem, the inventive digitalizing arrangement includes a multistage logarithmic amplifier chain (A) in which each stage is connected to a separate detector (D), the output signals of which are added in an adder. The adder output signals are then transmitted to a first A/D-converter (AD1) for digitalizing and converting the amplitude components of the signal. At the same time, the undetected signal from the saturated output stage in the amplifier chain is transmitted to a second A/D-converter for digitalizing and converting the phase components of the signal. The digital values obtained on the outputs of the AD-converters (AD1, AD2) are applied to different inputs of a digital signal processor (MP) for numerical processing of the pairwise received digital values in a manner such as to restore the complete vector characteristic of the signal.
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Citations
32 Claims
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1. A method for processing radio signals, that vary over a wide dynamic range, which comprises the steps of:
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amplifying the radio signals in a plurality of serial stages;
detecting the output of each amplifying stage;
summing the detected outputs of each amplifying stage together to provide a signal proportional to the logarithm of the amplitudes of the radio signals;
generating signals proportional to the phase of the radio signals from the output of the last amplifying stage; and
processing the signals proportional to the logarithm of the amplitudes and the signals proportional to the phase of the radio signals, in order to generate restored digital signals representative of the radio signals. - View Dependent Claims (2, 3)
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4. An apparatus for processing radio signals that vary over a wide dynamic range, which comprises:
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means for amplifying the radio signals in a plurality of serial stages;
means for detecting the output of each amplified stage;
means for summing the detected outputs of said detecting means in order to provide a signal proportional to the logarithm of the amplitudes of the radio signals;
means for generating signals proportional to the phase of the radio signals from the output of the last stage of said amplifying means; and
processing means for processing the signals proportional to the logarithm of the amplitudes and the signals proportional to the phase of the radio signals, in order to provide restored digital signals representative of the radio signals. - View Dependent Claims (5, 6, 7, 8, 9, 10)
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11. A method for processing radio signals, that vary over a wide dynamic range, which comprises the steps of:
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amplifying the radio signals in a plurality of serial stages;
clipping the output of the last amplifying stage such that the output at the last amplifying stage appears as a square wave, detecting the output of each amplifying stage;
summing the detected outputs of each amplifying stage together to provide a signal proportional to the logarithm of the amplitudes of the radio signals;
generating signals proportional to the phase of the radio signals from the output of the last amplifying stage, such that the generation of signals proportional to the phase is synchronous with the signal proportional to the logarithm of the amplitudes; and
processing the signals proportional to the logarithm of the amplitudes and the signals proportional to the phase of the radio signals, in order to generate restored digital signals representative of the radio signals.
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12. A method for processing complex radio signals that vary over a wide dynamic range, comprising the steps of:
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amplifying the radio signals in a plurality of sequentially saturating stages to produce a hardlimited output signal from the final stage;
detecting the output from each stage and summing the detected outputs to produce a log-amplitude value approximately proportional to the logarithm of an instantaneous amplitude of the complex radio signals;
converting the hardlimited output signal from the final amplifier stage to numerical values related to the cosine of the instantaneous phase and to the sine of the phase; and
processing the log-amplitude value and the cosine-related and sine-related values in order to produce numerical values representative of the real and imaginary parts of the complex radio signal. - View Dependent Claims (13, 14, 15, 16)
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17. An apparatus for processing a complex radio signal that varies over a wide dynamic range, which comprises:
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means for amplifying the radio signal in a plurality of sequentially saturating stages and producing a hardlimited output signal from the final stage;
means for detecting the output from each stage and producing detected output signals;
means for converting the detected output signals to produce a log-amplitude value approximately proportional to the logarithm of an instantaneous amplitude of the complex radio signal;
means for converting the hardlimited output signal from the final stage in order to extract values containing instantaneous phase information such that the extracted values are produced substantially synchronously with the log-amplitude value; and
processing means for processing the extracted values together with the log-amplitude value in order to provide digital values representative of the complex radio signal. - View Dependent Claims (18, 19, 20)
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21. An apparatus for processing a complex radio signal that varies over a wide dynamic range, which comprises:
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means for amplifying the radio signal in a plurality of sequentially saturating stages and producing a hardlimited output signal from the final stage;
means for detecting the output from each stage and producing detected output signals;
first means for converting the detected output signals to produce a first log-amplitude value approximately proportional to the logarithm of an instantaneous signal amplitude of the complex radio signal;
second means for converting the hardlimited output signal from the final stage in order to extract values containing instantaneous phase information; and
processing means, responsive to said first and second converting means, for determining a second log-amplitude value representative of the instantaneous amplitude of the radio signal at the same instant the extracted values are representative of the instantaneous phase of the radio signal and for combining the determined second log-amplitude value with the extracted values in order to provide digital values representative of the complex radio signal. - View Dependent Claims (22, 23, 24)
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25. A method of processing a radio signal comprising:
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amplifying said radio signal using a chain of progressively saturating amplifiers each including detectors in order to produce detected signals related to the logarithm of the signal amplitude of the radio signal and a saturated output signal from the last amplifier in the chain of amplifiers that preserves preserving phase information of the radio signal;
sampling and digitizing said detected signal and said saturated output signal using analog-to-digital converters in order to produce corresponding numerical sample values; and
numerically processing said numerical sample values in order to produce complex numerical samples representing said radio signal. - View Dependent Claims (26, 27, 28)
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29. An apparatus for processing a radio signal comprising:
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receiving means for converting said radio signal to a suitable intermediate frequency signal;
amplifying and detecting means, having a plurality of stages, for amplifying the intermediate frequency signal to produce a detected signal related to the amplitude of the intermediate frequency signal and to produce a saturated output signal from the last stage of the amplifying and detecting means;
analog-to-digital converting means for sampling and digitizing the detected output signal and the saturated signal to produce corresponding numerical samples; and
digital signal processing means to process the numerical samples in order to obtain complex numerical samples representative of the radio signal. - View Dependent Claims (30, 31, 32)
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Specification