Phase coded, micro-power impulse radar motion sensor
First Claim
1. An apparatus for detecting a characteristic of objects within a field, comprising:
- a transmitter which transmits a sequence of electro-magnetic signals in response to a transmit timing signal at a nominal pulse repetition frequency;
a receiver which samples echoes of the sequence of electro-magnetic signals from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples, the sample signal indicating a characteristic of objects within the field; and
a modulation circuit which imposes a modulation signal having the intermediate frequency on at least one of the transmitter signal amplitude, the transmit timing signal or the receive timing signal.
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Accused Products
Abstract
A motion sensing, micro-power impulse radar MIR impresses on the transmitted signal, or the received pulse timing signal, one or more frequencies lower than the pulse repetition frequency, that become intermediate frequencies in a "IF homodyne" receiver. Thus, many advantages of classical RF receivers can be thereby be realized with ultra-wide band radar. The sensor includes a transmitter which transmits a sequence of electromagnetic pulses in response to a transmit timing signal at a nominal pulse repetition frequency. A receiver samples echoes of the sequence of electromagnetic pulses from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples. A timing circuit supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver. The relative timing of the transmit timing signal and the receive timing signal is modulated between a first relative delay and a second relative delay at an intermediate frequency, causing the receiver to sample the echoes such that the time between transmissions of pulses in the sequence and samples by the receiver is modulated at the intermediate frequency. Modulation may be executed by modulating the pulse repetition frequency which drives the transmitter, by modulating the delay circuitry which controls the relative timing of the sample strobe, or by modulating amplitude of the transmitted pulses. The electromagnetic pulses will have a nominal center frequency related to pulse width, and the first relative delay and the second relative delay between which the timing signals are modulated, differ by less than the nominal pulse width, and preferably by about one-quarter wavelength at the nominal center frequency of the transmitted pulses.
239 Citations
30 Claims
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1. An apparatus for detecting a characteristic of objects within a field, comprising:
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a transmitter which transmits a sequence of electro-magnetic signals in response to a transmit timing signal at a nominal pulse repetition frequency; a receiver which samples echoes of the sequence of electro-magnetic signals from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples, the sample signal indicating a characteristic of objects within the field; and a modulation circuit which imposes a modulation signal having the intermediate frequency on at least one of the transmitter signal amplitude, the transmit timing signal or the receive timing signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. An apparatus for detecting motion within a field, comprising:
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a transmitter which transmits radio frequency signals in response to a transmit timing signal; a receiver which samples echoes of the transmitted radio frequency signals from objects within the field with controlled timing, in response to a receive timing signal, and generates a sample signal in response to the samples; a timing circuit which supplies the transmit timing signal to the transmitter and supplies the receive timing signal to the receiver, the timing circuit including a first circuit path coupled to the transmitter supplying the transmit timing signal and a second circuit path coupled to the receiver supplying the receive timing signal, one of the first and second circuit paths including modulation circuitry responsive to a modulation signal so that relative timing of the transmit timing signal and the receive timing signal is modulated between a first relative delay and a second relative delay; and a modulation control circuit which generates the modulation signal, the modulation signal having an intermediate frequency. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A method for detecting motion in a field, comprising:
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transmitting a sequence of RF signals with controlled timing; sampling echoes of the transmitted sequence with controlled timing so that a range is defined by a round trip time-of-flight of the RF signals; modulating at least one of the transmitting or sampling steps at an intermediate frequency; and amplifying the sampled echoes at the intermediate frequency, and synchronously detecting the amplified signal, synchronous with the modulating step. - View Dependent Claims (26, 27, 28, 29, 30)
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Specification