Micro movement pulsed radar system and method of phase noise compensation
First Claim
1. A method of reducing noise in a pulsed radar system, comprising:
- Transmitting pulses and receiving return signals to place an analog reference range gate on a stationary reference;
Placing an ensemble of analog range gates in close proximity to the stationary reference; and
Transmitting pulses and receiving return signals to collect data for said reference and ensemble of range gates and rotate the phase of such ensemble data by a phase shift of the reference data.
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Abstract
A pulsed radar system uses phase noise compensation to reduce phase noise due to drift of the reference oscillator to enable detection of micro movements and particularly human motion such as walking, breathing or heartbeat. The noise level due to A/D sampling must be sufficiently low for the phase noise compensation to be effective. As this is currently beyond state-of-the-art for high bandwidth A/D converters used in traditional receiver design, the receiver is suitably reconfigured to use analog range gates and narrowband A/D sampling having sufficiently low noise level. As technology continues to improve, the phase compensation techniques may be directly applicable to the high bandwidth A/D samples in traditional receiver designs. Whether phase compensation is applied to traditional receiver designs or a receiver configured with analog range gates, the steps are essentially the same: data is processed to position a reference range bin (either an analog range gate or a particular time sample) on a stationary reference and the phase variation of that reference range bin is used to compensate the phase of target data in range bins (either an ensemble of range gates or other time samples) near the stationary reference. This effectively moves the radar system and particularly the reference oscillator to the stationary reference thereby greatly reducing oscillator drift and phase noise and decoupling the stand-off range from the level of phase noise.
44 Citations
33 Claims
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1. A method of reducing noise in a pulsed radar system, comprising:
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Transmitting pulses and receiving return signals to place an analog reference range gate on a stationary reference;
Placing an ensemble of analog range gates in close proximity to the stationary reference; and
Transmitting pulses and receiving return signals to collect data for said reference and ensemble of range gates and rotate the phase of such ensemble data by a phase shift of the reference data. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A micro movement radar system, comprising:
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a reference oscillator for generating AC signals;
a pulse forming network that forms pulses from the AC signals;
an antenna that transmits the pulses and receives return pulses;
a receiver including a plurality of analog range gates for receiving return signals that lie within a time window with respect to the transmit pulse, an A/D converter that converts the gated signals into a digital signal;
a timing generator that generates clock signals to transmit the pulse and to activate the analog range gates; and
a processor that controls the timing generator to (a) transmit pulses and activate the range gates to place an analog reference range gate on a stationary reference, (b) place an ensemble of analog range gates in close proximity to the stationary reference, and (c) transmit pulses and receiver return signals to collect data from the digital signal for said range gates and rotate the phase of such ensemble data by a phase shift of the reference data. - View Dependent Claims (16)
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17. A method of reducing noise in a pulsed radar system, comprising:
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(a) Transmitting pulses and receiving return signals to place an analog reference range gate on a stationary reference;
(b) Placing an ensemble of analog range gates in close proximity to the stationary reference;
(c) Transmitting pulses and receiving return signals to collect data for said reference and ensemble of range gates, said return signals being gated by the analog range gates to form respective pulse trains that are band pass filtered to extract a center spectral line, multiplexed and A/D sampled;
(d) Calculating a phase shift for said reference range gate data between a first data set of digital samples and a next data set;
(e) Rotating the phase of the ensemble data for the next data set by the phase shift; and
(f) repeating steps c through e for a plurality of next data sets. - View Dependent Claims (18, 19)
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20. A method of reducing phase noise in a pulsed radar system, comprising:
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(a) Transmitting pulses and receiving return signals to position a reference range bin on a stationary reference;
(b) Transmitting pulses and receiving return signals to collect data sets from said stationary reference and a target in close proximity to the stationary reference;
(c) Calculating a phase shift for said reference range bin between a first data set and a next data set;
(d) Rotating the phase of the target data for range bins near the reference range bin in the next data set by the phase shift; and
(e) repeating steps b through d for a plurality of next data sets. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A micro movement radar system, comprising:
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a reference oscillator for generating AC signals;
a pulse forming network that forms pulses from the AC signals;
an antenna that transmits the pulses and receives return signals;
a receiver for receiving return signals, an A/D converter that converts the return signal into a digital samples;
a timing generator that generates clock signals to transmit the pulse and to activate the analog range gates; and
a processor that controls the timing generator to transmit pulses and process return signals in successive data sets to (a) place a reference range bin on a stationary reference, (b) calculate a phase shift for the reference range bin between a first data set and a next data set and (c) rotate the phase of range bins near the reference range bin in the next data set by the phase shift of the reference data. - View Dependent Claims (32, 33)
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Specification