Pulse radar detection system

• US 20030193430A1
• Filed: 05/21/2003
• Published: 10/16/2003
• Est. Priority Date: 03/22/2002
• Status: Active Grant

• Current Assignee: Veoneer US LLC (Magna International Incorporated)
• Original Assignee: Robert Egri, Robert Ian Gresham
• Inventors: Gresham, Robert Ian, Egri, Robert
• Granted Patent: US 6,879,281 B2
• Time in Patent Office: Days
• US Class Current: 342/70
• CPC Class Codes: G01S 13/106 using transmission of pulses having some particular characteristics G01S13/12, G01S13/22, G01S13/24, G01S13/26, G01S13/28 and G01S13/30 take precedence
• CPC Class Codes: G01S 13/18 wherein range gates are used
• CPC Class Codes: G01S 13/288 phase modulated
• CPC Class Codes: G01S 7/282 Transmitters
• CPC Class Codes: G01S 7/288 Coherent receivers
• CPC Class Codes: G01S 7/2886 using I/Q processing

Abstract

A radar based sensor detection system comprises a microwave source operative to provide a continuous wave signal at an output. A pulse-former is coupled to the output of the source and is operative to provide at an output a variable length pulse that increases the transmitted energy of the radar system according to the range of object detection. A modulator is coupled to the output of the pulse-former for providing a modulated pulse signal. A transmit receive switch coupled to the output of the modulator is selectively operative between a first transmit position and a second receive position. A transmit channel coupled to the transmit receive switch transmits the pulse signal when the switch is operated in the transmit position. A receiving channel coupled to the transmit receive switch receives the modulator signal when the switch is operated in the receive position. First and second voltage multipliers each have a local oscillator input for receiving the modulator signal in the receive position, and each have an input signal port, and an output port. A receiver channel receives a reflected transmitted signal from an output and applies the received signal to the receive signal input ports of the voltage multipliers. An autocorrelator coupled to the output ports of the voltage multipliers correlates the received signal to produce an output signal indicating the detection and position of the object.

Claims

1. A transmitter for a high resolution radar system, comprising:

a microwave oscillator for providing at an output a continuous wave signal at a predetermined frequency,

a pulse-former having an input coupled to said output of said oscillator and a first and a second switchable output whereby said oscillator signal can be applied to either output according to a control signal applied to a control terminal of said pulse-former,

a switch driver having an output coupled to said control terminal of said pulse-former and operative to selectively switch said output of said pulse-former between said first and second outputs to provide at said first output a pulse comprising a number of said oscillator cycles indicative of a desired pulse to pulse interval and selected according to a range gated time delay,

a bi-phase modulator having an input coupled to said first output of said pulse-former to provide at an output a bi-phase modulated signal, and

an antenna coupled to said output of said bi-phase modulator for transmitting said bi-phase modulated signal according to a selected object range.

2. The transmitter according to claim 1 further comprising:

an amplifier having an input coupled to the output of said phase modulator and an output coupled to said antenna, said amplifier having a gain control input,

a variable gain control circuit coupled to said gain control input of said amplifier for varying the gain of said amplifier and therefore the magnitude of the transmitted signal.

3. The transmitter according to claim 2 further comprising:

a modulation driver coupled to said modulator for controlling the number of phase inversion of said modulator as a function of said selected object range.

4. The transmitter according to claim 1 further comprising:

a dissipative load coupled to said second switchable output of said pulse-former for dissipating said oscillator signal when said pulse-former is switched to said second output.

5. The transmitter according to claim 1 further comprising:

an FM modulation circuit coupled to said oscillator for varying the frequency of said oscillator signal in a direction to compensate for changes in temperature or power supply variations.

6. The transmitter according to claim 1 wherein said oscillator, pulse-former, switch driver, bi-phase modulator and antenna are fabricated on a common substrate to provide a transmitter integrated circuit (IC).

7. A receiver for a high resolution radar of the type having a transmitter for transmitting a phase coded pulse compression signal, comprising:

a receive antenna capable of receiving a reflected signal from an object positioned to interrupt said transmitted signal and intercept a portion of said signal to said receiver antenna to provide said signal at an output,

first and second voltage multipliers, each having a local oscillator input port and a receive signal input port and each having an output port,

said receive antenna output coupled to said receiver input port of said first and second multipliers,

a microwave oscillator synchronized to said transmitter signal to provide at an output a continuous wave signal at a predetermined frequency,

a pulse-former having an input coupled to said output of said oscillator and a first and a second switchable output whereby said oscillator signal can be applied to either output according to a control signal applied to a control terminal of said pulse-former,

a switch driver having an output coupled to said control terminal of said pulse-former and operative to selectively switch said output of said pulse-former between said first and second outputs to provide at said first output a pulse comprising a number of said oscillator cycles indicative of a desired pulse to pulse interval and selected according to a range gated time delay,

a bi-phase modulator having an input coupled to said first output of said pulse-former to provide at an output a bi-phase modulated signal,

a phase shifter having an input coupled to said output of said bi-phase modulator to provide a phase shifted signal at an output, with said output of said phase shifter coupled to the local oscillator input port of said first voltage multiplier, with said output of said bi-phase modulator coupled directly to said local oscillator input port of said second voltage multiplier, said output port of said first modulator providing a quadrature output (Q) signal and said output port of said second voltage multiplier providing an in-phase (I) output signal,

an autocorrelator responsive to said I and Q signals from said voltage multipliers to process said signals for providing a detection signal indicative of the presence and distance of said object.

8. The receiver according to claim 7 further comprising:

first and second integrators each having an input and an output, the input of said first integrator coupled to the output of said first voltage multiplier, with the input of said second integrator coupled to the output of said second voltage multiplier,

first and second Doppler filters each having an input and an output, with the input of said first filter coupled to the output of said first integrator and with the input of said second filter coupled to the output of said second integrator,

the outputs of said Doppler filters coupled to the input of a switching circuit switched at the pulse repetition rate to provide an output signal indicative of information relating to said object.

9. A radar based sensor detection system, comprising:

a microwave source operative to provide a continuous wave signal at an output,

a pulse-former coupled to said output of said source and operative to provide at an output a variable length pulse that increases the transmitted energy of said radar system according to the range of object detection,

a modulator coupled to said output of said pulse-former for providing a modulated pulse signal at an output,

a transmit receive switch coupled to the output of said modulator and selectively operative between a first transmit position and a second receive position,

a transmit channel coupled to said transmit receive switch for transmitting said pulse signal when said switch is operated in said transmit position,

a receiving channel coupled to said transmit receive switch for receiving said modulator signal when said switch is operated in said receive position,

first and second voltage multipliers each having a local oscillator input for receiving said modulator signal in said receive position and each having an input signal port, and an output port,

a receiver channel for receiving a reflected transmitted signal from an output and applying said received signal to said receive signal input ports of said voltage multipliers,

an autocorrelator coupled to said output ports of said voltage multipliers for correlating said received signal to produce an output signal indicating the detection and position of said object.

10. The system according to claim 9 wherein said modulator is a bi-phase modulator for providing a sequence of phase inversions as a function of a desired pulse length indicative of said object detection range.

11. The system according to claim 9 wherein said pulse-former includes a switch driver operative to gate said applied oscillator signal.

12. The system according to claim 9 further including a single antenna,

a switch coupled to said antenna and operative between a transmit position and a receive position wherein said transmit position is coupled to said transmit channel and said receive position is coupled to said receive channel said switch operative between said positions to employ said single antenna for both transmit and receive operations.

13. The system according to claim 9 wherein said variable length pulse consists of a chip consisting of a single sub-pulse for objects with a close range distance and consisting of increased length chips of seven, eleven or thirteen sub-pulses as the range distance is increased.

14. The system according to claim 12 further including a switch driver coupled to said transmit receive switch for controlling the switching between said receive and transmit positions according to a time delay as a function of the range distance of an object.

15. The system according to claim 9 wherein said receive channel provides a matched filter response to said received signal.

16. The system according to claim 15 wherein said matched filter response has an impulse response in the frequency domain which is the complex conjugate of the received signal.

17. The system according to claim 9 wherein said transmit channel includes an output amplifier having an input coupled to the transmit position of said transmit receiver switch and an output coupled to a transmit antenna, said amplifier having a variable gain control for controlling the magnitude of the transmitted pulse signal.

18. The system according to claim 9 wherein said pulse-former includes a switch operative between a first position coupling said microwave source output to said modulator, and a second position coupling said microwave source output to a dissipative load for directing said microwave signal in said second position to said load,

a modulator driver coupled to said switch and operative to control said switch between said first and second positions.

19. The system according to claim 10 wherein the pulse length from said pulse-former varies as controlled by said modulator driver and according to desired object ranges.

20. The system according to claim 9 wherein said microwave source, said pulse-former, said modulator, said transmit-receiver switch, said transmit and receive channels, said first and second voltage multipliers and said autocorrelator are fabricated on a common substrate to provide a radar based sensor integrated circuit (IC).