Sensor front-end for vehicle closing velocity sensor

• US 6,639,543 B2
• Filed: 01/09/2002
• Issued: 10/28/2003
• Est. Priority Date: 01/09/2002
• Status: Expired due to Term

• Current Assignee: Veoneer, Inc. (SSW Partners LP)
• Original Assignee: Tyco Electronics Corporation (TE Connectivity Ltd. (United Kingdom))
• Inventors: Puglia, Kenneth V.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US10/042,613
• Publication Number:
  US 20030128152A1
• Time in Patent Office: 657 Days
• Field of Search: 342/70, 342/85, 342/118, 342/131, 342/134, 342/135, 342/194
• US Class Current: 342/70
• CPC Class Codes: G01S 13/18 wherein range gates are used

Abstract

A sensor front end is disclosed that is able to discriminate objects based on their range from the sensor. The sensor includes an antenna that transmits a sensor signal and, if an object is present receives a reflected signal therefrom. A pulsed oscillator provides a pulsed first signal having a first frequency and phase, and wherein the pulsed oscillator provides the pulsed first signal for a predetermined pulse duration and with a predetermined pulse repetition frequency. The pulsed oscillator provides the pulsed first signal to a first input port of a dual mode mixer that is further coupled to the antenna via a second port. The dual mode mixer transmits a portion of the pulsed first signal from the first input port to the second port and thus to the antenna to be transmitted as the sensor signal. In addition, the dual mode mixer uses a portion of the first signal to mix with the received reflected signal. The dual mode mixer then provides a mixed signal as an output at a third port. Thus, the pulsed first signal provides both the signal to be transmitted as the sensor signal and the local oscillator signal for the mixer as well. The dual mode mixer will only provide a mixed signal output if the received reflected signal is present in the dual mode mixer concurrently with the pulsed first signal. Accordingly, an object can only be detected when the range to the object is such that the signal propagation time to and from the object is less than or equal to the predetermined pulse length of the pulsed first signal.

Claims

1. A sensor front end for discriminating an object based on range, the sensor comprising:

an antenna having a common aperture for transmitting a sensor signal and receiving a reflected signal;

a first signal module configured and arranged to provide a first signal having a predetermined duration;

a mixer module coupled to the first signal module and to the antenna, wherein a portion of the first signal is passed by the mixer to the antenna and transmitted from the antenna, and wherein in the event that the object is present, receiving a reflected signal from the object via the antenna;

a phase shifter coupled between the mixer and the antenna; and

wherein the mixer is configured and arranged so that the first signal and the received reflected signal provides a mixed signal output when the received reflected signal and a portion of the first signal are present concurrently in the mixer.

2. The sensor front end of claim 1 wherein:

the phase shifter includes a first port and a second port, the second port coupled to the antenna, and the phase shifter is configured and arranged to selectively shift the phase of a reflected signal received at the second port from the antenna and to provide as an output from the first port a phase shifted reflected signal;

and wherein the first signal module includes a pulsed signal source providing a pulsed first signal having a predetermined signal duration and having a predetermined pulse repetition frequency, the first signal having a first frequency and a first phase;

and wherein the mixer module includes a dual mode mixer having first, second, and third ports, the first port of the dual mode mixer coupled to the pulsed signal source and receiving the first signal therefrom, the second port of the dual mode mixer coupled to the first port of the phase shifter, the dual mode mixer configured and arranged to transmit a portion of the first signal from the first port to the second port and to provide the transmitted portion of the first signal as an output from the second port,

and wherein the phase shifter receiving the transmitted portion of the first signal at the first port and the phase shifter for these configured and arranged to selectively shift the phase of the transmitted portion of the first signal and to provide as an output from the second port a transmitted phase shifted first signal;

the antenna receiving the transmitted phase shifted first signal and transmitting the transmitted phase shifted first signal as the sensor signal, in the event that the object is present, the antenna receiving the reflected signal therefrom and providing the reflected signal to the second port of the phase shifter;

the phase shifter receiving the reflected signal at the second port and the phase shifter configured and arranged to selectively shift the phase of the reflected signal and to provide as an output from the first port a phase shifted reflected signal;

the dual mode mixers receiving the phase shifted reflected signal at the second port, the dual mode mixer configured and arranged to mix the phase shifted reflected signal with the pulsed first signal provided by the pulsed signal source and to provide the mixed signal as an output from the third port;

a receiver having an input coupled to the third port of the dual mode mixer and an output providing indication of the presence and non-presence of the object; and

whereby the mixed signal will be provided, and the object detected, only if the object has a range that is less than one half the predetermined signal duration multiplied by the speed of light such that the phase shifted reflected signal is present at the dual mode mixer concurrently with at least a portion of the pulsed first signal.

3. The sensor front end of claim 2 wherein the phase shifter selectively provides a total of ninety (90) degrees of phase shift between the transmitted portion of the first signal and the reflected signal such that in phase and quadrature phase signals are formed.

4. The sensor front end of claim 3 wherein the phase shifter selectively provides a phase shift of forty-five (45) degrees of phase shift to the transmitted portion of the first signal and forty-five (45) degrees of phase shift to the reflected signal.

5. The sensor front end of claim 3 wherein the phase shifter selectively provides a phase shift of ninety (90) degrees to the transmitted portion of the first signal and zero (0) degrees of phase shift to the reflected signal.

6. The sensor front end of claim 3 wherein the phase shifter selectively provides a phase shift of ninety (90) degrees to the reflected signal and zero (0) degrees of phase shift to the transmitted portion of the first signal.

7. The sensor front end of claim 2 wherein the pulsed signal source includes a pulse modulator providing a pulse modulation signal having the predetermined signal duration and the pulse repetition frequency and an oscillator coupled to the pulse modulator and responsive to the pulse modulation signal by providing the first signal for the predetermined duration of the pulse modulation signal.

8. The sensor front end of claim 2 wherein the dual mode mixer is a double balanced mixer.

9. The sensor front end of claim 2 wherein the dual mode mixer is a single balanced mixer.

10. The sensor front end of claim 2 wherein the dual mode mixer is a quadrature hybrid mixer.

11. The sensor front end of claim 2 wherein the receiver includes:

a holding capacitor coupled between the third port of the dual mode mixer and a voltage reference node, wherein the holding capacitor stores at least a portion of the mixed signal;

a preamplifier coupled to the holding capacitor and providing as an output a preamplified mixed signal;

a sample module coupled to the preamplifier and configured and arranged to sample the preamplified mixed signal and to provide the sampled preamplified mixed signal as a sensor output signal.

12. The sensor front end of claim 11 further comprising a signal processing module coupled to the sample module to receive the sensor output signal and to provide as an output a signal indicative of the position of the object.

13. The sensor front end of claim 12 wherein the signal processing module provides as a second output a signal indicative of the velocity of the object.

14. The sensor front end of claim 2 wherein the first frequency is in the microwave range.

15. The sensor front end of claim 2 wherein the first frequency is in the millimeter wave range.

16. A method of discriminating an object based on range comprising the steps of:

providing a pulsed first signal having a predetermined duration;

transmitting the pulsed first signal from an antenna in the event the object is present;

receiving a reflected signal from the object;

processing the received reflected signal through a phase shifter; and

providing the pulsed first signal and the received phase shifted reflected signal to a mixer such that the mixer provides a mixed signal output when the received phase shifted reflected signal and a portion of the pulsed first signal are presently concurrently in the mixer.