Speed measuring apparatus

• US 6,272,071 B1
• Filed: 11/25/1998
• Issued: 08/07/2001
• Est. Priority Date: 11/26/1997
• Status: Expired due to Fees

• Current Assignee: Ricoh Microelectronics Co. Ltd. (Ricoh Company Limited)
• Original Assignee: Ricoh Microelectronics Co. Ltd. (Ricoh Company Limited)
• Inventors: Ikeuchi, Fumio, Takai, Takuo
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US09/199,820
• Time in Patent Office: 986 Days
• Field of Search: 367/90, 367/98, 367/903
• US Class Current: 367/90
• CPC Class Codes: G01S 15/586 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets
• CPC Class Codes: G01S 7/52006 with provision for compensating the effects of temperature
• CPC Class Codes: G01S 7/534 Details of non-pulse systems short-range imaging G01S7/52017

Abstract

A speed measuring apparatus including a transmitter for transmitting an acoustic reference wave toward a moving-target, the acoustic reference wave being generated based on a reference signal with a predetermined frequency. Also included is a receiver for receiving acoustic reflection waves which are generated by the transmitted acoustic reference wave being reflected by the moving-target, for converting the acoustic reflection waves to receiver signals, and for outputting the receiver signals therefrom. Further, a signal attenuating unit for selectively attenuating a signal component with the same frequency as the frequency of the reference signal in the receiver signals which are output from the receiver and outputting signals therefrom and a band pass filter unit for selecting at least one Doppler signal component from the signals output from the signal attenuating unit are included. Also included is a speed computing unit for computing the speed of the moving-target relative to the speed measuring apparatus, based on the Doppler signal component abstracted by the band pass filter unit.

Claims

1. A speed measuring apparatus comprising:

transmitting means for transmitting an acoustic reference wave toward a moving-target, said acoustic reference wave being generated based on a reference signal with a predetermined frequency;

receiving means for receiving acoustic reflection waves which are generated by said transmitted acoustic reference wave being reflected by said moving-target, converting said acoustic reflection waves to receiver signals, and outputting said receiver signals therefrom;

signal attenuating means for selectively attenuating a signal component with the same frequency as the frequency of said reference signal, corresponding to the acoustic wave which directly enters said receiving means from said transmitting means by diffraction, and/or the acoustic waves reflected by fixed objects, in said receiver signals which are output from said receiving means and outputting signals therefrom;

band pass filter means for selecting at least one Doppler signal component from said signals output from said signal attenuating means; and

speed computing means for computing the speed of said moving-target relative to said speed measuring apparatus, based on said Doppler signal component selected by said band pass filter means.

2. The speed measuring apparatus as claimed in claim 1, wherein said band pass filter means comprises at least one band pass filter which selectively allows said Doppler signal component to pass therethrough, and when said band pass filter means comprises a plurality of such band pass filters, said band pass filters are connected in parallel.

3. The speed measuring apparatus as claimed in claim 1, wherein said transmitting means comprises (a) a transmitting unit for transmitting said acoustic reference wave toward said moving-target, (b) a capacitor connected to said transmitting unit in parallel therewith, and (c) an inductive impedance element, thereby constituting a serial resonance circuit, with an inductance of said inductive impedance element being set in such a manner that a resonance frequency of said serial resonance circuit is equal to the frequency of said reference signal.

4. A speed measuring apparatus comprising:

transmitting means for transmitting an acoustic reference wave toward a moving-target, said acoustic reference wave being generated based on a reference signal with a predetermined frequency;

receiving means for receiving acoustic reflection waves which are generated by said transmitted acoustic reference wave being reflected by said moving-target, converting said acoustic reflection waves to receiver signals, and outputting said receiver signals;

band pass filter means for selectively attenuating a signal component with the same frequency as the frequency of said reference signal, corresponding to the acoustic wave which directly enters said receiving means from said transmitting means by diffraction, and/or the acoustic waves reflected by fixed objects, in said receiver signals which are output from said receiving means and outputting signals therefrom, and for selecting at least one Doppler signal component from said receiver signals output from said receiving means; and

speed computing means for computing the speed of said moving-target relative to said speed measuring apparatus, based on said Doppler signal component selected by said band pass filter means.

5. The speed measuring apparatus as claimed in claim 4, wherein said band pass filter means comprises at least one band pass filter which selectively allows said Doppler signal component to pass therethrough, and when said band pass filter means comprises a plurality of such band pass filters, said band pass filters are connected in parallel.

6. The speed measuring apparatus as claimed in claim 4, wherein said transmitting means comprises (a) a transmitting unit for transmitting said acoustic reference wave toward said moving-target, (b) a capacitor connected to said transmitting unit in parallel therewith, and (c) an inductive impedance element, thereby constituting a serial resonance circuit, with an inductance of said inductive impedance element being set in such a manner that a resonance frequency of said serial resonance circuit is equal to the frequency of said reference signal.

7. A speed measuring apparatus comprising:

transmitting means for transmitting an acoustic reference wave toward a moving-target, said acoustic reference wave being generated based on a reference signal with a predetermined frequency;

receiving means for receiving acoustic reflection waves which are generated by said transmitted acoustic reference wave being reflected by said moving-target, converting said acoustic reflection waves to receiver signals, and outputting said receiver signal;

signal attenuating means for selectively attenuating a signal component with the same frequency as the frequency of said reference signal, corresponding to the acoustic wave which directly enters said receiving means from said transmitting means by diffraction, and/or the acoustic waves reflected by fixed objects, in said receiver signals which are output from said receiving means and outputting signals therefrom;

analog-to-digital converting means for converting said signals output from said signal attenuating means to digital data, and outputting said digital data; and

digital signal processing means for selecting at least one Doppler signal component from said digital data output from said analog-to-digital converting means and computing the speed of said moving-target relative to said speed measuring apparatus, based on said Doppler signal component selected.

8. The speed measuring apparatus as claimed in claim 7, wherein said transmitting means comprises (a) a transmitting unit for transmitting said acoustic reference wave toward said moving-target, (b) a capacitor connected to said transmitting unit in parallel therewith, and (c) an inductive impedance element, thereby constituting a serial resonance circuit, with an inductance of said inductive impedance element being set in such a manner that a resonance frequency of said serial resonance circuit is equal to the frequency of said reference signal.

9. A speed measuring apparatus comprising:

a transmitter configured to transmit an acoustic reference wave toward a moving-target, said acoustic reference wave being generated based on a reference signal with a predetermined frequency;

a receiver configured to receive acoustic reflection waves which are generated by said transmitted acoustic reference wave being reflected by said moving-target, to convert said acoustic reflection waves to receiver signals, and to output said receiver signals therefrom;

a signal attenuator configured to selectively attenuate a signal component with the same frequency as the frequency of said reference signal, corresponding to the acoustic wave which directly enters said receiver from said transmitter by diffraction, and/or the acoustic output signals therefrom;

at least one band pass filter configured to select at least one Doppler signal component from said signals output from said signal attenuator; and

a speed computing unit configured to compute the speed of said moving-target relative to said speed measuring apparatus, based on said Doppler signal component measured by said at least one band pass filter.

10. The speed measuring apparatus as claimed in claim 9, wherein said at least one band pass filter selectively allows said Doppler signal component to pass therethrough, and when said at least one band pass filter comprises a plurality of band pass filters, said plurality of band pass filters are connected in parallel.

11. The speed measuring apparatus as claimed in claim 9, wherein said transmitter comprises (a) transmitting unit configured to transmit said acoustic reference wave toward said moving-target, (b) a capacitor connected to said transmitting unit in parallel therewith, and (c) an inductive impedence element, thereby constituting a serial resonance frequency of said serial resonance circuit is equal to the frequency of said reference signal.

12. A speed measuring apparatus comprising:

a transmitter configured to transmit an acoustic reference wave toward a moving-target, said acoustic reference wave being generated based on a reference signal with a predetermined frequency;

a receiver configured to receive acoustic reflection waves which are generated by said transmitted acoustic reference wave being reflected by said moving-target, to convert said acoustic reflection waves to receiver signals, and to output said receiver signals;

at least one band pass filter configured to selectively attenuate a signal component with the same frequency as the frequency of said reference signal, corresponding to the acoustic wave which directly enters said receiver from said transmitter by diffraction, and/or the acoustic waves reflected by fixed objects, in said receiver signals which are output from said receiver and to output signals therefrom, and to select at least one Doppler signal component from said receiver signals output from said receiver; and

a speed computing unit configured to compute the speed of said moving-target relative to said speed measuring apparatus, based on said Doppler signal component selected by said at least one band pass filter.

13. The speed measuring apparatus as claimed in claim 12, wherein said at least one band pass filter selectively allows said Doppler signal component to pass therethrough, and when said at least one band pass filter comprises a plurality of band pass filters, said plurality of band pass filters are connected in parallel.

14. The speed measuring apparatus as claimed in claim 12, wherein said transmitter comprises (a) transmitting unit configured to transmit said acoustic reference wave toward said moving-target, (b) a capacitor connected to said transmitting unit in parallel therewith, and (c) an inductive impedance element, thereby constituting a serial resonance circuit, with an inductance of said inductive impedance element being set so that a resonance frequency of said serial resonance circuit is equal to the frequency of said reference signal.

15. A speed measuring apparatus comprising:

a transmitter configured to transmit an acoustic reference wave toward a moving-target, said acoustic reference wave being generated based on a reference signal with a predetermined frequency;

a receiver configured to transmit an acoustic reflection waves which are generated by said transmitted acoustic reference wave being reflected by said moving-target, to convert said acoustic reflection waves to receiver signals, and to output from said receiver and to output signals therefrom;

an analog-to-digital converting unit configured to convert said signals output from said signal attenuator to digital data, and to output said digital data; and

a digital signal processor configured to select at least on Doppler signal component from said digital data output from said analog-to-digital converting unit and to compute the speed of said moving-target relative to said speed measuring apparatus, based on said measured Doppler signal component.

16. The speed measuring apparatus as claimed in claim 15, wherein said transmitter comprises (a) a transmitting unit configured to transmit said acoustic reference wave toward said moving-target, (b) a capacitor connected to said transmitting unit in parallel therewith, and (c) an inductive impedance element, thereby constituting a serial resonance circuit, with an inductance of said inductive impedance element being set so that a resonance frequency of said serial resonance circuit is equal to the frequency of said reference signal.