Radar apparatus for vehicle

• US 6,124,823 A
• Filed: 07/01/1999
• Issued: 09/26/2000
• Est. Priority Date: 07/03/1998
• Status: Expired due to Term

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Tokoro, Setsuo
• Primary Examiner(s): Lobo, Ian J.
• Application Number:
  US09/345,446
• Time in Patent Office: 453 Days
• Field of Search: 342/70, 342/71, 342/72, 342/128, 367/99, 367/101, 367/909, 340/903, 340/511, 340/904
• US Class Current: 342/70
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/48 using multiple beams at emission or reception
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/932 using own vehicle data, e.g. ground speed, steering wheel direction
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 7/288 Coherent receivers
• CPC Class Codes: G01S 7/2883 using FFT processing
• CPC Class Codes: G01S 7/2927 by deriving and controlling a threshold value
• CPC Class Codes: G01S 7/4021 of receivers
• CPC Class Codes: G01S 7/4039 of sensor or antenna obstruction, e.g. dirt- or ice-coating
• CPC Class Codes: G01S 7/4056 specially adapted to FMCW
• CPC Class Codes: G01S 7/4091 during normal radar operation

Abstract

A radar apparatus of the present invention is a radar apparatus for detecting an object around a vehicle, which comprises a transmitter section for radiating a frequency-modulated, transmitted wave a receiver section for receiving a radio wave re-radiated from an object exposed to the transmitted wave and mixing the radio wave received with part of the transmitted wave to obtain beat signals, and a signal processing section for analyzing frequencies of the beat signals to detect the object around the vehicle. This radar apparatus is arranged to set a first threshold value and a second threshold value higher than the first threshold value as to signal levels of a frequency spectrum of the beat signals. The signal processing section is arranged to detect the object around the vehicle, using a beat frequency of a signal level over the second threshold value, and to compare the frequency spectrum with the first threshold value in a predetermined frequency range to determine whether there is dirt on the transmitter section or on the receiver section.

Claims

1. A radar apparatus for detecting an object around a vehicle, said radar apparatus comprising a transmitter section for radiating a frequency-modulated transmitted wave, a receiver section for receiving a radio wave re-radiated from an object exposed to said transmitted wave and mixing said radio wave received with part of said transmitted wave to obtain beat signals, and a signal processing section for analyzing frequencies of said beat signals to detect said object around the vehicle,

wherein a first threshold value and a second threshold value higher than said first threshold value are set as to signal levels of a frequency spectrum of said beat signals, and

wherein said signal processing section is arranged to detect said object around the vehicle, using a beat frequency of a signal level over said second threshold value, and to compare said frequency spectrum with said first threshold value in a predetermined frequency range to determine whether there is dirt on said transmitter section or on said receiver section.

2. The radar apparatus for vehicle according to claim 1, wherein said signal processing section determines that there is dirt on said transmitter section or on said receiver section when the number of beat frequencies of signal levels over said first threshold value in said predetermined frequency range is not more than a predetermined value in a predetermined time.

3. The radar apparatus for vehicle according to claim 1, wherein said signal processing section determines that there is dirt on said transmitter section or on said receiver section when a beat frequency of a signal level over said first threshold value in said predetermined frequency range is absent in a predetermined time.

4. The radar apparatus for vehicle according to claim 1, wherein said first threshold value is set higher than an average of electric noise levels inside the apparatus.

5. The radar apparatus for vehicle according to claim 1, wherein said first threshold value is set higher in a low frequency region than in a high frequency region.

6. The radar apparatus for vehicle according to claim 1, wherein said first threshold value is variable according to a predetermined condition.

7. The radar apparatus for vehicle according to claim 6, wherein said predetermined condition is a transmission output.

8. The radar apparatus for vehicle according to claim 1, wherein said predetermined frequency range is determined according to speed of the vehicle.