Method and apparatus for measuring distance to a detection object

• US 6,665,056 B2
• Filed: 11/14/2002
• Issued: 12/16/2003
• Est. Priority Date: 12/04/2001
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Matsuoka, Keiji, Nozawa, Toyohito, Samukawa, Yoshie, Morikawa, Katsuhiro, Shirai, Noriaki
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): ANDREA, BRIAN K
• Application Number:
  US10/293,285
• Publication Number:
  US 20030103197A1
• Time in Patent Office: 397 Days
• Field of Search: 356/3-1-, 342/70, 342/91, 342/92, 367/98, 367/99, 180/167-169, 701/223, 701/301
• US Class Current: 356/5.05
• CPC Class Codes: G01S 17/14 wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/489 Gain of receiver varied automatically during pulse-recurrence period
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

A method and apparatus of measuring a distance to a reflection object is disclosed. A sensitivity time control (STC) process is applied to a received signal from the reflection object to provide an STC-processed signal. The radar apparatus includes a controller. The controller obtains a quantity corresponding to the distance from a transmission time of the transmission signal and a detection time of the STC-processed signal. The quantity is corrected by using a first correction value associated with the intensity of the STC-processed reflection signal to provide a corrected quantity. The corrected quantity is further corrected by using a second correction value associated with the corrected quantity and the intensity of the STC-processed reflection signal to correct the error regardless of the intensity of the STC-processed reflection signal.

Claims

1. A method of measuring a distance to a reflection object in a radar apparatus which transmits a transmission signal and applies a sensitivity time control (referred to as “

STC”

) process to a reflection signal from said reflection object to yield an STC-processed reflection signal, the method comprising the steps of;

obtaining a quantity corresponding to said distance from a transmission time of said transmission signal and a detection time of said STC-processed reflection signal; and

correcting said quantity considering an error which is caused by an STC distortion and depends on an intensity of said STC-processed reflection signal.

2. A method as defined claim 1, wherein said step of correcting said quantity comprises:

correcting said quantity by using a first correction value associated with said intensity of said STC-processed reflection signal to provide a corrected quantity; and

correcting said corrected quantity by using a second correction value associated with said corrected quantity and said intensity of said STC-processed reflection signal to correct said error regardless of said intensity of said STC-processed reflection signal.

3. An apparatus for measuring a distance to a reflection object, the apparatus includes;

means for transmitting a transmission signal;

means for applying a sensitivity time control process to a received signal from said reflection object to provide an STC-processed signal;

means for obtaining a quantity corresponding to said distance from a transmission time of said transmission signal and a detection time of said STC-processed signal; and

means for correcting said quantity considering an error which is caused by an STC distortion and depends on an intensity of said STC-processed reflection signal.

4. An apparatus as defined claim 3, wherein said means for correcting said quantity comprises:

means for correcting said quantity by using a first correction value associated with said intensity of said STC-processed reflection signal to provide a corrected quantity; and

means for correcting said corrected quantity by using a second correction value associated with said corrected quantity and said intensity of said STC-processed reflection signal to correct said error regardless of said intensity of said STC-processed reflection signal.

5. An apparatus as defined in claim 4, further including means for detecting a pulse width of said STC-processed signal through a comparison with a reference voltage, wherein said means for correcting said quantity and means for correcting said corrected quantity use said pulse width detected by said pulse width detecting means as said intensity of said STC-processed signal.

6. An apparatus as defined in claim 5, wherein said means for detecting a pulse width of said STC-processed signal comprises:

means for detecting a wider pulse width of said STC-processed signal by using a lower reference voltage, wherein the apparatus further includes;

means for detecting a narrower pulse width of said STC-processed signal by using a higher reference voltage higher than said lower reference voltage, wherein said means for correcting said quantity comprises;

means, in the event said narrower pulse width is obtained in addition to said wider pulse width, for correcting said quantity by using a first-class first correction value associated with said narrower pulse width to provide said corrected quantity; and

means, in the event only said wider pulse width is obtained, for correcting said quantity by using a second-class first correction value associated with said wider pulse width to provide said corrected quantity, and wherein said means for correcting said corrected quantity comprises;

means, in the event said narrower pulse width is obtained in addition to said wider pulse width, for correcting said corrected quantity by using a first-class second correction value associated with said corrected quantity and said narrower pulse width of said STC-processed signal; and

means, in the event only said wider pulse width is obtained, for correcting said corrected quantity by using a second-class second correction value associated with said corrected quantity and said wider pulse width of said STC-processed signal.

7. An apparatus as defined in claim 5, wherein said means for obtaining a quantity corresponding to said distance includes:

means for calculating a middle time of said pulse width of said STC-processed signal as said detection time of said STC-processed signal.

8. An apparatus as defined in claim 5, wherein said means for detecting a pulse width of said STC-processed signal includes:

means for providing a signal the level of which is kept at a certain level during a period when a level of said STC-processed signal is higher than said reference voltage; and

means for measuring said period.