Radar apparatus

• US 7,679,548 B2
• Filed: 11/15/2004
• Issued: 03/16/2010
• Est. Priority Date: 11/14/2003
• Status: Active Grant

• Current Assignee: Furuno Electric Co, Ltd
• Original Assignee: Furuno Electric Co, Ltd
• Inventors: Fujikawa, Takumi, Kondo, Motoji, Takemoto, Sae
• Primary Examiner(s): PIHULIC, DANIEL T
• Application Number:
  US10/579,197
• Publication Number:
  US 20070126624A1
• Time in Patent Office: 1,947 Days
• Field of Search: 342/185, 342/59, 342/176, 342/179, 342/360
• US Class Current: 342/185
• CPC Class Codes: G01S 7/14 Sector, off-centre, or expanded angle display
• CPC Class Codes: G01S 7/298 Scan converters

Abstract

A radar apparatus where the rate of writing detected image data into an image memory does not decrease, irrespective of an enlarged amount of the detected image data. When an azimuth direction enlargement section of a W data generator receives detected image data of a sweep, it outputs the data to an image memory, and delays the data, depending on a cycle of an azimuth direction shift timing signal. When detected image data of a next sweep is drawn into a pixel adjacent in a sweep moving direction to a pixel into which previous detected image data has been drawn and is located at the same distance in a sweep distance direction, the delayed data is compared with new data, and the greater data is drawn into the new pixel. When the delayed data is greater, this detected image data is enlarged in the azimuth direction.

Claims

1. A radar apparatus comprising:

a coordinate converter that converts detected data at each sample point obtained in a polar coordinate system into a rectangular coordinate system;

a detected image data generator that generates a pixel of detected image data based on each point of the converted detected data;

an image memory that stores the generated pixels of detected image data;

a data shifter that shifts detected image data input from the detected image data generator with predetermined timing and outputs the shifted detected image data; and

an azimuth direction detected image data corrector that compares generated pixels of detected image data of a current sweep with shifted detected image data of a previous sweep at the same position in a sweep distance direction, and outputs a maximum value of pieces of detected image data as detected image data of the current sweep.

2. A radar apparatus according to claim 1, the azimuth direction detected image data corrector comprising:

a correction stopper that, when a predetermined number or more of consecutive pieces of detected image data greater than or equal to a predetermined threshold value are present over a plurality of sweeps at the same position in a distance direction, stops replacement of detected image data of a current sweep with detected image data of a previous sweep based on a sweep on which detected image data at the same position in the distance direction has a value less than the threshold value.

3. A radar apparatus according to claim 1 or 2, the apparatus further comprising:

a distance direction detected image data corrector that compares a predetermined number of consecutive pieces of detected image data in the distance direction on the same sweep, and outputs most peripheral detected image data of the pieces of detected image data as a maximum value of the consecutive pieces of detected image data.

4. A radar apparatus according to claim 3, the apparatus further comprising a selector that selects the number of sweeps to be shifted by the data shi tier.

5. A radar apparatus according to claim 4, wherein the selector selects the number of pieces of detected image data to be compared by the distance direction detected image data corrector.

6. A method of generating image data from radar detection data, the method comprising:

converting detected data at each sample point obtained in a polar coordinate system into a rectangular coordinate system;

generating a pixel of detected image data based on each point of the converted detected data;

storing the generated pixels of detected image data;

shifting the generated detected image data with predetermined timing;

outputting the shifted detected image data;

comparing generated pixels of detected image data of a current sweep with shifted detected image data of a previous sweep at the same position in a sweep distance direction; and

outputting a maximum value of pieces of detected image data as detected image data of the current sweep.

7. The method according to claim 6, the method further comprising, when a predetermined number or more of consecutive pieces of detected image data greater than or equal to a predetermined threshold value are present over a plurality of sweeps at the same position in a distance direction:

stopping replacement of detected image data of a current sweep with detected image data of a previous sweep based on a sweep on which detected image data at the same position in the distance direction has a value less than the threshold value.

8. The method according to claim 6 or 7, the method further comprising:

comparing a predetermined number of consecutive pieces of detected image data in the distance direction on the same sweep; and

outputting most peripheral detected image data of the pieces of detected image data as a maximum value of the consecutive pieces of detected image data.

9. The method according to claim 8, the method further comprising selecting the number of sweeps to be shifted.

10. The method according to claim 9, wherein selecting includes selecting the number of pieces of detected image data to be compared during said comparing a predetermined number step.