Radar device, similar device, and received data write method

• US 6,441,775 B1
• Filed: 05/02/2001
• Issued: 08/27/2002
• Est. Priority Date: 08/21/1998
• Status: Expired due to Term

• Current Assignee: Furuno Electric Co, Ltd
• Original Assignee: Furuno Electric Co, Ltd
• Inventors: Kobayashi, Hiroyuki, Fujikawa, Takumi, Kondo, Motoji
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/763,228
• Time in Patent Office: 482 Days
• Field of Search: 342/27, 342/28, 342/41, 342/175-186, 342/195, 342/159-174, 315/367, 315/378
• US Class Current: 342/185
• CPC Class Codes: G01S 7/064 using a display memory for image processing G01S7/298 takes precedence
• CPC Class Codes: G01S 7/068 with data-rate converters preceding the display, e.g. flicker free display, constant brightness display G01S7/298 takes precedence
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals
• CPC Class Codes: G01S 7/298 Scan converters

Abstract

While received data is stored into a video memory through coordinate conversion, the level of image data is gradually reduced simultaneously with this, by which the image of a target is discriminately displayed readily from among a clutter even without performing adjustment which would conventionally be involved. The radar apparatus is composed of a video memory 6 for successively converting received data from polar to rectangular coordinates along with sweep rotation and storing the data, a FIRST detector for detecting a FIRST so that data write by the coordinate conversion is effected only at a time of FIRST detection, and a subtraction data generator 9 for subtracting a constant value from pixel data of a area designated by a subtraction area designator 14 on the video memory 6 during a period other than FIRSTs.

Claims

1. A radar and like apparatus, comprising:

a video memory for successively performing coordinate conversions on received data from a polar coordinate system to a rectangular Cartesian coordinate system along with sweep rotation and storing the converted data;

a subtractor for subtracting a constant value from pixel data of an area set on the video memory in parallel with data write accompanied by the coordinate conversion; and

a FIRST detector for detecting, as a FIRST access, when a pixel of the video memory is accessed for a first time in performing the coordinate conversion during one sweep rotation, wherein the subtractor performs a subtraction at a time other than the FIRST detection.

2. The radar and like apparatus as claimed in claim 1, comprising:

another video memory provided independently of the video memory; and

a correlation-process selector for, when a FIRST is detected by the FIRST detector, subjecting pixel data of said another video memory and received data present at that time to a specified correlation process, storing the data again into said another video memory, and moreover storing the correlation-processed data into the video memory, and for, at a time other than the FIRST detection, storing the pixel data of said another video memory again into said another video memory.

4. The radar and like apparatus as claimed in any one of claim 1 or 3, further comprising an area designator for designating the area.

5. The radar and like apparatus as claimed in any one of claim 1 or 3, further comprising a selector for selecting the constant value from a plurality of values.

6. The radar and like apparatus as claimed in any one of claim 1 or 3, wherein the subtractor has a comparator for comparing the image data with a specified threshold value, and subtract the constant value from pixel data having values less than the threshold value.

3. A radar and like apparatus, comprising:

a video memory for successively performing coordinate conversions on received data from a polar coordinate system to a rectangular Cartesian coordinate system along with sweep rotation and storing the converted data;

a subtractor for subtracting a constant value from pixel data of an area set on the video memory in parallel with data write accompanied by the coordinate conversion; and

a LAST detector for detecting, as a LAST access, when a pixel of the video memory is accessed for the last time in performing the coordinate conversion during one sweep rotation, wherein the subtractor performs a subtraction at a time other than the LAST detection.

7. A method for writing received data into a memory comprising:

a step for successively performing a coordinate conversion on received data from a polar coordinate system to a rectangular Cartesian coordinate system and storing the converted data into as video memory at each sweep rotation with the data being updated;

a subtraction step for subtracting a constant value from pixel data of an area set on the video memory in parallel with data write accompanied by the coordinate conversion, wherein data in the area is successively subtracted during one sweep rotation; and

a FIRST detection step for detecting, as a FIRST access, when a pixel of the video memory is accessed for a first time in performing the coordinate conversion during one sweep rotation,

wherein in the subtraction step, a subtraction is performed at a time other than the FIRST detection.

8. A radar and like apparatus, comprising:

a primary memory for temporarily storing received data;

a video memory for successively storing the data stored in the primary memory;

a display unit for displaying the data stored in the video memory;

a coordinate converter circuit for performing a coordinate conversion to convert a polar coordinate position of received data into a rectangular Cartesian coordinate address of the video memory;

a FIRST detector circuit for detecting, as a FIRST access, an access that a pixel of the video memory is accessed for a first time at the coordinate conversion during one sweep rotation, wherein the subtractor performs a subtraction at a time other than the FIRST detection;

a subtraction area address generator circuit for setting an area on the video memory as a subtraction area and successively generating addresses of this area;

a subtraction data generator circuit for generating, as subtraction data, data resulting from subtracting a constant value from pixel data in the subtraction area; and

a selector for, at the FIRST detection, selecting a rectangular-coordinate address derived from the coordinate converter as an address for the video memory and further selecting data of the primary memory as write data to be written into the video memory, and for, at a time other than the FIRST detection, selecting an address derived from the subtraction area address generator as an address of the video memory and further selecting subtraction data generated by the subtraction data generator as write data to be written into the video memory.

9. The radar and like apparatus as claimed in claim 8, wherein the subtraction data generator circuit comprises a comparator for comparing the pixel data with a specified threshold value and a subtracter for subtracting the constant value from pixel data having values not more than the threshold value.

10. The radar and like apparatus as claimed in claim 8 or 9, further comprising:

another video memory provided independently of the video memory; and

a correlation-process selector for, when the FIRST is detected by the FIRST detector circuit, subjecting pixel data of said another video memory and received data present at that time to a specified correlation process, storing the data again into said another video memory, and moreover storing the correlation-processed data into the video memory, and for, at a time other than the FIRST detection, storing the pixel data of said another video memory again into this same memory.