Communications: directive radio wave systems and devices (e.g. – With particular circuit – Display
Reexamination Certificate
2001-05-31
2002-06-11
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
With particular circuit
Display
C342S175000, C342S176000, C342S195000
Reexamination Certificate
active
06404384
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method of spoke filling for radar scan converter and a spoke filling processing unit for the same.
2. Description of the Related Art
FIG. 1
shows a block diagram of a conventional radar scan converter. The radar scan converter
100
shown in
FIG. 1
is a new generation of plan position indicator prominent in the technology trend. The used method converts the polar coordinates of the radar video into Cartesian coordinates through the coordinate converter
102
. The cartesian coordinates then are output in a raster scan fashion to the monitor
104
. Because of the innate characteristics of the coordinate conversion, the correspondence between the echoes and the conversion into cartesian coordinate points is different depending on whether the echoes are at short distance, medium distance, or long distance from the reference point of the radar sweep line. In the case where the polar video points are in short distance, there is no one-to-one correspondence between the polar video points and the corresponding Cartesian points, and more than one polar points can correspond to a single Cartesian point. This occurrence of point repeated hitting is conventionally called “collision”. The collision can cause the lifetime of the display point to be shortened. In the case where the echoes are at medium distance, the one-to-one correspondence can be obtained. And, at long distance, there are many cartesian points that cannot be corresponded to any polar point, which causes the occurrence of spokes.
In
FIG. 1
, the AZ_sync signal, delivered to the coordinate converter
102
and the FIFO buffer
106
, is the radar azimuth signal that comprises the azimuth reference pulse (ARP) and the azimuth change pulse (ACP). When the antenna rotates, each scan has 4096 azimuth change pulses (ACP) and 1 azimuth reference pulse (ARP), the azimuth reference pulse (ARP) appears when the antenna faces to the north during the rotation. The Trigger signal delivered to the coordinate converter
102
, the timing generator
108
and the A/D converter
110
represents the moment when the radar wave is triggered and from which the counting of the distance starts. According to the signals AZ_sync and Trigger, the coordinate converter
102
evaluates the polar coordinates (r, &thgr;) of the radar video that then are converted into Cartesian coordinates (x, y). According to the Cartesian coordinates (x, y) of the points, the occurrence of spokes between the two neighboring sweep lines are determined, the spoke filling then is performed via the spoke filling processing unit
112
. The overlay processor
114
integrates the radar video, the graphic and the text which are generated from the computer display unit (not shown).
FIG. 2
illustrates the method of spoke filling calculation procedure, according to the U.S. Pat. No. 4,697,185 issued to Thomas et al. If 0°≦&thgr;≦45°, a point (x
i
, y
i
) is selected on the sweep line L.
(1) A point (x
i
′, y
i
′) is selected on the sweep line L′ next to the sweep line L, wherein y
i
=y
i
′, and x
i
′=r cos &thgr; tan &thgr;′ from the geometrical relationship.
(2) If x
i
′−x
i
>1, there is at least a spoke occurrence; the series x
i+1
=x
i
+1 is then constructed till x
i
′−x
1+n
≦1, such that the n points (x
i+1
, y
i
), (x
1+2
, y
i
), . . . , (x
i+n
, y
i
) are filled up (this filling fashion is called horizontal fashion spoke filling).
(3) As shown in
FIG. 2
, the video value of the point (x
i+1
, y
i
) is taken from the video value of the point P which distance from the reference center O on the sweep line L is r+sin &thgr;. In the same manner, the video value of the point (x
i+2
, y
i
) is taken from the video value of the point Q which distance from the reference center O on the sweep line L is r+2 sin &thgr;, etc. till r+n sin &thgr;.
(4) If 45°≦&thgr;≦135° or 225°≦&thgr;≦315°, the vertical fashion spoke filling is applied as follows. For example, when 45°≦&thgr;≦90°, the foregoing steps are changed into y
i
′=r cos &thgr; cot &thgr;′. If y
i
−y
i
′>1, there is at least a spoke occurrence, and the series y
i+1
=y
i
−1 is constructed till y
i+m
−y
i
′≦1, such that the m points (x
i
, y
i+1
), (x
i
, y
i+2
), . . . , (x
i
, y
i+m
) are filled up.
The U.S. Pat. No. 5,530,450 issued to Sohn et al. relates to a spoke filling method wherein the sweep line plane is divided into four regions (region
0
~
3
), as shown in FIG.
3
. Two adjacent regions are such that the number of sweep lines of the outward region is the double increase of that of the inward region. This specific arrangement allows the spokes at long distance from the reference center to be filled.
The U.S. Pat. No. 5,554,992 issued to Toth et al. discloses a spoke filling method similar to the method of Sohn. The difference specifically lies in the applying of hyperbolic curves to divide the sweep line region, wherein the multiple increase of the sweep lines begins at the point which is the first spoke from the reference center (called “break point”).
Some phenomena should be considered from the foregoing conventional methods. Thomas et al.'s method may be deficient when the sweep line meets two adjacent points (x
i
, y
i
) and (x
i+1
, y
i
) with the same coordinate y
i
as shown in
FIG. 4
, which causes a collision. As a result, the spoke filling cannot be effectively completed. Moreover, a lot of memories are needed to store (cos &thgr; tan &thgr;′) numerical values and (cos &thgr; cot &thgr;′) numerical values.
With respect to the methods of Sohn et al. and Toth et al., the collision is unfavorably frequent. Besides, the design of the electrical circuit to implement the methods is relatively complicated and the usage of memory is increased.
SUMMARY OF THE INVENTION
A major aspect of the present invention is to provide a method of spoke filling for radar scan converter and also a processing unit that implements the same method in which the spoke filling can be efficiently performed while the collision issue is overcome.
To attain the foregoing and other objectives, the present invention provides a method of spoke filling for radar scan converter that, according to a preferred embodiment, comprises first, comparing the coordinate sector of a second sweep line with the coordinate sector of a first sweep line, wherein both adjacent sweep lines are referred to as respectively a present sweep line and a previous sweep line. The comparison of the coordinate sector values determines whether either a horizontal fashion or a vertical fashion spoke filling should be applied. If the coordinate sector of the second sweep line is different from the coordinate sector of the first sweep line, the sector value and the points of the second sweep line with their respective video value are stored in a memory. If the coordinate sector of the second sweep line is identical to that of the first sweep line, the sector value and each of the points of the second sweep line with their video value are stored in a buffer. The spoke filling thus is performed between the first sweep line points stored in the memory and the second sweep line points stored in the buffer. The determination of whether either a horizontal or vertical spoke filling should be applied is in accordance with the coordinate sector value stored in the buffer (that is the sector value of the second sweep line). Then, each of the cartesian points of the second sweep line is compared to each of the corresponding cartesian points of the first sweep line to obtain either an abscissa or ordinate difference, wherein the corresponding cartesian point of the first sweep line is, according to either a horizontal or vertical spoke filling, either the point that has the same ordinate or the point that has the same abscissa. If th
Liu Guang-Sheen
Tsao Yon-Ji
Yeh Fu-Min
Chung-Shan Institute of Science and Technology
Gregory Bernarr E.
J.C. Patents
LandOfFree
Method of spoke filling and spoke filling processing unit... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of spoke filling and spoke filling processing unit..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of spoke filling and spoke filling processing unit... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2925028