Versatile constant altitude plan position indicator for radars
First Claim
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1. A method to display weather radar data in a Constant Altitude Plan Position Indicator (CAPPI) system comprising:
- processing radar volume scan data along an azimuth angle of a radar;
interpolating the radar volume scan data taken from adjacent elevation angles along the azimuth angle of the radar and in a local vertical direction that is orthogonal to a CAPPI surface to obtain weather radar data corresponding to a predetermined altitude along the azimuth angle; and
displaying the weather radar data obtained corresponding to the predetermined altitude on a two-dimensional display.
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Abstract
A method and a system to process radar volume scan data along an azimuth angle of a radar, to interpolate the radar volume scan data taken from adjacent elevation angles along the azimuth angle of the radar to obtain radar data corresponding to a predetermined altitude along the azimuth angle, and to display the radar volume scan data obtained corresponding to the predetermined altitude on a PPI display.
37 Citations
27 Claims
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1. A method to display weather radar data in a Constant Altitude Plan Position Indicator (CAPPI) system comprising:
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processing radar volume scan data along an azimuth angle of a radar; interpolating the radar volume scan data taken from adjacent elevation angles along the azimuth angle of the radar and in a local vertical direction that is orthogonal to a CAPPI surface to obtain weather radar data corresponding to a predetermined altitude along the azimuth angle; and displaying the weather radar data obtained corresponding to the predetermined altitude on a two-dimensional display. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A computer-readable medium having program instructions to perform a method to display weather radar data in a Constant Altitude Plan Position Indicator (CAPPI) system, the method comprising:
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processing radar volume scan data along an azimuth angle of a radar; interpolating the radar volume scan data taken from adjacent elevation angles along the azimuth angle of the radar and in a local vertical direction that is orthogonal to a CAPPI surface to obtain weather radar data corresponding to a predetermined altitude along the aximuth angle; and displaying the weather radar data obtained correspondence to the predetermined altitude on a two-dimensional display.
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11. A process of generating CAPPI data at a point C having an altitude H along an azimuth angle θ
- , the process comprising;
using a computer processor for calculating arc length EC(φ
m) for each elevation angle φ
m of a radar using EC(φ
m)=(Re+H)×
[cos−
1 (Re cos (φ
m)/(Re+H))−
φ
m], where m includes an elevation number, where 0≦
m<
M, where M−
1 includes a number of elevation scans performed by the radar, where Re includes the radius of the earth, and H includes the altitude at which CAPPI data is to be generated;using the computer processor for generating a first technique of EC(φ
m) values indexed by a group selected from the elevation number m and the elevation angle φ
m of the radar;using the computer processor for determining the elevation angle φ
for arc length EC at each determined increment along the arc EC from EC(φ
M) to EC(φ
0) using φ
=tan −
1[((Re+H)cos (β
)−
Re)/((Re+H) sin (β
))], where β
= (EC)/(Re+H);using the computer processor for determining, at each incremented arc length EC in an interval 0<
EC<
EC(φ
M-1), a weight AC using weight AC=CD×
sin(φ
−
φ
M-1)/(cos(φ
M-1+β
), where CD =√
{[(Re+H)sin(β
)]2+[(Re+H)cos(β
)−
Re]2}, and calculating a range line DA for the domain [0;
EC(φ
M-1)] by solving equationusing the computer processor for determining, at each incremented arc length EC in an interval EC(φ
M-1)<
EC<
EC(φ
1), weights BC and AC, respectively corresponding to elevation angles φ
m and φ
m-1 adjacent to elevation angle φ
, where weight BC=CD ×
sin(φ
m−
φ
)/(cos(φ
m+β
) and weight AC=CD×
sin(φ
−
φ
m-1)/(cos(φ
m-1+β
), calculating a range DB for the domain [EC(φ
M-1);
EC(φ
1)]from the radar to a point B vertically above the point C along the azimuth angle θ
by solving equationand calculating the range line DA for the domain [EC(φ
M-1);
EC(φ
1)]from the radar to a point A vertically below the point C along the azimuth angle θ
by solving equationand using the computer processor for calculating, in an interval EC(φ
1)<
EC<
EC(φ
0), a weight BC using weight BC=CD×
sin(φ
1−
φ
)/(cos(φ
1β
), and calculating the range DB for the domain [EC(φ
1);
EC(φ
0)]by solving equation- View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
and using the computer processor for retrieving radar data (ZB) at the range DB, for the domain [EC(φ
1);
EC(φ
0)], from the radar volume scan data at the elevation angle φ
1and setting radar data ZC to radar data ZB for the domain [EC(φ
1);
EC(φ
0)].
- , the process comprising;
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18. The process of claim 17 further comprising:
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using the computer processor for setting arc length EC to a minimum distance ECmin; using the computer processor for setting the increment associated with the arc length EC, Δ
EC, to 1 km;using the computer processor for setting an azimuth angle increment Δ
θ
to 1°
;using the computer processor for setting azimuth angle θ
to a starting azimuth angle θ
min; andusing the computer processor for querying whether θ
≧
an ending azimuth angle θ
max.
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19. The process of claim 18 wherein if θ
- <
θ
max, then CAPPI data at point C is generated at the azimuth angle θ
, and the azimuth angle θ
is set to θ
+Δ
θ
.
- <
-
20. The process of claim 18 wherein if θ
- ≧
θ
max, and the arc length EC<
BC (0°
), then the azimuth angle θ
is reset to the starting azimuth angle θ
min, and the arc length EC is set to EC+Δ
EC.
- ≧
-
21. The process of claim 17 further comprising using the computer processor for displaying the CAPPI data generated at the altitude in a PPI display.
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22. The process of claim 21 wherein the PPI display supports an application selected from a group including rotation, zooming, magnification, distance interval, and sector selection.
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23. The process of claim 11 wherein the process includes a group selected from a graph, a chart, a table, an algorithm and a set of equations.
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24. The process of claim 11 wherein the process uses a processor using radar volume scan data obtained from a group selected from data obtained in real-time and data retrieved from storage.
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25. The process of claim 11 wherein each of the range lines DB and DA include curves representing bent propagation paths between the radar and the points B and A, respectively.
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26. A system to display weather radar data in a Constant Altitude Plan Position Indicator (CAPPI) system comprising:
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means for processing radar volume scan data along an azimuth angle of a radar; means for interpolating the radar volume scan data taken from adjacent elevation angles along the azimuth angle of the radar and in a local vertical direction that is orthogonal to a CAPPI surface to obtain CAPPI data corresponding to a predetermined altitude along the azimuth angle; means for performing the above two steps for the azimuth angles within a specified range; and means for displaying the CAPPI data obtained corresponding to the predetermined altitude. - View Dependent Claims (27)
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Specification