Patent US2306512A successfully refreshed from Google Patents.
Patent EP0032836A2 successfully refreshed from Google Patents.
EP0032836A2
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Radar display apparatus
Assignee: Decca Ltd
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Filing: 1981-01-19
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Granted: —
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Expires: 2001-01-19
Abstract
Abstract Radar display apparatus employs digital techniques to convert range/azimuth scan to T.V. scan. A digital store (17) contains data defining the brightness of levels for the picture cells of a T.V. display (30). The store (17) is continuously updated in accordance with received video from a digitiser (12). The correct cell in the store (17) for updating is identified by converting polar coordinates to Cartesian coordinates in a Sin ϑ, Cos generator (21) and integrators (22, 23). The contents of the store (17) for the addressed picture cell is modified by a control unit (16) in accordance with the digitised video return so as to represent the degree of positive correlation of returns in that cell on successive azimuth scans of the radar. Thus the brightness or colour of the cell on the T.V. display (30) represents this degree of correlation.
Inventors
- 👤 Harry Donald Cramp
- 👤 Malcolm Richard Blythe
- 👤 Philip David Lane Williams
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-28 22:12
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/28; G01S7/285; G01S7/295; G01S7/298; G01S7/04; G01S7/06; G01S7/10
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
142 words
Radar display apparatus for an azimuth scanning radar characterised in that the apparatus comprises a radar video digitiser (12); electronic digital storage means (17) having a storage location for each of a predetermined number of cells forming between them a radar display picture; store control means (16, 19-24) arranged to modify data in said storage means so that the digital data in each said cell location is representative of the degree of positive correlation of digital video returns occurring in the respective cell on successive radar azimuth scans; visual display means (30); and display control means (31,32,33,40,42) arranged to read said digital data from the storage means and to control said display means to provide a substantially real time radar display picture composed of said cells with the brightness or colour of each cell being representative of said degree of positive correlation.
Claim 2
Dependent Claim
142 words
Radar display apparatus for an azimuth scanning radar characterised in that the apparatus comprises a radar video digitiser (12); electronic digital storage means (17) having a storage location for each of a predetermined number of cells forming between them a radar display picture; store control means (16, 19-24) arranged to modify data in said storage means so that the digital data in each said cell location is representative of the degree of positive correlation of digital video returns occurring in the respective cell on successive radar azimuth scans; visual display means (30); and display control means (31,32,33,40,42) arranged to read said digital data from the storage means and to control said display means to provide a substantially real time radar display picture composed of said cells with the brightness or colour of each cell being representative of said degree of positive correlation.
Claim 3
Dependent Claim
56 words
Radar display apparatus as claimed in Claim 1 characterised in that said storage means has locations for cells in a rectangular matrix for a T.V. type display (30), and said store control means (19-23) converts the range/ azimuth angle co-ordinates of digitised radar video into Cartesian co-ordinates for identifying the store locations of the equivalent cells.
Claim 4
Dependent Claim
84 words
Radar display apparatus as claimed in Claim 2 wherein the range/azimuth angle (r,θ) co-ordinates are expressed digitally with unit range increments defining a range scan at each of successive azimuth increments and said store control means includes cell correlation means (24) arranged to identify.when successive range increments of a range scan in (r,6 ) co-ordinates convert to the same Cartesian co-ordinates and then to effect said modification of data in the respective cell location of the storage means only once in the range scan.
Claim 5
Dependent Claim
74 words
Radar display apparatus as claimed in Claim 3 wherein said cell correlation means includes means for storing (50) at least the two lowest order bits of the cell location identifying Cartesian co-ordinates following each said conversion from (r,θ)co-ordinates, means for comparing (51) said stored bits with the corresponding bits of the subsequent conversion and means for inhibiting (52) said modification of data if said stored bits and said corresponding subsequent bits are the same.
Claim 6
Dependent Claim
59 words
Radar display apparatus as claimed in claim 3 or claim 4 wherein the cell correlation means is further arranged to identify when (r,9 ) co-ordinates in sucdessive range scans convert to the same Cartesian co-ordinates and then to effect said modification of data in the respective cell location of the storage means only on one of said range scans.
Claim 7
Dependent Claim
113 words
Radar display apparatus as claimed in claim 5 wherein said cell correlation means comprises means for storing (53) during each range scan at least the two lowest order bits of the cell location identifying Cartesian co- ordinates following said conversion of all the unit range increments, means for comparing (56, 57, 58) the corresponding bits of the conversion of each range increment of the subsequent range scan with the stored bits for the corresponding and immediately adjacent range increments, and means for inhibiting said modification of data if said corresponding bits of said subsequent range scan are the same as said stored bits of any of said corresponding or immediately adjacent range increments.
Claim 8
Dependent Claim
36 words
Radar display apparatus as claimed in any preceding claim wherein the radar video digitiser provides a one bit digital video signal with a logic "O" indicating no video and logic "1" indicating a positive video return.
Claim 9
Dependent Claim
47 words
Radar display apparatus as.claimed in Claim 7 wherein said electronic digital storage means has three bits of storage for each said cell location, and said store control means (16) is arranged to write into said location digital numbers representing up to eight levels of said positive correlation.
Claim 10
Dependent Claim
61 words
Radar display apparatus as claimed in Claim 8 wherein said store control means is arranged so as, on each modification of data in a cell location, to read the digital number already stored in the location, to increment the number by one if the digital video indicates a positive video return and to write the thus-incremented number back into the location.
Claim 11
Dependent Claim
28 words
Radar display apparatus as claimed in Claim 9 wherein the digital number is progressively decremented and written back into the location in the absence of positive video returns.
Claim 12
Dependent Claim
48 words
Radar display apparatus as claimed in Claim 10 wherein the cell brightness is representative of the degree of positive correlation and wherein decrementing of the number in the location below a predetermined value is temporarily inhibited so as to generate a synthetic "afterglow" effect on the display means.
Claim 13
Dependent Claim
119 words
Radar display apparatus as claimed in Claim 11 wherein the store control means has a comparison device (60) arranged to produce a write inhibit signal, when the number read from the cell location being modified is said predetermined value and the digital video is logic "O", so as to inhibit writing of a decremented number in the location, a counter (64) arranged to be incremented in response to each said write inhibit signal, and a latch device responsive to the counter reaching a preset maximum count to prevent inhibiting of the writing of a decremented number in the cell location being modified on the next occasion the number read is said predetermined value and the video is logic "0".
Claim 14
Dependent Claim
45 words
Radar display apparatus as claimed in Claim 12 wherein the store control means has range dependent afterglow control means (67) arranged to prevent said inhibiting of the writing of a decremented number when in response to video logic "O" returns at below a predetermined range.
Claim 15
Dependent Claim
16 words
Radar display apparatus as claimed in Claim 13 wherein said predetermined range can be set manually.
Claim 16
Dependent Claim
79 words
Radar display apparatus as claimed in any one of claims 12 to 14 and in combination with radar apparatus having a video processor providing-a clutter level signal responsive to the level of clutter noise in the received video, wherein the store control means has clutter level dependent afterglow control means (70) arranged to prevent said inhibiting of the writing of a decremented number when the clutter level signal indicates the received clutter is above a predetermined clutter threshold level.
Claim 17
Dependent Claim
109 words
Radar display apparatus as claimed in any of claims 13 to 15 wherein said store control means is arranged to set aside one of said levels represented by digital numbers written into the cell locations, for identifying a marker cell on the visual display means, and a marker generator (80) is provided to designate predetermined cells as marker cells and to superimpose the number representing said.one level on the data being written by the store control means into said marker cells, said level which is set aside being selected to have a digital number which is below said predetermined value at which decrementing is temporarily inhibited to generate afterglow.
Claim 18
Dependent Claim
38 words
Radar display apparatus as claimed in Claim 16 wherein said display control means is arranged to identify said set aside marker level and to generate a relatively high brightness level on the display for marker cells so designated.
Claim 19
Dependent Claim
119 words
Radar display apparatus as claimed in Claim 16 or Claim 17 wherein said store control means is arranged to generate digital numbers for writing into said cell locations representing at least four said levels of positive correlation, distinct from the set aside marker level, the four levels being a top level for highly correlated video returns for generating high brightness cells on the display means, an intermediate level for less highly correlated returns for generating less bright cells, a low level for relatively uncorrelated returns for generating low brightness cells, and a bottom level for no returns for generating substantially dark cells, said intermediate level corresponding to the predetermined value at which decrementing is temporarily inhibited to generate afterglow.
Claim 20
Dependent Claim
64 words
Radar display apparatus as claimed in Claim 18 wherein said display control means is arranged to produce on the display means a non-linear response between brightness and the levels represented by the digital numbers read from said cell locations so that the higher level or levels representing highly correlated video returns are substantially brighter on the display means than the intermediate and lower levels.
Claim 21
Dependent Claim
58 words
Radar display apparatus as claimed in any of Claims 11 to 16 but wherein the visual display means and the display control means are arranged so that the colour of each cell, instead of the brightness, is representative of said degree of positive correlation, said synthetic "afterglow" effect being then a colour effect rather than a brightness effect.
Claim 22
Dependent Claim
59 words
Radar display apparatus as claimed in any preceding claim and including a video buffer store (13) arranged to store in real time digitised video returns from a single range scan, said store control means being arranged to read said stored video returns from the buffer store for use in modifying data in the cell locations of said storage means.
Claim 23
Dependent Claim
66 words
Radar display apparatus as claimed in Claim 21 and including a first clock (14) arranged for writing the video returns into the buffer store in real time at a first clock rate and said store control means having a second clock(15) arranged for reading the stored video returns from the buffer store and appropriately modifying the data in said storage means at a second clock rate.
References Cited (Backward Citations)
No citation records indexed.
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