Abstract:
The present invention relates to a radar video display and recording device, which can simultaneously display radar video signals of the whole and designated areas in the polar coordinates and Cartesian coordinates, respectively, and can store the radar video signals of the designated area in a hard disk drive (HDD) for obtaining long-time continuous radar video information for subsequent analysis and algorithm verification. A radar video capture card is utilized on a personal computer (PC) or workstation platform to analyze and store radar video signals of the whole and designated areas and to simultaneously display video signals at different processing stages in a digital video processing unit on a scope for monitoring the work condition at each processing stage.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     The present invention relates to radar video display and recording devices and, more specifically, to a radar video display and recording device that utilizes a radar video capture card on a personal computer platform to simultaneously display the whole and designated areas in the polar coordinates and Cartesian coordinates, respectively. 
     2. Related Art 
     Referring to FIG. 1, which shows a conventional radar system block diagram. The system includes a pulse generator  11 , a modulator  12 , a receiver  13 , a video signal processor  14 , a transmitter  15 , a duplexer  16 , an antenna  17 , and a scope  18 . 
     First, the pulse generator  11  produces and transmits a trigger signal T to the modulator  12 , the receiver  13 , and the video signal processor  14 . After receiving the trigger signal T the modulator  12  converts it into a pulse P and sends it to the transmitter  15  for transmission. The duplexer  16  couples a microwave signal M transmitted by the transmitter  15  to the antenna  17  and couples a radar return echo E received by the antenna  17  to the receiver  13 . The receiver  13  converts the radar return echo E into an original video signal V. The video signal processor  14  then performs preprocessing on the original video signal V to eliminate noises and clutters contained therein and to convert analog original video signal V into a digital video signal D. Finally, the scope  18  makes the digital video signal D into a visible image. 
     In particular, the scope  18  has many ways of displaying. The most common one is the P-scope, or plan position indicator (PPI) as shown in FIG. 2. A rotational beam B is provided on the scope  18  and synchronously rotates with the antenna  17 . When the radar return echo E is received by the antenna  17 , it is then converted into the digital video signal D according to the above method and displayed on the scope  18  in the form of a bright spot S to show the relative position of the detected object. For radar examination equipment and some special radar devices, they often need another style of display, namely, the B-scope as shown in FIG.  3 . The horizontal and vertical axes in the drawing represent the azimuthal angle and range, respectively. 
     However, the P-scope only displays single channel radar videos in the polar format. This display style has overlapped bright spots S for objects within a short distance adjacent to the transmission direction, which results in influential effects on the originality of the digital video signal D. Although the B-scope displays images in the rectangular format so that bright spots S adjacent to the transmission direction would not overlap and the image originality can be kept in the digital video signals, they are still single channel ones. Furthermore, the displayed range is so small that the whole area can not be shown. 
     Besides, when the video signal processor  14  performs preprocessing on the original video signal V to eliminate noises and clutters contained therein, the choice and design of algorithms depend upon the noise and clutter distributions. They are not only different by times and places, but receive more significant influences from weather changes. Therefore, subsequent signal analysis and algorithm verification are necessary. Nevertheless, the conventional P-scope or B-scope only displays single channel radar video signals and cannot simultaneously show the radar video signals of the whole and designated areas, the function provided thereby is so simple that subsequent signal analysis and algorithm verification become more tedious and time-consuming. 
     Currently, there are many patents or products in the United States of America that aim at solving the above problems. For example, the U.S. Pat. No. 3,634,887 and Pat. No. 3,840,874 proposed one type of recording and displaying device for radar video signals that can mix and store the digital video signals D and trigger signals T in a video tape for subsequent signal analysis and algorithm verification. The radar storage conversion system invented by Folsom Research, Inc. can provide both P-scope and B-scope display formats at the same time. It can also convert the digital video signals D of the two display formats into the RS-170A format and store them in a video tape for subsequent signal analysis and algorithm verification. With reference to FIG. 4, the U.S. Pat. No. 4,729,029 proposed a method for magnifying an inset on the scope  18  and displaying the magnified image on the same scope by providing an overlapped window W. 
     SUMMARY OF THE INVENTION 
     In spite the fact that the U.S. patents and products mentioned hereinbefore make some improvements in the problems that current P-scopes or B-scopes can only display signal channel radar videos and are unable to simultaneously display the radar video signals of the whole and designated areas, the methods proposed by the U.S. Pat. Nos. 3,634,887 and 3,840,874 would have distortion on the stored digital video signals D and trigger signals T due to the narrow frequency band of the video tapes. The method proposed by the U.S. Pat. No. 4,729,029 can simultaneously display radar video signals of the whole area and designated inset I magnified, but the magnified digital video signals D are displayed in the polar format. As mentioned above, this display style has overlapped bright spots S for objects within a short distance adjacent to the transmission direction, which damages the originality of the digital video signal D. 
     In view of the foregoing, it is a primary object of the present invention to provide a radar video display and recording device which can simultaneously display radar video signals of the whole and arbitrarily designated areas and store the signals of designated areas into a recording media (such as a hard disk drive) so as to obtain a long-time continuous radar video information of the designated areas for subsequent analysis and algorithm verification. In addition, the present invention can simultaneously display radar video signals at different processing stages in the video signal processor on a scope for the convenience of observing the work condition at each signal processing stage. Since two windows are utilized to display the radar video signals of the whole area and the designated area on a scope, and they are displayed in the polar and rectangular formats, respectively, the present invention can simultaneously solve the problems of displaying radar video signals of the whole and designated areas and of keeping the originality of radar video signals that cannot be done at the same time using the prior art. 
     To achieve the above goal, the present invention utilizes a radar video capture unit to analyze and store radar video signals of the whole and designated areas and to have the video signals at different processing stages in the digital video processing unit displayed on one scope for observing the work condition at each processing stage. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described in greater detail hereinafter relative to non-limitative embodiments and the attached drawings, wherein there is shown: 
     FIG. 1 is a system block diagram of a conventional radar; 
     FIG. 2 is a schematic drawing of a conventional P-scope; 
     FIG. 3 is a schematic drawing of a conventional B-scope; 
     FIG. 4 is a schematic drawing of the scope in the U.S. Pat. No. 4,729,029; 
     FIG. 5 is a schematic view of the application of the radar video display and recording device according to the present invention; 
     FIG. 6 is a detailed block diagram of the radar video capture unit of the present invention; and 
     FIG. 7 shows schematically a displayed image of the radar video display and recording device according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to FIG. 5, the radar video display and recording device of the present invention takes a personal computer or workstation platform. It comprises a radar video capture unit  28  and a video display unit  29 . First, a pulse generator  21  produces and sends out a trigger signal T to a modulator  22 , a receiver  26 , and a radar video capture unit  28 . After receiving the trigger signal T, the modulator  22  converts it into a pulse P and sends it to a transmitter  23 . Then a microwave direction control  24 , which can be a duplexer, couples a microwave signal M transmitted by the transmitter  23  to an antenna  25  and couples a radar return echo E received by the antenna  25  to the receiver  26 . The receiver  26  converts the radar return echo E into an original video signal V, which is preprocessed by a video processing unit  27  to eliminate noises and clutters contained therein and to convert the analog original video signal V into a digital video signal D. The radar video capture unit  28  captures a polar formatted video signal PV and a rectangular formatted video signal RV from the digital video signal D. Finally, a display driver  291  with display memory and controller, which can be a VGA card, in the video display unit  29  drives a monitor  292  to visualize the images of the polar formatted video signals PV and the rectangular formatted video signals RV. 
     The video processing unit  27  comprises an analog processor (AP)  271 , a constant false alarm rate (CFAR) control  272 , a binary integrator (BI)  273 , and a scan to scan integrator (SSI)  274 ; wherein the AP  271  further comprises a sensitivity time control (STC), a fast time control (FTC), and an analog-to-digital (A/D) converter. When the original video signal V is sent by the receiver  26  to the video processing unit  27 , the STC of the AP  271  first filters out sea clutters in the original video signal V. The FTC further filters out rain clutters. The AID converter then converts the original video signal V into a digital video signal D. The CFAR control  272  controls the false alarm rate caused by clutters at a constant. The BI  273  filters out noises in the digital video signal D. Finally, the SSI  274  filters out the sea clutters and rain clutters remained in the digital video signal D. 
     Referring to FIG. 6, the radar video capture unit  28  comprises an azimuth counter  281 , a range counter  282 , a coordinate converter  283 , a location counter  284 , a decimation filter  285 , a controller  286 , an overlay processor  287 , a first memory  2881 , a second memory  2882 , a first buffer  2891 , and a second buffer  2892 . The azimuth counter  281  obtains from the antenna  25  an azimuth synchronization signal (AZ) which contains the azimuthal information of the radar, including an azimuth reference pulse (ARP) and an azimuth change pulse (ACP), where the ACP refers to the azimuthal change while the antenna  25  rotates and the ARP zeros the ACP when the antenna  25  completes one turn and gets back to its original azimuth. When the antenna  25  rotates, there are 4096 ACPs and one ARP in each turn and the ARP appears when the antenna  25  points to the north. By using the azimuth counter  281 , AZ is converted into a 12-bit azimuth value TH. The coordinate converter  283  then looks up a table according to the azimuth value TH to obtain the horizontal and vertical components of the polar format and to compute the pixel location PL of each corresponding pixel in the polar format. The range counter  282  measures the range according to the trigger signal T and generates a 16-bit range value R. The controller  286  receives the starting azimuth value THO and the starting range value RO, from user as input parameters. When the TH and R match the input parameters TH 0  and R 0 ,the controller  286  enables the location counter  284 . The location counter  284  performs display position counting according to the trigger signal T so as to generate the display location RL of each corresponding pixel in the rectangular format. 
     On the other hand, the multi-channel digital video signal D input from the video processing unit  27  to the radar video capture unit  28  is first stored in the first buffer  2891  and the second buffer  2892  (both of which can be radial buffers) to await subsequent processing by the reduction filter  285  and the second memory  2882 , which can be first-in-first-out (FIFO) memory. After obtaining the digital vide signal D from the first buffer  2891 , the decimation filter  285  performs decimation processing on the digital video signal D according to the display range scale of the whole area determined by the user so as to obtain the decimated video signal A. This decimated signal A and the pixel location PL are stored together in the first memory  2881 , which can be FIFO memory, to await subsequent processing by the overlay processor  287 . Simultaneously, The controller  286  drives the second memory  2882  to store the digital video signal D, the azimuth value TH, and the display location RL to await subsequent processing by the overlap processor. The subsequent processing of the overlay processor  287  on the stored data in the first memory  2881  and the second memory  2882  are different. The first memory  2881  takes “the overlay method”, which processes 8-bit data each time. The overlap processor  287  first reads in the display location PL and the video signal A stored in the first memory  2881 . It then retrieves the display memory of the display driver  291  according to the display location PL. When there is no text or graphics at the display location PL on the display memory, the video signal A is written into the display memory of the display driver  291  through a multimaster bus, which can be a PCI bus or a VMS bus. This step can prevent the original text or graphics on the screen from being overwritten by the video signal A. The second memory  2882  takes the “overwrite method”, which processes 32-bit data each time. The overlay processor  287  reads in the starting azimuth value TH, the starting display location RL, and the digital video signal sequence D stored in the second memory  2882 . It then overwrites the digital video signal sequence D and the starting azimuth value TH onto the display memory of the display driver  281  according to the display location RL. Since the digital video signal D is stored in the bit-plane form in the display memory, the central processing unit (CPU) of the personal computer (PC) can modify the palette settings of the display memory, selecting to view the signal obtained by the AP  271 , the CFAR control  272 , the BI  273 , or the SSI  274  from the digital video signal D individually, or to view the overlapped images of the above four signals simultaneously. This helps observing the work conditions at each processing stage. The CPU can store long time continuous data in the display memory into the recording media of the PC, such as the hard disk drive (HDD), for the convenience of subsequent signal analysis and diagnosis and correction of algorithms. 
     Please refer to FIG. 7 for a schematic scope of the present invention. There are two windows on the screen that can simultaneously display the whole area radar video signal and the magnified radar video signal of a specific small area; wherein the whole area video signal is displayed in the polar format and by overlaying with texts or graphics on the screen, whereas the designated area radar video signal is displayed in the rectangular format and by the overwriting method. Therefore, spots adjacent to the transmission direction would not overlap one another and the originality of the video signal can be maintained. 
     The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 
     While the present invention has been shown and described with reference to the foregoing preferred embodiments, it is to be understood by those skilled in the art that other changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.