DESC:TECHNICAL FIELD
The present invention relates generally to the field of data processing of the receiver channel outputs of a radar and creation of 2D images of the targets. The invention, more particularly, relates to plotting 2D images of radar target detections.

BACKGROUND
The invention is related to the radars which have more than two receiver channels and where each receiver channel has its own range-profile. The range-profile of each receiver channel shows the range of the targets over time. In order to spot the location of the target in the radar Field of View (FOV) however, the azimuth angular location of the target with respect to the radar is required. The combination of the range and azimuth angle of the targets constitutes the 2D image of the target-space within the radar FOV. The determination of azimuth angle of targets and then association of these angles with the corresponding range-profiles requires a method which achieves the final 2D image optimizing time and memory use.
There are some existing methods which are widely discussed in literature and used in practice. However, many of the hardware requirements of these existing methods are not realisable in most of the practical radars used today. Particularly difficult to realise are the phase-time linearity of synthesizer or signal generator and the uniform beam-shape of antennae.
There is still a need of an invention which solves the above defined problems and provides an improved method and system to plot 2D images of radar target detections.

SUMMARY OF THE INVENTION
This summary is provided to introduce concepts of the present invention. This summary is neither intended to identify essential features of the present invention nor is it intended for use in determining or limiting the scope of the present invention.
In one embodiment, a method of plotting two dimensional (2D) images of radar target detections performed at a hand-held radar is disclosed. The method comprises: receiving, from a plurality of receiver channels, data in a specific format; calculating, range profile for a plurality of receiver channels for one or more periods of time; detecting, one or more target locations from the range profile; calculating, the difference in range profile for a target between a first period of time and a second period of time; checking, whether value of the difference in range profile is lesser than a radar range value; if value of difference in the range profile is lesser than the radar range value: initializing one or more values (nx, ny, nz) for one or more grids of radar field of view where the targets are present; calculating range profiles for one or more phantom targets; computing difference between range profiles of a phantom target and the target; and identifying the target to plot two dimensional (2D) image of the target.
In one aspect, calculating difference in range profile for the target is based on real time range profile is based on difference between range profile calculated for the first period of time, and range profile calculated for the second period of time.
In another aspect, the range profile for the phantom target is based on difference between range profile calculated for the first period of time and range profile calculated for the second period of time.
In yet another aspect, identifying the target comprises: comparing the value of the difference between range profiles based on time period.
In yet another aspect, computing difference between range profiles of a phantom target and the target, is based on minimum error margin between the range-profiles derived from one or more grids of radar field of view and derived from real-time radar target.
In another aspect of the invention, a hand-held radar is disclosed. The hand-held radar comprises: a plurality of receiver channels; a plurality of antennae to send/receive radar signals; a processing unit, configured to: receive, from a plurality of receiver channels, data in a specific format; calculate, range profile for a plurality of receiver channels for one or more periods of time; detect, one or more target locations from the range profile; calculate, the difference in range profile for a target between a first period of time and a second period of time; check, whether value of the difference in range profile is lesser than a radar range value; if value of difference in the range profile is lesser than the radar range value: initialize one or more values (nx, ny, nz) for one or more grids of radar field of view where the targets are present; calculate range profiles for one or more phantom targets; compute difference between range profiles of a phantom target and the target; and identify the target to plot two dimensional (2D) image of the target.
In one aspect of the invention, the plurality of antenna contain transmitter and receiver antennae, and wherein transmitter and receiver antenna are separate.
In another aspect of the invention, distance between successive receiver antenna is at least equal to the range resolution of the radar and coupling between transmit and receive antenna and different receive antenna is below -40 dB.
In another aspect of the invention, the processing unit is further configured to: difference in range profile for the target is based on real time range profile is based on difference between range profile calculated for the first period of time, and range profile calculated for the second period of time.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and modules.
Figure 1 illustrates a flow chart showing the calculations done in each receiver channel with respect to each possible pair of detected targets, according to an exemplary implementation of the present invention.
Figure 2 illustrates a flow chart showing the calculations done by considering all relevant locations grids within the radar detection space with respect to each data point obtained from the steps in FIG. 1 according to an exemplary implementation of the present invention.
It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative methods embodying the principles of the present invention. Similarly, it will be appreciated that any flow charts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION
The various embodiments of the present invention describe about a method and system to plot 2D images of radar target detections.
In the following description, for purpose of explanation, specific details are set forth in order to provide an understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without these details. One skilled in the art will recognize that embodiments of the present invention, some of which are described below, may be incorporated into a number of systems.
However, the systems and methods are not limited to the specific embodiments described herein. Further, structures and devices shown in the figures are illustrative of exemplary embodiments of the presently invention and are meant to avoid obscuring of the presently invention.
It should be noted that the description merely illustrates the principles of the present invention. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present invention. Furthermore, all examples recited herein are principally intended expressly to be only for explanatory purposes to help the reader in understanding the principles of the invention and the concepts contributed by the inventor to furthering the art and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and embodiments of the invention, as well as specific examples thereof, are intended to encompass equivalents thereof.
This invention relates to a method of plotting 2D images of radar target detections implemented in a radar. In the radar, each receiver channel should be capable of creating range-profile of any number of targets if the minimum inter-target distance is range resolution determined by the bandwidth of the transmitted waveform. The minimum distance between the consecutive antennae should be half-wavelength corresponding to the middle-frequency of the transmitted bandwidth. By performing the method steps, a 2D image (range, azimuth) of the targets is created with respect to the radar so that the locations of the targets are properly understood.
By performing the method, identification of the range-profiles from different receivers belonging to the same target is performed.
By performing the method, scanning of the relevant grid-locations based on the detected range-profiles of each target is performed.
By performing the method, determination of the minimum error margin between the range-profiles derived from the grid-locations and those derived from real-time radar target echo is achieved.
By performing the method, determination of possible target locations in the grid-space based on the minimum error margin is achieved.
This invention provides a method and a system that solves the problem of radars attempting to create 2D image of target-space in real-time. The range-profile of each receiver channel and the known antenna locations is used as the reference. The target-space is then divided into grids and relevant search and study is carried out to estimate the target-locations. The time and memory requirements of the method are optimized and therefore improve radar performance.
The invention has been implemented in a radar with following conditions. The radar has two receiver channels, and the radar antenna is used to transmit/receive. The distance between successive receiver antennae is at least equal to the range resolution of the radar. The coupling between transmit and receive antennae as well as different receive antennae is below -40 dB. In one embodiment, the radar may be a hand-held radar.
FIG. 1 illustrates a flow chart showing the calculations done in each receiver channel with respect to each possible pair of detected targets. At step 101 the radar receiver channel data is received. In one embodiment, the data format used is determined by the application and software used. At step 102, range profile of the receiver channel is obtained. Here, the number of receiver channels is represented by NRx, radar range resolution by R_r and grid dimensions of the radar- Field of View (FOV) by [NX,NY,NZ]. The range profile of each receiver channel ?RP?_(target_index)^(receiver_index) contains the Fast Fourier Transform (FFT)-information regarding the range of targets with respect to the receiver channel. The accuracy of this range profile and its change over the receiver channels determines the performance of the method. At step 103, the variable n is initialized to zero. At steps 104, 105 and 106, the parameter T that represents total number of targets detected in the range-profile of n^th receiver, variables, and the variables t and t1 are initialised to zero. These variables will be used to represent radar echo from different targets with respect to the radar. At step 107 the variable Diffy is calculated that shows the difference between the range-profile of the targets represented by t and t1 for the n^th receiver. At step 108 , a conditional as to check the relative values of t and t1 is performed that transfers the control either to step 107 or to step 112, where the variable t1is incremented based on the result. At step 109, it is examined whether Diffy is smaller than R_r. If the value of Diffy is lesser than Rr it means the range-profiles corresponding to the variables t and t1 belong to the same target or the receivers are unable to distinguish between different targets and the control is passed to step 111, which ends the process. If the value of Diffy is greater than Rr, the control is passed to A, which is explained with respect to Figure 2 below.
At step 113 checks whether t1 is less than T. If yes, then the present value of t1 is used in the necessary calculations at steps 121 and 122. Alternatively at step 114, t is incremented. A similar process as step 114 occurs in steps 115 and 116, involving variable t for variable n, is performed in steps 119 and 120. At steps 117 and 118 comprise of similar process involving the check n