DESC:4. DESCRIPTION

Technical Field of the Invention

The invention relates to testing and training onRadio Detection and Ranging (RADAR)systems prior to its actual field usage. More particularly, the invention relates to a Drone mounted Digital radio frequency memory basedRadar Target Simulator(DDRTS) system with multi antenna generated echo that enables radar operators to see live targets similar to what are observed in battle field.

Background of the Invention

Testing the functionality of RADAR prior to actual field test is mandatory. Now-a-days there are several techniques for this to be done, but the actual test covering all aspects is a lacuna. It has been an unfulfilled requirement for radar operators to see live targets exactly in similar manner as that of real situation, which is required for enabling them to declare system readiness for actual mission.

Developing search and track radars for military applications is a continuous process for defense R&D organizations. Since every new design requires thorough testing it is essential to establish sophisticated testing means before system is cleared for deployment.

The modern day adaptive Beamforming algorithms permit nulls theory by which adversary jammer can be rejected by high attenuation level. Testing this feature in 3D environment is a non-trivial task with existing methodologies.

The advancements in Drone systems with precise positioning capability permits new class of applications for radar test and validation.

To test the Far field radiation pattern of the antenna a static target should be placed at far field distance from the radar.

Testing at laboratory level or with ground based target simulators will provide opportunity to test only in one specific direction. This limits radar validation to a limited extent and demands flight trial (actual aircrafts) based advanced tests.

At some of the radar sites different type of static targets are ground installed and simple simulator solutions exist. These can be considered as a primitive health check only.

At frequent intervals it is necessary to calibrate the radar for its range and angles (Azimuth and elevation).

This becomes mandate as the performance of RF and other sub systems likely to change with ageing and with changes in climatic conditions. For this calibrated real target should be used for testing.

All these test methods are hectic, expensive and not sufficient for complete testing of radars
The Invention described here offers a solution meeting these requirements

There are multiple solutions in marketwhich are based on Digital Radio Frequency Memory (DRFM) and ground based target echo simulators. These can simulate only RADARecho from one direction in which the antenna is installed. The invention here can simulate a 3D target around the RADAR with dynamically changing azimuth and elevation with all real time effects as that of actual target.

Inventors also know the existence of prior artdescribingUnmanned Aerial Vehicles (UAV) based Radar Cross-Section (RCS) modeling and its applications for Radar test and validation.

The present invention made by the inventors propose a scheme with wider scope of simulation, in terms of utilizing combination of time, frequency, phase, drone position and multi point RCS manipulation to mimic real target effects.

Brief Summary of the Invention

The main objective of the present invention is to simulate real time targets in front of radar for its operational testing or training to crew. Once the radar is installed at a site, its performance under the same site for existing local clutter conditions is of high interest. The invention covers this aspect also.

Another object of the present invention is to test the RADAR range, Doppler, Angles (Azimuth and Elevation) and its performance against view angle based RCS fluctuations in all azimuth and elevation directions with distributed scatter type target.

Another object of the present invention is to test the radar performance in terms of tracking low RCS targets, resolving two closely spaced targets in range and azimuth.

Further object of present invention is to search radar network which involves doing data fusion and generating a single target track. Wherein, by this data fusion, detection of malfunctioning sensors can be carried out.

According to an aspect of the present invention, a Drone mounted Digital radio frequency memory basedRadar Target Simulator (DDRTS) systemthat enables radar operators to see live targets with known range and a characteristic is disclosed.

In accordance with the aspect of the present invention, the DDRTS consists of a Digital Radio Frequency Memory (DRFM) based simulator. This DDRTS employs the digital memory and other target modeling techniques to generate delay and Doppler shifts corresponding to the simulated targets. A drone flies near RADAR (between 100mts to 1000mts) to simulate targets which are present at a distance up to 1000kms (or even higher).Thesystem can be offered with multiple drones to simulate multi target scenarios.

In accordance with the aspect of the present invention, a GUI of the system facilitates radar user to draw a 3D trajectory of target. Based on the 3D trajectory, the drone flies such that it is in line connecting the radar and simulated target.

In accordance with the aspect of the present invention, thedrone moves in pre-defined 3D trajectory such that Radar receives test signals from selected directions (Azimuth and Elevation).

In accordance with the aspect of the present invention, the system consists of a ground control station, from which real time control of drone position and DRFM parameters are carried out.

In accordance with the aspectof the present invention, the above features configured in GUI will be preloaded in DDRTS before drone starts flying.

In accordance with the aspectof the present invention, theRTS can be simulated in both single and Multi-target mode.

In accordance with the aspectof the present invention,each target body depending on its material and its surface type it will have different RCS fluctuations. They will be achieved through the proposed scheme.

In accordance with the aspectof the present invention,the drone shall carry 2 axes gimbal system which has N(could be 8) patch elements.

Brief Description of the Drawings

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and together with the brief summary of the invention given above and the detailed description of the drawings given below, serve to explain the principles of these inventions.

Fig. 1 illustrates a Drone mounted Digital radio frequency memory basedRADAR Target Simulator (DDRTS) systemto simulate multi target scenario for real time testing of radar in accordance with an exemplary embodiment of the present invention;

Fig. 2a-d illustrates dronewith multi antenna system rotating using gimbal to simulate view angle based multi-point scattersin accordance with an exemplary embodiment of the present invention;

Fig. 3illustrateseach antenna output corresponding to RCS value on a multipoint scatter type target received by radar in accordance with an exemplary embodiment of the present invention;

Fig. 4 illustrates an RF circuit to generate required attenuation and phase shift for each scatter pointin accordance with an exemplary embodiment of the present invention;

Fig.5 illustrates2 DDRTS units at two radar stations, simulating a single targetin accordance with an exemplary embodiment of the present invention.

It should be understood that the drawings are not necessarily to scale. In certain instances, details that are not necessary for an understanding of the invention or that render other details difficult to perceive may have been omitted. It should be understood, of course, that the invention is not necessarily limited to the particular embodiments illustrated herein.

DetailedDescription of the Invention

Referring to Fig. 1 through 5, an exemplary embodiment of a Drone mounted Digital radio frequency memory basedRADAR Target Simulator (DDRTS) system (100) is disclosed. The DDRTS system (100) enables RADAR (101) operators to see live targets with known range and characteristics. The Fig.1 illustrates two targets (103) flying near RADAR (101), which can electronically generate delay and Doppler corresponding to simulated target echo. The invention allows the testing of the functionality of the RADAR(101) prior to its actual field test.

In accordance with the exemplary embodiment of the present invention, the DDRTSsystem (100) consists of a Digital Radio Frequency Memory (DRFM) (not shown in the figure) based simulator. The DDRTS system (100) employs digital memory and other target modeling techniques to generate delay and Doppler shifts corresponding to the simulated targets (103). The drone (102) flies near RADAR (101) (between 100mts to 1000mts) to simulate targets (103) which are present at a distance up to 1000kms (or even higher).Thesystem can be offered with multiple drones (102) to simulate multi target scenarios.

In accordance with the exemplary embodiment of the present invention, a GUI of the system facilitates radar (101) user to draw a 3D trajectory of target. Based on the 3D trajectory, the drone (102) flies such that it is in line connecting the RADAR (101) and simulated target (103).

In accordance with the exemplary embodiment of the present invention, thedrone (102) moves in pre-defined 3D trajectory such that Radar (101) receives test signals from selected directions (Azimuth and Elevation).

In accordance with the exemplary embodiment of the present invention, the system (100) consists of a ground control station, from which real time control of drone position and DRFM parameters are carried out.

Fig. 2a-dillustrates the drone (202) in different views (200a through 200d) with multi antenna system (204) rotating using gimbal to simulate view angle based multi-point scattersin accordance with the exemplary embodiment of the present invention.

Fig. 3illustratesthe system (300) showing that each antenna (304) output corresponding to an RCS value on a multipoint scatter type target (303) received by radar (301) in accordance with the exemplary embodiment of the present invention.

In accordance with the exemplary embodiment of the present invention, the ground control system consists of a laptop or a desktop based GUI in which user can define the trajectory and following settings:
1. Trajectory for the simulated target;
2. RCS type (Single point, multi-point models);
3. RCS Fluctuation type (Different Swerling models);
4. Range and Doppler (Fixed value or as per trajectory);
5. On board jammer (Enable/Disable);
6. Jammers Option (Spot/Sweep/Barrage);
7. Clutter Option (Land/Sea/Volume/Automatic from the terrain input).

In accordance with the exemplary embodiment of the present invention, the above features configured in GUI will be preloaded in DDRTS system (100) before drone (102) starts flying.

Fig. 4 illustrates an RF circuit (400) to generate required attenuation and phase shift for each scatter point to an antenna array (404) in accordance with the exemplary embodiment of the present invention.

In accordance with the exemplary embodiment of the present invention, theRTS can be simulated in both single and Multi-target mode.

In accordance with the exemplary embodiment of the present invention,each target body depending on its material and its surface type it will have different RCS fluctuations. They will be achieved through the proposed scheme.

In accordance with the exemplary embodiment of the present invention,the drone shall carry 2 axes gimbal system which has N(could be 8) patch elements. Rotating in both directions (horizontal and vertical). The angles are achieved through rotating antenna array as shown in Fig 2. Multiple scatterers of target are distinguished by their respective RCS values, relative RCS variations and phase shifts and angle separation among them as shown in Fig4.

Fig.5 illustrates 2 DDRTS systems (500) at two radar stations (502), simulating a single target (503) in accordance with the exemplary embodiment of the present invention.

Multiple DDRTS units to test multi-sensor surveillance systems
The proposed system will consist of 2 or more number of DDRTS units. Multiple drones at multiple radars simulating a single target can be done using this system as shown in Figure. The GPS 1-PPS based synchronization will be used in all DDRTS units. Computer software simulating the trajectory of target generates the position at which each drone need to be present so that they correspond to single target. This also depends on the RADAR position, which will be fed in software. When the mission starts, all the drones will get positioned at their corresponding positions. As simulation runs they move synchronously and also generate the delay, Doppler, phase shift and view angle based RCS effects such that the echo seen by all RADARs would correspond to single target.

Hence the target data from each radar will get fused and results in single track which consist of individual target characteristics.

Multiple modes of using DDRTS
The following table illustrates the different ways of DDRTS usage for RADAR test requirements.

Application/ test requirements Configurations and modes
Single drone and single radar station target echo mode Multi drone and single radar station target echo mode Multi drones and multiple radar systems
Radar performance testing (range accuracy, range resolving, velocity estimation,real time tracking and view angle based RCS effects)

Testing of multi sensor surveillance systems carrying out real time Radar Data fusion for track generation × ×

Testing of modern RADARs with Adaptive Beamforming (simultaneous targets tracking and jammer rejection with null) ×

(only if at least two DRTS units are flying around one radar)

Many changes, alterations, modifications and other uses and applications of the subject facility and method, will become apparent to those skilled in the art after considering this specification, together with the accompanying drawings. All such changes, alterations, and modifications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention, which is limited only by the claims that follow.
,CLAIMS:5. CLAIMS
I/We Claim
1. A Drone mounted Digital radio frequency memory based Radar Target Simulator (DDRTS) system (100) that enables Radar (101) operators to see live targets with known range and characteristics, comprises of:
a. a Digital Radio Frequency Memory (DRFM) based simulator, wherein the DDRTS employs the digital memory and other target modeling techniques to generate delay and Doppler shifts corresponding to the simulated targets;
b. the drone (102) is enabled to fly near Radar(101) (between 100mts to 1000mts) to simulate targets (103) which are present at a distance up to 1000kms (or even higher);
c. a GUI of the system facilitates radar (101) user to draw a 3D trajectory of target;
d. based on the 3D trajectory, the drone (102) flies such that it is in line connecting the RADAR (101) and simulated target (103);
e. thedrone (102) moves in pre-defined 3D trajectory such that Radar (101) receives test signals from selected directions (Azimuth and Elevation);
f. a ground control station, from which real time control of drone (102) position and DRFM parameters are carried out;
g. the ground control system consists of a laptop or a desktop based GUI in which user can define the trajectory and do settings, like:
i. a trajectory for the simulated target;
ii. aRCS type (Single point, multi-point models);
iii. aRCS Fluctuation type (Different Swirling models);
iv. a Range and a Doppler (Fixed value or as per trajectory);
v. an On board jammer (Enable/Disable);
vi. a plurality of Jammers Option (Spot/Sweep/Barrage); and
vii. a Clutter Option (Land/Sea/Volume/Automatic from the terrain input);
h. the Radar Target Simulator (RTS) can be simulated in both single and Multi-target mode; wherein, each target body depending on its material and its surface type it will have different RCS fluctuations;
i. the drone (102, 202, 502) shall carry 2 axes gimbal system which has N(could be 8) patch elements rotating in both directions (horizontal and vertical), wherein:
i. the angles are achieved through rotating antenna array;
ii. multiple scatterers of target are distinguished by their respective RCS values, relative RCS variations and phase shifts and angle separation among them;
j. the system (100) enables simulating realistic high-speed flight targets for radar (101)by the combination of digital delay and spatial movement of drone (102);
k. the system (300) enables view angle based distributed scatterers modeling with multi antenna array based scheme, wherein:
i. the scheme takes out the delayed echo from DRFM unit to divide it into ‘n’ parts;
ii. in each part an attenuator and phase shifter to model the multiple scatterers of relatively larger size targets is featured; and
iii. depending upon the current simulated view angle of the target as seen by the radar, specific number of antenna elements are excited with calculated attenuation and phase shift values;
l. the system (100) enables to achieve simulation capability of battlefield scenario as seen by radar through synchronous precise movement of drones (102) along with real time manipulation of time delay, frequency, phase and RCS parameters at each DRFM module;
m. the system (100) enables usage of multiple DDRTS units with single RADAR (101)to provide test scenarios to RADAR to test azimuth resolution capability and null steering capability for jammer rejection; and
n. the system (100/500) enables testing of multi RADAR (501) based surveillance system (500) with data fusion capabilities with multiple DDRTS (502) flying synchronously at multiple RADARs (501) simulating the same target (503).

2. The DDRTS system (100) according to claim 1, wherein the system (100) enables testing of multi RADAR based surveillance system(500) and consists of:
a. 2 or more number of DDRTS units (100/500);
b. the computer software (not shown) simulating the trajectory of target, generates the position at which each drone (502) need to be present so that they correspond to single target (503);
c. wherein, on start of the mission, the drones (502) will get positioned at their corresponding positions and on running the simulation they move synchronously to generate a delay, Doppler, phase shift and view angle based RCS effects such that the echo seen by all RADARs (501) would correspond to single target (503).

3. The DDRTS system (100) according to claim 1, wherein the target data fromeach radar (101/501) will get fused and results in single track which consist of individual target (103/503) characteristics.

6. DATE AND SIGNATURE

Dated this 14thday of August2020
Signature

(Mr. Srinivas Maddipati)
IN/PA 3124
Agent for Applicant