WO1992007282A1

WO1992007282A1 - Multibeam radar system mounted on an aircraft with a rotor

Info

Publication number: WO1992007282A1
Application number: PCT/US1990/005643
Authority: WO
Inventors: Hubert Warren Upton; William Latimer Mckeown
Original assignee: Bell Helicopter Textron Inc
Current assignee: Bell Helicopter Textron Inc
Priority date: 1990-10-10
Filing date: 1990-10-10
Publication date: 1992-04-30
Anticipated expiration: 1993-04-10

Abstract

A multibeam radar is described including a plurality of antennas (1-4) that scan differing elevations (1'-4') around a vehicle, such as a helicopter (10). Elevation information is determined by monitoring which antenna detects a particular target.

Description

MULTIBEAM RADAR SYSTEM MOUNTED ON AN AIRCRAFT WITH A ROTOR

BACKGROUND OF THE INVENTION

This invention relates in general to the field of radar systems, and more particularly to radar systems for use on aircraft such as helicopters. The invention is described in one embodiment with regard to helicopter applications, but it is contemplated that the principles and concepts of the invention may be used in other applications such as tilt rotor aircraft. Therefore, the descriptions relating to helicopter applications and comparisons to helicopter prior art should not be construed as a limitation to the scope of the invention. The placement and utilization of radar antennas in the rotors of helicopters is disclosed in various references, such as U.S. Patent Nos. 3,389,393 (Young, Jr.), 3,390,393 (Upton) and 3,896,446 (Kondoh et al.). However, none of these radar systems is adapted to distinguish the elevation angle of a detected target. Such information may be critical to a pilot in combat, because if the radar shows the pilot from which direction a threat is coming, the pilot can react to engage the target or take evasive action, without making a visual sighting. Therefore, it can be seen that a need exists for an airborne radar system adapted to distinguish targets or objects at different vertical positions.

SUMMARY OF THE INVENTION

The present invention provides apparatus and methods for detecting radar reflections and displaying the reflections such that a pilot or other monitor of the display may readily determine the elevation angle of the target from which the radar beam is reflected.

According to the invention, a multibeam radar system is adapted for attachment to a rotating member such that the areas scanned by the radar beam do not exactly overlap, but rather are skewed to increase the vertical area of coverage. In one embodiment of the invention, multiple rotating radar antennas are used to produce the multiple beams.

According to one embodiment of the invention, there is provided a device for detecting and displaying a target with azimuth and elevation information comprising: a means for scanning a plurality of scan areas, each scan area having a different angle of elevation associated therewith; a means for detecting a target in at least one of the scan areas mounted to the scanning means; a means for distinguishing the scan area from which the target is detected from other scan areas, positioned and arranged to be responsive to the means for detecting; a means for measuring the azimuth of the scan area from which the target is detected positioned and arranged to be responsive to an azimuth angle position, relative to a reference azimuth position, of the scanning means; and a means for displaying a representation of the target simultaneously with the elevation and azimuth information positioned and arranged to be responsive to the means for distinguishing and the means for measuring. According to another embodiment of the invention, there is provided a radar system for use on a vehicle, comprising: a rotatable mount attached to the vehicle; a first antenna connected to said rotating mount for scanning a first area of coverage and having a first antenna output signal for defining images in a first area of coverage; a second antenna connected to the rotating mount for scanning a second area of coverage different from said first area of coverage and having a second antenna output signal for defining images in said second area of coverage; and a display for displaying images of said first and second areas of coverage so as to distinguish said images.

According to another embodiment of the invention, there is provided a process for detecting and displaying a target with azimuth and elevation information comprising the steps of: scanning a plurality of scan areas, each scan area having a different angle of elevation associated therewith; detecting a target in at least one of said scan areas; distinguishing the scan area from which the target is detected from other scan areas; measuring the azimuth of the scan area from which the target is detected, and displaying a representation of the target simultaneously with the elevation and azimuth information from said distinguishing and said measuring.

One technical advantage of such embodiments is the allowance for the detection and display of elevation angle of a detected target without the need for a visual sighting. BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and for further advantages thereof, reference is made to the following Detailed Description of Embodiments of the Invention, taken in conjunction with the accompanying Drawings, in which:

FIGURE 1 shows a view of a helicopter radar system for scanning various elevation angles with no scan overlap. FIGURE 2 shows an embodiment of the invention similar to that shown in FIGURE 1, but including an overlap to the scanned elevation areas.

FIGURE 3 shows an embodiment of the invention using a hub-and-cuff assembly as a rotatable mount. FIGURE 3A is a block diagram of part of the circuit utilized by a display to generate a composite image.

FIGURE 3B is a block diagram of the timing circuitry 3A20 of FIGURE 3A.

FIGURE 4 shows an embodiment of the invention for connecting the antennas to the rotatable mount.

FIGURE 4A shows an embodiment of the invention for connecting the antennas to the mast with a defeathering capability.

FIGURE 5 shows another embodiment of the invention showing an alternative mounting of the antennas to the rotatable mount.

FIGURE 5A shows yet another antenna mount embodiment.

FIGURE 6 is a cross-sectional view taken through line 6-6 of FIGURE 5. FIGURE 6A is a cross-sectional view taken through line 6A-6A of FIGURE 5A.

FIGURE 7 shows an embodiment of the invention using cuff angle sensors connected to the cuffs. FIGURE 8 shows an embodiment using a circuit for signal stabilization with respect to variables such as pitch and roll.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION FIGURES 1-3 show a helicopter 10 having what is commonly known as a rotor hub-and-cuff assembly 20. In an embodiment of the invention, assembly 20 includes a plurality of antennas 1-4 which are arranged to scan different elevational areas l^,-4'. While four antennas are shown, fewer or more may be used. The various scanned areas l'-4' are shown with no overlap in FIGURE 1; however, in an alternative embodiment, such areas could have some overlap, as shown in FIGURE 2.

When antennas 1-4 are situated to produce an elevational overlap, a more detailed resolution can be achieved as to elevation angle information. As the rotor assembly rotates, the area of coverage of each antenna 1-4 is an azimuth angle of 360 degrees, while the elevational angle of coverage is smaller, being generally about 30 degrees. Referring to FIGURE 2, assume that areas l'-4 have vertical scan angle w, and half of areas 1' and 2' overlap (i.e., angle s = w/2) . If a radar reflection is detected by antenna 1 alone, antenna 2 alone, or antennas 1 and 2 together, then the reflection's angle of elevation may be known to an accuracy of w/2. If the radar antennas are arranged so that there is no overlap, then the electromagnetic reflection may be detected exclusively by antenna 1 or 2, but not both. Therefore, with radar antennas arranged to produce non-overlapping elevational areas of coverage, the angle of elevation will be known to a greater accuracy of w.

Radar antennas and techniques for mounting antennas in a helicopter rotor are disclosed in U.S. Patent No.

3,390,393, incorporated herein by reference. By mounting one antenna in association with each blade, and by skewing the mounting angle of each antenna with respect to the other antennas, the radar transmitting pattern shown in FIGURES 1 or 2 may be achieved.

FIGURE 3 shows an embodiment of a hub-and-cuff assembly 20 of a helicopter having multiple blades, each associated with a cuff having a radar antenna. As shown, a radar antenna 1 is mounted in rotor cuff 210. Each cuff 210-213 has mounted therein an antenna (2-4) , similar to that of antenna 1, except each antenna is vertically skewed with respect to the others to scan a partially different elevational angle from the rotational plane of the rotor assembly.

By way of example, assume that a target is in front of a helicopter 10 equipped with the embodiment shown in FIGURE 3. As each antenna 1-4 rotates with the rotor to scan an area in front of helicopter 10, each antenna 1-4 scans a different elevational angle with respect to the rotational plane of the rotor. By storing the reflected signals received by each antenna 1-4 during one rotation of the rotor, a composite picture or image showing all scanned areas is generated. In accordance with one embodiment of the invention, the elevation angle of the target can be determined by detecting which antenna receives reflections from the target. In one embodiment, color coding of the target is employed to display the elevation angle information associated with each of the antennas 1-4.

The visual display may take various forms. In one embodiment, the display comprises a system 3A1 shown in FIGURE 3A. As illustrated in FIGURE 3A, four radar signals A-D are received from the four corresponding antennas 1-4 of a four-bladed helicopter. At any given time, the various radar signals A-D represent echoes received at different azimuth angles. To produce a composite image of all elevation angle information about a specific azimuth angle, the image received by each antenna for the same azimuth angle must be displayed simultaneously. In one embodiment, a composite image for a particular azimuth angle is produced by storing representations of signals A-D in video frame memories 1A, 2B, 3C, and 4D until each of the images from that desired azimuth angle has been scanned. Video frame memories (also known as "stores") are well known in the art and need not be further detailed here. There are many frame grabbers (with associated video frame memories as in FIGURE 3A) on the market. In one embodiment, one used is made by POYNTING, INC. It allows a frame to be "grabbed" and processed at any rate, while a continuous frame output is being displayed at any other time desired. Processing can include edge enhancement, thresholding to eliminate noise, and logical operations on adjacent pixels to provide algorithmic image enhancement.

The output of each video frame memory 1A-4D is selected or connected to the input of an image processor 3A10 when the respective video frame memory 1A-4D is triggered by a timing circuitry 3A20. The input signal to timing circuitry 3 20 is generated by a mast rotation monitor 3A30, which in one embodiment is a magnetic pickup device. Monitor 3A30 is mounted to rotor mast 405 such that the input signal to timing circuitry 3A20 cycles at the same frequency as the rotational frequency of mast 405. Image processor 3A10, in one embodiment, is an IMAGE TECHNOLOGY, INC. unit which contains digital signal processing (DSP) hardware to allow execution of the processing algorithms in real-time.

Timing circuitry 3A20 generates timed trigger signals a-d once for each mast revolution to store the images received by each of antennas 1-4 in the respective video frame memories 1A-4D. Each image is associated with a particular azimuth angle. A timing reference signal t from timing circuitry 3A20 clocks the image processor 3A10, whereupon image processor 3A10 selects the stored images from image processing bus 3A40 at the time that corresponds to images obtained at the same azimuth angle.

FIGURE 3B shows an embodiment of timing circuitry 3A20, including a phase locked loop. The "loop" of the phase locked loop consists of the phase comparator 3B1, loop filter 3B2, voltage controlled oscillator (VCO) 3B3, and divide-by-360 divider 3B4. Loop Filter 3B2 is typical of phase-locked loops, used for the VCO 3B3. The number 360 is arbitrarily chosen, wherein the rotor azimuth will be divided, or resolved, into 1 degree increments. The resolution could be finer, if desired. The time reference 'a' is developed by another divide-by-360 divider 3B5 which has a variable starting time relative to mast magnetic pickup signal 3B30. While signal 3B30 acts as a master time reference for the system, the occurrence of

'a' can be varied so that the image display can rotate its effective radar viewing orientation (in the case of a 360 degree display) or it can serve to vary the starting point of a sector of radar information to be displayed. The occurrence of 'a' (which is a logic or trigger signal) is delayed from mast magnetic pickup signal 3B30 by divide-by-N counter 3B7. Counter 3B7 is reset at the occurrence of each signal 3B30 and is driven by the output of VCO 3B3. After N counts, counter 3B5 is reset by the output of the divide-by-N counter. This action causes 'a' to repeat once per mast revolution, delayed from the rotor master azimuth pulse by a count of N. Therefore, if N is ranged from 0 to 360, any azimuth can be chosen. N is a delay variable introduce from a control operated by the display operator. In many embodiments of counter 3B7, the N signal will be controlled by a knob-driven digital encoder or a digital input from a system controller. The other timing signals b, c, and d are also derived from the VCO output. For a four-bladed rotor with four antennas, signals a-d are 90 degrees apart, corresponding to the angular space between the rotor blades.

In some embodiments, the image frame grabber or frame memories 1A-4D contain azimuth-congruent video date when triggered by the signals a, b, c, and d.

The circuitry generates b, c, and d as follows: The 360/rev VCO output 3B3 is divided by additional divide-by-360 counters 3B5, 3B6, 3B7, and 3B8.

Each of these counter outputs is a 1/rev pulse a, b, c, and d. The start of each count cycle begins after the respective counter is loaded. The counters (b, c, d) start after being loaded with the appropriate number at the start of each new 360 degree cycle, that is: 90, 180 and 270. The signals generated by this process will allow a display system to combine the video data from the four antennas and to rotate the displayed field of view by changing "N" from 0 to 359. In like fashion, the counter divisor numbers can be varied to cause only sectors of the total radar scan to be taken in for processing. Those sectors might be, for example, only those ahead of the helicopter, or only those behind. The sector number, size and location can all be varied, as desired. Referring again to FIGURE 3A, image processor 3A10 is preferably a digital signal processor (DSP) for converting the composite signal into a display format (for example RGB) for display on a video display screen (CRT) 3A60. The representation of the image received by each antenna is displayed on the display 3A60 with a unique color. Each color thus represents a different elevational angle of radar coverage.

It will be noted that if the attitude of the helicopter 10 changes (i.e. if the pitch or roll angle from horizontal changes) , then the attitude of the antenna detecting the target will also change. Problems are apparent in a system designed to display the relative position from the rotational plane of the rotor. In some applications, an absolute elevation angle with respect to a horizontal plane may be desired. By way of example, assume that a target exists in range of antenna 1 (FIGURES 1 or 2) when the helicopter 10 is flying straight and level. If the helicopter 10 has changed pitch, then antenna 3, rather than antenna 1, will detect the reflection from the target, and display 3A1 would inaccurately show a target color coded for the elevation normally scanned by antenna 3.

Another reason for an inaccurate video display would result from the feathering of the rotor blade 250 (FIGURE 3) . If antenna 1 is attached directly to the cuff 210 of the rotor assembly, then even when the helicopter is level, a change in the pitch of cuff 210 (i.e. "feathering") will result in a change in the area scanned by antenna 1.

According to one embodiment of the invention, the inaccuracies introduced by feathering may be corrected by defeathering means. One type of defeathering means includes a mechanical apparatus. Another type of defeathering means includes an electronic system which also corrects for the display inaccuracies that result from changes in pitch and roll attitude of the helicopter 10. Simultaneous errors introduced by pitch, roll, and feathering can be compensated by image processor 3A10. Such an electronic defeathering means corrects for such inaccuracies by modification of the video image, to be further described below, after the description of the mechanical defeathering means.

For purposes of brevity, only one antenna and its cuff and mounting are described, but it should be understood that the other antennas and cuffs will be similarly adapted. FIGURE 4 shows an embodiment with a mechanical means to prevent feathering of a cuff-mounted antenna. The antenna 1 is rigidly connected to the helicopter mast 405, through the cuff 210, by a coupling 410. Coupling 410 prevents antenna 1 from pivoting about axis 420 during pivotal movements, i.e. feathering, of the cuff 210 and the rotor blade. A cuff support 430 does pivot about axis 420 as rotor blade 250 (FIGURE 3) is feathered. The radar antenna 1 is connected to the cuff support 430 by a free pivot mount 440. The cuff support 430 includes an ear having a hole through which a pin passes and is connected to the antenna 1, thus allowing it to pivot with respect to the rotor cuff 210. Thus, as rotor blade 250 is feathered, thereby changing its angle with respect to the rotational plane defined by cuffs 210-213, the angle of antenna 1 with respect to the rotational plane of cuffs 210-213 remains the same.

In a system in which an earth stabilized image is desired (such as with mapping and terrain avoidance systems) , antennas 1-4 can be cyclically articulated to cause the radar transmission patterns to be stable relative to the earth. This is accomplished by using an actuation device 510, such as a hydraulic actuator or motor, as seen in FIGURE 5.

Referring now to FIGURE 4A, shown is another embodiment using cyclic defeathering and stabilization of the radar antenna with respect to the earth, done either individually or in combination. Four sinusoidal signals (one for each blade) are generated, each 90 degrees from the other, for example by oscillators 451A-451D referenced or locked to the rotor mast 450 by magnetic pickups 453A- 453-D. Each actuator 510 is placed in a control loop to cause the antenna angle to follow commands generated by multipliers 452A-452D. Multipliers 452A-452D control the magnitudes of the sinusoidal oscillator signals so as to generate counteracting feathering motions of each antenna 1-4 as rotor 20 turns. Assuming the 451A oscillator is referenced to the fore-and-aft rotor azimuth angle (Psi) , the pitch attitude of the helicopter is fed into the multipliers 452A-452D after inversion. The swashplate angle, measured by sensors 454A and 454B, is added to the aircraft attitude (algebraically) . In like manner, the lateral attitude and swashplate-motion are accounted for. Alternative embodiments of means for defeathering are shown in FIGURES 5 and 6, where antenna 1 is mounted on pivot mountings 500 and 500', defining an antenna pivot axis 505. Actuator 510 is mounted to antenna 1 by antenna pivot arm 520 (seen in FIGURE 6) and to mast 405 by a fitting 530. Actuator 510 functions as a servo to cyclically change the angle of each antenna. A typical position loop closure makes the actuator follow electronically generated position commands. The commands to defeather are generated by measuring feather angles and using these as opposing commands. Thus, as the rotor blade 250 and associated cuff 210 are feathered to change their angle with respect to the rotational plane of cuffs 210-213, antenna 1 pivots about antenna pivot axis 505 and maintains the same angle with respect to the rotational plane of cuffs 210-213. Earth stabilizing commands can be superimposed on the feathering commands to introduce feathering in a way to stabilize the antenna patterns horizontal to the earth.

In yet another embodiment, the radar antenna 1 may be mounted as shown in FIGURES 5A and 6A. As shown, antenna 1 is mounted similarly to the embodiment shown in FIGURES 5 and 6, but on the trailing edge of the rotor cuff 210, rather than on the leading edge.

In still a further embodiment, the means for defeathering includes an electronic method that is incorporated within display 3A1. Shown in FIGURES 7 and 8, antenna 1 is mounted to the rotor cuff 210 with no pivot, so that the angle of antenna 1 changes as does the angle of the cuff 210 with respect to the rotational plane of the cuffs 210-213. The angle of the cuffs 210-213 is monitored, along with the attitude of the helicopter, and through signal processing the radar signals are stabilized with respect to the horizon.

In this embodiment, the angle of the cuffs 210-213 is monitored by cuff angle sensors 710-713, which in one embodiment take the form of linear variable differential transformers (LVDT'S), and which are connected to the cuffs 210-213 as shown in FIGURE 7. As seen in FIGURE 8, a sensor 810, which in some embodiments comprises a gyro, monitors the attitude of the helicopter 10. Pitch signal 812 and roll signal 814 correspond to the helicopter's pitch and roll angles. The signals from cuff angle sensors 710-713 and the signals from sensor 810 are input to image processor 815. FIGURE 8 shows an additional processing technique to earth stabilize the radar information with the fixed radar antenna in each blade. Digital image processor 815 is an embodiment of image processor 3A10. Digital image processor 815 first adds input signals from the cuff angle sensors 710-713 and the attitude gyro 810. First, signals 812 and 814 are summed and differenced with cuff angle signals 710-713 to provide composite signals 710'-713', representing the earth-reference attitude of each antenna. Image processor software then operates on the video from video frame memories 1A-4D of FIGURE 3A to rotate and translate the output image going to the display screen. The operation consists of carrying out a coordinate rotation of the data about the helicopter axes. For example, as the aircraft rolls, a forward sector displayed on the screen would rotate on the screen as a result of the attitude signals, while pilot-induced cyclic feathering motions, or changes in the rotor attitude with respect to the helicopter, would be accounted for by the cuff angle sensors and would not be apparent on the screen. The pitch motion of the helicopter would be accounted for by a vertical motion of the image on the screen.

A multi-beam rotor radar has all the advantages of a radar using a rotor mounted antenna system, as cited in previous references. The disadvantage of those systems is there being no elevation information. This is overcome by the multi-beam antenna configuration along with the means to utilize the radar information obtained by such a multiplicity of antennas. Earlier systems require the use of a very broad vertical beamwidth in the antenna(s) so that targets will be detected regardless of attitude changes and rotor blade feathering angles. With the multi-beam arrangement an advantage is the higher antenna gain naturally associated with the narrower vertical beamwidth, which is not only desired but also required by the multi-beam configuration. Since energy is concentrated into a much smaller vertical beamwidth, more range is available or a much lower radar power may be used. This lowers transceiver cost and weight, and in some cases more importantly, it reduces radiated power which can be used by an enemy as a detection means.

The elevation information gives an advantage over the other systems in providing terrain avoidance information. It also provides elevation information as to the location of enemy airborne threats in a combat situation. The elevation information allows discrimination between targets of equal range but different elevations, thus resolving ambiguities in target location and target identification, e.g., an aircraft versus a tree.

The above-described embodiments are given by way of example and not as limitations. Other embodiments will occur to those skilled in the art which do not depart from the scope of the invention for which reference is directed to the claims below.

Claims

I claim:

1. A radar system for use on a vehicle, comprising: a rotatable mount attached to the vehicle; a first antenna connected to said rotating mount for scanning a first area of coverage and having a first antenna output signal for defining images in a first area of coverage; a second antenna connected to said rotating mount for scanning a second area of coverage different from said first area of coverage and having a second antenna output signal for defining images in said second area of coverage; and a display for displaying images of said first and second areas of coverage so as to distinguish said images.

2. The radar system of claim 1, wherein the area scanned by said first antenna has a different elevation angle than the area scanned by said second antenna.

3. The radar system of claim 1, wherein said rotatable mount comprises a mast of a helicopter.

4. The radar system of claim 1, wherein said first antenna is mounted to a first cuff of a hub-and-cuff mount.

5. The radar system of claim 1, wherein the attitude of said antenna remains substantially constant with respect to the horizon of the vehicle.

6. The radar system of claim 1, further comprising means for defeathering each said antenna, said means being connected to each said antenna.

7. A radar system as in claim 6 wherein said means for defeathering comprises: a first signal generator responsive to the rotation of said rotatable mount; and a second signal generator responsive to the rotation of said rotatable mount; a first and a second multiplier, connected to said first and said second signal generators, respectively, and controlling the magnitudes of the signals generated by said first and said second signal generators so as to generate first and second counteracting feathering signals, said first counteracting feathering signals being connected to a first actuator positioned and arranged to defeather said first antenna and said second counteracting feathering signals being connected to a second actuator positioned and arranged to defeather said second antenna.

8. A radar system as in claim 7 wherein said first and said second signal generators are oscillators which are referenced to said rotatable mount by a first and a second magnetic pickup.

9. The radar system of claim 6, wherein said means for defeathering comprises a coupling connected respectively to each said antenna so that each said antenna has substantially no movement with respect to its respective coupling, each said coupling being connected to the rotatable mount so that there is substantially no movement between said coupling and said rotatable mount.

10. The radar system of claim 6, wherein said means for defeathering comprises a pivotal mount connected to said antenna so that said antenna is pivotal about a pivot axis of a respective said antenna, and wherein said pivotal mount is connected to a first cuff of a hub-and- cuff mount such that there is substantially no movement between said first cuff and said pivotal mount.

11. The radar system of claim 6, wherein said defeathering means is an electronic system and is electrically connected to said antenna.

12. The radar system of claim 1, further comprising a mast rotation monitor connected to said rotatable mount so that said mast rotation monitor generates a mast rotation signal corresponding to the rotational frequency of said rotatable mount, said mast rotation signal being connected to a mast frequency input of said display.

13. The radar system of claim 12, wherein said display comprises: a timing circuit having a phase-locked loop operating on said mast rotation monitor, said phase-locked loop input being said mast rotation signal; a video frame memory having a video frame input connected to said antenna, said video frame input being an antenna output signal from said antenna; an image processor having an image processor input, said image processor input being a video frame output; and said image processor having an image processor output for coupling image signals to a display screen.

14. The radar system of claim 13, wherein said display further comprises: a signal adjuster having a signal adjuster input, said signal adjuster input being connected to said image processor output; and said signal adjuster comprising said display screen.

15. The radar system of claim 1, further comprising a pitch gyro mounted to the vehicle, the vehicle having a front and a rear, said pitch gyro having a pitch output signal corresponding to the difference in angle between a line passing through the front and the rear of the vehicle and a horizontal plane, said pitch output signal being connected to said display.

16. The radar system of claim 1, further comprising a roll gyro mounted to the vehicle, the vehicle having a front and a rear, said roll gyro having a roll output signal corresponding to the difference in angle between a line normal to a line passing through the front and the rear of the vehicle and a horizontal plane, said roll output signal being connected to said display.

17. The radar system of claim 1, further comprising: a pitch gyro mounted to the vehicle, the vehicle having a front and a rear, said pitch gyro having a pitch output signal corresponding to the difference in angle between a line passing through the front and the rear of the vehicle and a horizontal plane, said pitch output signal being connected to said display; a roll gyro mounted to the vehicle, the vehicle having a front and a rear, said roll gyro having a roll output signal corresponding to the difference in angle between a line normal to a line passing through the front and the rear of the vehicle and the horizontal plane, said roll output signal being connected to said display; a signal processor within said display having a pitch input connected to said pitch output signal, a roll input connected to the roll output signal, a first antenna input connected to said first antenna output signal, and a second antenna input connected to said second antenna output signal; and said signal processor calculating the elevation angle of reflections received by said first or second antennas with respect to the horizontal plane, by comparing said pitch and roll inputs and assigning an elevation angle code to the reflections based upon the reflections' elevation angle with respect to the horizontal plane.

18. The radar system of claim 1, further comprising: a first cuff of a hub-and-cuff mount which connects said first antenna to said rotatable mount; a pitch gyro mounted to the vehicle, the vehicle having a front and a rear, said pitch gyro having a pitch output signal corresponding to the difference in angle between a line passing through the front and the rear of the vehicle and a horizontal plane, said pitch output signal being connected to said display; a roll gyro mounted to the vehicle, the vehicle having a front and a rear, said roll gyro having a roll output signal corresponding to the difference in angle between a line normal to a line passing through the front and the rear of the vehicle and a horizontal plane, said roll output signal being connected to said display; a signal adjuster within said display having a first antenna feathered input connected to a cuff angle output signal produced by a cuff angle sensor, said cuff angle sensor being connected to said first cuff, said cuff angle output signal corresponding to the difference between the angle of said first cuff and the rotational plane of said first cuff; and said signal adjuster calculating the angle of reflections received by said first antenna with respect to a rotational plane of said first cuff and assigning an elevation angle code to the reflections based upon the reflection's elevation angle with respect to the rotational plane of said first cuff.

19. The radar system of claim 1, further comprising: a first cuff of a cuff-and-hub mount which serves as the connection between said first antenna and said rotatable mount; a pitch gyro mounted to the vehicle, the vehicle having a front and a rear, said pitch gyro having a pitch output signal corresponding to the difference in angle between a line passing through the front and the rear of the vehicle and a horizontal plane; a roll gyro mounted to the vehicle, the vehicle having a front and a rear, said roll gyro having a roll output signal corresponding to the difference in angle between a line normal to a line passing through the front and the rear of the vehicle the a horizontal plane; a signal processor within said display having a first antenna feathered input connected to a cuff angle sensor, said cuff angle sensor being connected to said first cuff and having a cuff angle output signal corresponding to the difference between the angle of said first cuff and the rotational plane of said first cuff; and said signal processor calculating the angle of reflections received by said first antenna with respect to the horizontal plane and assigning an elevation angle code to the reflections based upon the reflections' elevation angle with respect to the horizontal plane.

20. A process for detecting and displaying a target with azimuth and elevation information comprising the steps of: scanning a plurality of scan areas, each scan area having a different angle of elevation associated therewith, detecting a target in at least one of said scan areas, distinguishing the scan area from which the target is detected from other scan areas, measuring the azimuth of the scan area from which the target is detected, and displaying a representation of the target simultaneously with the elevation and azimuth information from said distinguishing and said measuring.

21. A device for detecting and displaying a target with azimuth and elevation information comprising: a means for scanning a plurality of scan areas, each scan area having a different angle of elevation associated therewith; a means for detecting a target in at least one of said scan areas, said means for detecting being mounted to said means for scanning; a means for distinguishing the scan area from which the target is detected from other scan areas, positioned and arranged to be responsive to said means for detecting; a means for measuring the azimuth of the scan area from which the target is detected, said measuring means being positioned and arranged to be responsive to an azimuth angle position, relative to a reference azimuth position, of said means for scanning; and a means for displaying a representation of the target simultaneously with the elevation and azimuth information, positioned and arranged to be responsive to said means for distinguishing and said means for measuring.