DE1272396B - The azimuth-scanning radar arrangement for flying objects to display the terrain profile - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. Cl

GOIs

German class: 21 a4 - 48/44

Number: 1 272 396

File number: P 12 72 396.5-35 (N 25289)

Filing date: July 22, 1964

Opening day: July 11, 1968

The invention relates to an azimuth-scanning radar arrangement for flying objects for display purposes of the terrain profile, which generates a signal according to the sum-difference principle that shows the distance, the azimuth and the angle of a terrain profile with respect to one at a predetermined distance reproduces the safety distance plane located below the flying object, and which one the Facility detecting peaks of the terrain profile associated with each azimuth direction scanned Signal generated for the elevation angle of a peak in the terrain, a trigger generator for synchronization the signal generation and a display device for two-dimensional reproduction in polar coordinates whose coordinates are the measured azimuth and the pulse repetition interval correspond to the radar system.

Such a radar arrangement is known which can be referred to as an obstacle warning system. at This radar arrangement reproduces the ground obstacles in relation to an arc which delimits a safety area. The safety circuit corresponds to the desired distance of a distance reference plane in a desired direction. The combination of the distance on the one hand and the vertical measuring angle on the other hand results in the desired distance from the reference plane. With this known arrangement, only information about show the distance and the azimuth of the object in relation to the alignment line of the antenna, where a selected distance from the reference plane on that plane defines a distance arc that extends to appears as a circular arc in the panorama image (»PPI«). The distance and azimuth of such objects are that appear at a greater distance than the reference arc, on the outside of the Arc reproduced, while that of objects with closer spacing on the inside of this The reference arc.

This well-known reproduction of the stated values offers the pilot a representation from which he cannot can immediately read the necessary flight maneuver angle. Rather, there is a risk that him the representation simulates conditions that are opposite to the necessary flight maneuvers. So the point that appears most prominent in the representation corresponds to the one shown Curve an obstacle that is furthest away from the object's point of view and below the reference plane is completely harmless to the property. On the other hand, an on the representation corresponds to am furthest inward or inferior point one

Azimuth scanning radar array
for flying objects to display the
Terrain profiles

Applicant:

North American Aviation, Inc.,

El Segundo, Calif. (V. St. A.)

Representative:

Dr.-Ing. F. Wuesthoff, Dipl.-Ing. G. Pulse
and Dipl.-Chem. Dr. E. v. Bad luck man,
Patent Attorneys, 8000 Munich, Schweigerstr. 2

Named as inventor:

Algimantas Henry Kazakevicius, Fullerton, Calif .; Forest Johnson Dynan, La Mirada, Calif .;
Jerome Milton Page, Fullerton, Calif. (V. St. A.)

Obstacle that is above the reference plane, at a short distance from the point of view of the object. Such a deep point is representative of a highly dangerous obstacle, which is requires a corresponding immediate flight maneuver.

Arrangements are also known with which relative heights can be calculated and reproduced. However, such an indication is not sufficient for the flight safety of an object, since an obstacle nearby lower altitude can make a considerably larger flight path change angle necessary, in order to be able to avoid the obstacle than a further distant, but noticeably higher obstacle. In contrast, the invention is based on the knowledge that it is necessary for reasons of flight safety is, the terrain obstacles to the pilot in relation to the position of the aircraft essentially as they can be seen with the naked eye to ensure that that the pilot reacts with the correct flight maneuver.

According to the invention, this object is achieved in that for simultaneous reproduction of the position of the obstacle and its contours in relation to the safety distance plane a coupling device is provided which is responsive to the trigger generator and the signal during a predetermined first section of the radar pulse repetition

8OD 569/202

3 4

period appears for each on the display device. 2 shows the main ones in a block diagram Azimuth value at an input for the most modular elements of a known radar arrangement, lation of the reproduction intensity of the display device in which the arrangement according to the invention is redirected, and that the tops of the terrain can be turned to;

profile determining device a pulse delay 5 F i g. 3 shows a pictorial representation of FIG

Gerungseinrichtung is coupled to the on-ratios that are used to represent the terrain profile

run for the modulation of the playback intensity according to the invention;

the display device at the end of a second, the F i g. 4 gives a schematic representation of a typical PPI

The first following time segment generates a pulse, there would be a radar arrangement according to the invention in dependence on the output signal io again;

the input determining the peaks of the terrain profile. 5 is a block diagram of a preferred one

direction at the end of the first time segment and for the embodiment of the radar arrangement according to FIG

the displayed azimuth value, where the length Invention;

of the second time segment is a function of FIG. 6 shows the different size in a diagram of the maximum signal value during the 15 th waveforms at the various points

first time period is. of the block circuit diagram of FIG. 5.

With this radar arrangement, the starting point of the present invention is a position of an obstacle detected by means of radar, a radar arrangement which, according to the sum-difference principle, generates a signal that protrudes beyond the various safety distance planes that are fixed in relation to the flying object, as well as 20 values, in particular the distance and the azimuth, the contour of this obstacle in the form of a maximum and the angle of a terrain profile, compared to the flight angle as a function of the azimuth, again at a predetermined distance below the flight. The safety distance plane of the radar arrangement that is located with the moving object and that is used to reproduce safe appear on the display device. Such a radar arrangement is known in the 25 variants for many objects protruding from the distance and is also called "monopulse" radar top view, while the contour of the obstacle is called in device. In such radar arrangements, the shape of an obstacle profile line of the front view is generated which is characterized by the fact that obstacles correspond. Thus, the pilot has an immediate overview of the level of an output signal can be generated at any time from a single pulse of radar information, which the objects and the distance between these objects 30 deviation of the object from the adjustment line from the position of the aircraft. The illustration shows. In such a radar arrangement speaks about the normal image, which can be optically captured by the antenna Si-way, so that the pilot signals additively and subtractively combined and a normal response in the execution of the emergency two-channel reception system fed, which a can show agile flight maneuvers. This results in 35 sum signal E _s generated. This corresponds to the addition of a much greater security and a lightly combined energy. Furthermore, a differentiated recording of possible danger spots is possible. signal E & generated which combined the subtractively

Advantageously, the pulse delay includes reproduces energy.

set up a multivibrator and a pulse shape. In the following considerations, a win-

furnishings. 40 kel β is defined as the angle between the target and

The coupling device expediently has the alignment axis of the antenna in the height plane. Of the

The transmission time of a video angle is also determined by the relationship between

Amplifier for the sum signal and the difference signal in the form of the sum-difference signal

Principle generated signal controlling multivibrator based on the equation

while with the video amplifier on the one hand the connection 45 E ~ K · ß · E

Pointing device via a reference level coupling ^{1 s} '

device and a limiter circuit and on the other hand in which equation K ₁ a proportionality

the device that determines the terrain profile peaks is constant. Due to the automatically effective

connected is. instantaneous gain control in the radar

The arrangement can be arranged in any radar device, the sum signal E _{8 is} a constant,

Avoiding ground obstructions so that the above equation reads as follows:

that a signal according to the sum-difference principle g _ ^ - «

generated, which is decisive for the relative height of the ^d

surrounding terrain is. There are no major changes. For this reason, in a monopulse radar system, adjustments to existing radar arrangements are required, as is known, the difference signal is a direct one. With only a small circuit and wiring dimension of the angle ß at which the target of the height work, the desired new arrangement can be installed in existing systems in relation to the alignment axis of the antenna. This therefore goes on in FIG. 1 is the nature of the problems in the very simple and cheap way because that explains avoiding ground obstacles. In the known radar arrangement, the signal generated for the 60 a low-flying aircraft at point 18, which is used to represent the profile outline, moves along the flight path 12 over the ground structure 19, the aircraft longitudinal

The invention is illustrated below with reference to the schematic reference axis 14, which is the roll axis of the aircraft

Table drawings of an embodiment may correspond to the flight path 12 through a

explained in more detail. 65 Approach angle «. The adjustment axis 13 of the

F i g. 1 illustrates the geometrical antenna of the monopulse radar system, which occurs on the flight case, which is mounted in a radar arrangement for warning, is opposite the aircraft along the surface of earth obstacles; axis 14 inclined downwards at an angle η,

5 6

where the axis 13 is a reference or distance- The value of the angle β is within the scope of the

level 15 obtained in a predetermined or known previously explained monopulse method and

Cuts distances. The reference plane 15 is can be expressed as follows:

below a predetermined distance H ₀

the trajectory 12 and runs parallel to 5 KEg,

the horizontal plane in which the flight path runs. β = - (5)

From the geometry of FIG. 1 can be seen, ^s
that the instantaneous vertical distance H des

Flight path 12 from an obstacle, for example the introduction of this expression in the track

Bottom tip 16, which is obtained at an inclined distance R io chung (4)
away from the radar antenna

can. The inclined distance R is proportional to the γ - .___? (<5 ₀ + -—-— | (6)

Time for the video signal to return. The R \ E ₈ )

Angle β is determined by the difference or error signal

determines which in the monopulse radar system 15 in FIG. 2 are the means of realizing the

is generated while the angle η of the inclination equation (6) is represented. It is noted that

angle at which the adjustment line of the radar antenna is just one of the many possibilities which can be used for

appears under the flight path. This angle can be used to derive the warning signal γ

can also be easily calculated. Since a flight at nen.

20 The output pulse of a trigger generator 20,

values are applied at small angles, d. i.e. what the synchronization of the radar system will be

it can be assumed that the sine and the can is fed to a function generator 22,

Tangents of different angles are equal to the win- in which the generation of an exponential signal

none even if this is given in arc values _{ ^ _{d fa the value} l _tional

are. The angle β is treated as a negative quantity, 25 ^ö R ^v *

if the target 16 is (as in the case of FIG. 1) the generator 22 can, for example, be a Phantastron

is located above the adjustment axis 13 of the antenna, to generate a negative running rectangular

and as a positive variable if the targeted target waves depending on the trigger signal of the

located below this axis. It can be the F i g. 1 trigger generator 20 include, as well as a passive one

the following relationship can be taken: 30 .RC network in which the negative square pulse

η _ _{α =} s is transformed according to the value - = -. The out

output of this generator 22 is connected to a potentiometer

This results (taking into account a 25 applied. The potentiometer is adjusted with the aid of the negative value for the angle β in calculation 35 setting knob 30 so that it reproduces the case shown in FIG. 1) desired height distance H ₀ . The signal

on the arm of the potentiometer 25 is part of the output

H = R (δ ₀ + ß) . (1) output signal of the generator 22, which by Ein

position of the arm of the potentiometer 25 is determined

The height of each upwardly extending obstacle 40 _{wifd. This} proportion is, as shown, % -. A signal of the terrain penetrating the reference plane, ⁰ R

leads to a value Δ H, which is the difference corresponding to the value (5 ₀ , which is the angle between the measured height // and the desired between the setting line of the radar antenna and the th distance plane H _0. In an illustration of an equation flight path of the aircraft is, the antenna unit (not shown) becomes a summing amplifier

35 supplied. This signal is made from the target angle

Δ H = H ₀ - H, (2) and the information about the antenna position

generated by known means.

from which the introduction of equation (1) in _D H ₀ ci _ffna1des p _otent i _ometer s25anddasSiffnal

Equation (2) gives the following: 50 ^DaS ΊΓ ^{blgnal des} ™ ^{tentl0meters 25 and the} ^ S ™ ¹

corresponding to the value <5 ₀ from the antenna unit,

Δ H = H ₀ - R (<5 "+ ß) . (3), which is not shown, are fed to the summing amplifier 35, where they are used to generate the output

The increase in the flight path angle γ (where H ^ _ _{δ are summed up} . _The output

only small changes in angle are assumed) 55 R "° °

compared to the distance plane directly below that of the monopulse sum channel IF amplifier 37

Aircraft, which is necessary to the obstacle is fed to the amplifier 38, where it is connected to the output

is multiplied by the desired height distance H ₀ to the summing amplifier 35 above. Of the

can fly from Fig. 1 is taken from the output of the differential channel IF amplifier 39 as follows

are: 60 multiplied by a constant using

π of the potentiometer 40, and then the summation

γ = --- (δ ₀ + β). (4) more powerful 44 fed where it is from the output of the

^ Multiplier 38 is subtracted. The exit of the summing amplifier 44 therefore corresponds to that

The angle γ can be either positive or negative 65 value

and reflects the angle at which a

Subject of the terrain above or below W? S ₀ ] -KEa = γ E _s . O)

the distance plane appears. \ R

7 8

The output of the summing amplifier 44 is the phase detector for the obstacles which are shown in the silhouette representation 47 supplied, which also shows, avoids and can ensure that the reference signal from the sum channel IF amplifier 37 leads to these obstacles below the distance plane will. The output of amplifier 37 will remain as it pulls the aircraft up. He scanned in the video detector 50. The output of the 5 also receives security that it will not occur Video detector 50 is actually a function generator 48 of PPI signals on its screen in which a signal corresponding to the absence of obstacles in its flight path

■ ,,,. 1. . j τ-. , -, ijoi u · speaks and not its cause in an eventual

Value - = - is generated. The generator 48 can at- / ,, ■ _b . , * * T> jj λ. ι.

It ^s defectiveness have his radar arrangement.

for example comprise a passive jRC network. The io The F i g. 5 shows a block diagram of an output signal of the generator 48 and the phase-preferred embodiment of the device according to detector 47 are used in the multiplier 49 of the invention, and FIG. 6 shows the waves multiplied. The output signal of the multiplier forms at various points of the block switching device 49 is the warning signal γ, which is the image in FIG. 5. A synchronization or value 15 trigger signal 1 is fed to a multivibrator 75 from the radar trigger generator H ₀ , KEa 20. This trigger ~ n ~ £ ° signal is a sharp positive pulse, as at 1 ^s in F i g. 6 is shown. The multivibrator 75 is

is equivalent to. Due to the definition, the angle β is a monostable multivibrator, its time constant

the ratio between the error signal Ea and 20 is set so that it corresponds to a predetermined PPI

jo— j. τ- * KEa .j · r * λ corresponds to the range scanning range. The output the sum value E _s or - ^ -. For this reason _{the monc} | _stable multivibrator 75 is a right can the warning signal of the multiplier 49 corner voltage, which is shown in FIG. 6 is displayed at 2. can be reproduced as follows: The output of the multivibrator 75 becomes the gate

25 circuit of the video amplifier 77, namely to

γ - (Jh § \ --ß. (8) its switching into the conductivity state

\ R j is used. The video amplifier 77 is normally

switched off and only becomes continuously conductive when

It is noted that the value β is turned on negative for winter by the multivibrator 75, which appears above the adjustment axis of the 30 The output 3 of the multiplier 49, which antenna is located and corresponds to positive for angles below the γ warning signal, is through the video of this axis. amplifier 77 only allowed through during the period,

In the F i g. 3 and 4 the type and during which this amplifier is in the conductivity mode is generally described and shown in which the warning phase is due to the output signal γ in the device according to the invention. The output signal turns and is used. In the case of an aircraft 52, the video amplifier 77 is at 4 in FIG. 6 again this is given with a fixed height distance H ₀ above. The output signal of the video amplifier 77 is distance plane 55, a warning signal + γ _α is generated by a corresponding device 80 on through the elevation 57 at azimuth α , while a suitable direct current reference voltage is connected to a warning signal - y & at an azimuth b to 40 pelt and one Limiter circuit 82 is supplied to the bottom of the deep point 59 is generated. It is biased that only positive components of the elevation 60 at azimuth c are generated, which reflect positive values of γ , to warning signal + y _c . The playback can be forwarded to a video mixer 85. PPI display element includes all maximum points. The output of the limiter circuit 82 is at 10 in of the terrain between the azimuth angles α and c, 45 F i g. 6 reproduced.

likewise all those before and beyond this azimuth angle. The output of video amplifier 77 becomes

and represents a silhouette-like outline of the terrain, further fed to an apex sensor 87, in welrains, as represented by the line 63. chem is the peak value of all those signals that F i g. Figure 4 depicts a typical device in accordance with each PPI range scan by the invention in a PPI system. With the so forwards to be saved. This stored PPI video system displays items above signal is at 5 in FIG. 6 reproduced. The signal stored half of the distance plane by the light spots is displayed after each PPI distance 67. The distance plane itself is held back by the scan until the trigger pulse is reproduced on line 70, while a silhouette at 1 in FIG. 6 is indicated for the following outline of the terrain above and below the distance measurement. This distance plane trigger pulse reproduced by line 73 discharges that is stored in the vertex feeler. Line 71 indicates the end of the PPI removal signal and sets a predetermined reference level, scanning. In this way, the pilot receives a so that the detector output exactly the most normal PPI reproduction to avoid positive or least negative γ- value during the terrain, which reproduces those objects 60 rend each separate scan and indicates which are located above the distance plane, a remanent signal is generated during the subsequent mapping and, in addition, a silhouette-like outline of the scans.

Objects both above and below the

Distance plane. In this way, he receives a device 87 becomes a monostable multivibrator 90 show the exact characteristics of the terrain that was fed up before 65 in which it is used to control the time period to him, at all times. This reduces the conductivity state of this multivibrator essential flying an airplane and turning. The output signal of the multivibrator the avoidance of obstacles by the pilot the 75 is fed to a pulse shaping circuit 93, which

the supplied signal differentiates and the positive running differentiated rising edge of the square wave cuts off. The differentiated trailing edge of the square pulse of the multivibrator 75, at 6 in F i g. 6 is indicated, is fed to the monostable multivibrator 90 as a trigger signal.

The output of the monostable multivibrator 90 shown at 7 in FIG. 6 is a square wave, which is synchronized with the output 6 of the pulse shaping circuit 93 and a time period which is determined by the amplitude of the output signal 5 of the peak sensor 87. The output signal 7 of the monostable multivibrator 90 is fed to a pulse shaping circuit 97, which differentiates the signal, the positive-going signal, which is caused by the leading edge of the square wave is generated, cuts off and has an output pulse 8 which is shown in FIG. 6 shown is and represents a negative going pulse, which with the trailing edge of the output 7 ao of the multivibrator 90 collapses. The output signal 8 of the pulse shaping circuit 97 is sent to the video mixer 85 supplied.

The monostable multivibrator 105 is activated by the differentiated pulse 6 in FIG. 6, which coincides with the trailing edge of the output of the multivibrator 75. The time period of this multivibrator is determined by the voltage which is supplied to it by the potentiometer 110. The potentiometer 110 has a bias voltage which is supplied by a direct current source 112. The movable arm of the potentiometer 110 is mechanically connected to a button 114 which represents a calibration setting and is used to set a reference line which is indicative of the angular value γ = 0. The output of the multivibrator 105 is fed to a pulse shaping circuit 107 in which the rising and falling edges are differentiated and positive-going pulses generated by the rising edge are cut off. The output of the pulse shaping circuits 107 is shown in FIG. 6 represented at 9 and is a negative pulse which is applied to the video mixer 85. This pulse represents the distance reference plane and is a direct function of the setting of the arm of potentiometer 110 with the aid of knob 114. This signal, which appears at 6 in FIG. 6 is a negative going pulse indicating the end of the PPI range scan. The through the signals 9 and 6 in F i g. 6 generated trace is shown in FIG. 4 indicated by lines 70 and 71. Line 70 represents the position of the reference plane with respect to the silhouette outline shape, while line 71 indicates the end of the PPI range scan.

The output signal of the video mixer 85, which is indicated at 11 in Fig. 6, the PPI display device 115 supplied. By reference line 11 in FIG. 6 it can be seen that this composite Video signal a video playback corresponding to the targets above the distance plane during a first time interval corresponding to the PPI range scan. It includes also a signal corresponding to the end of the PPI range scan and a signal which represents the setting of the clearance plane by button 114, as well as a signal which represents the maximum angle at which any object during each PPI range scan is encountered.

The device according to the invention thus provides a simple but highly effective arrangement for generating a silhouette-shaped outline representation of the terrain which is represented by the Radar device is scanned to avoid obstacles in the ground. This playback can additionally be attached to such a radar device with the slightest change to the existing one Circuit. The display then follows the display of the PPI distance information, providing a graphic representation of the surrounding terrain.

Claims (5)

Patent claims: 1. The azimuth scanning radar arrangement for flying objects to display the terrain profile, which generates a signal according to the sum-difference principle that shows the distance, the azimuth and the angle of a terrain profile with respect to one at a predetermined distance below the flying object reproduces the safety distance plane, and which one the Facility detecting peaks in each azimuth direction scanned corresponding signal for the elevation angle of a peak in the terrain is generated, a trigger generator for synchronizing the signal generation and a display device for two-dimensional reproduction in polar coordinates, the coordinates of which are the measured azimuth and the pulse repetition interval correspond to the radar system, characterized in that for simultaneous reproduction of the position of the obstacle and its contours in relation to the Safety clearance level (55) a coupling device (75, 80, 82) is provided which on the trigger generator (20) is responsive and the signal during a predetermined first portion the radar pulse repetition period for each appearing on the display device (115) Azimuth value to an input for modulating the reproduction intensity of the display device (115) forwards, and that to the device (87) determining the peaks of the terrain profile Pulse delay device (90, 97) is coupled to the input for the modulation the reproduction intensity of the display device (115) at the end of a second following the first Period of time generated a pulse, depending on the output signal of the Peaks of the terrain profile determining device (87) at the end of the first time segment and for the displayed azimuth value, the length of the second time segment being a function is of the size of the maximum signal value during the first time segment. 2. Radar arrangement according to claim 1, characterized in that the pulse delay device connected in series comprises a multivibrator (90) and a pulse shaping device (97). 809 569/202 3. Radar device according to claim 1 or 2, characterized in that the coupling device (75, 80, 82) also has a transmission time of a video amplifier (77) for the signal generated according to the sum-difference principle and controlling the multivibrator (75) the video amplifier (77), on the one hand, the modulation device (85) of the display device (115) via a reference level coupling device (80) and a limiter circuit (82) and, on the other hand, the device (87) determining the terrain profile peaks. 4. Radar device according to claim 3, characterized in that with the output of the multivibrator (75) of the coupling device (75, 80, 82) the modulation device (85) of the display device (115) on the one hand and the multivibrator (90) of the pulse delay device (90, 97) on the other hand is connected via a further pulse shaping device (93). 5. Radar arrangement according to claim 4, characterized in that a further monostable multivibrator (105) is also connected to the output of the pulse shaping device (93) connected to the multivibrator (75) of the coupling device, the time period of which is connected via an adjusting device (110, 112, 114 ) is adjustable and to which the modulation device (85) of the display device (115) is connected via a pulse shaping device (107). Considered publications:
British Patent No. 959 159;
U.S. Patent No. 3,119,106;
Electronics, 1952, June, pp. 110-113. For this purpose 2 sheets of drawings 809 569/202 7.68 © Bundesdruckerei Berlin