DE1591169C1 - Data processing system for a missile impulse Doppler radar device with synthetic antenna - Google Patents

Description

5. Data processing system according to claim 3 or 4, characterized in that between the azi

mut-deflection generator (82) and the output device (10) a device (101,105,110) is switched on, the controls the time sequence with which the output pulses corresponding to the Doppler Sifenalen are sent to the output device (10) and that this time sequence is essentially a function of the square root of the distance is.

6. Data processing system according to one of the preceding claims, characterized in that

the output device (10) comprises a cathode ray tube (112) responsive to the stored Doppler signals corresponding output impulses and a visual or permanent map display of the targets located on the observed avenge.

The invention relates to a data processing system for a system installed on board a missile Impulse Doppler radar device with an antenna directed transversely to the aircraft and inclined towards the ground, whose radiation diagram is a. Section of a strip of terrain extending parallel to the flight path covered, with a device for storing one of the Doppler frequencies contained in the echo signals comprehensive signal by range and azimuth, a device for sampling the stored signals azimuth ranges assigned in different distance intervals, a device for normalizing of the sampled signals in terms of center frequency and frequency rise, a compression filter with a to the frequency increase of the signals inverse frequency dependence of the transit time and one the output signals of the compression filter according to the distance and azimuth recording output device.

Systems with synthetic antenna diagrams for generating radar map images are known (US-PS 32 71 765; IEEE Transactions ANE-11, Sept. 1964, 173-179), in which pulses from a coherence radar system periodically transmitted by the antenna located on a moving aircraft and the Doppler signals returning a selected distance interval on a two-dimensional Film can be saved in the form of distance tracks that indicate the various positions of the radar, Antenna along the flight path of the aircraft correspond. For the following explanations, the positions along the flight path as azimuth positions, while with "distance" the distances from

flight path are designated, which are measured perpendicular to the flight path. A certain number of ; named distance traces are in azimuth over successive distance elements with the help A light spot scanner is scanned to produce a plurality of Doppler waveform signals, one of which is each represents a point reflector or earth target that reflects incident energy. These signals are on the other hand electronically cross-correlated with a reference function in order to avoid undesirable for all distances To eliminate signals and noise components, so that the Doppler curve signals are essentially independent of the distance are. Accordingly, the radar generate echo signals from targets that are in the chosen one \ section of the area illuminated by the real (actually present) antenna ier processing of infrequent components that fall within a selected frequency band. These components are then used to create a strip map or high resolution representation. That for all ent- "> distance-focused "synthetic" (artificially generated) antenna pattern that is achieved in this way, is characterized by a single, very narrow club of pencil, which is in the antenna diagram of the true Antenna falls.

Another known system with an artificial antenna diagram serving to generate radar map images is able to perform a multi-beam correlation. The well-known system makes for this purpose make use of a battery of filters with a narrow passband, each of which operates on a slightly different center frequency is tuned within the frequency band of the Doppler curve signal. With this arrangement generate the radar echo signals from targets that are within the selected range of the real radar antenna are illuminated when parallel processing frequency components that are in one of several preselected and spaced frequency bands fall so that the processing produces the equivalent of a number of high resolution lobes of each of which, starting from a common phase center, points in a somewhat different azimuth direction. By tapping the signals at each bandpass filter in a specific sequence and feeding in the signals, for example to a cathode ray tube, two-dimensional representation can be achieved in real time. In this multi-beam system, the artificial diagram focused for all distances is through a multitude marked with very narrow pencil clubs, the number of which is equal to the number of narrow band filters. All pencil clubs point at different azimuth angles that differ only slightly from one another and are in the radiation pattern of the real antenna.

In contrast, a data processing system for generating an artificial radar antenna diagram, this effectively creates a multitude of simultaneous lobes that run parallel along the flight path are arranged to each other, so each effective beam has a different phase center or time position has many advantages. In such a system, the distance shifting of point targets would be in of each equivalent high resolution lobe independent of the distance. Continue this Type of processing the formation of effectively simultaneous radiation chains on a route along the flight path which is very much greater than the distance which at any time depends on the beam width of the true antenna! 5 is covered. Therefore, multi-beam recording can take place at short distances without going through the Beam width of the real antenna to be limited. This type of beam forming system would be used in a relatively simple and reliable processing equipment can provide a continuous high resolution image.

The invention provides such an improved radar system with an artificial antenna pattern high resolution created, in which a plurality of parallel synthetic radiation lobes formed at the same time which are reliably defined along the flight path.

The invention consists in that in einet data processing system of the type described above sampled signals limited to an equal frequency deviation and the stored signals in an azimuth range are scanned, the of several arranged in azimuth next to each other, still separable Targets originating, limited to said frequency deviation includes signals.

With the aid of the data processing device according to the invention, an area of the recorded data which is larger than the width of the real antenna pattern, and it is possible through the limitation of the frequency deviation of the sampled signals ensures a perfect separation of the Doppler course signals achieve, which are assigned to different positions along the flight path. As a result, the synthetic Radiation diagram shows a number of parallel radiation lobes, the spacing of which corresponds to the azimuth resolving solution of the synthetic diagram is the same. In other words, it takes place in a system according to the invention a correlation between a plurality of rays and a set simultaneously with offset phase centers artificially formed rays that run parallel to each other and at intervals along the flight path of the Aircraft on which the radar device is arranged, point in the same direction. The signals for each of the Artificial radiation lobes are characteristic of Dopplerver '?, ufs signals for different Formed time ranges, which, however, each extend over the same frequency range.

The radar sends pulses of energy in a specific direction at a specific angle with respect to the path of the aircraft and records the Doppler echo signals for each range scan in a first dimension on a storage device such as a storage tube or a movie. The flight path or the azimuth position is determined by the second dimension of the storage device <> o shown. For processing, the recorded data are read orthogonally in the manner of a raster to form Doppler curve signals for each distance range. A variety of Doppler course sigaaien who represent the group of radiation lobes of the artificial antenna diagram, are in each distance range read out or formed. Each group signal represents a different point reflector in this distance range and the entire range of the Doppler frequency deviation is the same for each point vein flexor. The vectors stored in each distance range are combined in this way in such a way that that their phase angles add up. The sum of the echo vectors is the RF vector addition for each distance in a waveguide with a large number of feed elements of a physically very long antenna

arrangement equivalent.

In one embodiment of the invention, the lengths of the read lines are programmed as a function of the square root of the distance to allow the use of a focusing oscillator with a constant rate of change in frequency. However, this operating mode results in a shift in the center frequency of each reading line or group as a function of the distance. The Doppler signals are then fed to a mixer which is used for frequency shifting and which is used to introduce a frequency which is offset from the Doppler signals according to a specific function of the distance. The Doppler waveform signals are then focused by compensating for the phase or Doppler waveform of each recorded echo for the change in path length over the length of each group. Focusing can be done at all distances by mixing the Doppler waveform signal with the signal of a swept oscillator which is programmed to focus all of the signal vectors forming the group by sweeping the oscillator with an inclination which is in a certain relation to the read out Doppler signals, and by a selected frequency shift. The modified Doppler waveform signals generated by the focusing mixer are variable frequency signals that occur at locations along the reading line that depend on the position of the point reflector along the flight path. Since the times during the reading of each Doppler course signal correspond to the target positions along the flight path, the Doppler course signals meet with the swept oscillator at different points on its frequency curve, so that each of the successive doubles! E-rircqu? Nz-S>gr> »! ^e i ⁿ the mixer is frequency shifted. The frequency-time rise of the Doppler signals is selected so that it is compatible (adapted) with a device for pulse compression, for example with a delay line having a frequency dispersion and used as a compression filter. The signals with varying frequency are fed from the focusing mixer to the compression filter in order to form a plurality of compressed pulses which are offset in their time sequence by a period of time which is equal to or shorter than the time corresponding to a reading line. Each pulse represents a synthetic radiation lobe. Because of the time shift of the Doppler curve signals with respect to the swept oscillator along each reading line, the filter works in a different section of its frequency range in order to compress the Doppler curve signals from different point reflectors that are offset in time Each output signal of the compression filter is then characteristic of a point reflector and correctly positioned in azimuth and distance Azimuth, that is, along the flight path, as well as over all distances s each of the equivalent high-resolution radiation lobes independent of the distance, and all the radiation lobes are parallel to one another, so that they lead to the type of processing with an offset phase center. By using the swept oscillator to reduce the Doppler slope, the compression ratio of the filter in one embodiment of the invention approximates the number of azimuth elements to be processed per reading line rather than the ratio of the group length to the resulting resolution element in azimuth. In another embodiment of the invention, the reading frame can be kept constant and the swept focusing oscillator can be programmed as a function of the distance.

The invention is described in more detail with reference to the exemplary embodiments shown in the drawing explained. It shows

1 shows the block diagram of a system for generating map images with a synthetic multi-beam antenna diagram,

4ϊ F i g. FIG. 2 shows a block diagram of a first part of a system which includes the coherence radar device according to FIG Invention,

Fi g. 3 the block diagram of a second part of a system according to the invention, which is based on non-linear reading and makes use of display grids,

4 shows the block diagram of another embodiment of the second part of a system according to the invention dung, be! which uses a linear reading frame,

F i g. 5 and 6 block diagrams of a storage tube arrangement which is used in systems according to the invention a film can be used as a memory,

F i g. 7 is a diagram for explaining the processes involved in forming the synthetic antenna patterns and FIG Radiation lobes in the system according to the invention,

"FIG. 8 shows a diagram of the instantaneous frequency as a function of time to explain the Doppler curve signals, received by the radar from point targets,

F i g. 9 shows a diagram of the current frequency as a function of the distance on the recording medium to explain the characteristics of the recorded Doppler curve signals,

FIG. 10 is a schematic representation of the film used in the system of FIG. 3 can be used, to to explain the reading frame,

Fig. 11 is an illustration of the true antenna and synthetic lobe diagrams of a system which uses an antenna which operates at a squint angle with respect to the transverse direction,

12 to 15 are diagrams of signals as a function of time to explain the mode of operation of systems according to the invention,

16 is a diagram to further explain the mode of operation of the system according to the invention the compression filter used,

Fig. 17 is a perspective view of a typical frequency dispersion delay line which can be used as a compression filter.

18 shows a diagram of signals as a function of time to explain the radar operation according to FIG Invention,

19 shows a diagram of signals for explaining the bandwidth reduction of the Doppler curve signals; which according to the invention can be effected before entering the compression filter,

20 and 21 are diagrams of the storage area for explaining the recording and reading frames used in a scan storage tube according to the invention can be used,

22 is a diagram of signals as a function of time to explain the mode of operation of the scanning Speicner tube according to the F i g. 5 and 6,

23 shows a diagram of signals as a function of time to further explain the mode of operation of the Sampling storage tube according to FIGS. 5 and 6, and ι ο

24 shows a diagram of the storage medium for further refining of the egg as a function of the square root the distance scanning according to the invention.

The in F i g. 1 illustrated data processing system door a radar device for generating a synthetic |

Antenna pattern according to the invention comprises an output device 10 and the actual, a synthetic ■

Multi-beam antenna diagram forming processing device 12 for processing the radar echo signals, which is %

from targets that are illuminated by a sideways antenna 14. A broadcast; j

Receiving device 16 emits energy pulses and responds to the energy received by the antenna 14 ij

to form coherent Doppler signals which are stored in a recorder 18 before vj

. they are further processed by the processing device 12. The antenna 14 can be an antenna jji

act of any known type, for example an antenna with a parabolic reflector or in the form of a 20 jj

rectilinear group and one with respect to the axis of an aircraft that has a Doppler radar device with ||

a system according to the invention carries, either fixed or alternatively changeable direction of their _; ; |

Beam axis. It is further understood that the output device, for example, a display device, a memory, an i'j

Combination of such devices or an arrangement for the transmission or forwarding of the data to others i

Places can be. The output device 10 can still be controlled by a system for using the processed 25 rj

Data are formed which, for example, forms signals which are used for the position and the intensity of selected ':!

ten point targets within the observed area are characteristic.

As can be seen from FIG. 2, the coherence transceiver 16 contains a reference oscillator 20 for -i

Generation of an IF signal with the frequency Z ₀ , which a frequency multiplier 22 and single sideband.;.;

Modulators 24 and 26 is supplied. The output signal of the multiplier 22, which has the frequency a / ₀ , is in turn fed to a mixer 30 and the modulator 24. At the output of the modulator 24 there is in ■■

consequently an RF signal with the frequency (a1) / ₀ is available. ||

A synchronizer 28 is also provided in the transceiver 16, which generates clock pulses according to curve 29. A pulse shaper 32 forms square-wave signals according to curve 33 from the synchronization signals 29, which are used to control a pulse amplifier 34 to which the RF signals with the frequency (a1) / _{0 are} continuously fed. The output signal of the pulse amplifier 34 is accordingly a keyed RF carrier, which is shown in FIG. 2 is illustrated by curve 35. This scanned carrier is fed to the antenna 14 via a transceiver switch 36 and emitted in a direction known to the flight path of the aircraft or a carrier and at a certain angle with respect to the horizontal, so that it is directed to the area ι, that is to be recorded or monitored as a card.

The radar echo signals that come back from such reflecting points or targets that are illuminated by the directional antenna 14 are fed through the Sendc / receiving splitter 36 to the mixer 30 at a frequency which is the RF carrier frequency (a1) / ₀ and a Doppler frequency // contains. In the mixer 30, the output signal of the multiplier 22 with the frequency a / _{0 is} superimposed with the received signals of the frequency (a1) f ₀ + //, so that a signal with a frequency results which is a combination of the IF- -r « Represents the signal frequency and the Doppler frequency, namely / ₀ - / ,. The output signal of the mixer 30 with the frequency / - / can first be fed to an amplifier 38 before it reaches a mixer 40. The mixer 40 receives a second signal with a frequency which is formed from the frequency / and a shift frequency /. The component with the frequency / ₀ is supplied by the reference oscillator 20, while the component with the frequency / is supplied by a displacement oscillator 42. Both components are combined in the single sideband modulator 26. The bipolar video output signal of the mixer 40, which can have the frequency / + /, and the clock pulses of the synchronizer 28 form the output signals of the transceiver 16, which are fed to the recording device 18. As is known, the Doppler frequency / for a target that is broadside or in an azimuth orthogonal to the flight path is zero. In order to avoid this phenomenon, the oscillator 42 generates such a frequency shift that the Doppler signals to be processed do not pass through the value zero at target positions which are broadside or in an azimuth orthogonal to the path of the aircraft carrying the radar system. The shift frequency / can have any suitable predetermined value. When operating at a squint angle, ie with an antenna oriented at an angle θ to the normal of the flight path, the displacement oscillator 42 is monitored by a squint control system 41 which is responsive to the speed ν of the aircraft and the squint angle θ . In this way the member which is introduced by the squint angle is eliminated, so that the signal processing can take place in the same way as when the antenna is directed transversely to the path of the aircraft, as will be explained in detail later.

As can be seen from FIG. 2, the recording device 18 has a video amplifier 44 for the signals from the mixer 40 received bipolar video signals provided. The amplified video signal is then, for example, a βϊ Distance gate 46 and from it the intensity control grid of a cathode ray recording tube 50 fed with line-by-line scanning. A range gate generator 48 receives the synchronization pulses the form 29 from the synchronizer 28 of the radar device and opens the gate 46 as a function of these pulses

for a specified time during each pulse period, as illustrated by curve 45. This The finite time interval generally corresponds to the width of, for example, the strip of terrain that is being observed should be and can be defined by the radiation diagram of the antenna 14. In this way, the Video signals that are fed to the distance gate 46 via the video amplifier 44, only then to the in-

^{5, the} intensity control grid is fed to the cathode recording tube 50 when the removal gate 46 has been opened. All other video signals, for example those that correspond to targets in distances or positions, (^ e outside the observed strip of land, are rejected by the range gate 46 at the right time and at the right speed during each recording period

^{10 to} deflect, for example by a roof-shaped input signal 55, if it is triggered by the distance gate generator 48 at the right time. Both when the antenna 44 is oriented transversely to the direction of flight and in a direction deviating therefrom, the writing line of the cathode ray tube runs parallel to the arrow 61 in the direction of the distance. Voltage sources 54 and 56 are also provided in order to determine both the intensity and the position of the electron beam on the cathode ray recording tube 50.

'■' men as it is known in this art.

The recorder 18 may employ any suitable type of storage and scanning device in accordance with the invention, such as an arrangement derived from photographic film . Makes use as shown in Fig. Figure 2 shows or a sample storage tube as shown in Figure 2. S is shown. The recorder 18 of FIG. 2 contains a Fiimiransporivurrichiüng 60 with irr. Spaced angeord- ²⁰ Neten film coils 62 and 64. The coil 64 is coupled to a motor drive 68, by performing a film strip 66 on the cathode ray-storage tube 50, so that the bipolar radar video using a Linsensy-, stems 58 on the photosensitive film 66 can be converted into light images. For the motor drive 68

a control can be provided 69, the speed of the film 66 as a function of velocity ■: - ν ness controls of the aircraft or carrier, and for example, a pitot tube system or in any other way

■; '; ³⁵ responds measured or calculated speed. A speed signal can, for example, from

■ derived from a speed indicator not shown in more detail in order to influence the control circuit 69 and '" ^J. The motor drive 68, which can be designed, for example, as a servo motor

Antenna 14 is operated at a squint angle θ, the radar movement is taken into account

.. 'Control circuit 69 is supplied with a voltage which is characteristic of the value of the angle θ, and it is in

so the motor drive 68 a sign! is formed to give the film a rate of V / Cos θ as in the

will be described in detail below. Furthermore, a station 70 for film treatment can be pre-

:,. be seen to develop the film 66 immediately after its exposure, if from a continuous

Use is made of irrational operation.

ΐ As shown in Fig. 3, the stored and chemically developed Doppler data are

■ | "Record carrier, such as the film 66, read with the aid of a scanning device, the scanning lengths during

^. of each reading frame are programmed so that they increase, for example, as a function of the square root of the distance, as indicated by the abiasing lines 72 and 74 of the grid 65 at the corresponding distances R ₄

..-:> and R _{2 is} indicated, which shows the distances to the nearest and most distant edge of a

U can be monitored or mapped area. The data processing system 12 develops

?; ⁴ O holds a converter in the form of a light spot scanner 85 which has a scanning cathode ray tube 80,

f 'facing one side of the film 66 and a photomultiplier tube 90 facing the other side of the

J'i film 66 is disposed and preferably axially aligned with the scanning cathode ray tube 80. For one

ff Lenses 63 α and 63 b ensure good optical imaging. Voltage sources 81 and 81 α are also provided,

To control the beam intensity and cathode bias of the scanning cathode ray tube 80.

; i | · »■> The electron beam of the scanning cathode ray tube 80 tangles in the longitudinal direction of the filmstrip 66 through

Ö an azimuth deflection generator 82 taking into account the radar movement and an amplifier 87 with

j | changeable gain and transversely to the film strip 66 by a distance deflection generator 84 according to Art

} | of a grid deflected so that reading frames are formed as shown in FIG. 3 are indicated at 65. The Azi-1

[I mut deflection generator guides the beam in every distance position over the course of the Doppler frequency j

| j 50 while the range deflection generator 84 determines the range position of the Azi-1

S: mut-diversion lines changed. A read clock circuit 83 controls the timing relationship between the movement |

% supply of the radar device and the distance scans and can use conventional digital counters or coasters andl

e0 _t contain appropriate logic gates as are well known in the art. A square root genera- |

Gate 86 sets the center frequency of the signals indicating the Doppler curve by changing the frequency of a

■ | i ⁵ S displacement oscillator 88 as a function of the square root of the distance, so that a focusing oscillator with!

Έ a constant center frequency can be used. The square root generator 86 can be anyone

i |; Be a good analog function generator, such as a triode, to whose cathode a diode is coupled

|| is. The variable gain amplifier 87, which is the length of the azimuth scans as a function of the

i | Square root of the distance controls can be formed by any suitable circuit arrangement where-]

ΐ \ ^{b0, for} example, from a circuit arrangement with a conventional tube of type 6 AR 8 with deflection control-J

si tion, the azimuth deflection signals from the azimuth deflection generator to the deflection plates and from the

p square root generator 86 square root function signals are fed to a control grid. Dal

g azimuth deflection signal can be picked up at the anode of such a tube and has a course, des |

Its rise lies on both sides of a temporal middle position of the deflection intervals.

| j 65 The energy emanating from the scanning beam of the scanning cathode ray tube 80 and the film 66 in For

H penetrated by intensity modulated light is received by photomultiplier tube 90 and then ii

⁽ I converted an analog voltage that is characteristic of the Doppler curve, i.e. for the information di |

* £ on on film 66 during the scan time interval of the particular distance element scanned

have been saved. These scans are sequential for each of the removal elements repeats that form the scanning raster. When the film 66 moves in the direction of arrow 75 successive rasters or areas scanned in the same way.

The Doppler history or the stored Doppler signals, which are supplied from the photomultiplier tube 90 are then fed to a video amplifier 52 and further to a mixer 93 which also dps varying in ¹ frequency signal from the voltage controlled displacement oscillator 88 receives. The square root generator 86 is responsive to the range deflection generator 84 and azimuth deflection generator 82 to develop a voltage to control the frequency of the shift oscillator 88 and, for example, to decrease the frequency of that oscillator as a function of the square root of the distance. As a result, the frequency of the displacement oscillator 88 is constant during the scan at a certain distance, but decreases with each scan line corresponding to a greater distance. By varying the width of the reading frame in proportion to the square root of the distance, all signals indicating the Doppler curve have a constant rise, but the center frequency increases with each scan corresponding to an increasing distance. The displacement oscillator £% accordingly restores the frequency of the Doppler signals read out and compensates for the offset which is due to the change in the line length of the reading frame. This simplifies subsequent processing and maintains a low bandwidth. It is noted that use is made in another embodiment of the invention which is illustrated in Figure 4, of a grid of samples of constant length and the sampled Osziiiaiu ¹ is changed in its slope to maintain a constant increase of the signals of Doppierveriaufes for to create further processing.

It should be noted that when the side-facing antenna 14 is arranged as shown in FIGS. 1 and 2 under a forward or backward squint angle compared to an orthogonal angle to the flight path Reading frame 65 and variable gain amplifier 87 may be of the same type as in FIG a precise transverse arrangement of the antenna.

The signal formed by the Doppler curve with a constant center frequency is from the mixer 93 a Bandpass 100 which is responsive to the square root generator 86 and one with the root from the distance has increasing bandwidth. Because of the increased speed of the reading point at larger Distance, the synthetic diagram also occupies a wider range. The bandpass 100 transmits the signals in the spectrum range from the changes in the Doppler frequency and eliminates unwanted noise as well as unwanted reflected signals. The bandpass filter 100 can be of any conventional type and, for example, -Jo wisely make use of a variable capacitance in the form of a voltage-controlled capacitance diode. The signal transmitted by the filter 100 is fed to a focusing mixer 97, which is swept by a Oscillator 98 is controlled which changes its frequency during each line scan or distance interval changes. In the arrangement of FIG. 3, the swept oscillator is controlled by a voltage Oscillator formed, which is controlled by the output voltage of the azimuth deflection generator 82. The output signal of the mixer 97 contains the sum frequency from the Doppler signal for each spatial point and the Beiugsfrequer.z-Sigr.al that before. the wobbled. Oscillator 98 is formed. The Sürnrncnfrcqucnz takes over time during each reading line.

In the embodiment shown, the swept oscillator 88 and the swept oscillator, respectively Oscillator 98 formed sum frequencies used. It should be understood, however, that according to the invention also all other sum or difference frequencies generated in the mixers 93 and 97 in any combination can be used. If the difference frequency given by mixer 97 is used, the result is a reduction in the bandwidth, which in turn leads to a reduction in the required compression ratio of the subsequent compression filter.

The signals representing the Doppler curve, each of which has a different frequency shift due to the different time shift along the flight path, are fed via an amplifier 104 to a compression filter 106 or a delay line with frequency dispersion which has a linear or substantially linear frequency-time characteristic . The change in the signal which is formed by the swept oscillator 98 is adjusted so that the frequency-time characteristic of the Doppler sum or difference signal at the output of the mixer 97 corresponds essentially to the frequency-time characteristic of the filter 106. Since such targets 14 different positions or displacements along the flight path corresponding Doppler signals are sampled for reading purposes over different frequency segments, rather have the same rise or the same frequency-time characteristic as the filter, the linearly frequency-modulated pulses that are fed to the filter 106 and originate from certain targets or points in space, compressed to very short output pulses, the amplitudes of which are proportional to the v> integral over the input pulse. The amplitude of the output pulse depends on the reflectivity of the target point, for example the corresponding element of the earth's surface, and therefore enables an exact mapping of the area to be recorded. Furthermore, the amplitude of various parts of the signal indicating the Doppler course is dependent on the angle with respect to the antenna axis at which the reflected energy is incident.

The timing of the output pulse of the compression filter depends on the time shift of the reading signal with respect to the start of the reading deflection. The filter 106 is constructed so that, taking into account the delay inherent in the electrical path through amplifier 92, mixer 93, filter 100, mixer 97, and amplifier 104, it causes the targets to appear on the output line of the filter in a time sequence similar to theirs Corresponds to position along the flight path. Since the width of the reading frame is changed proportionally to the square root of the distance, the time shift of the signals at the output of the compression filter is time-dependent. This state is corrected by the display grid. All the signals indicating the Doppler curve at a certain distance are provided by the mixer 97.

switched bandpass filter 100 filtered so that they cover the same frequency ranges. The corresponding signals of the plurality of azimuth scans indicating the Doppler curve actually represent a single artificial beam in space, although the width of this artificial beam is dependent on the distance, as will be explained in detail later. The filter 106 forms various time-compressed pulses from the signals indicating the Doppler curve, so that a beam arrangement with an offset phase center is effectively formed, that is, each beam has a different transmission phase center 108 rectified. In order to eliminate additional reading results which go beyond the limits of the beam arrangement with an offset phase center, a time gate 110 , indicated by dashed lines in the drawing, can be provided between the envelope curve detector and the control grid of the display device. Masks, as indicated at 119 and 121, could also be used on the display areas instead of the time gate 110 . If a time gate is used, a gate controller 105 may be responsive to the azimuth and range deflection signals which have been delayed by respective delay lines 101 and 103 to form gate pulses. The delays are needed to compensate for the delay caused by the compression filter 106 and the time shift of the pulses during each azimuth scan due to the pulse integration and compression.

During each reading scan or, because of the delay caused by the compression filter 106, a certain period of time thereafter, the rectified signals from the envelope detector 108 or gate 110 are fed to the control grid of a cathode ray tube 112 for continuous display.The rectified signals can also be fed to the control grid, a light point scanning tube 114 to form a card. At the same time, the electron beam of the tube or tubes is deflected horizontally, as indicated by an arrow 115, so that its position corresponds exactly to the azimuth position of the artificial beam. The variable width deflection signal used for the reading frame is used by the variable gain amplifier 87 via a delay line 118 to control the azimuth deflection of the beams corresponding to the radar movement. In the distance coordinate, the electron beams used for illustration are deflected by the distance deflection signal which is fed from the distance deflection generator 84 via a delay line 107 to the distance deflection plates of the tubes 112 and 114. Furthermore, an energy source 118 a is provided for generating the cathode voltage for the cathode ray tube 12 used for display. The light point scanning tube 114 is also controlled by means of a cathode voltage source, not shown, and a card is formed on a film 120 , which is shown by means of the control 69 of FIG. 2 is moved past the tube 114 at a speed proportional to the speed of the aircraft while the grids 117 are being formed. The film 120 can be developed either continuously or at a later time. Furthermore, with the device according to the invention it is possible to send the rectified signals as well as the azimuth and distance signals with the aid of suitable coding devices, for example to distant stations.

The square root of grids that are a function of distance, such as grids 113

and 117, is formed on tube 112 and film 120 so that the resolution elements are equidistant from each other in azimuth at all distances in the illustration. As explained above, the masks 119 and 121 can be used instead of the time gate 110 to ensure that regardless of the distance

If an equal number of reflective points is recorded in each azimuth line.

In another, in Fi g. 4-4, the data processing apparatus includes a variable rate swept oscillator which is used in conjunction with a constant speed or linear reading frame, ie a grid of rectangular or square shape, in accordance with the teachings of the invention. The reading frame 124 has with all decision-distances S ⁴ as in the distances A ₄ and A ₂ - Same scan lengths, such as are illustrated by lines 126 and 128th The azimuth deflection generator 82, which simulates the radar movement, supplies the tube 80 with increasing signals of equal inclination so that each beam deflection occurs at the same speed as it passes over the film 66. The range deflection generator 84 supplies signals to the tube 80, which are controlled by the clock 83 so that they are in a certain time relationship with the azimuth deflections, which in turn are a function of the speed of the aircraft and the pulse repetition rate of the radar device which may be constants in some systems according to the invention. The signals indicating the Doppler curve, which are sampled by the photomultiplier tube 90, are fed via a video amplifier 92 and through a bandpass filter 130 to a time gate 131 , shown in dashed lines, which can be used to eliminate undesired areas at shorter distances. The times during which signals from timing gate 131 are allowed to pass may decrease in duration as a function of distance as a function of range deflection generator 84 at successive intervals controlled by azimuth deflection generator 82. Instead of the time gate 131 , a trapezoidal mask 127 can be used in front of the film 66. The signal is fed from the timing gate 131 or from the bandpass filter 130 to a focusing mixer 132 which is controlled by a focusing deflection oscillator 134. A m> variable gain amplifier 136 is responsive to the azimuth deflection amplifier 82, the deflection signals of which are varied in inclination as a function of the range input by the ascending signal from the range-deflection generator. As indicated by curve 138 , the frequency change per unit time of the variable frequency signal which is formed by deflection oscillator 134 increases with distance, so that the signals reproducing the Doppler curve at the output of mixer 132 have a constant increase. The signals at the input and output of the mixer 132 which indicate the Doppler curve and which originate from points at different points on the flight path are arranged in time on each reading line of the sampling period.

The variable gain amplifier 136 can be formed from any conventional circuit, such as

with respect to the variable amplifier 87 of FIG. 3. It should be noted that in the arrangement of FIG. 3 making use of a linear reading frame. 4 the center frequencies of all the signals reproducing the Doppler curve at the input of the mixer 132 are essentially the same. An amplifier 104 feeds the signals with changing frequency to the compression filter or the frequency-dispersing delay line 106 . The compressed pulses are the envelope detector 108 and a time gate 110 by the α Steuergitier the display tube 112 or the write tube 114 supplied a recording apparatus, as is also the case in the embodiment of FIG. 3. The tubes 112 and 114 are controlled by a delayed deflection signal from the range deflection generator 84 and a delayed azimuth deflection signal. The azimuth deflection signal corresponding to the radar movement is supplied from the azimuth deflection generator 82 through a variable gain amplifier 87 and a delay line 118 to the Ό tubes 112 and 114 are supplied. The variable amplifier 87 is controlled by the range deflection signal to change the azimuth deflection signal as it rises, so that display rasters 152 and 155 having a trapezoidal shape are formed. The delay line 118 compensates for the delay in the compression filter 106 , while the delay line 107 delays the range deflection signal so much that they fall within the time range at which the pulses of the raster are fed to the control grids of the tubes 112 and 114. In this way, the lengths of the horizontal lines that correspond to the azimuth or the direction of movement of the radar, such as lines 150 and 152, change as a function of distance, so that the resolution elements or point reflectors at all distances in azimuth at the same distance being represented. Since the temporal separation at the output of the filter 106 between point reflectors of equal distance changes inversely with the distance, the speed of the azimuth deflection is changed in direct proportion to the distance in order to create an equal distance between such reflectors on the display surface. Therefore, a time gate for eliminating echoes from other areas can be used α 110, which is coupled to a gate signal generator 141st This generator is in turn controlled by the deflection signals which are added by the azimuth deflection generator 82 and the range deflection generator 84 via respective delay lines 101 and 103 . The width of the gate pulse changes inversely with the distance. Instead of a time gate 110 α , corresponding masks 151 and 153 could be provided on the surface of the tube 112 and in front of the film 120, that is to say between the tube 114 and the film.

In operation, the signals indicating the raw data of the Doppler curve, one of which is represented by curve 154 , are fed to mixer 132 together with the swept oscillator signal illustrated by curve 156 to produce a signal! to be formed according to curve 158 with variable frequency. Compression filter 106, formed by a frequency dispersion delay line, is responsive to the variable frequency signals of curve 158 , each signal on each azimuth read line having a different center frequency, and forms integrated and compressed pulses as indicated by the Curve 160 can be shown. Each pulse of curve 160 is characteristic of a Doppler frequency and a point element of the area to be imaged. During each scan of an azimuth line, film 66 reads a number of similar signals which, like curve 158, represent a single point element. The rectified signals from envelope detector 108 , illustrated by curve 162 , are then fed to the control grid of tubes 112 and 114 , the beam of which is deflected in the direction of the range and azimuth coordinates such that its position corresponds to azimuth and the distance of the point element to be displayed corresponds to -to

5 and 6 show an arrangement for storing the raw data which makes use of a storage tube 170 rather than a film as used in the embodiments of FIGS. 2,3 and 4 is used. It will be understood that the invention, making use of either / λ scanning or linear scanning, is not limited to the use of any particular storage device or display device, but rather encompasses the use of any suitable arrangement. The tube 170 may be a conventional type of storage tube, such as a CK 7702 tube, which is well known and commercially available. The coherent, shifted video signals are fed from range gate 46 (FIG. 2) via delay line 180 as well as directly to summer 182 so that storage tube 170 stores two redundant sets of raw data. Delay line 180 delays the data a little more than the range gate pass interval. The signal is then fed to a gamma correction circuit 184 , as is known in the art, and then through a bias selector circuit to a grating of the tube 170 controlling the intensity of the write beam. The bias selector 186 is responsive to write and erase clock pulses provided by a timing circuit 183 can be derived. Depending on the radar synchronization pulses, this time control circuit generates write and read clock pulses as well as synchronization pulses for the entire system. As is known in this technique 55 | the timing circuit 183 may include a clock, a plurality of counters connected in series, and the required logic gates. Dynamic focusing for the write beam is achieved by means of “ a focusing coil 190 which responds to a dynamic write focusing circuit 185 which in turn | receives horizontal and vertical write deflection signals. To write or store the information on a memory screen 187 , a vertical deflection generator 191 responds to synchronizing pulses for vertical writing provided by the timing circuit 183 and applies vertical deflection signals to a vertical deflection coil around the vertical or range lines to form each grid. In the embodiment shown, the azimuth deflection signal for horizontal writing in the DC voltage level decreases in such a way that half the width of the tube screen is covered, and changes in level so that the left and right halves of the screen are written alternately and both t> alternately s Pages of the reading frame at a distance corresponding to a certain number of vertical lines. A pulse generator 189 responds to synchronizing pulses for horizontal writing, which are also supplied by the timing control circuit 183 , and supplies pulses of alternating polarity to a summing;]

circuit 195 which determine the alternating positions on the left and right halves of the storage area of the tube. A DC voltage generator 196 for horizontal writing supplies the summing circuit 195 with a decreasing DC voltage with a selected offset of five lines for erasing. In order to maintain a constant equivalent ground clearance, which is recorded in the dimension of the radar movement, the speed of each recording is controlled over the entire width of the tube as a function of the aircraft speed ν with the aid of a voltage generator 197 which generates _{a voltage E 1}

An integrator 198, which contains a resistor 205 which is coupled to the summing circuit 195 via a Ve amplifier 200, and a capacitor 201 and a switch-off circuit 203, which are both connected in parallel to the amplifier 200, responds to the voltage E _1. A jump pulse is fed to the input of the amplifier 2W »from the timing control circuit 183, which changes the charge of the capacitor 201 during erasing and writing Voltage E ₃ to close the gate in the shutdown circuit 203 and discharge the capacitor zn. When the voltage on the output line is of the amplifier 200 drops to a certain value, the Multiar ignites and feeds the shutdown circuit 203 a short pulse. At the same time, the multiar is reset, as is known in the art. In this way, the deflection signal for horizontal writing is fed to the horizontal deflection yoke of the tube 170. It is further provided 196 similar circuit 196 a is a circuit which includes a retrace erase pulse Generates 199 α to supply to the summer 195 during selected erase times signals and to control the erase band to thereby when a new recording on the surface of the tube 170 is started. An integrator 198 similar integrator 214 α is responsive to the voltage Ej to a Multiar 204 to control α and to determine the time at which α from the generator 199, a pulse which is terminated by the Multiar 204 is triggered. The multiar circuit 204 α also responds to a specific voltage E ₄ , which determines its ignition level.

A changeover switch 199 for the voltage of the storage screen changes the potential on the storage screen 187 depending on the corresponding write and erase pulses supplied by the timing control circuit 183, for example between +300 and +20 volts. The power supply units 192 and 194 control the various grids of the tube , while the power supply units 204 'and 204 Ό supply the correct potentials to the cathodes of the tube. A bias circuit 206 maintains a certain potential at the control grid of the reading portion of the tube 170.

Reading is done on the opposite end of tube 170 at the same time as saving.

taken, in a certain time relationship and a certain scanning position on the Storage screen as determined by timing circuit 183. A dynamic focus at Reading is achieved with a focus coil 207 connected to a dynamic read focus circuit 209 is.

A vertical read deflection generator 208 is responsive to timing circuit synchronization pulses 183 that determine the lower and upper bounds of each reading frame. A deflection generator speaks accordingly 210 for horizontal reading on synchronization pulses of the timing circuit * 83 to the summing circuit 211 to apply horizontal deflection pulses. When working with a - //? - reading frame according to FIG. 3 a square root circuit 212 is responsive to the vertical deflection voltages to increase the length of the horizontal deflection signals as a function of the square root of the distance. A DC voltage generator 213 for horizontal reading forms a DC voltage signal which decreases during its duration, see above that each of the plurality of reading frames is formed in the direction from the left to the right side of the tube face will. This signal is fed to the summing circuit 211. An integrator 214, the integrators 198 and 214 ο is the same, receives the voltage Ei, which is proportional to the aircraft speed, from the voltage generator 197, while a shutdown circuit 217, which forms part of the integrator 214, of the multiar 204 one Receives switch-off pulse. A multiar is commonly known as an amplitude comparison circuit, the two Amplifier contains and serves to generate a pulse when the output signals of the two amplifiers assume the same amplitude. A summer 215 responds to the voltage generated by the integrator 214 and a DC voltage which is half the voltage for offsetting the erase line and from a corresponding bias circuit can be formed in the timing control circuit 183. Hence the DC voltage generated by generator 213 reset by multiar 204 after the reading frame of the left side has been transferred to the right side of the tube surface.

7 shows an aircraft 222 moving along a flight path 224 and thereby emitting energy pulses by means of an antenna 14 which points downward at a certain angle relative to the horizontal so that the ground or the earth's surface is irradiated in an area , which contains the strip to be recorded, defined by the distance gate (FIG. 2). The aircraft 222 is calculated from a starting point in which it is at the time / = 0, at every instant at the point vr if ν die Speed of the aircraft is. For purposes of illustration, the aircraft will be assumed to be in a straight flight path, although motion compensation systems may be used to compensate for changes in flight path in accordance with the invention. The pulse repetition frequency is that the true lobes 230,232,234 itself etc. overlap such that of point targets or energy reflective ground targets such as T _1, T is _chosen,:, Ty, T _t, T t and T ₆ reflected energy is received repeated. The distance between the point reflectors or ground targets, such as between 7] and T ₂ and between Ti and Tj at distance b5 R ₂ , as well as between neighboring point targets at all other distances, is determined by the resolution distance D / 2 of the system, where D is the 3rd -dB width of the synthetic beam formed by the system according to the invention for the determined distance. It should be noted that the resolution distance chosen is the same for all distances, so that the width of the synthetic beam for larger ones

Distances must be made smaller. There are synthetic radiation lobes 231,233,235,23 '/ and 239 so represented as if they were parallel to one another in the corresponding real radiation lobes, such as the radiation lobes 230, 232 and 234, and there are these synthetic radiation lobes in the invention System formed simultaneously in parallel with each other by scanning during an azimuth much more than the width of a synthetic radiation lobe is scanned. It should be noted that the synthetic Radiation lobes 231,233,235,237 and 239 are not really radiated like the real radiation lobes, denoted by the reference numbers 230, 232 and 234 siad. Since in the system shown during three signals indicating the Doppler curve are read out for each azimuth scan, become three Beams such as 233, 235 and 237, essentially simultaneously for the duration of a readout frame educated. During the duration of each of the successive reading frames are continued along the Flugwsg formed three adjacent radiation lobes, so that effectively new groups of parallel lobes along the Flight path are formed.

For the purpose of explanation it is assumed that the targets T ₄ and T ₁ at the time t = 0, at which the aircraft assumes the position vi = 0, lie in the vertical center plane of the true radiation lobe 232. The distances A ₄ and R ₁ should essentially lie at the furthest and closest edge of the strip 226 to be recorded. A stored or true Doppler signal, as opposed to a shifted Doppler signal, is illustrated by curve 240, which represents the Doppler curve signal for the individual point drawing! T ₁ represents formed during a single range scan after storage and during scanning of the film. As the aircraft 222 moves along the flight path 224, a certain echo element such as T ₁ approaches the vertical line on the velocity vector, so that the speed decreases its phase rotation or its Doppler shift and becomes perpendicular which is the shortest path to this point represents zero. This changing speed of phase rotation or Doppler shift of a specific reflected signal is the course or history of the Doppler frequency of the corresponding point. Therefore, the Doppler curve or history of an echo element, assuming that no correction has been made by a frequency shift, is approximately a linear chirp or FM signal that begins with an initial Doppler component of several hundred Hertz, the frequency of which decreases to zero and then rises again after the said vertical has been exceeded. It is these unprocessed or raw data, which is illustrated by curve 240, and both the phase and also include the amplitude variation or the Doppler history of each echo point and for the following signal processing, as discussed above, is stored by means of the χ circuit arrangement of FIG. 2 will. The transmission positions or times are repeated as in positions 242 and 244. It should be noted that a plurality of transmission points with corresponding true radiation lobes can lie between the time positions 242 and 244, but these transmission positions have been omitted to simplify the illustration. From each transmission pulse echo signals are received from all distances of the irradiated azimuth range, as indicated by the vectors 246 and 248 for the corresponding target points Τ _λ and T ₁ . The entire true antenna pattern is illustrated by curve 252, which varies along the flight path during which target T _{1 is} irradiated.

In order to facilitate the subsequent processing of the stored raw data is (g F i. 2) in the coherent reference frequency d ^ s transmitter with the aid of oscillator 42 introduced a displacement frequency, prior to the storage takes place with for all echo signals, a phase detection. The frequency shift can generally be of the order of a few hundred Hertz so that the recorded echo signals do not assume frequency zero in a region in which the true antenna pattern has a considerable relative gain, which can be determined by acceptable levels of the folded power spectrum. Curve 256 illustrates the offset Doppler signal for target T ₁ as fed to the film od-γ of the storage tube. Curves 258 and 260 show the accumulated and offset Doppler curve for points 7] and 7 * ₃ , which are later or earlier than the Doppler curve according to curve 256 along the flight path. It should be noted that a large number of signals indicating the Doppler curve as represented by curves 256, 258 and 260 can be read during each scan of an azimuth line at each range interval.

For example, in order to store the raw data on film 262, the bipolar coherent video signal from mixer 40 (FIG. 2) is used to modulate the intensity of light beam scanning tube 50. The bias of the tube is set so that in the absence of a signal a medium film exposure is achieved in order to be able to evaluate pulses with positive and negative polarity. The light traces 266 indicating the Doppler course, which after film development represent the signals 256 indicating the Doppler course, can only store the envelope curve of the signal due to the resolution properties of the film or a storage tube. Generally known as the envelope curve of a signal is the curve which is drawn through the peak values of a diagram which reproduces the course of a modulated RF carrier signal. Further stored Doppler profiles, as is indicated by curves 258 and 260 for the targets 7] and 7 _{"3 o} are flat, are superimposed on the film 262 in the removal position A _2, so that they beispielswetee a grid can be read during scanning. The reading takes place simultaneously for certain parts of the courses, which depend on their temporal extent, the width of the reading frame and the position of the reading frame on the film. The film 262 moves from a zero position, which it assumes at the time r = 0, by a distance X = v, t, where v _{f is} the film speed The film is moving in a direction opposite to the aircraft because the position of the grid formed is stationary.

To further explain the system, the envelopes of the bipolar video pulse trains for the b5 point reflectors T ₂ , T _t and T ₁ as received by the true antenna can be expressed by the following equations:

= A ₁ cos 2 η

if, ι - - ^ r) ,

( V ² t ^Z \

= A * cas2 π If, t - ■? -! -),

\ "4 Λ J

e _t (t) = .4, cos 2 η

U ₁ -.

Λ, A

where / l is the amplitude, which is a function of the reflectivity of the point reflector, D is an azimuth resolution factor (zero to zero), / is the frequency of displacement, t is the point in time on the flight path and λ is the wavelength of the emitted energy. It should be noted that the expression v ² 1 ¹ JR ₇ λ is the linear frequency change as a function of time or the rise of the signals indicating the Doppler curve, which is a function of the distance.

As in F i e. 8, the instantaneous frequencies / are used by the radar for the point targets at distances R ₂ and /? ₄ made in real time. The lines 270, 27z and 274 represent the signals of the Deppler course which are received by the point reflectors 7}, 7} and 7], which have the spacing of the resolving power in azimuth. For the smaller distance A ₄ , curves 276, 278 and 280 represent the instantaneous frequencies of the signals received by the corresponding reflectors T ₆ , 7i and T ₅ , which also have the resolution distance. Since the aircraft has to fly a shorter distance for targets at shorter distances in order to receive a complete Doppler curve, the increase in frequency in relation to the time of the Doppler curve signal is significantly greater here than for targets at a greater distance. The entire frequency swing of interest of the Doppler curve signal is 2 v / D for all distances. The time duration of signals such as 276 and 272 closer and further away are LJv and L ₂ / v, where L is the length of the artificial system, namely L ₄ " A ₄ XJD and L ₂ = A ₂ XJD. Therefore, the time duration is each The system length or the duration of the Doppler course is directly proportional to the distance of the corresponding point reflector. The time interval between the Doppler courses of neighboring point reflectors is D / 2 v at all distances. The frequency differences between neighboring signals at the two distances A ₄ and R ₂ are vDIRi A and vD, respectively //? ₂ / and are therefore inversely proportional to the distance.

The following expressions represent the instantaneous frequencies / i received by the true antenna from point reflectors 7 " ₂ , T ₄ and 7", where f _t through

is pictured:

The envelope functions e '(X), as they are recorded on the storage film 262, are now intended to be based on FIG. 9 and 7 will be explained. The function e '(X) can be viewed as standing perpendicular to the surface of the film.

In these equations, A is proportional to the amplitude of the signal received by the true antenna. The instantaneous (spatial) frequency f _s is recorded on the storage film 262 with respect to a point X away from the O reference point. The frequency f _iS , which as

id y ι

· -— [arc cos Φ (X)]

In dx

can be expressed for the point reflectors 7 " ₃ , T ₄ and 7] as follows:

JiS 2 ^v r R ₂ X \ r (- f, S 4 = L. 2 v ² ; / s, = ^v r R ₄ Xs /, 2 v ² R ₂ X

(JL. -JL) _L.

The curves 283.286 and 288 represent the Doppler history signals for the point reflectors F _3, T ₂ and 7 ", represent the ^'5 to A are centrally and extending over a distance of ^ -L ·., And a distance of the instantaneous

V ₁ ν

Frequency of

vD 1

to have. Curves 290, 292 and 294 represent the Doppler history signals for point reflectors T ₆ , T ₄ and T ₅ extending on the film a distance of v _f L _A / v and a distance of the instantaneous frequency of v £ > / Ä ₄ A Vf have. Accordingly, the spatial length of the Doppler waveform signals on the film is a function of the system length L, which in turn is proportional to the distance, namely equal to R XID .

The processes involved in reading the information in the recording film 262 is further explained with reference to Fig. 10 in detail, in relation to a grid 298, which is centered in a neutral position on the film and wherein the distance v along the film by X = / is shown, where v is the speed of the reading beam of the Lieh point scanner. The rasters 298 and 300 are continuously repeated and overlap sufficiently along the length of the film that all of the Doppler waveform signals are read once or portions thereof are read several times. In one embodiment of the invention, the duration of the reading frame is chosen so that the film moves the width of the frame and the next frame begins at the end of the data read out during the previous frame so that all data is read only once. The length of the reading lines is greater than the length of a stored Doppler curve in order that a certain number of Doppler curve signals, such as three groups or Doppler curve signals in the illustrated arrangement, can be read. The length of the reading lines such as 302 and 304 are programmed according to the square root of the vertical reading (deflection in the distance coordinate) so that, for example, at half the distance, the width of the reading frame is 0.707 times the width at the maximum distance. For a half-distance group, the data is recorded in half the time of the maximum distance and its inclination is twice that of the maximum distance. By reducing the reading frame width according to the square root of the distance from the maximum to the minimum distance, the speed v, of the reading line is reduced in the ratio of one in the maximum distance to 0.707 at half the distance. However, since at half the distance the group only occupies the 0.707th part of the reduced grid width, i.e. only half the length of the maximum distance, the read ratio of the frequency change to time for each Doppler curve signal is the same for all distances. In this way, a greater number of groups are read out at the maximum distance than at the minimum distance, but in the system according to the invention they are masked out by gate circuits or masks so that the final display has the same intensity characteristics at all distances. The increase in the length of the reading line with increasing distance, which is due to an increased speed of the reading point, also sets all Doppler frequencies, including the center frequency, high by a constant amount. Curves 306 and 308 show the extent of reading frame 298 when controlled as a function of k VR , while lines 310 and 312 indicate the locations of constant Doppler frequency or iso-Doppler points of the data recorded on the film. The additional elements and sub-elements that are read off because the line excursion is greater than is required for the selected number of groups are eliminated in the system according to the invention by means of time gates.

The functions of the envelope curves, which are formed by reading out the point reflectors T ₂ , 7 " ₄ and 7", can be described by the following equations:

-A ₁ COS2, (/, - £, -

L \ v / Iv)

■ v _f K ₄ AV ₇ /

In these equations, v _{r is} the speed of the reading point. - and R is the slant distance to the corresponding point target.

The instantaneous frequencies of the Doppler waveform signals read from the film can be can be described as follows, where

/, · Η = -τ— -τ- [arc cos Φ (/)]:
2π at

ν 2 ² V ⁷

C02 -Jr - —ΪΓΊΤ ''
Vf R} X Vf

ν 2 ² V ²

f - γ ^v r * -ν * rt

.//04 -Jr- '.

^{fm L} VfX A ₂ Av / 2 J Vf- If ν, is replaced by kifR , the result is

Xv} kVR * Hk ² Vf Xv / kVR ₂ 2] k ²

Jim ~ Jr ; ~ —— - ι,

// 04 ⁼ fr

/ (0I = /,
JO

As mentioned above, the true antenna 14 can also form a squint angle θ with the direction transverse to the flight path 299 of the flight path, as FIG. 11 shows. The squint angle θ can be constant or variable when using the invention. The instantaneous center plane 303 of the radiation lobe 301 of the true antenna falls on the point targets T _A and 7 " ₂ , which are at the distances Λ ₄ and A _2. The point targets T _x , T _iy, T ₃ and T _b are at a distance D / 2 perpendicular to the center plane 303 of the radiation lobe. The distance parallel to the flight path 299 between adjacent point reflectors, which is the selected azimuth resolution, is D / 2 cos Θ. The envelope curve e (t) of the bipolar video pulse train for the reflectors T ₂ , 7 ₄ and Γι provided by the radar system is expressed by the following equations:

ejii) = A ₂ cos 2 π (f, t + ^ j- sin θ - -jj-y cos ² θ),
e ₄ (f) = A ₄ cos2 / r (f _r t + ^ - sin θ - - = r ^ r cos ² ©),

\ / / CjA /

v ² t - cos ² θ
_sine - 2VCOS0

R ₇ X

It should be noted that the expression v ² 1 ² ZR ₇ λ, which indicates the linear frequency change in each Doppler curve, ^{is multiplied by the factor cos 2} θ , so that the speed of the frequency change decreases with increasing squint angle. The time interval between the Doppler curves of neighboring point reflectors is D / 2 ν cos Θ for all distances.
The instantaneous frequencies of the signals generated by the radar system can be determined by

fi = ^ —— [arc cos Φ (O]
2π at

given in the above equations:

/ _f 2 - /, + - ^ - sin «- ^ f cos ² 0,

λ K

Ι, * ⁼ ί, ^{Λ s} ' ⁿ Θ Jr-J- ^cos2 0-

The expression (2 ν / λ) sin θ represents the additional mean frequency shift introduced by the cross-eyed antenna. The linear frequency variations change as a function of cos ² θ for point reflectors that are along the line of sight of the antenna. The instantaneous frequency difference between adjacent resolution elements is a function of DIl ν cos θ for reflectors that are not on the line of sight at the particular instant under consideration.

With reference to FIG. 8, the bandwidth of the Doppler curve results from the presence of a squint angle iu 2 ν cos Θ / D and it is the duration of the groups in the distances R ₄ and A ₂ corresponding to LJv cos 0 and L ₂ Iv cos 0. The The time interval between the group centers is D / 2 ν cos 0 and the frequency spacing in the distances A ₄ and R ₂ corresponds to vD cos 0 / A ₄ λ and vD cos θ / Λ ₂ Ä The center frequency is /, +2 ν sin 0/1

In the system according to the invention, a squint control is used to eliminate the effect of 2 ν sin θ / λ by correcting the shift frequency in the radar system and changing the film speed v _f so that the subsequent processing can be carried out in the same way as in an operation with antennas directed exactly to the side according to FIGS. 3 and 4. As in FIG. As shown in FIG. 2, the aircraft speed ν and the squint angle 0 are fed to the control circuit 69 to take account of the radar movement, so that the film speed assumes the value v} = v / cos ©. The squint control 41 also responds to the aircraft speed ν and the squint angle θ and also to the wavelength Aan, which can be a constant to eliminate the additional Doppler frequency 2ν sin θ / λ caused by the squinting antenna. Thus, the displacement oscillator 42 forms a signal having a frequency

- /, cos θ + 2 ν sin θ'λ.

The single sideband modulator 26 forms a signal having a frequency

/ 0 + 2 ν sin θ / λ - /. cos θ ,

which is fed to the mixer 40 as a corrected shift frequency. The signal formed by the mixer 30 has the frequency

/> + 2v sin θ / λ - 2v ² t cos ² ΘIRλ.

The mixer 40 responds to the signal received by the antenna at an angle of 0, and the signal with the compensated shift frequency and forms a mixed frequency -to

/ 0 cos Θ + 2 v ² / cos ² θ / λ ,

which represents a signal that is the same as the signal that is shown in FIG. 9 explained broadside system is recorded on the film. It should be noted that both the square root scanning " System according to FIG. 3 or the linear scanning system according to FIG. 4 with a specific or changeable Schielwinkel is able to work.

Before the data processing is dealt with further, should be based on the F i g. 12 and 13 in connection with the Fi g. 2 and 3 the timing relationships of the transfer and read operations are explained. The radar synchronization pulse 29 triggers a square pulse 33, which is formed in the pulse shaper 32 and, as a gate pulse, controls the transmission of the carrier pulse 35 to the antenna 14 so that it is transmitted into the room with the frequency (a1) / o. After the reflected energy has been received by the antenna 14, a signal is formed which has the frequency / ₀ - / at the output of the IF amplifier 38 and is represented by the curve 43. The distance-determining time interval, which limits the strip to be recorded, is defined by a distance gate pulse of the form 45 and the horizontal deflection signal of the form 55 which covers all distances is fed to the recording cathode ray tube 50. It should be noted that in the device according to FIGS. 2, 3 and 4 the azimuth dimension is controlled by moving the film 66 as a function of the speed of the radar device or its carrier.

In FIG. 13, the time relationship between the deflection signals at the output of the amplifier 87 can be varied Gain (Fig. 3) and range deflection generator 84 during each reading frame through the & o Curves 320 and 322 shown. Curves 324 and 326 show the azimuth and range blanking pulses, which can be fed to the control grid of the reading cathode ray tube to monitor its electron beam during to suppress its return. It should be noted that in the system of FIG. 3 the azimuth deflection signals according to curve 320 for controlling the reading deflection in each distance range with a constant Position at half time have an increasing slope, so that the point is with increasing distance ω moves with increasing speed as a function of the square root of the distance. In the system 4, on the other hand, the reading azimuth deflection maintains a constant increase. In FIG. 14, the instantaneous frequencies read from film 66 are indicated by lines 330.

332 and 334 for the corresponding point reflectors T ₆ , T ₄ and 7} at distance A ₄ and represented by lines 336, 338 and 340 for point reflectors 7}, T ₂ and 7Ί at distance R _2. Lines 342 and 344 at the distance R ₁ are subgroups which can be masked out in the display by a time gate 110 or by the masks 119 or 121. It will be understood that an increased number of complete groups, which are not shown, can be read with an increased distance of a strip to be recorded, each group of which is processed with the aid of the compression filter 106. Because of the reading function, which is proportional to VR , the time interval between neighboring resolution elements is significantly smaller at the maximum distance than at the Mirumal distance. In order to obtain a constant brightness of the display, all additional groups are eliminated either from the time gate 110 or the masks 119 or 121. ίο At distance A ₄ the duration of each group time is V ₁ L ₄ Iv k V ^ T and it is the common center frequency./; kVRpv _f . At a greater distance R ₁ is the length of time of each group, such as group 336, v, L ₇ Zv k ν R2 and the center frequency is / ,, k VRTIv ^ Da L ₄ = A ₄ XID and L ₂ = A ₂ XID, the duration of the groups in the distances R ₄ and R _{2 can} also be expressed by v _f VA ₄ XIv D Ar and V ₁ VR ₂ XIv D k . The time interval between adjacent groups such as 336 and 332 at distance R ₄ is v _f DI2 ν Jt VR ~ T is and between adjacent groups, such as groups 336 and 338, at distance R ₂ is v _f D / 2 ν k VH * Dtr total frequency deviation at each distance is 2 ν kVRID V / and increases with the square root of the distance. The increases / _o of groups such as 330 and 336 can be given for all distances with / _e = 2 v ² Ic ¹ IX v / because the distance parameter has been eliminated by changing the duration of the deflection as a function of VR. Therefore, reliable processing can take place at all distances and the oscillator 98 thus ge.wobbeite can operate with a constant ratio of the frequency change to time for each of the many azimuth reading periods.

As a result of the change in the inclination of the reading azimuth deflection according to curve 320 and the resulting increase in the speed of the scanning point proportional to VR, the center frequency of the groups also increases in proportion to the square root of the distance.

The displacement oscillator 88 has a frequency which is a function of - / R and decreases with increasing distance for each azimuth read line of each raster, as shown by curves 346 and 348. By using the sum (or difference) output signal of mixer 93, the groups that have been completely read out at all distances are _{shifted to a common center frequency / w} , as indicated by lines 350, 352 and 354 for distance R ₄ and lines 358, 360 and 362 for the distance R ₂ jo is displayed. These groups are then fed to mixer 97. Although the sum frequency at the output of the shift mixer 93 is used in the illustrated arrangement, the difference frequency can be used instead. As will be explained in the following, when the differential mixing product of the mixer 97 is used, the bandwidth of the Doppler curve signal is reduced.

As in Fig. As shown in FIG. 15, swept oscillator 98 provides increasing, constant slope signals for the duration of each read line, as illustrated by curves 370 and 372 for the respective distances R ₄ and A _2. The swept oscillator has a linear frequency swing over the entire duration of each reading line with a slope which is set such that the output signal of the mixer has a change in frequency over time which corresponds to the change in frequency of the compression filter 106. Although the sum signal is fed to the output of the mixer in the system shown, the difference signal resulting from the superposition can also be used according to the invention. Regardless of the position of the target or point reflector along the flight path, the same magnitudes of the Doppler frequency deviation for each point reflector at a certain distance are processed at the output of the mixer 97. Due to the action of the swept oscillator 98, a different Doppler time shift results in a different frequency shift at the output of the mixer 97, which is only converted into a time shift of the main maximum of the envelope curve at the output of the compression filter. For distance A ₄ , the sum signals on the output line of mixer 97 are signals 378, 380 and 382. The sum signals formed by mixer 97 for distance A ₂ are signals 384, 386, 388, 390 and 392. With increasing azimuth the group signals have an increasing center frequency. The signals of curve 398 represent the compressed pulses which are formed by the frequency-dispersed delay line 106 from the data read out during two previous sweeps and which have a certain delay by a portion of the sweep time, as shown in FIG 16 will be explained. The pulses read out according to curve 398 are formed in the system according to FIG. 3 at the correct time with respect to a deflection signal of the form 401 for the display. The azimuth deflection signal has an increasing slope with increasing distance. The envelope signals according to curve 400 are generated by the detector 108 and are used to control the grids of the display tubes.

The function of the compression filter 106, which is formed by a delay line having a frequency dispersion, will now be explained in more detail with reference to FIG. To simplify the explanation, the time is either from the start of the azimuth deflection for the distance R ₄ or from the start of the azimuth deflection for the distance /? ₂ applied. Although each read line is shown to have a duration of 40 ^ s and S us are provided for beam return, the invention is not limited to any particular read times or processing times. Read deflection signals 466 and 404, which form the reading frame as a function of the square root of the distance, are shown for distances R ₄ and R ₂ and both slope for distances greater than R ₄ and R ₂ , respectively , to. Lines 418,420 and 422 represent the groups at the output of mixer 97 for distance R ₄ and lines 408,410,412,414 and 416 di <b5 represent groups for distance A _2. Line 426 shows the frequency swing as a function of time of the swept oscillator 98 during the scanning of an azimuth line for the formation of sum signals according to the lines 428, 430 and 432 for the distance A ₄ and the lines 436, 438, 440, 442 and 444 for the distance R ₁ . A line 448 represents the characteristic of the delay line serving as a compression filter, which is

Delay time is a linear function of frequency. The slope of the characteristic is inverse to that Frequency change of the output signals of the mixer caused by the selected inclination of the frequency deviation of the swept oscillator 98 is It is desirable to have the output pulses over the entire active part of the read line of the compression filter, each of which represents an element of the azimuth resolution. So that the data that make up a particular group are timed in the illustrated delay line be compressed, the time delay caused by the line must be due to the frequency change decrease in the group by an amount exactly equal to the time it takes the group to read will, d. H. that the slope of the characteristic of the compression line is numerically equal but of opposite Must be the sign of that of the raw data readout. The change in the time lag through the compression line resulting from the frequency swing of the swept oscillator between the End elements of the group result, plus the further time interval when reading between the End elements of the group should not exceed the effective part of the read line.

The groups 428, 430 and 432 are compressed by the delay characteristic 448 of the compression filter so that they form corresponding pulses according to curve 450 , while the groups 436, 438, 440, 442 and 444 are compressed to corresponding pulses according to curve 452. The pulses in curves 450 and 452 appear at a time which is the sum of the time span from a reference point in time to the start of reading a group and the delay time caused by the compression filter. It will be understood that the pulses following curves 450 and 452 appear at different points on the range scan. The table below shows the duration t _{e of} its duration for each group, the delay time i "of each group at the specified frequencies and the time t. indicated at which the main maximum of the output pulse occurs, calculated from the zero point shown. at which the line deflection is triggered:

Point reflector Ic U ι, 75 25th 35 the group 95 Ti 0 to 15 60 to 75 115 74 12 to 27 70 to 83 78 Distance R ₂ 30 7 * 5 24 to 39 80 to 91 95 Ty 0 to 20 60 to 78 112 T ₁ 10 to 30 67 to 85 Distance A ₄ Ά 20 to 40 74 to 92

Accordingly, all groups assigned to the same distance are distributed evenly by the compression line and the inclination of the delay line is chosen so that all pulses appear within a reading interval at the minimum distance. As curve 450 shows, the compressed pulses at the minimum _{distance A 4} are arranged at a greater time interval from one another, which can be traced back to the - / R reading frame. The corresponding rectified pulses derived from pulses 450 and 452 are illustrated by curves 454 and 456. The subgroups, which are represented by the lines 436 and 444 , are integrated into pulses of small amplitude and removed by the time gate 110 with the aid of the gate pulse 460 or by the masks 119 and 121 . It should be noted that the gate pulse 460 decreases in width as a function of distance.

A middle group, such as group 412, which is read in the period from 10 to 30 ys , appears at the output of the delay line as a compressed pulse at time 95 ^ s. Accordingly, the data from the middle of the read line are available for display after 67 microseconds after the reading of this group has been completed. In order to bring the display azimuth deflection into time correspondence with this, the deflection signals of the final display according to curves 462 and 464 are delayed by 15 ^ s with respect to the reading deflections 404 and 406 by means of delay line 118. Further, as with the read deflection, the deflection signals 462 and 464 have a different slope which is a function of the square root of the distance so that the final display data is properly recorded. In order to synchronize the distance deflection with the raster period, the delay line 107 introduces a time delay which is equal to the delay time caused by the compression filter 106 . The display grids 113 and 107 shown on the tube 112 and the card film 120 (Fig. 3) are the same as the reading frame 71. The pulses 468 and 470 show the effective azimuth position of the resolution elements at various distances A ₂ and Λ ₄ as recorded for display as a result of the use of azimuth deflection signals 462 and 464 of variable pitch. It should be noted that the deflection delay is chosen so that rectified pulses coincide with the time of the azimuth deflection signals for display. The return time for the distance deflection can be set so long that the display of each grid is completed before the next grid is started. Because of the constant time delay caused by the compression filter, the last part of the recording of the last line read can also take place at the beginning or after the true trigger time of the next raster. It should be noted that the compression filter for the two systems according to FIGS. 3 and 4 operates in the same manner as explained with reference to FIG.

A typical embodiment of a frequency dispersed delay line such as her Can be used in the systems of FIGS. 3 and 4 is shown in FIG. This is what it is

an ultrasound line. In the system according to the invention, the line 106 can, for example also have several ultrasonic delay lines connected in series. The line 1 * 6 can from a body 474 made of a suitable, low-loss material such as aluminum or spring steel. At frequencies above 10 MHz, spring steel is superior. To convert the electrical Energy into mechanical energy at the input and mechanical energy into electrical energy at the output are an input transducer 476 and an output transducer 478 at the corresponding points of the delaying Body 474 arranged. Along the edges of the retarding body 474 there may be U-shaped rails 480 and 482 made of an absorbent material. The electrical input signals stimulate the input transducer 476, which is set in vibration and introduces an elastic wave into the body. the

ι ο wave runs through the body 474 at the speed of sound and mechanically excites the output transducer 478 so that it is converted back into an electrical signal. Since the speed of sound in solid bodies is low compared to the speed of light in space, the wavelength of the ultrasonic signals in the delaying medium 474 is correspondingly shorter than an electromagnetic wave of the same frequency in space, and the delay over the distance L 'is proportionally longer . Correspondingly, a strip of delay body a few cm long is equivalent to many km of electrical waveguide.

The required dimensions for the delay line can be specified as follows:

(t) © ■

/ "= Frequency,

C ₁ = shear rate of the retardation material,

/, = the desired center frequency,

, ffh

h '

^lü - = the desired slope of the frequency-time characteristic,
d /

T = the group delay, i.e. the time it takes for the energy to travel through the medium, A = the thickness of the strip 474.

The delay T ₀ at frequency / ₀ is:

^To 'KiTJKJ

For a typical spring steel delay line with frequency dispersion, the following expressions give the above parameters:

. _ 0.0938

«I.

~ ⁷ ' ⁵¹ '

T ₀ = 11.5 / - '.

The transducers 476 and 478 can be made of any suitable material, with materials having piezoelectric or magnetostrictive properties providing the highest conversion efficiency. For example, the transducers can and can consist of thin layers of piezoelectric semiconductors or magnetostrictive ferrites that have a fundamental resonant thickness the value of which is equal to the thickness h of the body 474

5i> be applied directly to the end face of the retardation body 474, for example by vapor deposition in vacuum or electrolysis. For piezoelectric semiconductors, for example, the zinc blende class Cubic crystal systems belonging to the class, such as gallium arsenide, and hexagonal crystal systems belonging to the wurtzite class, such as cadmium sulfide can be used. The delay body 474 advantageously consists of one electrical conductor, so that an earthing is possible and prevents direct transmission of the input signal will.

Now, based on FIG. 18 and 4, the operation of the linear sweep system will be described in which the read lines are of constant length and the tilt of the swept oscillator 134 is varied as a function of distance. The groups read out are shown for distance A ₄ by lines 488, 490 and 492 and for distance A ₃ by lines 494, 496 and 498. The time interval between the read out Doppler course signals is the same at all distances and the bandwidth of the read out Doppler course signals is also the same at all distances. In contrast, the frequency-time increase of the groups is different for each distance and decreases with increasing distance. Therefore, the slope of the swept oscillator 134 is varied in inverse proportion to the distance, as is the case

IS

Curves 500 and 502 show for the corresponding distances R ₄ and A ₂ so that groups with constant inclination are formed which can be fed to the compression filter. The range deflection signal is fed from the range deflection generator 84 to the controllable amplifier 136 to reduce the rise in the deflection signal as a function of distance for each range as the distance increases during each reading frame. On the output line of mixer 132, G s 504, 506 *> jnd 508 at distance R ₄ and groups 510, 512 and 514 at distance R ₂ all have the same slope of the frequency-time curve as all other groups on other reading lines or azimuth lines during the repeating grid. In Fig. 18 the sum signal of the mixer 132 is shown. The center frequencies of the groups increase from the beginning of each reading line, as is also the case with the arrangement according to FIG. 3, but with a slope which is also a function of the falling slope of the swept oscillator signal ι ο 500 or 502. The bandwidth of the longer distance groups, such as Doppler waveform signals 510, 512 and 514, increases because of the increasing duration of the Doppler waveform signals from each point reflector. The processing of the signals in the compression filter 106, the envelope detector 108 and the time gate 110 α corresponds to that which is illustrated with reference to FIG. 3 has been explained, however, the output pulses from shorter distances have a greater time interval than the pulses from greater distances, which can be attributed to the increase in the swept oscillator which varies as a function of the distance. In the system of FIG. 4, the deflection in display tubes 112 and 114 is varied as a function of distance to form a trapezoidal grid. The viewing device 112 or the recording device not shown in detail responds to the delayed azimuth deflection signals of the deflection generator 82 and to the delayed distance deflection signals of the generator 84. Therefore, in the arrangement according to FIG. 4 the length of the azimuth lines, such as 150 and 152, on the Darsleiiungsge rates as a function of distance. As mentioned above, the difference signal from mixer 132 can also be fed to compression filter 106 instead of the sum signal. In FIG. 19, the input signal of the mixer 132 is represented by groups of Doppler curve _{signals 489 and 491 for the corresponding distances A 4} and A _2. The swept oscillator signal 493 is superimposed on these input signals in mixer 132. The Doppler progression signals are shown in close proximity as part of the read data of a system in which more than three groups are read out in order to illustrate the bandwidth reduction. The difference signal is represented by two groups of Doppler curve signals 495 and 497, the bandwidth of which is substantially reduced compared to the bandwidth of the corresponding signal groups 489 and 491, respectively. Thus, in this embodiment of the invention, the compression filter 106 requirements, which are a function of the product of bandwidth and time, are reduced. Thus, in a system with a selected overlay operation in which the swept oscillator is used to remove some of the slope of the Doppler signal, the compression ratio of the filter at one removal approaches the number of azimuth elements to be processed per read line rather than that Ratio of the group length to the resulting azimuth resolution element. For example, in the case of a compression filter with a compression ratio of 10: 1, the ratio of the group quantity to the resolution element can be 450 m to 6 m, 0: 0 (D), i.e. 75: 1.

In the same way, in the system according to FIG. 3 reduces the required compression ratio of the filter are, internally, the difference signal of the mixer 97 is also used to, similar to iri F i g. 19th shown reducing the bandwidth. Depending on the selection of the reading speed and the overlay <to The system according to the invention can either use the sum or difference signals Make use of them to feed them to the compression filter. If the differential signals are used, the compression ratio of the compression filter used according to the invention is reduced.

Based on the F i g. 20 to 23 and FIG. 5 and 6 should now look at how the processing systems work the F i g. 3 and 4 explained for the case that a storage tube is used instead of a storage film will. In order for the correlator to operate without interruption, the storage tube 170 can have two redundant Store sets of raw data, which is done with the aid of a delay device such as delay line 180 is achieved. Any suitable type of delay line can be used, such as one Ultrasonic line or a line made up of concentrated elements. Line 180 delays the data slightly more than the duration of the sampling interval of interest and the delayed data will also be ^ o like the instantaneous data are fed to the same control grille of the tube 170. Accordingly, the data is available available twice in succession, so that they are available by means of two successive deflections of the Write beam of the storage tube can be registered.

The reading process takes place simultaneously and independently of the writing process. 20 illustrates the state after the start of recording, for example at time t _{ + ε, where f indicates the point in time at which the deletion of lines N-290 and / V'-290 on memory screen 187 has been completed. Upon completion of this erasure process, the erased tapes include such. B. the tape 537, five vertical erase positions each. Before this erasure time, track N was recorded on the left edge of the storage area next to an erased tape 537, after which the write beam was deflected by leaps and bounds to an area on the right side of the tube during its vertical return and the deflection was repeated, thus recording track N ' which is a delayed repetition of the same range data. During the time interval following the state shown in FIG. 20, which may be denoted by fi + 1 / PFF, where PFF is the pulse repetition rate, the two tracks N + 1 and N '+ 1 are recorded on the tube, of which track N '+ 1 is on the right half of the tube. At this time, the erase tapes are four vertical lines wide. The reading frame 523 for linear operation and a portion of 525 I ¹ J a square root operation are maintained over 250 lines in the illustrated arrangement. It should be noted that the square root grid 525 contains 250 lines only in the portion corresponding to the maximum distance.

The sequence of operations is therefore such that immediately after a track has been recorded, the potentials of the tube grids are switched to the erasure condition, the write beam is deflected step by step to the recording point of the oldest track on the left side of the recording screen and then moved vertically with constant intensity, which the subsequent erase tape holds in positions other than the permanent edge bands. Likewise, the track to the right of center and adjacent to the reading raster is erased to maintain the leading erase band of five or four erased vertical lines. Currently i | + 1 / PFF + ε illustrated in Figure 21, tracks / V-291 and / V'-291 are erased to begin the formation of the erase band on the left side of the tube. At the end of this time, the erased tapes on the left and side of the reading frame are five and four tracks wide. The process is repeated in the same way until

in the reading frame, such as B. 530, is moved to the left side of the tube next to the erasing tape in the middle of the tube and the subsequent erasing tape is the leading erasing tape. It should be noted that in the system of Figs. 20 and 21 a tube with 580 vertical tracks has been selected for purposes of illustration. As a result, the illustrated write, erase and read operation is continuous by storing two sets of redundant distance information. On curve 540 in FIG. 22 the times of the transmission of the W-th and the (N + 1) -th radar pulse are given. All ZV pulses are received and recorded for the duration of a / V range gate and are also delayed so that they are recorded on the right half of the tube during a delayed / V interval, the / V 'interval. Like the Signa! 542- shows; the tracks N-290 and N'-290 are deleted during the "dead time" of the radar device. The same sequence is repeated after the (N + 1) th radar pulse has been transmitted. The interlace pulses according to curve 544 are fed to the integrator 198 for recording and erasing with opposite polarity in order to change the charge on the capacitor 201 (FIG. 6). The DC voltage signal according to curve 546 is generated with a decreasing level during the duration of the recording across the tube surface 187, that is, between the multiar switch-off pulses. The combination of the integrated signal 544 and the signal 546 represented by curve 548 is applied to summing circuit 195 (FIG. 5) to effect the vertical scan and the five line jump between writing and erasing.

The pulse generator 189 forms pulses whose shape is the same as the pulses 550 , but which have a constant DC voltage level. The change in voltage from the level of a positive pulse to the level of a negative pulse causes a deflection by half the width of the tube surfaces 187. The summation

The circuit 195 generates the deflection voltage 550, which causes the deflection by half the tube width, the recording and erasing positions and the constant movement of the recording and erasing positions across the tube from left to right. The multiar circuit 204 is controlled so that it discharges the capacitor 201 and the deflection position door resets the recording and erasing to the left when the right outer part of the tube has just been written. On the right side of the tube will be at the moment in which

r> the last track in the erasure span of the edge has been written, a summing pulse from the pulse generator 199c is fed to the adder 195 so that it is combined with the signal 550 during the erase intervals, until the last track written is in the extreme right position occupies on the tube. In the example shown, this summing pulse will occur for the selected PFF during four erasing intervals. The recording and erasing operation is in - / R and linear reading frames

The reading out of repetitive rasters is controlled by a signal for vertical deflection 522 according to FIG. During each deflection period, the beam is guided from the lower edge to the upper edge of the grid. These deflection signals are generated by the deflection generator 208 . When using the linear system according to FIG. 4, horizontal deflection voltages 554 are applied to the horizontal deflection coils and the summing circuit 211. The integrator 214 forms the decreasing DC voltage level during each movement of the grid over the entire area 187, as is defined by the switch-off pulses of the multiar circuit 213. The horizontal deflection generator 210 generates horizontal deflection signals 556 each of which defines a horizontal azimuth line. A horizontal read synchronization pulse controls the deflection generator 210. The multiar circuit 203 increases the DC voltage level of the signal 554 by discharging the

μ integrator, so that the grid is periodically shifted to the left side of the tube surface 187 in order to start the new series of reading frames.

To operate with a nonlinear deflection, the line deflections such as 560 and 558 have an increasing length and slope from the bottom to the top of each reading frame. This change is controlled by the / R generator 212 which is responsive to the vertical read deflection signals 552 . The pulses 562 show the

«Time gate control. which can be achieved with the aid of the time gate 110 (FIG. 3) for a non-linear deflection system and with the time gate UOa (FIG. 4) for a linear deflection system. During each reading frame, the width of the pulses decreases in order to avoid reading out additional groups due to the increasing length of the reading lines. Accordingly, the reading process takes place during a large number of successive rasters. It is scanned with rapid deflections perpendicular to the recorded distance deflections

w> and it is started in the left half of the stored data, as shown in FIG. 20 and 21 explained has been. Successive scans of each reading frame scan the Doppler history of targets that are present at increasingly greater distances. The process takes place continuously with a certain time Relationship between recording and reading. For example, the data can only be entered once read, d. This means that with each subsequent rastr reading begins at the edge of the data that was

existing raster were read out. If the speed ν of the aircraft is 300 m / s, the PFF 2000 Hz and the azimuth resolution at -3 db is 15 m, the grid time for three artificial groups is offset Phase center 45/300 or 0.15 sec. According to this, 2000 x 0.15 or 300 distance tracks are recorded, while reading a full grid.

With reference to F i g. 24 the scanning of a reading frame according to a - // {- program will now be further explained for another illustrative example in which six groups or Doppler course signals are read during each line of the raster. The center line 471 of the grid can run centrically to a certain number of groups, such as six groups for example, which result in an azimuth resolution at a distance of 6 m between adjacent point reflectors. Each of the groups 475 and 477 in the maximum distance can represent a distance of 540 m on the surface of the earth, which is a proportional distance on the film or the tube. *>. \ & e.g. corresponds to 5 cm. The group or Doppler curve signals 475 and 477 can each represent the data from one of two adjacent resolution elements of the area illuminated by the radar device. The center line 473 of the first group 475 is offset to the left by 15 m with respect to the center line 471 of the grid. At half the distance, the groups 479 and 481 represent the Doppler course of two resolution elements of the grid, which correspond to a length of 270 m, i.e. half the length of the maximum distance. The width of the reading raster, which is programmed as VR , is about 400 m at half the distance. The time required for scanning lines should be 50 as at each distance and group 475 should be read in 47.37 μ% , so that the Group 479 requires a time of 33.4 μ $ . With a resolution of 6 m in azimuth, reading group 477 begins 0.53 \ js later than reading group 475 and ends at 47.9 μ $. At half the distance, group 479 is read in the time from 8.23 μϊ to 41.63 μβ and group 481 from 8.98 μ5 to 42.38 μs. Accordingly, the point in time at which reading out of a group is started is inversely proportional to VR with increasing distance. To read the group

pen The time required for the increasing distance is the value · //? directly proportional. a

It is assumed that the group 475 changes in frequency from 8 MHz to 4 MHz and the frequency zo |

change in group 479 is between 5.66 MHz and 2.83 MHz. The frequency f i read out is then |

,,, writing time \

^f '° ^fd reading time' «I

In this equation, / _{rf is} the input Doppler frequency when recording. The frequency conversion fe

The »write time / read time« factor is at half the distance 0.707 times the value of the maximum distance. (,: ■ '

However, it affected the center frequency at the maximum distance of 6 MHz and at half distance 4.24 MHz. 30 |

The center frequency of the groups thus increases for greater distances as a function of VR due to the altitude |

ren read rate at greater distances, so that a displacement oscillator is required to all Mittelfre- jf

sequences to give the same value.

It goes without saying that the principle of the invention does not extend to the use of the square root function for the Reading and writing is restricted, but that every suitable function, fixed or variable, is within the framework the invention lies. Furthermore, the teachings of the invention are not limited to a specific storage medium such as a film or a storage tube, but all suitable within the scope of the invention: Find memory arrangements use. The invention also does not apply to card manufacturing systems or limited a certain type or certain frequency of the emitted energy. Operation with staggered The phase center is not limited to a special type of compression filter or one that is subject to dispersion Line and includes any suitable arrangement such as individual filters with exactly matched transmission time and passbands controlled in accordance with the teachings of the invention.

Accordingly, a system for the formation of a plurality of synthetic radiation lobes has been described by all of which are essentially parallel to each other in order to effectively transmit an antenna beam to simulate the prescribed parameters at predetermined locations, the various positions of a system arranged in an aircraft along the flight path. By painting over more than one Doppler history signal during readout and by processing each Doppler history signal Over the same total frequency deviation, the synthetic rays become effective with one another Phase center formed so that they correspond to different points of origin along the flight path. Each synthetic ray corresponds to a reflective one extending over the entire distance range Resolution point because a selected number of groups from the smallest to the furthest Distance is scanned in succession in each reading frame. Those at different times during each azimuth reading line Read out Doppler curve signals are fed to a mixer, which is swept by a Oscillator is controlled so that the time shift along the flight path at each distance in a frequency shift is converted. The filter works in conjunction with the delay that occurs along the azimuth reading lines shows that the targets appear in a time sequence that is along their position of the flight path in each azimuth reading line. Focusing for all distances is made possible by the Combination of a deflection oscillator and the pulse compression device achieved. The inventive System gives a high degree of azimuth resolution of point targets as well as range resolution. The distance resolution can be determined by the width of the transmission pulses and the quality of the storage and display devices to be influenced.

Another feature associated with the invention is the teaching that the reading frame width is proportional to a suitable function, such as the square root of the distance, to vary and continue to shift the read out Doppler curve signals in frequency so that the frequency change is compensated caused by changing the size of the reading frame. For this purpose a t> 5 made use of swept oscillator, which has a constant slope, in order to be distance-independent Form signals and adapt them to the frequency-time characteristics of the compression filter. At the final Representation, a similar grid is formed, which is controlled by a similar function, such as

for example as a function of the square root of the distance, so that a constant resolution of the representation is achieved for all distances.

In other arrangements according to the invention, a linear read scan is used in conjunction with a swept oscillator with variable slope is used to get the desired representation using a 5 to achieve trapezoidal display function.

In addition 20 sheets of drawings

10

211 25 30 35 40 45

55 60

Claims (4)

Patent claims: 1. Data processing system for a pulse Doppler radar device installed on board a missile with an antenna directed transversely to the flight path and inclined towards the ground, its radiation diagram covers a portion of a strip of terrain extending parallel to the flight path, with a device for storing a Doppler frequencies contained in the echo signals comprising Signal by range and azimuth, a device for sampling the stored signals in different distance intervals associated azimuth ranges, a device for normalizing ίο of the sampled signals in terms of center frequency and frequency increase, a compression filter with a frequency dependence of the transit time that is inverse to the frequency increase of the signals and one the output signals the compression filter according to the distance and azimuth recording output device, characterized in that the sampled signals are limited to an equal frequency deviation and the stored signals are scanned in an azimuth range that corresponds to that of several in azimuth is arranged next to each other, still separable targets originating on the mentioned frequency deviation more limited. Signals included. 2. Data processing system according to claim 1, characterized in that in a manner known per se the means (18) for storing the signal comprises a recording medium (66) and a cathode ray tube assembly (50), which responds to the signals comprising the Doppler frequency and a drawing of these signals on the recording medium (66), and furthermore the device (82, 84, 85) for scanning the stored signals is set up for selective scanning of the recording medium (66) according to a specific scanning scheme, the successive of the distance intervals (A ₂ , / J ₄ ) in a number of consecutive positions along the flight path 3. Data processing system according to claim 2, characterized in that the device (82,84,85) a range deflection generator (84) having such a controller for sampling the stored signals of the scanning scheme: .- causes it to be a function of distance for each scan, and one Azimuth deflection generator (82) which controls the scanning scheme such that it occurs at each scan is a function of radar movement. 4. Data processing system according to claim 3, characterized in that the device for standardization of the scanned signals a displacement generator coupled to the range-deflection generator (84) Oscillator (88) producing a frequency shift signal as a function of distance, and a first Mixer (93), dr, r with t?, M shift oscillator (88) is coupled and serves to shift the To effect frequency of the output signals supplied by the device for sampling the signals, as well as a swept oscillator (98) for generating a frequency swept signal for each sample the stored signals corresponding to one of the successive positions along the flight path, and another mixer (97) associated with the swept oscillator (98) and the first mixer (93) is coupled to change the center frequency of the output signals as a function of time and thereby giving the output signals a certain change in frequency dependence on time.