DE19731262A1 - Aircraft avionic system using onboard radar - Google Patents

Abstract

The avionic system uses an onboard radar device with a 2-dimensional representation of the radar data received from an area positioned upstream in the flight direction provided using a synthetic aperture radar based processing principle for the radar data from a forwards-looking radar. The radar antenna (1) uses a number of horn elements (10), arranged next to one another in a line transverse to the flight direction of the aircraft, so that the main radiation direction of each horn element lies in the flight direction.

Description

The invention relates to the use of a flie forward-looking radar for two-dimens sional mapping of a second in the direction of flight gate area including objects detectable there.

From DE 40 07 611 and DE 40 07 612 is such a front Forward-looking radar is known, in which, for example, of flying carriers from land or sea surfaces in one sector in front can be mapped in two dimensions. For this purpose, one is rigid in the known forward view radar provided antenna mounted on a carrier, which either straight out of a number in a row next to each other ordered individual elements (DE 40 07 611) or from one number in a straight line next to each other and in two rows one above the other arranged individual elements (DE 40 07 612), preferably in Form of horn antennas. At a given Aperture length l of each individual element and at a given one The antenna has an indication of a distance of n individual elements Tennenlänge L = n.l (DE 40 07 611) or an antenna length L = n.l / 2 on (DE 40 07 612).

Here, in the first-mentioned case (DE 40 07 611) of sent incoherently and then with receive the remaining individual elements simultaneously. In the Execution mentioned in the second place (DE 40 07 612) Send and connect using the individual elements eating one after the other, from the first to the first last of the number of individual elements. To realize a di Each individual element becomes a digital coupling of the individual elements separately evaluated digitally and by correlating one special, predetermined reference function is used in both cases digital processing for every angular range guided.

With such a forward view radar with a rigidly mounted antenna, numerous advantages can be achieved with a downstream, specially designed processing method:

• a) a high swiveling speed of the antenna lobe, because these not mechanically, but electronically with the help of an egg ner special data processing is realized;
• b) higher accuracy and therefore better quality in the illustration as with all previously available devices ten;
• c) independence from the speed of the carrier, and
• d) significantly lower maintenance costs.

Furthermore, the forward vision radar according to the invention systems also in connection with helicopters for search, Use rescue and environmental tasks because the forward vision radar systems have no forward speed is required and the inherent movement of one on a pre the location of the helicopter, as it were, is irrelevant is.

The object of the present invention is both for Airplanes as well as avionics system suitable for rotary wing aircraft to create that enables a pilot to even under the most unfavorable visibility conditions to fly to a desired target area without any view, if necessary, land safely or without any visibility per to start without a problem.

According to the invention, this object is through the use solved a forward view radar, with which one in flight direction of sector ahead including there detectable objects in the form of a map corresponding, high-quality image is shown. Here, according to the invention, the electronic Ver receive received data in map-like top view image into a central perspective projection from a quasi pilot perspective implemented. Advantageous further developments are Ge subject of subclaims.

By using one of DE 40 07 611 and DE 40 07 612 known forward view radar systems or their combina  tion, an avionics system is available that is wide can be used and with which both of planes and also of rotary wing aircraft without any view, d. H. at sight ratios "zero", both to each target area can be flown to can be safely recognized as well as obstacles as well landed without any problems or who started safely from the ground that can.

Because of these properties of the avionics system according to the invention arises for the use and application of the pre forward-looking radar systems have a wide range of applications for example from military reconnaissance and combat hubs screwdrivers, rescue and offshore helicopters to sufficient for use in transport and civil aircraft. With the image quality achieved by the system according to the invention is cannot be achieved with any other system.

By using the patent mentioned in the two known forward-looking radar is therefore an all-rounder suitable sensor, created even for the worst Visibility or in conditions without any visibility and can also be used during the night. Thanks to the central perspective projection from a quasi-pilot perspective according to the invention is a quasi-optical image with a constant through the present high refresh rate Nuclear picture representation, for example on a high color monitor.

According to a further advantageous embodiment of the Erfin In addition to the map-true representation of the earth's surface che also information regarding the height above ground from na Natural and / or artificial obstacles from a quasi-pilot perspective brought.

According to an advantageous development of the invention for example on such a highly sensitive color moni gate also between a map-like top view and a central perspective tivical representation switched to quasi-pilot view the. Likewise, both in the map-like top view as  also in the perspective view from a quasi-pilot perspective between different distances can be switched, so that this guarantees a farsighted mode is accomplished.

In addition, according to yet another advantageous Embodiment of the invention depending on the respective the forward view radar system between ver different frequency ranges are switched, for example as from the L-band (1.3 GHz) over the X-band (9.6 GHz) up to the Ka band, which is around 35 GHz. When switching to the Ka band can be seen using the forward view radar system for example high-voltage lines or for limitation chain-link fences used by surfaces can be recognized.

According to an advantageous embodiment of the invention the map-like top view and the central perspective Presentation in quasi-pilot view of the flight altitude and the Airspeed adjusted automatically.

Furthermore, as further advantageous developments of the Invention additional data are displayed, so at for example distances to marked targets, the amount of marked obstacles or a marking of moving targets, so that an MTI (Moving Target Indication) Fashion is realized. Moving targets can also be used be cated.

In addition, it is possible within the scope of the invention Central perspective representation in quasi-pilot view with other operating modes, such as weather radar, surveillance radar etc. can be combined.

Due to the use of the forward vision radar high resolution can be achieved with the help of received and specifically selected data, for example a facility be triggered or triggered, which before obstacle warns. In addition, there is also a so-called head-up Display presentation possible.  

Due to the use of the forward vision radar system accessible, high-resolution, pictorial Dar position of the flight sector ahead in the direction of flight an application for flights in the civil and military area possible, so that, for example, autonomous landing approaches, targeted te, precise load shedding u. a. are reliably feasible.

The invention is based on various examples play with reference to the accompanying drawings in individual explained. Show it:

Figure 1 is a schematic representation of a composed of a plurality of juxtaposed individual radiator antenna for use in forward looking radar.

Fig. 2 is a schematic representation of a lighting geometry, as it results from an aircraft flying in a predetermined direction of flight;

Figure 3 is a plan view in cards faithful representation of part of a runway and its immediate surroundings from a flight altitude of 1000 m.

FIG. 4 shows a central perspective illustration corresponding to the illustration in FIG. 3 in a quasi-pilot view of the same part of the runway and its immediate surroundings;

Shows a plan view in cards faithful representation m. 5, in turn, a portion of a runway from a flying height of 300, and

Fig. 6 one of the map-true representation of Fig. 3 corre sponding central perspective representation in quasi-pilot view.

In Fig. 1 schematically n individual radiators in the form of horn antennas 10 of an array antenna 1 are arranged in a straight line the nebeneinan. As not shown in detail, the antenna arrangement 1 is rigidly attached to an aircraft - reproduced considerably reduced - transversely to the direction of flight indicated by an arrow so that the main radiation direction of the horn antennas 10 points in the direction of flight.

According to DE 40 07 611, this is only transmitted by a single radiator, ie only by a horn antenna 10 ; subsequently, however, all other individual elements are received in the form of the horn antennas 10 , for example. In contrast, in DE 40 07 612 the n individual radiators are used in succession from the first to the nth element for transmitting and then for receiving.

The raw data can be processed in a similar way be carried out as in the known SAR principle, where a synthetic aperture in DE 40 07 611 by half Distance or in DE 40 07 612 by the distance between the first and the nth single radiator of the horn antenna arrangement must be replaced.

During processing, the respective signal is correlated in terms of amplitude and phase depending on the distance with a complex conjugate reference function which is not specified here in detail. It is crucial, however, that the Emp signal at each individual element 10 has a different phase to the transmission pulse due to the different location between the transmitter and receiver. This means that in the case of incoherent operation, the phase relationship between the individual elements must be constant and known (DE 40 07 611). Since according to DE 40 07 612 in the transmitting and receiving branch gear must be processed, the phase relationship of the signals received at different locations must be known to each other in this mode of operation.

If the distance between the n individual radiators 10 is now Δx, this distance can be expressed by

Δx = l = λ / Θ in DE 40 07 611 or through

Δx = l / 2 = λ / 2Θ for DE 40 07 612,

where each with l the aperture length of each individual radiator, with λ the wavelength and with Θ the illumination angle be. The illumination angle Θ is entered in the illumination geometry shown schematically in FIG. 2.

If the distance between a target point T and a single radiator 10 of the respective antenna arrangement is denoted by r, the distance r can be expressed, as can be seen from the schematic representation of FIG. 2, by:

r = √R² + (ax) ²,

where with a the distance between the antenna center axis O and a point target T, with x the distance between the antenna center axis O and a single radiator 10 and with R the distance gate distance Ent, as in the individual case just the schematic representation of the Fig. 2 can be seen.

In Fig. 3 from a flight altitude of 1000 m in the X-band a map-like representation in plan view is shown with a relatively short antenna, with a part of an airstrip can be seen in the middle of the picture.

In Fig. 4, the corresponding central perspective Dar position is shown in a quasi-pilot view, which has been obtained by accordingly implementing the map-true representation in plan view of FIG. 3. In the upper area of FIG. 4, part of the runway and in the lower area the area lying in the direction of flight in front of the runway can be seen.

Both in Fig. 3 and in Fig. 4, the illuminating angle in the azimuth direction was 60 ° and the depression angle ranged from 14 ° to 60 °. The resolution in the azimuth direction was 10 m in the near range and 35 m in the far range, while the resolution in the elevation direction was 3 m.

In Fig. 5, a part of the same runway is a card faithful representation in plan view, this time m from an altitude of 300 reproduced again.

FIG. 6 shows the central perspective representation in a quasi-pilot view of the lower third of the representation of FIG. 5. Both in FIG. 5 and in FIG. 6, the resolution area was 1.8 m ² in the near area and 3.2 m ² in the far area .

Claims (9)

1. Use of one carried by a flying carrier Forward view radar for two-dimensional imaging of an in Sector area ahead including flight direction objects detectable there in the form of a map corresponding high-quality image, the through electronic processing of received data in cards faithful top view image obtained in a central perspective quasi-pilot perspective. 2. Use of a forward view radar according to claim 1, there characterized in that in addition to the map-true illustration the surface of the earth also information about the altitude Floor of natural and / or artificial obstacles in Quasi-pilot view are brought. 3. Using a forward view radar according to one of the types sayings 1 or 2, characterized in that at one high-resolution color monitor between map-like top view and a perspective view from a quasi-pilot perspective is switchable. 4. Use a forward view radar according to one of the before forthcoming claims, characterized in that the zen perspective perspective projection in quasi-pilot perspective between different distance ranges can be switched. 5. Use a forward view radar according to one of the before forthcoming claims, characterized in that in depend the frequency range (L-band to Ka-band) of the forward view radar is switchable. 6. Use a forward view radar according to one of the before forthcoming claims, characterized in that the map-like top view and the central perspective Dar position in quasi-pilot view of the flight altitude and the flight speed is automatically adjusted.   7. Use a forward view radar according to one of the before forthcoming claims, characterized in that to the central perspective representation in quasi-pilot view additional data / information are mapped. 8. Use a forward view radar according to one of the before forthcoming claims, characterized in that in the central perspective representation in quasi-pilot view marked goals are marked. 9. Use a forward view radar according to one of the before forthcoming claims, characterized in that the zen perspective view in quasi-pilot view with other operating modes, such as weather radar, surveillance radar u. a. is combined.