DE102023133088B3 - Noise filter for radar measuring systems, radar measuring system and launch device with radar measuring system - Google Patents

Abstract

The invention relates to a passively effective noise filter (1) for radar measuring systems for increasing the signal-to-noise ratio. The noise filter (1) comprises a rotationally symmetrical hollow body (2), the hollow body wall (2.1) of which is made of a base material that is permeable to radio waves, with rod-shaped shielding inserts (3) made of a shielding material that is impermeable to radio waves being embedded in the hollow body wall (2.1). The radar measuring system provided with the noise filter (1) is particularly suitable as an add-on unit for launchers (6) for monitoring the trajectory of projectiles and missiles.

Description

The invention relates to a noise filter for increasing the signal-to-noise ratio for radar measuring systems that operate using electromagnetic radio waves. The invention also relates to a radar measuring system with such a noise filter and a launch device with the radar measuring system. The noise filter serves to improve the reception sensitivity of radar measuring systems when receiving electromagnetic radio waves, in particular in the wavelength range from 100 MHz to approximately 500 GHz.

Measurement and detection methods using electromagnetic waves have the advantage that the objects to be detected or examined can be made visible under a wide range of conditions by appropriately determining the wavelength of the electromagnetic waves used. For example, if visibility is obstructed by vapors in the visible wavelength range, the vapors can be penetrated by switching to low-frequency waves.

The detection of (metallic) objects using radar waves, i.e. electromagnetic waves in the radio range, is well known - in both civil and military applications. The known radar measuring systems emit radio waves that are reflected diffusely, i.e. distributed in all directions, by (moving) objects, and record the radio waves reflected by the objects. This makes it possible to record or prove the existence, distance, direction and speed of the objects. Due to the constant speed and straight-line propagation of the electromagnetic waves, the distance and speed of such objects can be measured precisely. By choosing the radio wavelength, it is also possible to adapt to the geometric dimensions of the object to be measured.

DE 23 12 065 A describes a waveguide mode filter which, in order to assist the propagation of circular electrical wave modes in a hollow cylinder, provides for the attachment of several longitudinally arranged resistive strips to the inner surface of the waveguide lining to absorb the energy of unwanted modes.

The accuracy of the distance measurement and thus of the recorded speed depends essentially on the signal-to-noise ratio. The less the received echo signal is overlaid by interference signals (noise), the more accurate the measurement.

For small objects, such as rifle projectiles, the effective backscatter area is small. In addition, the transmitted power arriving at the object to be measured is reflected in all directions. Usually only a small proportion of this reflected power is received by the radar measuring system.

In addition, the resolution of the captured image is limited - not least due to the significantly longer wavelength of radio waves compared to light waves - so that details of the objects detected by radio waves are hardly or not at all visible, especially at larger measuring distances.

The power of the emitted radio waves also influences the signal-to-noise ratio and thus the maximum possible resolution. The tendency to further miniaturize radio wave emitters of radar measuring systems inevitably leads to reduced emission power and thus to a deteriorated resolution or a reduced signal-to-noise ratio.

Preferably, smoke suppression or filtering is carried out passively to improve the signal-to-noise ratio, i.e. without additional energy supply or complex control components. DE 10 2019 108 741 A1 A noise suppression device for electromagnetic measuring systems for improving the signal-to-noise ratio is known in the form of a hollow cylinder made of a metallic foam that can be attached to a radio wave emitter.

The invention is based on the object of avoiding the above-mentioned disadvantages, such as poor resolution of the images of objects detected by means of long-wave electromagnetic waves, in particular when using radio wave emitters with low transmission power, whereby an improved noise filter for radar measuring systems is to be provided which makes it possible to implement radar measuring systems which operate on the basis of electromagnetic radio waves - in particular in the wavelength range from 100 MHz to 500 GHz - whereby the noise filter is intended to enable an increase in the signal-to-noise ratio and the spatial resolution during a measurement without the need for electronic components.

This object is achieved by a noise filter with the features of claim 1 and a radar measuring system with the features of claim 8; expedient embodiments of the invention can be found in the subclaims. An advantageous integration of the radar measuring system into a launching device is described in claim 10.

According to the invention, a noise filter is provided for a radar measuring system that emits electromagnetic radio waves and detects the reflected signal thereof, wherein the noise filter has a hollow body that is rotationally symmetrical to a hollow body axis of the hollow body and is extended along the hollow body axis over an axial total length. The hollow body of the noise filter has an axially continuous cavity that extends along the hollow body axis and is surrounded by a hollow body wall.

In this context, rotational symmetry is understood to mean that bodies or arrangements (here, for example, the hollow body) are imaged onto themselves when rotated by certain angles around an axis (here, the hollow body axis). For example, self-image when rotated by 120° is referred to as three-fold rotational symmetry and self-image when rotated by 60° is referred to as six-fold rotational symmetry. The special form of rotational symmetry in which self-image occurs when rotated by any angle is referred to as rotational symmetry for the purpose of differentiation.

The hollow body preferably has the shape of a straight hollow cylinder that is open on both sides, whereby the term hollow cylinder is understood to mean any shaped body that has a centrally arranged through opening. The base area of the hollow cylinder can have any shape, but is preferably rectangular or oval (including circular).

Likewise, the cross-sectional area of the cavity enclosed by the hollow body wall can have any shape, whereby the shape of the cavity cross-sectional area can be variable along the hollow body axis, but usually remains the same.

In its design as a hollow cylinder, the hollow body preferably has a cross-sectional geometry that is constant along the hollow body axis with respect to the hollow body wall and the hollow space. However, it can also have the geometric shape of a hollow cone or hollow pyramid truncated shape, for example.

The noise filter also has several straight rod-shaped shielding inserts that extend over the entire length of the hollow body and are embedded in the hollow body wall. Each of the shielding inserts runs or lies in an axial plane of the hollow body that includes the hollow body axis. The hollow body wall has insert openings or insert recesses that match the shape of the shielding inserts, into which the shielding inserts are inserted. If the shielding inserts are designed as round rods, for example, the insert openings are correspondingly adapted holes. As a rule, the rod-shaped shielding inserts have a consistent cross-sectional geometry over their entire extension or rod length.

According to the invention, the shielding elements are arranged in the hollow body wall with at least a three-fold rotational symmetry to the hollow body axis. The arrangement of the shielding elements preferably has a four-, five- or higher-fold rotational symmetry with respect to the hollow body axis, in particular a six- or eight-fold rotational symmetry.

According to the invention, the hollow body wall of the hollow body is constructed from a base material that is permeable to electromagnetic radio waves; the shielding elements, on the other hand, are each formed from a shielding material that is impermeable to electromagnetic radio waves. The base material is preferably a compact material or a solid material.

The radar measuring system according to the invention comprises - in a basically known manner - a radio wave emitter for emitting the radio waves and a radio wave receiver for receiving the (reflected) radio waves. The radio wave emitter and the radio wave receiver can be integrated, for example, in a radar measuring system chip. The noise filter is, for example, DE 10 2019 108 741 A1 described, attached to the radar measuring system chip, i.e. installed as an attachment or front attachment in front of the radio wave receiver. The noise filter with the described features is therefore arranged in front of the radio wave emitter (also radar wave emitter) or radio wave receiver (also radar wave receiver) of the radar measuring system in such a way that the radio waves emitted or to be detected run through the cavity from the radio wave emitter or to the radio wave receiver. The hollow body axis is preferably aligned parallel to the electromagnetic radio waves emitted by the radio wave emitter of the radar measuring system.

The wavelength of the radio waves emitted by the radio wave emitter is preferably in the wavelength range of 100 MHz to 500 GHz.

The radio wave emitter of the radar measuring system is preferably designed to emit electromagnetic radio waves with a predetermined radio wavelength. The arrangement of the shielding elements is suitably adapted to this predetermined radio wavelength. For this purpose, the shielding elements in the hollow body of the noise filter are arranged, for example, in such a way that in each radial plane of the hollow body that is perpendicular to the hollow body axis, each of the shielding elements has a distance from its adjacent shielding element that is in the range of 50% ± 10% of the predetermined radio wavelength.

In particular, the radar measuring system can comprise a radar measuring system chip in the form of a semiconductor chip or can be designed as such a semiconductor chip, wherein the area of the semiconductor chip preferably does not exceed 100 square centimeters.

It has been shown that the noise filter constructed as a perforated, symmetrical hollow body, when arranged in front of the radio wave emitter or radio wave receiver of the radar measuring system, can significantly improve the signal-to-noise ratio and improve the resolution of the image captured by the radar measuring system by orders of magnitude.

The symmetrical arrangement of the rod-shaped shielding elements placed around the cavity acts as a cage-like, lateral enclosure for the radio wave emitter or the radio wave receiver. In this respect, the noise caused by lateral, incident stray waves is dampened. The inventive alignment of the rod-shaped shielding elements allows the radio waves that are aligned in the direction of the cavity axis, i.e. the radio waves that are the primary signal carriers, to pass preferentially through to the radio wave receiver.

The advantages of the noise filter according to the invention when used as intended in a radar measuring system include the simple, compact design, the feasibility of small component sizes and the elimination of error-prone, power-consuming electronic components.

The radar measuring system according to the invention can be used, among other things, when joining workpieces or when repairing steel structures by means of welding. The radar measuring system allows the edges of the workpieces or the gap to be welded to be detected, the size and/or position of the gap to be determined, and the positioning and alignment of the workpieces to be joined in space or in relation to one another to be detected. Since fumes often develop during welding, the radar measuring system enables the aforementioned variables to be reliably detected through the fumes. It can also be used for underwater welding when visibility is obstructed by murky water or the formation of steam.

Another useful application of the radar measuring system is the trajectory monitoring of projectiles or missiles, whereby parameters such as distance, direction and speed of the projectiles or missiles can be recorded using the radar measuring system.

According to the invention, a launching device is provided which has a barrel for launching projectiles or bullets and which comprises the described radar measuring system, wherein the hollow body axis of the hollow body of the noise filter is preferably aligned parallel to the barrel of the launching device. The radar measuring system can be attached, for example, to the shaft or to the aiming optics of a launching device designed as a rifle. It is also possible to install the radar measuring system with a hollow body of the noise filter arranged coaxially at the muzzle of the barrel. By integrating the radar measuring system into the launching device for projectiles or bullets, the accuracy of the aiming can be increased - for example by readjustment - through improved parameter recording. The recorded information can therefore be used in particular in the field of sport shooting to optimize shooting performance during shooting training.

According to a preferred embodiment of the noise filter, the base material of the hollow body wall is a non-metallic material, for example a plastic or a ceramic material.

The shielding material from which the shielding elements are formed is preferably a metallic material, for example an aluminum, a copper or an iron material.

The shielding elements can, for example, consist of a wire-shaped shielding material, i.e. the shielding elements are designed as wires made of compact material.

Alternatively, the shielding material can be a powdered material that is introduced into the insert openings or insert recesses in the hollow body wall and fixed therein. Similarly, the shielding material can be a powder-based material, for example a sintered material. Powdered and powder-based materials offer an improved filtering effect due to the larger internal surface.

Furthermore, it can be provided that the shielding elements within their entirety or within each of several subsets in a perpendicular to the hollow body axis, each have the same cross-sectional geometry. On the one hand, all shielding elements, i.e. all of the shielding elements, can have the same cross-sectional geometry. On the other hand, or alternatively, the shielding elements can be divided into subsets, whereby only within the subset is the cross-sectional geometry the same in a radial plane of the hollow body perpendicular to the hollow body axis; the cross-sectional geometry of the shielding elements from different subsets can, however, differ. In this way, it is possible, for example, to realize certain particularly filter-effective symmetrical arrangement patterns of the shielding elements in the hollow body wall.

According to the design described above, the shielding elements with the same cross-sectional geometry can also be arranged at equal distances from one another in each radial plane of the hollow body that is perpendicular to the hollow body axis on a circle that is concentric to the hollow body axis. This generally forms a rotationally symmetrical rod cage, in the simplest case with a coaxial arrangement of the rod-shaped shielding elements to the hollow body axis.

• 1: eine erste Ausführung des Rauschfilters in perspektivischer Ansicht,
• 2: eine zweite Ausführung des Rauschfilters in perspektivischer Ansicht,
• 3: eine dritte Ausführung des Rauschfilters in perspektivischer Ansicht,
• 4: das Radarmesssystem mit einer vierten Ausführung des Rauschfilters in perspektivischer Ansicht,
• 5: ein Jagdgewehr mit möglichen Installationspositionen des Radarmesssystems im Längsprofil, und
• 6: einen Sportschützen beim Training mit einem das Radarmesssystem umfassenden Kleinkalibergewehr in perspektivischer Ansicht.

The invention is explained in more detail below using embodiments and with reference to the schematic drawings, wherein identical or similar features are provided with identical reference numerals; in this respect:

• 1 : a first version of the noise filter in perspective view,
• 2 : a second version of the noise filter in perspective view,
• 3 : a third version of the noise filter in perspective view,
• 4 : the radar measuring system with a fourth version of the noise filter in perspective view,
• 5 : a hunting rifle with possible installation positions of the radar measuring system in the longitudinal profile, and
• 6 : a sports shooter training with a small-caliber rifle incorporating a radar measuring system in perspective view.

The noise filter 1 according to 1 has a hollow body 2 designed as a straight hollow circular cylinder open on both sides with the hollow body wall 2.1 made of plastic that encloses the inner cavity 2.2. Eight circular cylinder rod-shaped, metallic shielding inserts 3 are embedded in the hollow body wall 2.1. Each of the shielding inserts 3 runs longitudinally in an axial plane 4.1 of the hollow body 2 containing the hollow body axis 4. The rod-shaped shielding inserts 3 according to the first embodiment of the noise filter 1 according to 1 are aligned parallel to the hollow body axis 4. In addition, the shielding inserts 3, which all have the same cross-sectional geometry, are arranged evenly spaced from one another in each radial plane 4.2 perpendicular to the hollow body axis 4 on a circle concentric to the hollow body axis 4. This arrangement of the shielding inserts 3 according to 1 has an eightfold rotational symmetry with respect to the hollow body axis 4. To illustrate the position and orientation of the axial planes 4.1 and the radial planes 4.2 of the hollow body 2, 1 An axial plane 4.1 and a radial plane 4.2 of the hollow body 2 are shown as examples; the shielding inserts 3 are shown with partially hidden edges for better understanding.

The second embodiment of the noise filter 1 according to 2 also has a hollow body 2 designed as a straight hollow circular cylinder that is open on both sides. It comprises 18 rod-shaped shielding inserts 3, which consist of two subsets, each with a different cross-sectional geometry. The shielding inserts 3 are arranged parallel to the hollow body axis 4 in a six-fold rotational symmetry with respect to the hollow body axis 4. The shielding inserts 3 with the larger cross-section are arranged evenly spaced from one another in each of the radial planes 4.2 lying perpendicular to the hollow body axis 4 on a circle lying concentrically to the hollow body axis 4. Two shielding inserts 3 with a smaller cross-section are arranged between two shielding inserts 3 with a larger cross-section, whereby these two shielding inserts 3 with a smaller cross-section, each lying between two adjacent shielding inserts 3 with a larger cross-section, run in an axial plane 4.1. In the radial planes 4.2, the shielding inserts 3 with smaller cross-sections lie on two concentric circles.

The third embodiment of the noise filter 1 according to 3 corresponds with regard to the shielding inserts 3 or their arrangement to the first embodiment according to 1 , but in contrast to the first embodiment, it has a hollow body 2 with a cuboid-shaped outer contour and a circular-cylindrical cavity 2.2.

The noise filter 1 according to the fourth embodiment of 4 has a hollow body 2 designed as a straight hollow truncated cone that is open on both sides. The rod-shaped shielding inserts 3 are in turn each in a hollow body axis 4 containing the axial plane 4.1 of the hollow body 2; they follow the surface lines of the hollow truncated cone, running approximately in the middle of the wall thickness in the hollow body wall 2.1.

Furthermore, 4 the noise filter 1 according to the fourth embodiment as part of the radar measuring system according to the invention: The noise filter 1 with the conical hollow body 2 is mounted on the radar measuring system chip 5, which contains the radio wave emitter and the radio wave receiver, in such a way that the radio waves emitted by the radio wave emitter run parallel to the hollow body axis 4 through the cavity 2.2 of the hollow body 2.

The 5 shows, based on the design of the launching device 6 in the form of a hunting rifle, two possible positions for attaching the radar measuring system, namely, on the one hand, a position in the muzzle area of the barrel 6.1 and, on the other hand, a position on the aiming optics of the hunting rifle.

Another mounting position of the radar measuring system illustrates the 6 , in which a sports shooter is shown with a launching device 6 in the form of a small-caliber rifle during shooting training. The radar measuring system is attached to the forearm of the small-caliber rifle. Using the radar measuring system, it is possible to record the parameters of the projectile fired by the small-caliber rifle. Based on the precise knowledge of the projectile parameters, the shooting performance of athletes can be specifically optimized.

list of reference symbols

1

noise filter

2

hollow body

2.1

hollow body wall

2.2

cavity

3

shielding insert

4

hollow body axis

4.1

axial plane of the hollow body

4.2

radial plane of the hollow body

5

radar measurement system chip

6

launcher

6.1

run

Claims (10)

Noise filter (1) for a radar measuring system operating by means of electromagnetic radio waves, which has a hollow body (2) which is rotationally symmetrical to a hollow body axis (4) of the hollow body (2) and is extended along the hollow body axis (4) over an axial total length, wherein the hollow body (2) has an axially continuous cavity (2.2) which extends along the hollow body axis (4) and is surrounded by a hollow body wall (2.1), and wherein the hollow body wall (2.1) is made of a base material which is permeable to electromagnetic radio waves, characterized in that the noise filter (1) has a plurality of rod-shaped shielding inserts (3) which extend over the entire length of the hollow body (2), are embedded in the hollow body wall (2.1), are each straight and are each formed from a shielding material which is impermeable to electromagnetic radio waves, wherein each of the shielding inserts (3) is in an axial plane containing the hollow body axis (4) (4.1) of the hollow body (2), and wherein the shielding elements (3) are arranged in the hollow body wall (2.1) with at least a threefold rotational symmetry to the hollow body axis (4). Noise filter (1) after claim 1 , characterized in that the base material of the hollow body wall (2.1) is a non-metallic material. Noise filter (1) after claim 1 or 2 , characterized in that the shielding material from which the shielding elements (3) are formed is a metallic material. Noise filter (1) according to one of the Claims 1 until 3 , characterized in that the shielding elements (3) are formed from a wire-shaped, a powder-shaped or a powder-based shielding material. Noise filter (1) according to one of the Claims 1 until 4 , characterized in that the hollow body (2) is a straight hollow cylinder. Noise filter (1) according to one of the Claims 1 until 5 , characterized in that the shielding elements (3) within their entirety or within each of several subsets in a radial plane (4.2) of the hollow body (2) lying perpendicular to the hollow body axis (4) each have the same cross-sectional geometry. Noise filter (1) after claim 6 , characterized in that the shielding elements (3) with the same cross-sectional geometry are arranged at equal distances from one another in each radial plane (4.2) of the hollow body (2) lying perpendicular to the hollow body axis (4) on a circle lying concentrically to the hollow body axis (4). Radar measuring system, characterized in that it comprises a noise filter (1) according to one of the Claims 1 until 7 wherein the hollow body axis (4) is aligned parallel to the electromagnetic radio waves emitted by a radio wave emitter of the radar measuring system. radar measuring system according to claim 8 , characterized in that the radio wave emitter of the radar measuring system is designed to emit electromagnetic radio waves with a predetermined radio wavelength (λ), wherein the shielding elements (3) in the hollow body (2) of the noise filter (1) are arranged such that in each radial plane (4.2) of the hollow body (2) lying perpendicular to the hollow body axis (4), each of the shielding elements (3) has a distance from its respectively adjacent shielding element (3) which is in the range of 40% to 60% of the radio wavelength. Launching device (6) comprising a barrel (6.1) for launching projectiles or projectiles, characterized in that the launching device (6) comprises a radar measuring system according to claim 8 or 9 wherein the hollow body axis (4) is aligned parallel to the barrel (6.1) of the launching device (6).

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