Device and method for measuring the muzzle velocity of a projectile or similar

Device and procedure for measuring the velocity in the mouth of a projectile or similar

In DE 697 09 291 T2 (EP 0 840 087 B1) means for controlling the initial speed of a bullet are disclosed. In this regard, a detector means is provided that can measure a parameter related to the speed in the mouth. This is done with the help of the sensors placed at least in or on the barrel of the weapon, which can register a greater pressure in the barrel of the weapon that appears due to the heating of the propellant gases in the tube of the weapon. As sensors, strain gauges are proposed that are adapted in such a way that they have contact with the gun barrel. In this regard, the extent of the gun barrel is measured. The movement and, with it, the velocity of the projectile are established from the difference in time between the recording of the projectile's passage through the two individual sensors.

Document DE 10 2005 024 179 A1 completely dispenses with a direct measurement of the current speed in the mouth, since the actual speed in the mouth is determined by the information of the current flight speed of the bullet, that is, Calculate from it. By means of this current speed of the bullet, the ignition time of the bullet is then corrected with the help of a preset ignition time with a normalized velocity in the mouth and is used as the current time of adjustment of the fuze. For the transmission of this information to the bullet a microwave emitter is used, preferably in the GHz range, which sends the current time programming determined, for example, by a fire direction computer to the ammunition or to a bullet.

An additional method is to operate the tube as a round waveguide and measure the Doppler velocity of the projectile in the tube, as can be found in EP 0 023 365 A2. In this regard, the signal frequency is above the limit frequency for the respective waveguide mode. The electromagnetic wave that is generated at the same time propagates in the tube and is reflected by the projectile. In addition, a displacement of the Doppler frequency is obtained which depends on the momentary speed.

Document DE 27 17 949 A1 describes an apparatus for measuring velocities in the barrel by means of the use of electromagnetic waves, using the wavelength wave of the barrel as a scale for the modification of the trajectory of a bullet in the barrel. For this, a transmitter and a reception detector with a constant separation from the barrel are arranged. In this regard, the bullet is used as a reflector for electromagnetic waves. A horn antenna is placed in the mouth of the barrel in an embodiment with rotational symmetry. In the direction of the bullet, a mirror is disposed, inclined, which deflects the waves from the rectangular horn antenna corresponding to the barrel. The wavelength of the waveguide of the barrel is determined by moving in the barrel slowly in a defined way, in a particular test, instead of the bullet a mirror for the electromagnetic waves and when registering, therefore, the separation between two maxima by technique measurement.

From EP 0 331 670 A1, a procedure and equipment for the determination of internal ballistics parameters in cannon weapons are known, an electromagnetic wave being coupled through a waveguide transition provided laterally in the gun tube and decoupling again after reflection in the bullet that is in the gun tube, such that significant measurements are possible even with a bullet shot. In this regard, it is based on the fundamental consideration of irradiating at least half of the energy of the electromagnetic waves from the mouth of the gun tube instead of coupling it in the direction of the bullet. For the coupling of the waves, they are divided and supplied at least two separate points from the transition of the waveguide to the weapon tube, so that the wave parts that propagate in the direction of the bullet are added and compensated the wave that propagates in the opposite direction.

The document DE 10 2006 058 375.2 published later proposes to use the gun tube or the firing tube and / or mouth brake parts as waveguide (as waveguide a tube with a characteristic cross-sectional shape, which has an electrically wall Very conductive.They are technically widespread, especially rectangular and round waveguide), which, however, is operated below the limit frequency of the corresponding waveguide mode. In this case, the separation between the emission coupler and the reception coupler is fixed.

Pursuing the same idea, the invention aims to indicate another measurement procedure and a device for carrying out this measurement procedure, which enables an excellent and precise establishment of the velocity in the mouth of a projectile or the like.

The objective is solved by the characteristics of claim 1 with respect to the measuring device and of claim 6 with respect to the measurement procedure. Advantageous embodiments are indicated in the respective dependent claims.

The invention is based on the idea of ​​measuring or determining the velocity itself in the mouth, preferably, in front of or behind the projectile, a combination of the measurement accuracy increasing considerably. The measurement in front of the projectile then takes into account the fact that the tip of the projectile, when passing through the waveguide, influences the electromagnetic field. This influence is compensated by being known, as a general rule, the type of ammunition, in such a way that values ​​that determine the projectile are used, which then allow the influence of the tip on the measurement to be compensated. With the measurement behind the projectile, the cylindrical shape of the bottom is used, so the measurement is carried out independently of the shape of the projectile's tip. In this case, the

5 background influences the electromagnetic field. The measurement method after projectile passage is reasonable because most types of projectile have cylindrical flat bottoms. This respective modification is registered by a receiving coupler and is supplied to an evaluation team.

Preferably, as a waveguide a smooth tube of any cross-section is used, unlike the application

10 published later (see above), in which a waveguide with a profile is used as waveguide. In addition, with the help of at least one emission coupler and one reception coupler, the electromagnetic field is registered without the presence of the projectile, that is, before the projectile crosses the waveguide. The last scan values ​​before the passage of each projectile are used for the measurement calibration. In this way, all influences due to temperature or others are recorded in the calibration. When passing the projectile is registered

fifteen Temporary change of the electromagnetic field and normalizes with calibration. Therefore, the measurement of the speed in the mouth is performed independently of changes in temperature or other influences.

The signal generator (for example, oscillator) provides a signal with a constant medium frequency, which is operated below the lower frequency limit of the waveguide. Due to the geometry and type of the emission coupler (coil, dipole, etc.) several waveguide modes are excited (TEmn with m = 0, 1, 2 ... and n = 1, 2, 3 ...). The signal generator generates a carrier in continuous mode (CW mode) or a modulated signal.

The separation between an emission coupler, which, in turn, obtains the oscillator signals, and the reception coupler is variable and can be chosen individually depending on the waveguide mode selection, without

25 However, it depends on the caliber, the internal dimension of the waveguide as well as the frequency.

By means of an exemplary embodiment with drawing, the invention has to be explained in more detail. It shows:

In Figure 1, a measurement arrangement for measuring the velocity at the mouth of a projectile in front of the projectile,

In Figure 2, a measurement arrangement for measuring the velocity at the mouth of the projectile behind the projectile.

35 With 1, a smooth waveguide (tube) is indicated, in which (at least) an emission coupler 2 as well as (at least) a reception coupler 3 are incorporated. An oscillator 4 is connected with the emission coupler 2 and an evaluation device 5, with the reception coupler 3. With the elements mentioned above, the speed in the mouth of a projectile 6 can be determined. With 7 the mouth of the gun or firing tube 1 is indicated.

40 The oscillator 4 excites, through the emission coupler 2, a waveguide mode (transversely electric = TE and transversely magnetic = TM. The desired waveguide mode is excited by a selection of mechanical and electromagnetic modes.) In a first stage measures the electromagnetic field without projectile 6. Through the "tube" system 1 (waveguide 1) a signal strength is obtained that picks up the receiving coupler 3, for example, a pick-up sensor, and is conducted to the evaluation unit 5. Then the

Four. Five measurement in front of projectile 6 (Figure 1) or behind projectile 6 (Figure 2).

The separation between the emission coupler 2 and the reception coupler 3 is variable and can be chosen individually depending on the mode selection of the waveguide 1, however, it depends on the caliber, the internal dimension of the waveguide 1 as well as the frequency.

fifty If waveguide modes are excited through the emission coupler 2, the received signal (for example, voltage

being at the internal radius of waveguide 1 and depending on An as well as Pn of n. In this regard, it is true that P1 <55 P2 <P3 <....

In turn, zk is chosen in such a way that the reception signal is dominated, for example, only by the term n = 1 (one way operation).

This is possible since the terms for n = 2, 3, 4 in zk become much smaller than the term n = 1. This is important as long as the term with n = 1, in particular, guarantees a reliable measurement of the projectile speed in flight.

Mainly,

It depends on a. a is determined by caliber. Since the signal frequency of

emission is less than the limit frequency, an exponential path for the reception signal occurs.

If measured after the passage of projectile 6, the receiving coupler 3 must be placed between the bottom of the projectile and the emission coupler 2. If the velocity measurement V0 is carried out before the passage by flight of the projectile 6, then the receiving coupler 3 should be placed between the tip of the projectile and the emission coupler 2. If both measurement methods are combined, two reception couplers 3 must be incorporated accordingly. Then, the transmission coupler 2 would have to be incorporated between the two reception couplers 3.

Signal processing should be carried out as follows:

When the projectile 6 flies past the receiving coupler 3, a characteristic signal is obtained, as is known. The time travel of the received signal provides information about V0.

To now obtain the V0 from the received signal, the signal is constantly sampled over time in the evaluation equipment 5 and the sampling values ​​are stored. This also occurs when there is no projectile 6. If, now, a projectile 6 flies through the waveguide 1, the evaluation unit 5 perceives the presence thanks to the characteristic path of the reception signal. These values ​​are evaluated for the determination of V0.

Since the evaluation algorithm uses the internal radius a of the waveguide 1, changes in the internal radius due to temperature can cause a measurement inaccuracy. To compensate, for example, these influences, the empty waveguide is measured before each step of the projectile. This current value is used to change the scale of the relevant sampling values ​​and is stored, and is consulted during the measurement evaluation by the evaluation unit (calibration).