RU2467349C1 - Rls for measurement of initial speed of projectile installed on weapon barrel - Google Patents

Abstract

FIELD: measurement equipment.

SUBSTANCE: invention relates to radiolocating equipment. The target set is achieved by transfer of a measured base at a closer distance to a weapon barrel end. An RLS for measurement of an initial speed of a projectile installed on a weapon barrel, comprises a transceiving antenna, an input of which, operating for transfer*, is connected to a high-capacity output of a transmitter of a continuous signal with frequency modulation in accordance with a one-sided saw-tooth linearly descending law, and an output operating for reception is connected to the first input of a mixer, the second input of which is connected to a low-capacity output of a transmitter of a continuous signal with frequency modulation in accordance with a one-sided saw-tooth linearly descending law, and an output - via a filter of differential frequencies, to the first input of the second mixer, and also the following components connected in series - a wideband filter, a limiting amplifier, a narrowband bandpass filter, an amplitude detector, a comparator, a pulse shaper, a metre of a time interval, a calculator of an initial speed of a projectile and a generator of continuous frequency, and also a trigger, the second generator of continuous frequency, an analog key, the output of which is connected to the second input of the second mixer, and a control input is via a trigger connected to the output of the pulse shaper.

EFFECT: improved accuracy of measurement of initial speed of projectiles.

Description

The invention relates to radar technology and can be used to measure the initial velocity of the shells.

In accordance with the theory of external ballistics, the initial velocity of a projectile is determined as follows.

On the line coinciding with the longitudinal axis of the gun barrel, select a section of the trajectory (base) of a fixed length S, measured with high accuracy. At the beginning of D ₁ and the end of D _{2 of the} base, sensors are installed that respond to the passage of the projectile (target frame, solenoid, photo blocker, etc.) The sensor installed at the beginning of the base is located at a distance Do = D ₁ from the cut of the gun barrel, which also measured with high accuracy. After the shot, with the help of a precision meter, the time tv of the projectile’s flight of a given base is estimated and the average projectile speed is calculated on it using the formula:

Using the obtained Vcp, the initial velocity of the Vo projectile is calculated by the formula:

Vo = ΔV (D) + Vcp,

where ΔV (D) = 10 ⁴ id ² x / 2mΔD (V), the decrease in the velocity of the projectile when it spans a range from the cut of the gun barrel to the middle of the base (i.e., on a length of D = x = Do + S / 2) .

Here: i is the shell shape coefficient; d is the caliber of the projectile; m is the mass of the projectile;

m ΔD (V) is the function of the dependence of range on the velocity of the projectile, the values of which for the Siacci law are found in special tables.

We write the value of the initial velocity of the projectile through the dependence of the decrease in its linear velocity on the distance from the cut of the gun barrel. Why determine the values of the linear velocity of the projectile at the beginning and end of the selected base:

V _D1 = Voi-ki D ₁ ,

V _D2 = Voi-ki D ₂ .

Then the average velocity of the projectile is defined as:

Vcp = [2Voi- (ki D ₁ + ki D ₂ )] / 2 = Voi-0.5 (ki D ₁ + ki D ₂ ).

Where from

Voi = 0.5 (ki D ₁ + ki D ₂ ) + (D ₂ -D ₁ ) / tv

or

Voi = 0.5ki (2D ₁ + S) + S / tv.

Analyzing the last expression, it can be argued that the initial velocity of the Voi projectile depends on the distance D _{1 of the} base S = D ₂ -D ₁ from the radar and on the time tv of its projectile passage.

Starting from the 70s of the last century, the simplest Doppler radars began to be used to determine the initial velocity of ammunition, creating artillery ballistic stations (ABS) based on them, monitoring them on the flight path. Moreover, the observation begins after a predetermined time after the departure of the projectile from the gun barrel. So, for example, in the Ramp product, an extrapolation method is implemented, according to which the type of “high-speed” projectile trajectory is assumed to be known, and the discrete values of its current speed determine the parameters of this “high-speed” trajectory necessary to extrapolate the projectile speed from the beginning of its radar observation to the moment of departure from the gun barrel [Patent RU, No. 2250476, 2002].

When the projectile leaves the gun’s barrel, an ionized cloud appears, which shields the projectile from the ABS radar, which, according to the authors of the patent, dissipates, and the projectile motion becomes more stable only after about (0.05 ÷ 0.15) s. Therefore, in the ABS, a delay is set for the start of the formation of the Doppler echo of the projectile, the processing of this signal and the calculation of the actual initial velocity of the projectile, i.e. base S is installed at a certain distance D ₁ from the ABS.

Known radar for measuring the initial velocity of a projectile using a method for determining the moments of passage by a projectile of the beginning and end of a known distance interval [patent 2367975, RU, G01S 13/58] containing a transmitting and receiving antenna, the input of which is working on a transmission, connected to a high-power output of a continuous transmitter a signal with frequency modulation according to a one-sided sawtooth linearly decreasing law, and the output operating at the reception is connected to the first input of the mixer, the second input of which is connected to the low-power output of the transmitter a, and the output is to the input of the difference frequency filter, as well as a series-connected continuous frequency generator, a second mixer, a broadband filter, an amplifier-limiter, a narrow-band pass filter, an amplitude detector, a comparator, a pulse shaper, a time interval meter and an initial projectile velocity calculator, the second input of the comparator is connected to the voltage reference bus, and the first input of the second mixer is connected to the output of the difference frequency filter.

Due to the ionized cloud shielding the projectile from the radar, in the known radar also the base S is set at a certain distance D ₁ from it.

One of the main requirements for measuring the initial velocity of shells is to ensure high accuracy in determining the velocity of the shell at the time of its departure from the gun’s barrel with minimum mass-dimensional and cost characteristics of the products.

The aim of the invention is to improve the accuracy of measuring the initial velocity of the projectile.

The goal is achieved by transferring the measured base to a closer distance to the cut of the gun barrel.

The radar for measuring the initial velocity of the projectile mounted on the gun’s barrel is made in the form of radar for measuring the initial velocity of the projectile according to Patent No. 2367975, RU, G01S 13/58 with an additional trigger, a second continuous frequency generator and an analog key. The outputs of the first and second continuous frequency generators are connected respectively to the first and second inputs of the analog switch, the output of which is connected to the second input of the second mixer, and the control input is to the output of the trigger, the input of which is connected to the output of the radar pulse shaper.

Let us analyze, including, by way of example, the work of the radar measuring the initial velocity of a projectile mounted on the gun’s barrel.

As already noted, when the projectile leaves the gun’s barrel, an ionized cloud appears, which shields the projectile from the radar, which leads to the need to establish the measuring base S at a certain distance from the radar and reduce the accuracy of measuring the initial velocity of the projectile. It should be noted that at projectile velocities of the order of 2000 m / s, S base due to the ionized cloud screening the projectile will need to be installed at a distance of about 2000 m / s from the radar × (0.05 ÷ 0.15) c = (100 ÷ 300) m.

Consider whether it is possible to make radar measurements of the initial velocity of the projectile with the minimum possible distance from her base S, in order to improve the accuracy of measuring the initial velocity of the projectile. Why add to the detector signals of the narrowband frequency spectrum of the radar measuring the initial velocity of the projectile [patent No. 236775, RU, G01S 13/58] a continuous signal generator with a frequency of, for example, 500 kHz. At the same time, we will connect the used (with a frequency, for example, 100 kHz) and newly introduced continuous frequency generator to the second radar mixer via an analog key controlled by voltage. And also, let signals with, for example, parameters: fo = 100 GHz, Fm = 50 kHz, dfm = 200 MHz, satisfying, for example, at a distance Do = 1.5 m and Vo = 150 m / s condition:

Do / Vo = fo / Fm dfm = 1.5 m / 150 (m / s) = 100 GHz / 50 kHz 200 MHz = 0.01 s.

Then it is obvious that when a projectile leaves the gun barrel a reference signal with a frequency of 100 kHz arrives at the second radar mixer, then a short pulse will appear at the radar output when the projectile is at a distance of D _21.5 = 21.5 m from the radar, t. e. when a difference signal is generated at the output of the microwave radar mixer:

Fp _21.5-C = [(2D _21.5 ) Fm dfm / C] - (2V ₂₀₀₀ fo / C) = 100 kHz -

- a signal from reflections from a projectile moving away with a radial velocity of 2000 m / s.

The first short pulse from the output of the radar, for example, the trigger is translated into a state with a potential at the output, allowing through the analog key to the second mixer to pass the reference signal with a frequency of 500 kHz. In this case, a difference signal with a frequency of 100 kHz at the output of the microwave radar mixer will cease to be formed even if, for example, a long projectile still does not completely pass a space point 21.5 m away from the radar antenna. Since this projectile will travel faster than the ionized one cloud, and in this case the reference frequency changes at the input of the second radar mixer, then at the output of the microwave radar mixer, a difference signal with a frequency of 100 kHz from the ionized cloud will not be formed.

A second short pulse at the radar output will appear when the projectile is at a distance of D _24.5 = 24.5 m from the radar, i.e. when a difference signal is generated at the output of the microwave radar mixer:

Fp _24.5-C = [(2D _24.5 ) Fm dfm / C] - (2V ₂₀₀₀ fo / C) = 300 kHz.

With a second short pulse from the radar output, the shift register is transferred to a state with a potential at the output, which allows the reference signal to pass at a frequency of 100 kHz through an analog switch to the LF mixer. In this case, a 300 kHz difference signal at the output of the microwave radar mixer will cease to be formed even if the projectile does not completely pass a space point 24.5 m away from the radar antenna. That is, at the output of the 300 kHz difference microwave radar mixer the signal is generated from the ionized cloud also will not be.

Obviously, as follows from the above, with the proposed method for measuring the initial velocity of the projectile, the base S = (24.5-21.5) = 3 m is located at a distance of 21.5 m from the radar antenna. In the well-known radar for measuring the initial velocity of the projectile, the base S would need to be installed at a distance, as already noted, (100 ÷ 300) m from the radar.

Claims (1)

The radar for measuring the initial velocity of the projectile mounted on the barrel of the gun, containing the transmitting and receiving antenna, the input of which is working on the transmission, is connected to the high-power output of the transmitter of a continuous signal with frequency modulation according to a one-sided sawtooth linearly decreasing law, and the output working on reception is connected to the first input of the mixer, the second input of which is connected to the low-power output of a continuous signal transmitter with frequency modulation according to a one-sided sawtooth linearly decreasing law, and in the path is to the input of the difference frequency filter, as well as a second mixer, a broadband filter, an amplifier-limiter, a narrow-band pass filter, an amplitude detector, a comparator, a pulse shaper, a time interval meter, an initial projectile velocity calculator, and a continuous frequency generator, while the second the comparator input is connected to the voltage reference bus, and the first input of the second mixer is connected to the output of the difference frequency filter, characterized in that a trigger is additionally introduced into it , a second continuous frequency generator and an analog switch, while the outputs of the first and second continuous frequency generators are connected respectively to the first and second inputs of the analog switch, the output of which is connected to the second input of the second mixer, and the control input to the output of the trigger, the input of which is connected to the output pulse shaper.