RU1801217C - Method for measuring closing speed - Google Patents

Abstract

The invention relates to electron-optical systems, in particular to aircraft heat direction finders and homing systems for guided missiles with a thermal homing head. An object of the invention is to provide proximity measurement in passive location systems. The goal is achieved by calculating the atmospheric attenuation index under these conditions, which is multiplied by the value of the received signal from the emitted object, the received signal from the emitting object is differentiated by time, the value of which is divided by the product of the atmospheric attenuation index by the value of the received signal . 1 ill.

Description

The invention relates to electron-optical systems, in particular, cavitation heat direction finders and homing systems for guided missiles with a thermal homing head.

An object of the invention is to provide proximity measurement in passive location systems.

Achieving this goal can be achieved using the well-known laws of attenuation of radiant energy by the atmosphere. The attenuation in the haze, as well as during dispersion on large foreign particles of fog, obeys an exponential law, according to which the intensity of the received signal W at any distance D from the radiating energy source can be determined from the expression.

"Ok

(D

where W0 is the radiation intensity of an object in a given direction at zero range; . .

and a is a general indicator of atmospheric attenuation.

Differentiating expression (1) in time, we obtain

  ,

From this expression we obtain the value of the approach velocity

DW

aa-wo t. or, taking into account (1), we have W

D

aa W

(2)

00

about

hO

no

Xi

 CO

To date, it has not been possible to use this dependence to measure the speed of approach to the observed object due to the unknown value of the total atmospheric transmittance a a.

The ccp value is not known in practice, as it can vary markedly from one day to another. Since the time of tracking, for example, an air target by a heat direction finder, as well as the flight time of a rocket to a target is short, although the value of a a is an unknown but constant value. The value of a is defined

to fly directly in flight under the same weather conditions in which a passive location system will be used, for example, before launching a rocket. For experimental determination of a a, a firing is carried out, for example, of a signal rocket, the emission spectrum of which corresponds to the working spectrum of a radiant energy receiver, which is on board passive.

Having logarithmized (1), it is easy to obtain an expression for determining the general indicator of atmospheric attenuation under given conditions applicable only to a signal rocket

,

"and.

In W to - In W

where the value of the distance Dp to the flare is a known function of time. Provided that the direction of the signal rocket’s shot coincides with the direction of the velocity vector of the aircraft itself, the time of the active sections of the signal rocket’s flight is small and the acceleration of the rocket at a given height remains constant, the relative range in (3) can be determined from the expression

(H)

.il 2

where jP (H) is the known acceleration of a signal flare at a given height H;

tp is a predetermined time (e.g.); after firing a signal packet, at which moment the total atmospheric transmittance aa is experimentally determined according to expression (3) with allowance for (4). By measuring the value of aa, we can determine the approximation rate of b according to

expression (2).

Thus, the goal is achieved by measuring the total

5

 ABOUT

fifteen

twenty

25

thirty

„- 4Q 45

fifty

55

transmitting the atmosphere aa under the given conditions and then dividing into it the ratio of the time derivative of the received signal A / to the value of the received signal W.

A method for measuring the approach speed in passive location systems is as follows.

The received signals from the observed object are time differentiated to determine their derivative. The resulting time derivative of the received signal is divided by the magnitude of the signal itself. A signal rocket with predetermined energy and aerodynamic characteristics is launched, and after a specified time, the total atmospheric attenuation is measured. The ratio of the time derivative of the received signal from the observed object to the magnitude of the signal itself is divided by this measured indicator.

The measurement of the total atmospheric transmittance during the launch of a signal rocket can be carried out using a device whose functional diagram is shown in the drawing, where it is indicated:.

1 - receiver of radiant energy,

2,3 - logarithm,

4 - subtractive device,.

5 - start button signal flare,

6 - time sensor,

7 - altimeter,

8 - calculator acceleration of the rocket at a given height,

9 - multiplier device

10 - relay

11 - dividing device

12 is a storage device,

JP (°) acceleration of a flare at zero altitude.

The total atmospheric transmittance meter operates as follows.

After pressing button 5, the start of the signal rocket starts the time sensor, 6. The signal W received by the radiant energy receiver 1 is logarithmized by the logarithmator 2 and fed to the second input of the computing device 4, the first input of which is supplied from the output of the logarithmator 3 logarithm of the initial signal intensity W0. From the output of the subtractor 4, the logarithm difference (In W0- -InW) through the relay 10 is fed to the first input of the divider 11, the second input of which is supplied from the output of the multiplier 9 with the calculated distance to the signal rocket Dp at a given point in time after it start up. The measurement time Dp is set by a time sensor 6, the first output of which sends a signal to the relay 10, which ensures the passage of the logarithm difference signal, and from the second output the current time is supplied after starting to the first input of the multiplier device 9. The calculated acceleration value is applied to the second input of this device signal rocket obtained by the entered value of this acceleration at zero height and the value of the height supplied to the second input of the transmitter 8 from the altimeter 7. At the output of the dividing device 11 at a given point in time t after launch, we will have the value of the total atmospheric attenuation index aa. It is stored for the duration of the task in memory 12.

Claims (1)

The claims A method of measuring the speed of approach, which consists in receiving a signal from the observed object, differentiating it in time and determining the speed of approach, characterized in that, with In order to provide measurement of the approach speed in passive location systems, the atmospheric attenuation indicator is additionally measured for a given time, and the approach speed V is determined by the formula: aa, where W is the received signal intensity and aa is the atmospheric attenuation indicator.