GB2081546A

GB2081546A - Apparatus for testing a position finding system

Info

Publication number: GB2081546A
Application number: GB8118769A
Authority: GB
Original assignee: Eltro GmbH and Co
Current assignee: Eltro GmbH and Co
Priority date: 1980-06-28
Filing date: 1981-06-18
Publication date: 1982-02-17
Also published as: FR2485746A1; FR2485746B1; DE3120344A1; GB2081546B; DE3120344C2

Abstract

Apparatus for testing a position finding system 1 which includes an input lens for receiving visual or infra-red radiation from a remote moving radiation source such as a missile, comprises a target simulator 3, 6 for mounting on the position finding system 1, the unit having a collimator for developing an image of a test radiation source in the simulator, a deflecting unit including a pair of rotatable optical wedge prisms, and an electronic unit 7 which (a) controls the deflecting unit to project the test source image into the input lens at a desired position, and (b) compares 8 data representing the desired position with actual position data received from the position finding system 1 to produce a display 9 indicating deviation of the actual position from the desired position. <IMAGE>

Description

SPECIFICATION Method of and apparatus for testing a position finding system This invention relates to a method of and apparatus for testing the operation of a position finding system, the system including a goniometer for determining the deviation values of a missile or target.

German Offenlegungsschrift No. 2722018 discloses observation apparatus in which, by means of a diaphragm in the form of a liquid crystal matrix, the field of vision can be narrowed around an observed target or completely darkened. Such a diaphragm suppresses undesired peripheral radiation while transmitting only visual radiation required for observation and/or guidance of a projectile.

German Offenlegungsschrift No. 26 28 11 7 shows and describes an electronically operating signal simulator for rocket weapon systems. Due to the high cost involved, such systems are not suitable for carrying out practice shots. This simulator enables simulated practice shots to be undertaken and allows the guidance system to be checked. A first frequency divider chain is used to simulate radiation intensity fluctuations while a second frequency divider chain simulates the amount and phase of target or missile deviation from a reference axis.

It is an object of this invention to provide a means of functionally testing position finding systems of the type referred to above without requiring the presence of actual missiles or targets.

According to the invention, there is provided a method of testing the operation of a position finding system which includes a goniometer for determining deviation values of a remote moving radiation source such as a missile from a reference axis and which comprises an input lens and fields of vision for detecting radiation emanating from the source, wherein a test radiation source symbolising a source whose position is to be determined, or an image of the test source, is projected into the input lens from an adjacent test unit as a desired reference position, and which position is compared with an actual position indicated by the position finding system, and wherein a deviation of the actual position from the desired position is shown on a display.

Use may be made of a reducible field of vision provided in the position finding system for tracking and/or background radiation suppression, or a reduced field of vision in the test unit.

In this way, functional breakdowns, attributable for example to the goniometer or to a failure in the tracking of the reduced field of vision, can be checked in real time, that is allowing only for the time constant peculiar to the system. The testing processes can be carried out automatically. Simulated target movement can be achieved by mechanical, visual, or electronic means, or by combination of any or all of these.

Advantageously the desired position can be statically or dynamically predetermined. As a result, a maximum possible tracking speed can be ascertained. Preferably, the result of the comparison of actual and desired positions is given as a YES/NO display and/or as an effective deviation value. In this way, it is possible virtually simultaneously with undertaking the actual test also to be able to display the required information.

Apparatus for carrying out the method of the invention preferably includes a test unit attachable to the position finding system for projecting a test radiation source or an image of the said test source into the input lens, the test unit comprising a collimator for forming the test source, and a deflecting unit, which unit is coupled to a first electronic unit for establishing a desired position of the test source radiation projected to the position finding system, the test unit further comprising a second electronic unit connected to the position finding system for receiving signals representing an actual position from the latter and for comparing the actual position with the desired position.

The position finding system may form part of a missile launcher unit. An economical factor of the apparatus in accordance with the invention is that a commercially available collimator may be used which can be easily connected to the position finding system together with the deflecting unit and the electronic units. The deflecting unit may be used to vary the position of a spot of light projected by the collimator within the field of vision, the position also being variable at an adjustable rate. The deflecting unit may comprise a refracting or reflecting visual or electrovisual system generating appropriate movement functions, e.g. a mirror, a prism, a diaphragm, a rotary wedge or a plurality of rotary wedges, the diaphragm preferably being a liquid crystal matrix.It is furthermore expedient for one pair of rotary wedges or the individual elements thereof to be jointly or individually movable with a mutually defined phase relationship.

A further feature of the preferred apparatus provides for the target point collimator to be augmented by a movable second diaphragm.

The invention will now be described by way of example with reference to the drawings in which: Figure 1 is a block diagram of the mechanical layout of apparatus for carrying out the invention shown in an operative position adjacent a position-finding system to be tested; and Figure 2 is a block circuit diagram of the apparatus of Fig. 1.

Referring to Fig. 1, a position-finding system 1 to be tested has an input lens 2 which in normal use receives radiation from a moving radiation source such as a missile. Fixed to the lens 2 for testing purposes is a deflecting unit 3 which forms part of testing apparatus. The deflecting unit 3 has a pair of rotatable wedges 4 and 5, and is coupled to a collimator 6. The latter signals or transmits an infinitely depicted spot of light. An integral or physically separate electronic unit 7, 8 controls operation of the deflecting system 3 and the collimator 6. In other embodiments not shown in the drawings the deflecting unit 3 may also comprise a mirror, a prism, a diaphragm or just a single rotary wedge, without departing from the scope of the present invention.Alternatively, the deflecting unit may be dispensed with, and instead the collimator 6 could be arranged so that it is itself movable, or is augmented by a second, movable diaphragm.

Fig. 2 shows the signal paths required for data comparison. A missile is simulated by a radiation source or its image 10 which is focussed by the lens 2 (Fig. 1) in the positionfinding system 1. By accordingly actuating deflecting system 3 (which is here combined with the collimator 6 in the "target simula tor") all the necessary movement patterns of a missile image can be simulated in the fields of vision of the position finding system 1. The rotary wedges 4 and 5 can be moved either jointly or individually with a mutually defined phase relationship. The simulated missile generated by the simulator 3, 6, may be considered for the present as representing a desired position having co-ordinates which are fed to an electronic position determining unit 7.

When testing the system 1, ideally these coordinates shall match the position information, the so-called actual position, emanating from a goniometer or reduced field of vision (not shown in the drawings) forming part of the system 1.

Coincidence of desired and actual positions happens when the diaphragm tracked by the goniometer with its own electronic unit allows radiation from the simulated missile to reach the goniometer substantially without attenuation. Coincidence of desired and actual positions is detected by the electronic device 8 and indicated in the display 9. On the other hand, the positions are not coincident, but within a certain tolerance, this means that the reduced field of vision of the radiation source or its image is not being perfectly tracked mechanically, visually or electronically. The actual display may take the form of an image or a YES/NO indication in the display 9. The test processes described may be performed automatically. They may be dynamic or static tests.

In summary, the combination of a position finding system with a collimator and a deflecting unit allows an otherwise static spot of light to be placed on any required point in the field of vision of the position finding system for test purposes. Apart from the few moments while it is being coupled to the target simulator, the position finding system remains ready for use at all times.

Claims

1. A method of testing the operation of a position finding system which includes a goniometer for determining deviation values of a remote moving radiation source such as a missile from a reference axis and which comprises an input lens and field of vision for detecting radiation emanating from the source, wherein a test radiation source symbolising a source whose position is to be determined, or an image of the test source, is projected into the input lens from an adjacent test unit as a desired reference position, and which position is compared with an actual position indicated by the position finding system, and wherein a deviation of the actual position from the desired position is shown on a display.

2. A method according to claim 1, wherein the actual position is determined by means of a reducible field of vision device in the position finding system.

3. A method according to claim 1 or claim 2 wherein the desired position is statically or dynamically predetermined.

4. A method according to any preceding claim, wherein the result of the comparison of desired and actual positions is indicated as a YES/NO display and/or as an effective deviation.

5. Apparatus for testing a position finding system which includes a goniometer for determining deviation values of a remote radiation source from a reference axis, the system having an input lens for passing radiation emanating from the source to the goniometer, wherein the apparatus comprises a test unit attachable to the position finding system for projecting a test radiation source or an image of the said test source into the input lens, the test unit comprising a collimator forming part of the test source, and a deflecting unit, which unit is coupled to a first electronic unit for establishing a desired position of the test source radiation projected to the position finds ing system, the test unit further comprising a second electronic unit connected to the position finding systems for receiving signals rep resenting an actual position from the latter and for comparing the actual position with the desired position.

6. Apparatus according to claim 5, wherein the deflection unit is arranged such that the position of the projected test source image in the field of vision is alterable at a variable rate.

7. Apparatus according to claim 5 or claim 6, wherein the deflecting unit comprises a refracting or reflecting optical or electrooptical system for generating corresponding movement functions.

8. Apparatus according to any of claims 5 to 7, wherein the deflecting unit comprises a mirror, a prism, a diaphragm, or a rotary wedge, or a plurality of rotary wedges.

9. Apparatus according to claim 8, wherein the diaphragm comprises a liquid crystal matrix.

10. Apparatus according to any of claims 5 to 7, wherein the deflecting unit comprises a pair of rotary wedges which are jointly or individually movable with a mutually defined phase relationship.

11. Apparatus according to claim 5, wherein the collimator is movable.

1 2. Apparatus according to claim 5, wherein the collimator is augmented by a further movably disposed diaphragm.

1 3. A method of testing a position finding system substantially as herein described with reference to the drawings.

1 4. Apparatus for testing a position finding system constructed and arranged substantially as herein described and shown in the drawings.