FR2714495A1 - System for remote guidance of missile to target - Google Patents

Abstract

The guidance system has a transmitter to send guidance information to the missile and a receiver on the missile to accept this information. The transmitter directs a modulated electromagnetic beam toward the missile. The beam carries coded information for the missile. A receiver on the missile gathers the transmitted signal. Before the missile is launched there is a link circuit connecting transmitter and receiver. Initialisation data is transmitted over this link, including coding information. After launch the missile uses the coding information to compare the received data and the decoded version of the received data. If the comparison indicates the decoded data is valid the information is sent to the missile flight control system.

Description

"REMOTE CONTROL SYSTEM FOR GUIDING A MOBILE ON A TARGET"

  The present invention relates to a remote control system for guiding a mobile device with control surfaces on a target, system comprising on the one hand a transmitter formed by an emission device for sending to the mobile at least one beam of radiation and of a first coding circuit acting on the transmitting device to transmit position information by radiation modulation and on the other hand a receiver attached to the mobile formed by a receiving circuit to supply information from the detected modulation for a control circuit for a control circuit, a link circuit being provided for

  connect the transmitter and the receiver before launching the mobile.

  Such systems are well known and find important applications in the military field where the target is a target.

  destroying and moving a projectile carrying an explosive charge.

  A problem which arises with this kind of system is that due to interference. This jamming can have at least two causes: a first resides in the fact that the enemy can emit a beam of radiation near the mobile in order to distort the position information. A second, in the fact that several mobiles can be directed on the same or on other targets located in the same

  neighborhood. It is therefore important that mobiles receive the right information.

  position training intended for them.

  U.S. Patent No. 4,102,521 describes a

  system like that. To largely eliminate interference

  In the case of untimely readings, a random code word is stored on the one hand in the transmitter to code the position information and on the other hand, via the link circuit, in the receiver to decode it. The link circuit must therefore transmit relatively complex information without error so that decoding can

  be performed satisfactorily at the receiver.

  The present invention provides a system of the kind mentioned in the preamble having good interference immunity while

  avoiding a complex transmission to the link circuit.

  For this, such a remote control system for guiding a mobile target is remarkable in that the receiver includes a second coding circuit, an information comparison circuit for comparing the information transmitted with information produced from the second circuit. coding and a validation circuit for transmitting the control information to the control control circuit only if the comparison circuit indicates that the information to be compared is compatible with each other while

  that the link circuit transmits only initial information

  to initialize the second coding circuit on the

first coding circuit.

  The following description made with reference to the appended drawings,

  all given as nonlimiting examples will make it clear

  how the invention can be realized.

  Figure 1 shows a guidance system.

  Figure 2 shows the shape of the pulse modulation.

  FIG. 3 represents a remote control system conforming

to the invention.

  FIG. 4 represents an alternative embodiment of a receiver suitable for a remote control system according to the invention. In FIG. 1, which represents an overall view of the remote control system, the target bears the reference 1 and the mobile, the reference 3. This mobile 3 is in this example a rocket which carries an explosive charge and which is provided with control surfaces 4 ; the mobile is guided from a shooting station 5. To guide this mobile, a beam of infrared radiation 10 is used, scanning on both sides the target 1; the beam 10 oscillates from an angle cG to an angle c-D; if the shot is aimed correctly the target 1 is located

  on the bisector of the angle odG - cD.

  We call o- (t) the beam angle with respect to ctLD. To define the value of oL (t), the beam of radiation is modulated into pulses; the time between two pulses is it. successive gives a value cLi (t). Figure 2 shows the pattern of the distribution

  temporal of these impulses. Thus the time intervals t.

  between two pulses evolve from a value tMIN for Co (t) close to O (D to a value at tMAX. We can admit, for the sake of convenience, that this law is linear, that is to say that ck, (t) = k At. = k (Ati-l + st)

  where k is a constant and t is a fixed time difference.

  This kind of law which makes a time interval correspond to an angle value is known in particular from the patent of the United States of America

no.3191 175.

  Figure 3 shows the remote control system in more detail.

  To the shooting station 5 (FIG. 1) is attached the transmitter bearing the reference 20 in FIG. 3 and to the mobile 3.1e receiver 25. In this example described, the transmission device 45 is constituted first of all by an assembly rectilinear 50 of laser diodes operating in infrared - the radiation emitted by this assembly 50 is reflected by an oscillating mirror 55 to form the beam 10. This oscillating movement is such that the beam 10 pivots at angles ranging from coD to cG. vs. These extreme positions are detected by probes not shown in the figures and their output signals are confused with the references odD and c, .G. This mirror is driven by a motor 57 of the stepping type; this motor is supplied by pulses coming from an "OR" door 60 provided with two inputs; in order to be able to reverse the direction of rotation of the motor 57, an inverter 62 has been arranged at the output of the door 60, the reversal command of which is provided by the output signal of a flip-flop 64. This flip-flop is set to state "1" by signal x G and state 0 "by signal ED. Thus the motor 57 changes direction as soon as

  an extreme mirror position 55 is detected.

  To modulate the beam 10 Infrared radiation use a first decoding circuit 70 which supplies pulses at its MOD output for the assembly 50. It also supplies the MOT output, via Gate 60, with the pulses for the motor57. The circuit 70 is formed first of all of a down-counter 84 whose clock input CK is connected to the output MOT connected to the first input of the door 60; thus these inputs receive the same signal and it follows that at each position of the mirror 55

  corresponds to a value contained in up-down counter 84. This counter-

  downcounter 84 has a TC outlet which provides a signal as soon as its content reaches an extreme count: maximum or minimum. The active signal causes a flip-flop 86 to change state. The output signal from this flip-flop acts on the command UD of this up-down counter 84 to put it in the up or down counting position. Thus mounted, this downcounter counter 84 is put in the counting position as soon as its content is minimum and in the downcounting position as soon as its content is maximum. The content of this up-down counter 84 is used to address a read-only memory 90. At each address code this memory makes

  match a position code whose numeric value is pro-

  portional to the required time interval duration. This position code is loaded into a down counter 92 which is provided with an input CK for clock signals connected to the output of a quartz oscillator 94; it should be noted now that for the implementation

  in implementing the invention, a quartz of good stability will be chosen.

  The down-counter is provided with an output Z; at this output a signal appears which, active, means that the content of the down-counter 92 is at zero. This output Z is connected to the input CK of the up-down counter 84, to the first input of the door 60 and also to the input L of the down-counter 92, via an OR gate 95 to load the code of position provided by memory 90. Thus the active signal

  at the exit Z appears after a time following loading, pro-

  portable to the code contained in the down-counter 92; a monostable circuit 96 formats the signal at the output Z which is thus made available at the output MOD of the coding circuit 70 and which finally modulates

pulses the whole 50.

  The receiver 25 is formed by a reception circuit 100 comprising a diode 101 sensitive to infrared radiation which, in cooperation with an amplification circuit 105, makes it possible to supply

  pulses each time an infrared radiation reaches it.

  These pulses are supplied to the reset inputIZ of a counter and to a first input of an AND gate 112. The purpose of this counter is to measure the time interval between the reception of two

  impulses. Its capacity greatly exceeds the time between the

  Largest time valle corresponding to the extreme position information. These excess positions of this counter 110 are processed by a "NON- OR EXCLUSIVE" gate 115, the output of which is connected to the second input of gate 112. The output of this gate 112 is connected to the input L of loading of a register 120 whose parallel inputs are connected to the outputs of the non-surplus positions of the counter 110. A surplus account results in the appearance of at least one "1" in the excess positions this therefore inhibits the gate 112. Thus the register 120 cannot contain information corresponding to suitable position information. The times which elapse between each scanning frame when the moving body is no longer in the beam are not taken into account. The content of the register 120 serves as an address to a read-only memory 125 programmed to give control surface information, that is to say a code which causes a command on the control surface 4 to correct, if necessary the trajectory of the mobile. This governance information is presented

  in digital form can be processed by a digital converter-

  analog 130 whose output is connected to the rotation control

  a 135 engine mechanically coupled to the control surfaces 4.

  In addition, the remote control system comprises a link circuit which connects the transmitter 20 with the receiver 25 before launching the mobile; this connection is undone when the mobile separates from the

  firing station 5. A connector 155 allows this removable connection.

  According to the invention, the receiver attached to the mobile 3 includes a second coding circuit 170 (therefore similar to the circuit), a comparison circuit 172 for comparing the control information available at the output of the reception circuit 100 with that supplied to from the second coding circuit 170 and a validation circuit constituted here by a set 174 of switches so as not to transmit control surface information to the control circuit for control surfaces (constituted here by the digital-analog converter 130 and the motor 135) only if the comparison circuit 172 indicates that the information to be compared is compatible with each other, while the link circuit transmits only initialization information produced by a push button 175 coupled to a monostable circuit 176 to initialize the second circuit

  coding 170 on the first coding circuit. For this initialization

  tion the output signal of the monostable circuit 176 is applied on the one hand to the INI inputs with which the coding circuits 70 and 170 are provided and on the other hand to a first input of an "AND" gate 177 with two inputs whose second receives the signal co) after an inversion obtained by a

logic signal inverter 178.

  The output of gate 177 is connected to one of the two inputs of an "AND" gate 179, the second input of which receives pulses from a generator 180. The output of gate 179 is connected to the second

  input of gate OU- 60, the first of which is connected to the MOT output.

  The INI input is connected, via the gate 95, to the input of the counter 92, to the reset input RS of the

  flip-flop 86 and at the reset input RZ of the up-down counter 84.

  On the receiver side, this INI input is connected in the same way to the corresponding elements. In the receiver shown in FIG. 3, the counter 192 (corresponding to the counter 92 of the circuit 70) is used to serve as an addressing device for a memory 185 programmed in a manner identical to that of the memory 125. It will be noted that the clock signal input CK of the counter 110 is connected to the output of a quartz oscillator 194 corresponding to the oscillator 94 and making

part of circuit 170.

  The remote control system of the invention operates from the

  next way. Before launching the mobile, we press the button-

  pusher 175 which can obviously be coupled to the fire control. The monostable circuit 176 is triggered; tilting is slightly more than twice the duration of the rotating mirror

  to rotate the beam from the angle etG towards the anqledD, The pivot-

  ment taking place at the rate of the impulses produced by the generator 180.

  This duration corresponds to the time it takes the mirror to return to the anal & D

  whatever its position and whatever the state of the scale 64.

  The active signal provided by the monostable circuit 176 opens the doors 177 and 179 so that the pulses of the generator 180 are

  applied to motor 57; this lasts until the dD signal becomes active.

  When the signal "D becomes active, the door 177 closes, leading to the closing of the door 179; the mirror 55 is then immobilized. The active signal supplied by the monostable circuit 176 sets the up-down counter inside the circuit 70. 84 and down counter 96 by loading the exit code from

  memory 90 which is addressed by the code '0 developed by the counter

  84. The same applies to the corresponding down-counter and up-down counter.

  layers of circuit 170; flip-flops 86 and the corresponding flip-flop (not shown) of circuit 170 are also both set to

state "0".

  Once the switching time of the monostable circuit 176 has elapsed, the signal at its output becomes inactive the down-counter 92 and 192 are released, they contain the value of the code coming from memory 90 and the corresponding memory contained in circuit 170. This code is stored in these memories at the address "0" provided by the up-down counter 84 and the up-down counter corresponding to the circuit 170. From this moment the mobile is started and the link circuit 150 is interrupted. As Quartz 94 and 194 are quartz with good stability, the contents of the downcounters 92 and 192 will evolve practically in synchronism during the duration of the shot. Then pulses of infrared radiation will be received; the counter 110 will provide an indication of the duration of the interval which separates them; if this duration is less than the AtMAX time interval then the content of this counter is transferred to the register 120. This content determines the direction in which the mobile is moving, so a correction must be determined so that the mobile reaches its target; this correction is preset in memory 125. This correction before being directed to the engine is compared with that provided by memory 185 programmed in the same way as memory 125. This memory 185 is addressed by counter 192 whose content is, with a few slight drifts, identical to that of the counter 92. These contents indicate the duration of the time intervals between each pulse so that a time interval measured by the counter 110 and transferred into the register must correspond to that indicated by the register 192. The comparison circuit 172 determining a coincidence between the information provided by the memories 125 and 185 closes the assembly

  of switches174 and the correction is therefore applied to the control surfaces 4.

  It is obvious, without departing from the scope of the invention, that this comparison can be made at different levels. The comparison

  could have been done at register 120 and counter 192.

  Figure 4 shows another way to make this comparison.

  This is carried out by an AND gate 195 inserted at the output of circuit 105. The purpose of this gate is to allow the pulses to pass or not to the rest of the circuit 100. This gate is opened by pulses produced by a corresponding monostable circuit 196 to the monostable circuit 96 but with the difference that the pulses supplied by this monostable circuit 196 have a large width thus allowing a certain tolerance. The output of memory 125 is directly connected to converter 130. Thus we realize that the remote control system is protected by interference pulses since only the information sent by

  the transmitter are decoded by the receiver, prior-

  ment initialized by him and thus it is possible to make coexist several remote control systems

  according to the invention in a restricted neighborhood.

Claims (4)

CLAIMS:   1. Remote control system for guiding a mobile with a control surface on a target, system comprising on the one hand a transmitter formed by an emission device for sending to the mobile at least one beam of radiation and a first circuit of coding acting on the transmission device to transmit position information by modulation of the radiation and on the other hand a receiver attached to the mobile formed of a reception circuit to supply, from the detected modulation, control information intended for a control circuit, a link circuit being provided for connecting the transmitter and the receiver before launching the mobile, characterized in that the receiver has a second coding circuit, an information comparison circuit for comparing the information transmitted with information developed from the second coding circuit and a validation circuit so as not to transmit the information governs to the control circuit only if the comparison circuit indicates that the information to be compared is compatible with each other, while the link circuit transmits only initialization information to initialize the second coding circuit on the first coding circuit.   2. Remote control system according to claim 1, characterized in that the comparison circuit is designed to make a comparison directly between the control information at the output of the reception circuit with output information of the second coding circuit.   3. Remote control system according to claim 1, characterized in that the comparison circuit is designed to make a comparison directly between the position information available in the reception circuit with information of   output of the second coding circuit.   4. Remote control system according to claim 1, characterized in that the comparison circuit is designed to make a comparison directly between the modulation detected in the reception circuit with output information from the second circuit decoding.