Other Classes:
342/62, 342/50, 244/3.190, 244/3.140
Field of Search:
244/14,14.3,14.2,3.13,3.14,3.15,3.19 343/7,13,7A,7ED
Description:
The invention herein described may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.
The present invention relates to a missile guidance system and more particularly to a missile guidance system which functions as a command guidance system with homing capabilities. Command and beam riding missile guidance systems have the disadvantages that they are not sufficiently accurate at great distances. Homing systems have sufficient accuracy, but become complicated if they are to operate in a countermeasures environment and with multiple targets present.
A missile guidance system embodying the present invention, in the initial part of the missile flight, performs solely as a command guidance system. As the missile approaches the target close enough to receive guidance information, the guidance information is relayed back to its launcher. The command guidance unit in the launcher then uses this information to correct the flight of the missile so as to intercept the target.
Accordingly an object of the present invention is to provide an improved missile guidance system which overcomes the above-mentioned disadvantages.
Another object is to provide a missile guidance system which is simple in construction but is accurate and has the ability to function properly in the presence of multiple targets and electronic countermeasures.
A further object of the invention is the provision of a relay system to relay back homing information for correcting command guidance sent to the missile.
Still another object is to provide a relay system wherein the carrier signal is transmitted to the missile and relayed back supermodulated with homing information from the target.
Still a further object is to provide a relay system wherein traveling wave tubes amplify, repeat back and modulate with homing information the transmitted carrier signal.
Other objects and many of the attendant advantages of this invention will become readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
FIG. 1 is a schematic diagram illustrating the operation of the system of the present invention; and
FIG. 2 is a block diagram for the missile portion of the present system.
Referring now to the drawings there is shown in FIG. 1 a missile 10 which has been launched from an aircraft 11 toward a target aircraft 12. Mounted on the rear of missile 10 are receiving antenna 13 and transmitting antenna 14 (see FIG. 2). Coupled to receiving antenna 13 is traveling wave tube 16 which has an output coupled to the input of detector and decoder 17, as an input to mixer 18, and as an input to traveling wave tube 19. Mounted in the front portion of missile 10 are scan antennas 21, 22 which are controlled by ferrite phase shifters 23, 24 respectively to produce a conical scan pattern (four antenna scanners are required for full four-quadrant coverage). Scan control signals are supplied to phase shifters 23, 24 from detector and decoder 17. The output of ferrite scanners 23, 24 is coupled as a modulating input to traveling wave tube 19 through mixer 18 and IF amplifier 26.
In operation, aircraft 11 illuminates target aircraft 12 with a radar beam and also sends guidance commands to missile 10 by means of radar. During the command portion of the missile flight command signals are received by receiving antenna 13, amplified in traveling wave tube 16 and detected and decoded in device 17. Detector and decoder 17 may be a crystal diode. The decoded command signal is coupled to the autopilot (not shown) through terminal 27.
As missile 10 gets closer to target 12, the guidance information from aircraft 11 will rise above the noise level in the homing portion of the missile, i.e., missile 10 gets sufficiently close to target 12 so that radar signals reflected therefrom can be picked up by the scan antennas 21, 22. The reflected signals thus received, modulate the signal transmitted from antenna 14 to launch aircraft 11 to provide information which is used to correct the command signal sent to missile 10 by launch aircraft 11. The signal transmitted from aircraft 11 now serves two additional functions: it supplies a local oscillator frequency for mixer 18; and serves as a carrier for relaying back guidance and doppler information on target 12. As can be seen from the block diagram of FIG. 2, the received signal is amplified in traveling wave tube 16 and a portion of the amplified signal which functions as a carrier signal is fed to traveling wave tube 19 where it is amplitude modulated by applying the signal from scan antennas 21, 22 to its grid, thus, producing amplitude modulation of tube 19 output at the intermediate frequency. The signal at antenna 13 is the same signal received at antennas 21, 22 and contains the same variations. The signal received at antennas 21, 22, however, is delayed in time proportional to the range between missile 11 and target 12. Thus, the variations of the two received signals will match, except for the time delay. A further control signal is applied to traveling wave tube 19 from generator 28 for missile identification. The sawtooth voltage is applied to the helix of tube 19 so as to give signal sideband modulation. By this means each of the missiles fired from aircraft 11 will send back a signal with a different frequency.
Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.