Communications: directive radio wave systems and devices (e.g. – Determining distance – Miss distance indicator
Patent
1991-09-16
1993-01-19
Tubbesing, T. H.
Communications: directive radio wave systems and devices (e.g.,
Determining distance
Miss distance indicator
342136, G01S 1318
Patent
active
051810395
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a system for sensing the approach of a moving missile to a target, and more particularly (but not exclusively) to a system for determining the trajectory and miss distance of a missile approaching a target, for testing of the system. Such systems are generally called "scoring systems". The missile can be any high speed projectile, such as an air-to-air missile, a ground-to-air missile, a sea-to-air missile, a shell or a large bullet. The target can be stationary, airborne or on water but is preferably an aircraft, tank or other moving vehicle.
BACKGROUND TO THE INVENTION
Several scoring systems have been developed previously, which rely on radio transmission. These can be divided into those which require equipment on both missile and target (called cooperative systems) and those which are accommodated entirely on the target (called non-cooperative systems) where the missile behaves as a passive reflector or scatterer. The invention is concerned with non-cooperative systems.
U.S. Pat. No. 4,057,708 discloses a known non-cooperative system which measures the minimum miss distance and three dimensional coordinates of a missile trajectory with respect to a target in the form of an aircraft. This system uses pulses having a duration of 40 nanoseconds. Each transmitted pulse is derived by gating a continuously running oscillating signal so the transmitted pulse consists of several oscillations. The pulses reflected by the missile are received by a receiver on the aircraft, but accurate detection of missile presence is not possible, firstly because of multipath effects due to reflection from the aircraft skin and secondly because of the difficulty of correctly identifying the received signal with the multiple scatterers on the missile, such as nose fins or tail wings. The nature of the transmitted pulse does not enable these different features to be resolved.
DISCLOSURE OF THE INVENTION
According to the invention there is provided a system for sensing the approach of a moving missile to a target, comprising transmitting means on the target for transmitting a succession of transmit pulses, receiving means on the target for receiving the pulses reflected by the missile, gating means on the target for sampling the reflected pulses received at the receiving means during a succession of time windows each of which is delayed with respect to the time of transmission of a corresponding transmit pulse by a predetermined time delay corresponding to the pulse travelling a predetermined distance from the transmitting means to the missile and thence back to the receiving means, so that sampled signals from the receiving means are indicative of the missile entering or leaving a notional envelope surrounding the target at a range corresponding to said predetermined time delay, and processing means which are responsive to the sampled signals and which compute the approach of the missile, wherein each transmitted pulse commences, from a level of no significant transmitted power in the frequency band width of the pulse, with a rapid rise to a power peak, such that the sampled signals are indicative of reflected pulses and not of reflections at the level of no significant power.
It will be appreciated that the envelope is an ellipsoid having the transmitting means and the receiving means as the foci.
Each transmit pulse preferably has a duration of less than 4 nanoseconds and each pulse may have, after the rapid rise to the power peak, a rapid fall, continuing to rise to a power peak of opposite polarity so that the complete pulse is substantially sinusoidal in shape.
In the simplest system according to the invention, the transmitting means comprise a single transmitter and the receiving means comprise a single receiver. This system provides a scalar result, that is it senses whether the missile has penetrated the notional envelope without giving any more information about the spatial position of the penetration. A system providing a vector result, i.e. giving a three dimensio
REFERENCES:
patent: 4005420 (1977-01-01), McDonald
patent: 4057708 (1977-11-01), Greeley et al.
Neal Christopher S.
Oswald Gordon K. A.
Richardson Alan T.
Cambridge Consultants Limited
Tubbesing T. H.
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