Emi, LLC

Thorn Emi Electronics Limited

Electrical & Musical Industries Limited

Roger Voles

Simon Watts

A radar for a terminally-guided sub-munition is capable of differentiating between spatial depositions of target scatterers and clutter. The radar frequency f is swept, in stepwise manner, over a frequency range F, the frequency of 2N successive batches of M pulses being incremented in steps ofTo minimise variability of hybrid spectrum with relative target velocity, v, a duplexer transmits the 2 NM pulses with a monotonic frequency sequence derived from control circuit and the returns being reordered.

Radar

To provide stationary or mobile radar with the capability of measuring the true range profile, a radar system includes a voltage oscillator coupled to a duplexer via a pulse modulation circuit. A digital control circuit provides a sweeping 500 Mhz frequency (F) of 6N successive batches of pulses being incremented in steps of F/6N. Returns received in response to each transmitted pulse are then combined in a mixing circuit with the signal from the local oscillator to generate a signal IF; each signal is summed with signals for the same range cell derived from earlier pulses transmitted at the same frequency; thereafter the signals pass through a FFT circuit. To maintain the 'dissected' spectrum centered at the 2N.sup.th cell, respective summations are carried out in two circuits, and then differenced in and normalized by the total signal energy present in the true profile range obtained from a summing circuit, the output therefrom providing an error signal whose magnitude and sign are used to estimate any change required in the value of prf, fr, thereby to achieve the value of T which will maintain the dissected spectrum centered on the 2N.sup.th range cell.

A thermal imaging device includes an array of pyroelectric infra-red detector pixels. An array of pillars carries electrical signals between each detector pixel and a respective signal processing circuit formed on a semiconducting substrate. Each circuit is connected to an individual display device carried by the substrate.

Thermal imaging device

A pyroelectric film has a pattern of interconnected electrodes formed on one major surface, and a pattern of discrete electrodes and electrically conductive patches formed on the other major surface. The film 21 is supported by pillars connected to the patches, the pillars also producing a path for electrical signals between the patches and a signal processing means. Each discrete electrode is connected to a respective patch by a respective strip of electrically conductive material.

A thermal imaging device comprises a layer 11 of pyroelectric material, an array of interconnected electrodes 13, and an array of discrete electrodes 15 supported from a substrate 27 by pillars 23 of thermally insulating material. Heaters 17 and associated control electrodes 19 are also provided to reduce the temperature difference between the discrete electrodes 15 and the pillars 23 and substrate 27. Control circuits 25 are provided to control energisation of the heaters 17. In a preferred embodiment the heaters may be provided on the substrate 27 for heating the discrete electrodes 13, the control current to the heaters providing an indication of the temperature of the source of radiation.

A pyroelectric film has a pattern of interconnected electrodes formed on one major surface, and a pattern of discrete electrodes and electrically conductive contacts formed on the other major surface. Each discrete electrode is connected to a respective contact by a respective strip of electrically conductive material. Regions of the film each including a contact and part of the associated strip are formed in tongues pulled out of the plane of the film. The contacts are thus able to make electrical contact with respective input terminals of an integrated circuit.

An angular rate sensor comprises a pair of driven tines and a pair of output tines connected to the driven tines by a stem portion. A detection circuit including a set of output electrodes, associated with each output tines, generates a detection signal related to angular rate. A feedback circuit, including a further set of electrodes associated with each driven tine; utilizes a phase quadrature component of the detection signal so as to drive the driven tines towards a condition of torsional balance.

Rate sensor

The IFF system uses basic identification codes which are transmitted between an interrogator and a responder. The basic codes are chosen in dependence upon the time and position of the interrogator or responder at the time of choice. In one version of the system, the lifetime of a code is less than or equal to the propagation time of a radio signal for a given maximum range between the interrogator or responder. Interactive interrogation may also take place using codes chosen in the same way as the basic codes. Local information may also be transmitted between the interrogator and transponder. An example of apparatus for performing these operations transmits basic or other codes together with a time code defining the time of production of the basic or other codes. It is not essential to transmit a time code in some circumstances. Position and time information may be gained from an external communications system.

Identification of friend or foe (IFF) systems

In an improved target detector, echo signals received from the same range range bracket on successive scans of the same angular direction are stored. Different combinations of elements from said echo signals are sampled and integrated, each combination being chosen to include elements indicative of a target moving with a particular velocity. Different combinations are indicative of different target velocities, or of targets situated at different initial ranges, and means are provided for signalling an alarm when the integral of any combination exceeds a threshold.

Target detectors

A method and apparatus for imaging a target, such as a ship, exhibiting rotational movement about respective, mutually orthogonal axes. The method involves identifying a scattering center at the target exhibiting rotational movement about one axis only (the yaw axis, say, in the case of a ship) and then correlating an electrical signal related to the Doppler frequency of a return derived from that scattering center, and indicative of the angular velocity of the target about the one axis, with other electrical signals related to the Doppler frequencies of returns derived from other scattering centers. Correlation signals generated in this way provide an indication of the relative positions of the other scattering centers in relation to the one axis. The apparatus may include means (12, 13, 14, 15) for generating electrical signals indicative of the Doppler frequencies of returns derived from different scattering centers at the target and means (17) for selecting signals derived from a scattering center exhibiting rotational movement about the one axis. An electrical signal indicative of the angular velocity of the target about the one axis is then computed at (21) and correlated at (22) with electrical signals indicative of the Doppler frequencies of returns derived from other scattering centers at the target. The correlation signals generated at 22 are then passed to a display (23) which presents the positions of the other scattering centers in relation to the one axis. A circuit (30) is used to generate another electrical signal related to the Doppler frequency of a scattering center exhibiting rotational movement only about a mutually orthogonal axis (the roll axis, say, in the case of a ship). The signal is also correlated at (22) so that a two dimensional representation of the target can be developed at the display (23).

Doppler imaging of targets

An automatically focussed optical system in which two arrays of photosensitive detectors have different optical spacings respectively in front of and behind the image plane of the system, and sense different portions of the image. Differences in electrical signals generated by adjacent detectors (C,D and E,F) in each set, and indicative of differences in intensity of the corresponding portions, are processed to generate a focus drive signal (Fd) of a value related to an error in the focus of the image. This signal is used to adjust the focus. Two discrete arrays of detectors (FIG. 2B) can be used or alternatively a single array (FIG. 2D) tilted relative to the image plane can be used. In another example (FIG. 2C) a transparent block is inserted adjacent to a part only of a single detector array to thereby lengthen the optical path length of that part relative to the remainder of the array.

Automatically focussed optical system

A gun aiming arrangement uses a visible light or infra-red television camera to feed target area data to an auto-lock-follow (ALF) circuit. The ALF circuit is caused to lock onto a part of the area chosen using a sighting arrangement operated by the gunman. The gun automatically fires when the deviation between the aim of the gun and the target as sensed by the ALF circuit has a predetermined characteristic.

Aiming arrangements

A phase modulation system is described in which the phase of a carrier wave can assume one of a number of permitted values in each symbol period and wherein transitions between the permitted values occur at transition periods between symbol periods. Difficulties associated with phase transitions are reduced or overcome by storing or generating the transitions with a number of cycles of the carrier wave of the appropriate phase(s) on either side thereof, a wave train being built up by merging the corresponding oscillations of the same phase which succeed and preceed respectively two adjacent transitions.

Phase modulation system for combining carrier wave segments containing

The invention relates to a system for tracking and/or guidance of a vehicle or projectile using a correlation arrangement for comparing representations from a sensor mounted on the vehicle or projectile with a reference representation, the correlation being carried out by comparing portions of the representations and like portions of the reference representation to derive position coordinates for each of said portions and to evaluate from said position coordinates compensation signals for rotational misalignment and/or changes of scale as between the reference and subsequent representations.

Tracking and/or guidance systems

There is disclosed a synthetic aperture radar arranged to survey a region from a mobile location. The radar returns received from the region are first phase weighted by a series of predetermined factors. They are then stored and combined with later returns to give an output signal which has a maximum value when any target present in the region is in a predetermined direction from the location.

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London, United Kingdom

Roger Voles