Rotating antenna array and rotary joint calibration system

An antenna system 1, or a method for calibrating an antenna system 1, comprises: generating an RF calibration signal 62 which is applied to an RF input port of one or more RF receiver units 4, not involving the antenna elements 3; measuring the response of the antenna system 1 to the calibration signal 62 and calculating the signal corrections and applying these signal corrections to subsequently received signals by the antenna and receiver system. The calibration system may be applied to a rotating antenna array involving modulated analogue optical signals being transmitted through an optical rotary joint 10 such that the calibration system corrects signal errors introduced by the said rotary joint during rotation over a 720° azimuth angle rotational range. The optical rotary joint 10 may have multiple optical channels transferred through a Dove or Abbe-Konig reversion prism. Mach-Zehnder (MZ) electrical-optical signal modulators 6 and opto-electrical converters 14 may be used. The antenna ...

Directional antenna array arrangements

A directional antenna 1 comprises a first plurality of antenna elements 2 11 forming an antenna array and a second plurality of RF receiver units 13 19 which are fewer in number than that of the first plurality. Each receiver unit 13 19 is arranged to receive RF signals from one or more of the antenna elements 2 - 11 and for outputting a receiver signal accordingly. A signal processor 20 processes the receiver signals 34 according to a directional antenna beam pattern. At least two non-neighbouring antenna elements 2, 5 provide output signals which are coupled to a common RF receiver unit 13 to provide a combined RF signal. The antenna elements 2 11 may each be a sub-array of antenna elements. Also disclosed is a directional antenna comprising a plurality of antenna elements each providing output signals to a respective RF receiver unit where neighbouring RF receiver units are connected to non-neighbouring antenna elements. The output signals from the RF receiver units are provided to a ...

Anomalous propagation detection

A method of detecting an anomalous propagation condition in a Radar system, resulting from refraction of waves over the horizon due to atmospheric (environmental) effects, comprising the steps of: subtracting returns received in a first time period from returns received in a later second time period, and repeating this step over many time periods; if the result of a subtraction calculation exceeds a predetermined threshold, then the period is registered as a possibly including clutter, from multiple time around echoes. The scan may be divided into sectors around the azimuth in which at least a predefined number of sectors (preferably one) must register a result above the threshold to confirm anomalous propagation. The radar operation may change automatically or manually to include at least one guard pulse. If clutter is no longer detected the Radar may automatically revert to its previous mode of operation. An additional claim covers the physical system to implement the method.

Rotating antenna array and rotary joint calibration system

Means and Method to Minimize RF Interference in Scanning Radar

An antenna system (1) comprises a directional antenna (2) adapted to rotate through a range of directions in azimuth. It is responsive to radio-frequency (RF) signals received from directions within the range of directions in azimuth. A receiver (7) is arranged to receive the RF signals from the antenna within a signal frequency response band of the receiver and to provide a corresponding output for signal processing. A signal filter (11) is operable to block the output from the receiver when the frequency of the RF signal lies at a frequency within the signal frequency response band of the receiver and a detector unit (8) is arranged to apply the signal filter when the directional antenna is directed to a predetermined azimuth at which an interference source is located and to not apply the signal filter otherwise.

Improvements in and relating to radar

Anomalous propagation detection

Improvements in and relating to radar

Improvements in and relating to radar

A tracking radar apparatus 5 for detecting multipath signal propagation when determining an elevation angle of an object, comprising an antenna array with which the radar apparatus is arranged to form at least three separate antenna beams 11, 12, 13 comprising a first antenna beam 11 having an angle of elevation above horizontal, and a separate second antenna beam 12 having an angle of elevation at or above horizontal which is less than that of the first antenna beam, and a separate third antenna beam 13 having an angle of elevation below horizontal. The magnitudes of the received signals of the three beams are compared to identify multipath propagation in the echo. The multipath propagation may be identified through a creation of matrix of the received signals and calculation of its eigenvalues and/or eigenvectors. The radar may comprise of one or more amplitude comparison monopulse transmitters and/or pencil beam transmitters. The beams may be spaced equidistantly.

IMPROVEMENTS IN AND RELATING TO RADAR

A radar apparatus ( 5 ) for detecting multipath signal propagation when determining an elevation angle of an object, comprising an antenna array with which the radar apparatus is arranged to form at least three separate antenna beams ( 11, 12, 13 ) comprising a first antenna beam ( 11 ) having an angle of elevation above horizontal, and a separate second antenna beam ( 12 ) having an angle of elevation at or above horizontal which is less than that of the first antenna beam, and a separate third antenna beam ( 13 ) having an angle of elevation below horizontal. The apparatus is arranged to transmit radio pulses from the antenna array; to receive return radio signals within the first, second and third antenna beams; to calculate a measure of the magnitude of a return radio signal received within the third antenna beam using all of said received radio signals collectively; and, to detect multipath signal propagation using said measure.

ANOMALOUS PROPAGATION DETECTION

Disclosed is a method of detecting an anomalous propagation condition in a Radar system, comprising the steps of: subtracting returns received in a first receive period from returns received in a succeeding second receive period, and repeating this step for a plurality of receive periods; and if the step of subtracting gives a result in excess of a predetermined threshold in one of the plurality of receive periods, then registering this as a possible anomalous propagation condition. 1. A method of detecting an anomalous propagation condition in a Radar system , the method comprising:subtracting returns received in a first receive period from returns received in a succeeding second receive period;repeating the subtracting for a plurality of receive periods; andif the subtracting gives a result in excess of a predetermined threshold in one of the plurality of receive periods, registering this as a possible anomalous propagation condition.2. The method of wherein an azimuthal scan is divided into a plurality of sectors claim 1 , and in order to confirm an anomalous propagation condition claim 1 , a possible anomalous propagation condition must be registered in at least a predetermined number of the plurality of sectors.3. The method of wherein the predetermined number of sectors is one.4. The method of wherein in response to an anomalous propagation condition being detected claim 1 , the method comprises: issuing an alert and allowing operation of the Radar to be manually altered accordingly.5. The method of wherein detection of an anomalous propagation condition automatically triggers the insertion of one or more additional guard pulses.6. The method of wherein if an anomalous propagation condition is no longer detected claim 5 , the Radar automatically reverts to its previous mode of operation and any additional guard pulses are removed.7. A Radar system arranged to detect the presence of anomalous propagation conditions claim 5 , the system comprising:a transmitter; ...

ANTENNA SYSTEM CALIBRATION

A method for calibrating an antenna system () including a antenna elements () connected to signal receiver units () at an RF signal input port thereof comprising, generating an RF calibration signal (), applying the RF calibration signal to the RF signal input port of the signal receiver units without applying the calibration signal via the antenna elements (). The response of the antenna system to the calibration signal is measured, and a signal correction is calculated according to the measured response. The signal correction is applied to the response of the antenna system to signals subsequently received at the signal receiver units via the antenna elements of the antenna system. 1. A method for calibrating an antenna system including an antenna element(s) connected to a signal receiver unit(s) at an RF signal input port thereof , the method comprising:generating an RF calibration signal;applying the RF calibration signal to the RF signal input port of the signal receiver unit(s) without applying the calibration signal via the antenna element(s);measuring the response of the antenna system to the calibration signal;calculating a signal correction according to the measured response; andapplying the signal correction to the response of the antenna system to signals subsequently received at said signal receiver unit(s) via the antenna element(s) of the antenna system.2. A method according to including generating said RF calibration signal using an RF signal transmitter and transmitting said RF calibration signal to said RF signal input port directly via a signal transmission line connecting the RF signal transmitter to the RF signal input port of the signal receiver.3. A method according to in which a value of the signal correction is calculated according to the inverse of a value of the measured response.4. A method according to wherein the antenna system comprises a rotary antenna claim 1 , the method comprising:outputting from the signal receiver unit(s) an RF ...

IMPROVEMENTS IN AND RELATING TO RADAR

An antenna system () comprises a directional antenna () adapted to rotate through a range of directions in azimuth. It is responsive to radio-frequency (RF) signals received from directions within the range of directions in azimuth. A receiver () is arranged to receive the RF signals from the antenna within a signal frequency response band of the receiver and to provide a corresponding output for signal processing. A signal filter () is operable to block the output from the receiver when the frequency of the RF signal lies at a frequency within the signal frequency response band of the receiver and a detector unit () is arranged to apply the signal filter when the directional antenna is directed to a predetermined azimuth at which an interference source is located and to not apply the signal filter otherwise. 1. An antenna system comprising:a directional antenna adapted to rotate through a range of directions in azimuth and responsive to radio-frequency (RF) signals received from directions within said range of directions in azimuth;a receiver arranged to receive said RF signals from the antenna within a signal frequency response band of the receiver and to provide a corresponding output for signal processing;a signal filter operable to block a said output from the receiver when the frequency of the RF signal lies at a frequency within the signal frequency response band; anda controller arranged to apply said signal filter when the directional antenna is directed to a predetermined azimuth and to not apply the signal filter otherwise.2360. An antenna according to in which the directional antenna is arranged to rotate periodically through degrees and the controller is arranged to apply said signal filter periodically.3. An antenna according to in which with the controller is arranged to apply said signal filter with a periodicity corresponding to the rotation period of said directional antenna.4. An antenna according to in which said predetermined azimuth is a ...

IMPROVEMENTS IN AND RELATING TO ANTENNAS

An optical signal transmission apparatus () for a rotating antenna comprising a plurality of optical modulators () arranged for receiving a respective plurality of analogue RF signals () and for modulating a respective plurality of optical signals therewith to produce a plurality of modulated analogue optical signals (). A plurality of opto-electrical converters () each converts a respective modulated analogue optical signal () into an analogue electrical signal. The plurality of optical modulators () are rotationally coupled in optical communication with the plurality of opto-electrical converters () via an optical rotary joint () including a reversion prism. 1. A directional antenna comprising:a first plurality of sub-antennas forming an antenna array;a second plurality of RF receiver units fewer in number than the first plurality of sub-antennas and each RF receiver unit arranged for receiving RF signals from one or more of said sub-antennas and for outputting a receiver signal accordingly; anda signal processor for receiving and processing said receiver signals according to a directional antenna beam pattern;wherein at least two non-neighbouring said sub-antennas are connected to a common one said RF receiver unit to provide a combined RF signal thereto.2. A directional antenna according to in which more than two non-neighbouring said sub-antennas are connected to a common one said RF receiver unit to provide a combined RF signal thereto and none of the sub-antennas so connected are neighbouring sub-antennas.3. A directional antenna according to in which at least two said RF receiver units are separately connected to a respective at least two non-neighbouring said sub-antennas which provide a combined RF signal thereto.4. A directional antenna comprising:a plurality of sub-antennas forming an antenna array;a plurality of RF receiver units each arranged for receiving RF signals from a respective one of said sub-antennas and for outputting a receiver signal ...

Interference nulling of multipath signals in stacked beam pulse radar

XA4170WO 18 Improvements in and Relating to Radar Abstract A radar apparatus (5) for detecting multipath signal propagation when determining an elevation angle of an object, comprising an antenna array with which the radar apparatus is arranged to form at least three separate antenna beams (11, 12, 13) comprising a first antenna beam (11) having an angle of elevation above horizontal, and a separate second antenna beam (12) having an angle of elevation at or above horizontal which is less than that of the first antenna beam, and a separate third antenna beam (13) having an angle of elevation below horizontal. The apparatus is arranged to transmit radio pulses from the antenna array; to receive return radio signals within the first, second and third antenna beams; to calculate a measure of the magnitude of a return radio signal received within the third antenna beam using all of said received radio signals collectively; and, to detect multipath signal propagation using said measure. [Fig.2]

Anomalous propagation detection

Disclosed is a method of detecting an anomalous propagation condition in a Radar system, comprising the steps of: subtracting returns received in a first receive period from returns received in a succeeding second receive period, and repeating this step for a plurality of receive periods; and if the step of subtracting gives a result in excess of a predetermined threshold in one of the plurality of receive periods, then registering this as a possible anomalous propagation condition.

Radar

An antenna system ( 1 ) comprises a directional antenna ( 2 ) adapted to rotate through a range of directions in azimuth. It is responsive to radio-frequency (RF) signals received from directions within the range of directions in azimuth. A receiver ( 7 ) is arranged to receive the RF signals from the antenna within a signal frequency response band of the receiver and to provide a corresponding output for signal processing. A signal filter ( 11 ) is operable to block the output from the receiver when the frequency of the RF signal lies at a frequency within the signal frequency response band of the receiver and a detector unit ( 8 ) is arranged to apply the signal filter when the directional antenna is directed to a predetermined azimuth at which an interference source is located and to not apply the signal filter otherwise.

Improvements in and relating to radar

An antenna system (1) comprises a directional antenna (2) adapted to rotate through a range of directions in azimuth. It is responsive to radio-frequency (RF) signals received from directions within the range of directions in azimuth. A receiver (7) is arranged to receive the RF signals from the antenna within a signal frequency response band of the receiver and to provide a corresponding output for signal processing. A signal filter (11) is operable to block the output from the receiver when the frequency of the RF signal lies at a frequency within the signal frequency response band of the receiver and a detector unit (8) is arranged to apply the signal filter when the directional antenna is directed to a predetermined azimuth at which an interference source is located and to not apply the signal filter otherwise.

antenna system and method for controlling a directional antenna system

1 / 1 resumo “sistema de antena, e, mã‰todo para controlar um sistema de antena direcional” um sistema de antena (1) compreende uma antena direcional (2) adaptada para girar por uma gama de direã§ãµes em azimute. ㉠responsivo a sinais de radiofrequãªncia (rf) recebidos de direã§ãµes dentro da gama de direã§ãµes em azimute. um receptor (7) estã¡ arranjado receber os sinais de rf da antena dentro de uma banda de resposta de frequãªncia de sinal do receptor e prover uma saã­da correspondente para processamento de sinal. um filtro de sinal (11) ã© operã¡vel para bloquear a saã­da do receptor quando a frequãªncia do sinal de rf se acha a uma frequãªncia dentro da banda de resposta de frequãªncia de sinal do receptor e uma unidade de detector (8) estã¡ arranjada para aplicar o filtro de sinal quando a antena direcional ã© dirigida a um azimute predeterminado ao qual uma fonte de interferãªncia estã¡ localizada e nã£o aplicar o filtro de sinal caso contrã¡rio. 1 / 1 abstract “antenna system, and method for controlling a directional antenna system†an antenna system (1) comprises a directional antenna (2) adapted to rotate through a range of directions in azimuth. It is responsive to radio frequency (RF) signals received from directions within the range of directions in azimuth. a receiver (7) is arranged to receive the RF signals from the antenna within a signal frequency response band of the receiver and provide a corresponding output for signal processing. a signal filter (11) is operable to block the output of the receiver when the frequency of the RF signal is at a frequency within the signal frequency response band of the receiver and a detector unit (8) is It is arranged to apply the signal filter when the directional antenna is directed at a predetermined azimuth at which an interference source is located and not apply the signal filter otherwise.

Calibración de un sistema de antena

MÉTODO PARA CALIBRAR UN SISTEMA DE ANTENA, QUE COMPRENDE GENERAR UNA SEÑAL DE CALIBRACIÓN DE RF, APLICAR LA SEÑAL DE CALIBRACIÓN DE RF AL PUERTO DE ENTRADA DE SEÑALES DE RF DE LA UNIDAD DE RECEPTOR, MEDIR LA RESPUESTA DEL SISTEMA DE ANTENA A LA SEÑAL DE CALIBRACIÓN, CALCULAR UNA CORRECCIÓN DE SEÑAL DE ACUERDO CON LA RESPUESTA MEDIDA, APLICAR LA CORRECCIÓN DE SEÑAL A LA RESPUESTA DEL SISTEMA DE ANTENA A LAS SEÑALES RECIBIDAS POSTERIORMENTE EN DICHA UNIDAD; SISTEMA; PROGRAMA DE COMPUTADOR

Antenna system calibration

Antenna system calibration

XA4168WO -34- IMPROVEMENTS IN AND RELATING TO ANTENNAS ABSTRACT A method for calibrating an antenna system (1) including a antenna elements (3) connected tosignal receiver units (4) at an RF signalinput port thereof comprising, generating an RF calibration signal (62), applying the RF calibration signal to the RF signal input port of the signal receiver unitswithout applying the calibration signal via the antenna elements (3). The response of the antenna system to the calibration signalis measured, and a signal correction is calculated according to the measured response. The signal correction is applied to the response of the antenna system to signals subsequently received at the signal receiver unitsvia the antenna elementsof the antenna system. [Fig.1]

método para calibrar um sistema de antena, sistema de antena, e, programa de computação ou pluralidade de programas de computação

1 / 1 resumo “mã‰todo para calibrar um sistema de antena, sistema de antena, e, programa de computaã‡ãƒo ou pluralidade de programas de computaã‡ãƒo” mã©todo para calibrar um sistema de antena (1) incluindo elementos de antena (3) conectado a unidades receptoras de sinal (4) em uma porta de entrada de sinal rf das mesmas compreendendo gerar um sinal de calibraã§ã£o rf (62), aplicar o sinal de calibraã§ã£o rf para a porta de entrada de sinal rf das unidades receptoras de sinal sem aplicar o sinal de calibraã§ã£o via elementos de antena (3). a resposta do sistema de antena para os sinais de calibraã§ã£o medidos, e uma correã§ã£o de sinal ã© calculada de acordo com a resposta medida. a correã§ã£o de sinal ã© aplicada ã  resposta do sistema de antena para sinais subsequentemente recebidos nas unidades receptoras de sinal via elementos de antena do sistema de antena.

Antenna system calibration

A method for calibrating an antenna system ( 1 ) including a antenna elements ( 3 ) connected to signal receiver units ( 4 ) at an RF signal input port thereof comprising, generating an RF calibration signal ( 62 ), applying the RF calibration signal to the RF signal input port of the signal receiver units without applying the calibration signal via the antenna elements ( 3 ). The response of the antenna system to the calibration signal is measured, and a signal correction is calculated according to the measured response. The signal correction is applied to the response of the antenna system to signals subsequently received at the signal receiver units via the antenna elements of the antenna system.