Bae Systems, Inc.

Bay Systems Plc

Mohammed Nawaz

Christopher Ralph Pescod

Andrew James Smith

Simon Charles Giles

Clive William Miller

Michael Andrew Scott

Colin James Harper

Robert John Mark Longstone

David John Aitken

Nicholas John Easton

Richard Peter Joyce

An optical selector arrangement (), comprising: a first set of optical ports (), having a first number of optical ports, the first number being greater than or equal to 2; a second set of optical ports (), having a second number of optical ports, the second number being greater than the first number; the second set of optical ports being for communicating with the first set of optical ports, a selector interface () for the optical selector arrangement, the selector interface comprising the second set of optical ports (), a part of the optical selector arrangement functioning as a selector (), the selector being arranged to selectively optically couple the first set of optical ports () to a set of ports of the second set of optical ports () of the selector interface, the selector () being rotatable relative to the selector interface () to facilitate the selection by optically aligning the first set of optical ports () to the second set of optical ports () of the selector interface (); the selector () being configured to be continuously relatively rotatable over multiple rotations, to selectively optically couple the first set of optical ports () to a different set of ports of the second set of optical ports of the selector interface.

Optical selector arrangement

An optical transmitter () comprising: a laser diode () for transmitting an optical signal; a first temperature sensor () configured to measure a temperature at or proximate to the laser diode (); a second temperature sensor () configured to measure a temperature of an environment in which the optical transmitter () is operating; a thermoelectric device () configured to apply heating or cooling to the laser diode (); and a controller () configured to, using the temperature measurements taken by the first temperature sensor () and the second temperature sensor (), control the thermoelectric device () to heat or cool the laser diode ().

Optical transmitter

Methods and apparatus for controlling a bias voltage () supplied to an optical modulator that comprises a biasable component configurable to be biased by application of the bias voltage (), the method comprising: providing a target for the modulator output power; applying, to the biasable component, a bias voltage () that biases the biasable component so that the output power is within a pre-defined range of the target; monitoring the output power and, if the output power of the modulator is determined to be outside the pre-defined range, varying the value of the bias voltage () to bring the output power back within the pre-defined range; and monitoring the optical input to the modulator and, if it has been disabled, maintaining the bias voltage () at its current level for a pre-determined length of time that is dependent upon how long the modulator has been operating at quadrature.

Controlling bias voltages for optical modulators

A method and apparatus for operating an optical rotating joint (); comprising: providing redundancy for camera sensor signals to be passed through an optical rotating joint () by: (i) passing signals from a plurality of camera sensors () via an optical changeover switching arrangement () to the optical rotating joint (); and/or (ii) passing signals for a plurality of camera sensors () toward the camera sensors () from the optical rotating joint () via an optical changeover switching arrangement (). The signals may be sensor control signals or sensor output signals to/from a plurality of sensors (), for example camera sensors. The apparatus may further comprise one or more wavelength division multiplexers () and/or wavelength division demultiplexers ().

Apparatus and methods for use with optical rotating joint

A method and apparatus for operating an optical rotating joint (); comprising: routing optical signals through an optical rotating joint () by using a first optical circulator () on a first side of the optical rotating joint () to receive an optical signal and direct the optical signal onward to a first side of the optical rotating joint (), and using a second optical circulator () on a second side of the optical rotating joint () to receive the optical signal from the second side of the optical rotating joint () and direct it onwards. The signals may be sensor control signals or sensor output signals to/from a plurality of sensors (), for example camera sensors. The apparatus may further comprise one or more wavelength division multiplexers () and/or wavelength division demultiplexers ().

An optical signal transmission apparatus () for a rotating antenna comprising a plurality of optical modulators () arranged for receiving a respective plurality of analog RF signals () and for modulating a respective plurality of optical signals therewith to produce a plurality of modulated analog optical signals (). A plurality of opto-electrical converters () each converts a respective modulated analog optical signal () into an analog 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.

Relating to antennas

Methods and apparatus for controlling a bias voltage supplied to an optical modulator, the modulator comprising a biasable component, the biasable component being configurable to be biased by application of the bias voltage () such that the modulator operates at quadrature, the method comprising: providing a target for the output power of the modulator, the target for the output power of the modulator being an output power corresponding to the modulator operating at quadrature; applying, to the biasable component, a bias voltage () having an initial value of 0V; and, thereafter, varying the bias voltage () until the value of the bias voltage () is the value that is closest to the initial value and that biases the biasable component so that the output power of the modulator is within a pre-defined range of the target output power.

An optical rotating joint installation; comprising: a drive shaft for a rotating interface, the drive shaft comprising a hollow central bore; and an optical rotating joint located in the hollow central bore. The proportion of the cross-sectional area of the material retained in the annular section of the drive shaft is preferably greater than or equal to 50%, more preferably 60%, yet more preferably 75%. The diameter of the hollow central bore is preferably less than or equal to 20 mm, more preferably 16 mm. The optical rotating joint installation may be provided as a retro-fit to replace an existing solid drive shaft that does not have an optical rotating joint, for example by hollowing out the existing solid drive shaft or by replacing the existing solid drive shaft with a drive shaft with a hollow central bore.

Provision of an optical rotating joint installation

Methods and apparatus for finding a bias voltage () corresponding to a quadrature point of an optical modulator, the modulator comprising a biasable component which is configurable to be biased by application of the bias voltage () such that the modulator operates at quadrature, the method comprising: providing a target for the output power of the modulator which corresponds to quadrature; applying, to the biasable component, a bias voltage () having an initial value; thereafter, finding a value for the bias voltage () that biases the biasable component such that the output power of the modulator is within a pre-defined range of the target by, starting at the initial value, alternately increasing and decreasing (or decreasing and increasing) the bias voltage () with gradually increasing amplitude; and identifying the found value for the bias voltage () as a bias voltage corresponding to a quadrature point of the optical modulator.

Finding bias voltages for optical modulators

A bias controller and a method for controlling the bias of an electro-optic modulator are provided. In the method, for a received indication of modulator temperature, steps are provided for accessing a look-up table to determine a corresponding value of bias voltage, for a required bias point, to apply to the modulator. If no such value is stored, additional steps are provided to generate a pilot tone for input to the modulator and to recognize, from the signal content of a modulated optical signal output by the modulator, operation of the modulator at the required bias point, adjusting the value of bias voltage being applied to the modulator as required. When operation at the required bias point is recognized, the respective value of bias voltage for that modulator temperature is stored in the look-up table. The same method is provided to configure a bias controller in respect of a given modulator, if necessary ab initio.

Bias controller

A bias controller for an optical modulator. The modulator includes a bias electrode that is operable when appropriately biased by an applied bias voltage to configure the modulator to operate at quadrature, and the bias controller includes: a generating arrangement for generating power signals indicative of the optical output power of the modulator; and a processor operably connected to the generating arrangement and said bias electrode and arranged to receive said power signals from said generating arrangement and to control the bias voltage applied to said bias electrode. The processor is configured to vary the bias voltage applied to said bias electrode and to determine from power signals received from said generating arrangement a peak optical output power for said modulator, and to determine in dependence upon said peak optical power a target optical power for quadrature with reference to a store of predetermined values for peak output power and respective corresponding values of target optical power for quadrature. Other embodiments relate to a multi-channel bias controller, and to a method for controlling voltage bias in a modulator.

Bias controller for an optical modulator

A base station is provided for communicating data to a mobile terminal unit by means of at least one antenna unit, wherein the at least one antenna unit is linked to the base station by means of at least one optical fiber and the at least one antenna unit is operable to communicate wirelessly with the mobile terminal unit. The base station comprises an optical transmitter for transmitting modulated data signals to the at least one antenna unit for wireless transmission, an optical receiver for receiving modulated data signals forwarded by the at least one antenna unit and a demodulator for demodulating received modulated data signals. The optical transmitter comprises a first optical modulator arranged to modulate an optical carrier with a radio frequency oscillator signal to generate an optical oscillator signal, a second optical modulator, coupled optically to the first optical modulator, operable to modulate the optical oscillator signal with an input data signal of a predetermined frequency to generate a downlink optical data signal and an optical output for directing the downlink optical data signal to the at least one antenna unit by means of the at least one optical fiber.

Data communications system

An apparatus and method are provided for communicating data between a first and a second terminal unit, wherein at least one of the terminal units is a mobile terminal unit. The apparatus includes a base station and a number of antenna units each linked to the base station. The base station has a transmitter that transmits modulated data signals to each of the antenna units, a receiver that receives modulated data signals forwarded by at least one of the antenna units, demodulator that demodulates received modulated data signals that have been modulated according to a predetermined modulation scheme. In the predetermined modulation scheme, successive blocks of modulated data are arranged such that a predetermined minimum time period elapses between the arrival, at the receiver, of a first and the arrival of a second of the successive modulated data blocks and wherein, in operation, the predetermined minimum time period being adjusted based on the maximum delay at the receiver between the arrival of a modulated data block a first antenna unit to a time of arrival of the same modulated data block of a different antenna unit.

Growing community of inventors

Chelmsford, United Kingdom

Mohammed Nawaz