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Researchers Submit Patent Application, "Systems and Methods for Implementing Optical and RF Communication between Rotating and Stationary Components...

July 30, 2014



Researchers Submit Patent Application, "Systems and Methods for Implementing Optical and RF Communication between Rotating and Stationary Components of a Rotary Sensor System", for Approval

By a News Reporter-Staff News Editor at Electronics Newsweekly -- From Washington, D.C., VerticalNews journalists report that a patent application by the inventors Jones, Thomas Webster (Boulder Creek, CA); Baloun, James Edward (Palo Alto, CA), filed on January 8, 2013, was made available online on July 17, 2014.

The patent's assignee is L-3 Communications Corporation.

News editors obtained the following quote from the background information supplied by the inventors: "Radar and passive RF detection systems having one or more rotating antennas are used in airborne, shipboard and ground based installations. The typical electrical interface to an antenna is one or more radio frequency (RF) transmission line(s). In general, this type of system employs a RF rotary coupler to interconnect the rotating antenna to the electronics that remains stationary relative to the rotating antenna. Such rotary couplers are capable of providing radio frequency (RF) energy to and receiving RF energy from, the rotating antenna(s) through one or more separate transmission lines or channels. A typical rotary coupler with separate transmission lines has one coaxial transmission line (RF channel 1) through which no other RF transmission lines pass. The remaining coaxial transmission lines (RF channels 2 and more) are arranged such that each additional transmission line is coaxial with the other transmission lines, and such that each given additional transmission line allows the other transmission lines to pass through the center of the given additional transmission line.

"The rotating antenna assembly may also house sensor electronics to support a variety of different applications. The sensor electronics, housed in the rotating antenna assembly, require the bi-directional flow of data and/or control signals and these signals are typically passed through a rotary device which provides the interface to the stationary platform electronics.

"Traditionally the data/control signal for sensor electronics, in a rotating antenna application, is realized with a multi-circuit slip ring assembly. Multi-circuit slip ring assemblies are designed to pass electrical data/control signals. Some draw-backs with this technology include the potential for a large number of circuits required to support the electronic bus architecture, potential bandwidth limitations in passing data across a multi-circuit slip ring assembly and potential EMI (electromagnetic interference) concerns in high power RF applications. It is also not uncommon for certain applications, such as airborne installations, to have physical packaging constraints which will limit the available volume for a slip ring installation which could limit system capability.

"FIG. 1 is a cross sectional view of a conventional two channel radio frequency (RF) rotary coupler assembly 100 having a stator portion 102 and a mating rotor portion 104. Rotary coupler 100 is configured to transmit two RF channels, referred to as Channel 1 and Channel 2, across rotational interface/s of the coupler 100 that are formed between mating stator portion 102 and rotor portion 104 of the coupler 100. Channel 1 is a RF channel transmitted on the central axis of rotary coupler 100 and Channel 2 is a RF channel transmitted off of the central axis of rotary coupler 100. As shown, a stationary coaxial signal input 113 is provided on stator portion 102 for the RF signals of Channel 1, and a stationary coaxial signal input 115 is provided on stator portion 102 for the RF signals of Channel 2. Similarly, a rotating (rotor) coaxial signal output 114 is provided on rotor portion 104 for the RF signals of Channel 1, and a rotating (rotor) coaxial signal output 116 is provided on rotor portion 104 for the RF signals of Channel 2.

"Still referring to FIG. 1, rotor portion 104 is rotationally guided relative to stator portion 102 by a pair of ball-bearing assemblies 144. Rotary coupler 100 is sealed to allow for control of the internal environment which is exposed to RF energy by, o-ring seals 145 between parts of the coupler that do not rotate relative to each other, and by wiper seals 146 provided between parts of the rotor 104 that rotate relative to parts of the stator 102 of the rotary coupler 100. RF energy is conducted through Channel 1 of rotary coupler 100 by way of a transmission line formed between the surfaces of the internal cavities 147a and 147b. RF energy is conducted through Channel 2 of rotary coupler 100 by way of a transmission line with matching stub circuits formed between the surfaces of internal cavities 148a and 148b. Between the rotor portion 104 and stator portion 102 of the rotary coupler 100, RF energy of Channels 1 and/or 2 is made to pass by close-fitting concentric cylindrical surfaces separated by a thin layer of dielectric material which form corresponding stepped impedance chokes 117, 118, 119 and 120, between the rotor and stator portions 104 and 102 of the rotary coupler 100.

"As shown in FIG. 1, a coaxial transmission line is provided for transmitting RF signals of Channel 1 between stationary coaxial signal input 113 and rotating coaxial output 114, and a coaxial transmission line is provided for transmitting RF signals of Channel 2 between stationary coaxial signal input 115 and rotating coaxial output 116. Specifically, a center conductor is provided for Channel 1 that includes a stationary on-axis inner conductor portion 122 in RF signal communication with a rotating on-axis inner conductor portion 121 across a rotational interface formed by close-fitting concentric cylindrical surfaces of an innermost stepped impedance choke 117 that is located between the stationary portion 122 of the inner conductor of Channel 1 and the adjacent rotating portion 121 of the inner conductor of Channel 1. An outer conductor is formed for Channel 1 by stepped impedance choke 118 that is located between the stationary portion 192 of the outer conductor of Channel 1 and the adjacent rotation portion 191 of the outer conductor of Channel 1. Similarly, a center conductor is provided for Channel 2 that includes a stationary off-axis inner conductor portion 192 in RF signal communication with a rotating coaxial inner conductor portion 191 across a rotational interface formed by close-fitting concentric cylindrical surfaces of a stepped impedance choke 120 that is located between the stationary portion 192 of the inner conductor of Channel 2 and the adjacent rotating portion 191 of the inner conductor of Channel 2. Similarly, an outer conductor is formed for Channel 2 by outermost stepped impedance choke 119 that is located between the rotating portion 181 of the outer conductor of Channel 2 and adjacent stationary portion 182 of the outer conductor of Channel 2 and the bearing inner race support housing 125.

"FIG. 2 is a partial enlarged view 200 of the stepped impedance choke 117 of the rotary coupler assembly 100 of FIG. 1. As shown, the stepped impedance choke 117 is formed between stationary on-axis inner conductor portion 122 of the Channel 1 transmission line and the rotating on-axis inner conductor portion 121 of the Channel 1 transmission line. Also shown, the stepped impedance choke 118 is formed between stationary outer conductor portion 192 of the Channel 1 transmission line and the rotating outer conductor portion 191 of Channel 1 transmission line."

As a supplement to the background information on this patent application, VerticalNews correspondents also obtained the inventors' summary information for this patent application: "Disclosed herein are systems and methods for transferring both optical and RF energy through a rotary coupler. Using the disclosed systems and methods, optical and RF energy may be provided simultaneously or otherwise across a rotary coupler using separate communication paths through a coaxial transmission line that incorporates an on-axis fiber optic transmission line, e.g., to simultaneously transfer optical signals and RF signals between a stationary and a rotating section of a coaxial transmission line that extends across rotational interface/s of the rotary coupler. The disclosed systems and methods may be advantageously implemented in one exemplary embodiment to provide a rotary coupler that interconnects components of a rotating assembly (e.g., rotating antenna assembly including any associated rotating electronics) in optical and RF signal communication with other electronics that remain stationary relative to the rotating assembly of a given mobile or fixed platform (e.g., platform such as aircraft, ship, train, automobile, land installation such as radar station or satellite station or control tower, etc.). Wherever the term 'rotating' is used herein to describe a given component it will be understood that such a given component may be also be described as rotatable, i.e., configured to rotate relative to a corresponding stationary component whether or not actual rotation is occurring at any given time.

"In one exemplary embodiment, a rotary coupler may be provided with an optical transmission line (e.g., a single or multiple mode fiber optic line) that passes inside or through the center of an inner conductor of a coaxial RF transmission line that itself extends across the rotational interface/s of the rotary coupler. In such an embodiment, both the optical transmission line and the RF transmission line may be positioned at, or close to, the axis of rotation of the rotary coupler. In a further embodiment, a rotary coupler may be provided that is configured to transfer optical signals and multiple RF channels across the rotational interface/s of a rotary coupler. In another exemplary embodiment, a rotary coupler may be configured to transfer optical and RF energy across rotational interface/s of the rotary coupler using an optical rotary joint positioned inside the inner conductor of a first RF channel transmission line that itself is substantially centered at, and in line with, the rotational axis of the rotary coupler. When integrated inside or within an on-axis RF transmission line of a rotary coupler, an optical transmission line may advantageously provide on-axis optical signal communication through the rotary coupler without adversely impacting or affecting the on-axis RF signal transmissions through the rotary coupler. In a further embodiment, the optical rotary joint may be positioned adjacent to a stepped impedance choke that is provided between the fixed and rotating portions of the inner conductor of the first RF channel transmission line.

"In one exemplary embodiment, the disclosed systems and methods may be implemented to convert multiple signals and/or types of signals (e.g., RF signals, video signals, audio signals, control signals, data signals, computer network signals such as Ethernet, etc.) to a common multiplexed optical signal stream that includes information from the various signals for transmission together across an on-axis rotational optical interface (e.g., optical rotary joint) of the rotary coupler. Such optical communication may be bidirectional or unidirectional, and may occur through the inside of an on-axis RF transmission line that simultaneously transmits RF signals across the an on-axis rotationally RF interface.

"In one respect, disclosed herein is a rotary sensor system, including: rotatable system components including rotatable sensor electronics, at least one rotatable RF sensor, and at least one rotatable optical signal communication component; stationary system components including stationary RF sensor electronics for the at least one rotatable RF sensor, and at least one stationary optical signal communication component; and a rotary coupler coupled between the stationary system components and the rotatable system components, the rotary coupler having a stator portion rotatably coupled to a rotor portion. The stator portion may be coupled between the stationary system components and the rotor portion, and the rotor portion may be coupled between the rotatable system components and the stator portion such that the rotor portion rotates together with the rotatable system components relative to the stator portion and the stationary system components. The stator portion may include a stationary RF conductor portion of a center RF transmission line, and the rotor portion may include a rotatable RF conductor portion of the center RF transmission line, with the rotor portion being configured to rotate about a rotational axis relative to the stator portion. The stationary RF conductor portion and the rotatable RF conductor portion of the center RF transmission line may be disposed in adjacent rotatable relationship to form a first part of a center RF signal channel that extends across a rotational RF signal interface defined between the stationary RF conductor portion and the rotatable RF conductor portion of the center RF transmission line to couple the at least one rotatable RF sensor in RF signal communication with the stationary RF sensor electronics. The stator portion may further include a stationary optical conductor portion of an optical transmission line, and the rotor portion may further include a rotatable optical conductor portion of the optical transmission line. The stationary optical conductor portion and the rotatable optical conductor portion may be disposed in adjacent rotatable relationship to form an on-axis optical signal channel coincident with the rotational axis of the rotor portion and extending across a rotational optical signal interface defined between the stationary optical conductor portion and the rotatable optical conductor portion to couple the at least one stationary optical signal communication component in optical signal communication with at least one rotatable optical signal communication component. The rotational optical signal interface may be disposed within the center RF transmission line.

"In another respect, disclosed herein is a method of operating a rotary sensor system, including the step of providing a rotary sensor system. The rotary sensor system may have rotatable system components including rotatable sensor electronics, at least one rotatable RF sensor, and at least one rotatable optical signal communication component. The rotary sensor system may also have stationary system components that include stationary RF sensor electronics for the at least one rotatable RF sensor, and at least one stationary optical signal communication component. A rotary coupler may be coupled between the stationary system components and the rotatable system components of the provided rotary sensor system. The rotary coupler may have a stator portion rotatably coupled to a rotor portion, with the stator portion being coupled between the stationary system components and the rotor portion, and the rotor portion being coupled between the rotatable system components and the stator portion such that the rotor portion rotates together with the rotatable system components relative to the stator portion and the stationary system components. The stator portion may include a stationary RF conductor portion of a center RF transmission line, and the rotor portion may include a rotatable RF conductor portion of the center RF transmission line, with the rotor portion being configured to rotate about a rotational axis relative to the stator portion. The stationary RF conductor portion and the rotatable RF conductor portion of the center RF transmission line may be disposed in adjacent rotatable relationship to form a first part of a center RF signal channel that extends across a rotational RF signal interface defined between the stationary RF conductor portion and the rotatable RF conductor portion of the center RF transmission line to couple the at least one rotatable RF sensor in RF signal communication with the stationary RF sensor electronics. The stator portion may further include a stationary optical conductor portion of an optical transmission line, and the rotor portion may further include a rotatable optical conductor portion of the optical transmission line. The stationary optical conductor portion and the rotatable optical conductor portion may be disposed in adjacent rotatable relationship to form an on-axis optical signal channel coincident with the rotational axis of the rotor portion and extending across a rotational optical signal interface defined between the stationary optical conductor portion and the rotatable optical conductor portion to couple the at least one stationary optical signal communication component in optical signal communication with at least one rotatable optical signal communication component. The rotational optical signal interface may be disposed within the center RF transmission line, and the method may further include communicating optical signals between the at least one stationary optical signal communication component and the at least one rotatable optical signal communication component across the rotational optical signal interface.

BRIEF DESCRIPTION OF THE DRAWINGS

"FIG. 1 is a cross-sectional view of a conventional coaxial rotary coupler.

"FIG. 2 is a partial enlarged view from FIG. 1.

"FIG. 3 is a cross sectional view of a rotary coupler assembly according to one exemplary embodiment of the disclosed systems and methods.

"FIG. 4 illustrates a partial enlarged view from the embodiment of FIG. 3.

"FIG. 5 illustrates a partial enlarged view from the embodiment of FIG. 3.

"FIG. 6 illustrates a partial enlarged view from the embodiment of FIG. 3.

"FIG. 7 illustrates a partial enlarged view of stationary optical input according to one exemplary embodiment of the disclosed systems and methods.

"FIG. 8 illustrates a partial exploded cross-sectional view of components of the embodiment of FIG. 3.

"FIG. 9 illustrates an outer perspective view of the embodiment of FIG. 3.

"FIG. 10 illustrates an exploded perspective view of the embodiment of FIG. 3.

"FIG. 11 illustrates an exploded perspective view of an optical rotary joint assembly coupled to stationary fiber optic conductor portion and rotating fiber optic conductor portion according to one exemplary embodiment of the disclosed systems and methods.

"FIG. 12 illustrates an exploded perspective view of an optical rotary joint assembly and rotating on-axis inner conductor coupler portion according to one exemplary embodiment of the disclosed systems and methods.

"FIG. 13 illustrates an exploded perspective view of an optical rotary joint assembly, rotating on-axis inner conductor coupler portion, and stationary on-axis inner conductor coupler portion according to one exemplary embodiment of the disclosed systems and methods.

"FIG. 14 illustrates an exploded perspective view of an assembled optical rotary joint assembly, rotating on-axis inner conductor coupler portion, and stationary on-axis inner conductor coupler portion according to one exemplary embodiment of the disclosed systems and methods.

"FIG. 15 illustrates a simplified block diagram of optical signal communication components and electronic components of a rotary antenna array system according to one exemplary embodiment of the disclosed systems and methods."

For additional information on this patent application, see: Jones, Thomas Webster; Baloun, James Edward. Systems and Methods for Implementing Optical and RF Communication between Rotating and Stationary Components of a Rotary Sensor System. Filed January 8, 2013 and posted July 17, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=3037&p=61&f=G&l=50&d=PG01&S1=20140710.PD.&OS=PD/20140710&RS=PD/20140710

Keywords for this news article include: Electronics, L-3 Communications Corporation.

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Source: Electronics Newsweekly


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