Abstract:
A method of modular design/manufacturing of active optical cables (AOC) enables multiple functions with minimal non-recurring engineering. Customized AOCs combine standardized interface boards, hybrid cable assemblies, and connector assemblies into various combinations to implement the required functions. Standardized boards support various data types. Conversion of electrical data types to/from optical signals are transmitted over the AOC. Connections to the boards use board connectors attached to a ruggedized connector. Customized connections are made by changing the layout of a customizable interconnect board attached to the ruggedized connector without significant design, verification and/or qualification. Standardized boards using a mother board manage the boards and monitor board health. Power isolation, regulation, and/or distribution to other boards are handled on the mother board or a dedicated power board. Modular AOCs are customized to different connectors and/or pin-outs, combinations of electrical data, and/or power distribution requirements with minimal redesign and/or requalification.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application Ser. No. 61/747,295 entitled “Apparatus for Modular Implementation of Multi-Function Active Optical Cables” filed Dec. 29, 2012 and U.S. Provisional Application Ser. No. 61/747,349 entitled “Method and Apparatus for Modular Design, Manufacturing and Implementation of Multi-Function Active Optical Cables” filed Dec. 30, 2012. Both of the above-referenced provisional applications are hereby incorporated herein by reference in their entireties. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This invention relates to the design and/or manufacturing of active optical cables, particularly for aerospace, military, and/or industrial applications in harsh environments. 
         [0003]    Most interconnects in harsh environments, particularly for aerospace, military, and/or industrial applications, may be implemented using electrical cables. Using electrical cables has significant advantages, including: the ability to use ruggedized, blind-mateable electrical connectors such as the MIL-DTL-38999, flexibility in integrating different types of data, the ability to distribute electrical power, and/or the ability to operate in harsh environments including those with extended temperature ranges and/or high levels of contamination. However, the use of electrical cables for these interconnects also has disadvantages, including: susceptibility to electromagnetic interference, large cable size and/or weight, and/or limited ability to upgrade to higher bandwidths and/or longer transmission distances. 
         [0004]    In principle, optical data transmission may address these disadvantages, but existing optical interconnect solutions have fallen drastically short of providing a viable solution to interconnects in these applications and/or environments. Examples may be found at: (http://rhu004.sma-promail.com/SQLImiages/kelmscott/Molex/PDF_Images/987650-5361.pdf; http://www.dvigear.com/fiopca.html; http://protokraft.com/products/media-converters/d38999-33vdc.html). 
         [0005]    Existing optical solutions only enable the transmission of a single type (namely, electrical format) of data and may not include the ability to distribute electrical power and/or perform significant health monitoring functions. Such solutions may be also standardized to a specific electrical connector and/or pin-out. The standardization may be done to create standard products with sufficient manufacturing volume to make them profitable. 
         [0006]    Much of the interconnect market in these applications includes a wide variety of customized cabling including different connectors, pin-outs, power distribution requirements, and/or types of electrical data. In addition, the electrical data often consists of multiple channels of different types of data, usually requiring media conversion before the electrical data may be used for optical data transmission. Another challenge may be the small volumes typically associated with these applications. Overall the potential market for optical solutions in aerospace, military, and/or industrial applications may be substantial, but the potential market may be comprised of a very large number of customized cables, each with only a small volume. 
         [0007]    Although optical interconnects may be incorporated in limited situations in applications such as aerospace, military, and/or industrial markets, these applications tend to be for high-bandwidth interconnects where only a single standardized type of data may be present. While a much larger section of the interconnect market in these applications may greatly benefit from some of the inherent advantages of optical interconnects, they require solutions that may be drastically different from existing products in both form and/or function. The lack of a modular design and/or manufacturing method that scales to small volumes limits the ability to provide the required optical interconnect solution for many of these applications. 
       SUMMARY OF THE INVENTION 
       [0008]    To this end, in an embodiment of the invention, a method of making modular multi-function active optical cables is provided. The method may have the steps of: ruggedizing an electrical connector at each end of the active optical cable; providing one or more board connectors; providing an interface between the ruggedized electrical connector and/or the board connectors; providing one or more modular boards; providing a mechanical assembly for the modular boards; providing a hybrid cable assembly having one or more optical fibers, zero or more electrical conductors, connectors for the optical fibers and/or conductor terminations for electrical connection; and/or providing an enclosure for the modular boards. 
         [0009]    In an embodiment, the method may have the step of accommodating a variety of the ruggedized electrical connector types without changing the modular boards. 
         [0010]    In an embodiment, the ruggedized electrical connector may be a MIL-DTL-38999. 
         [0011]    In an embodiment, the ruggedized electrical connector may be a D-sub type connector. 
         [0012]    In an embodiment, the method may have the step of accommodating a variety of pin arrangements without changing the modular boards. 
         [0013]    In an embodiment, the method may have the step of accommodating a variety of connector sizes without changing the modular boards. 
         [0014]    In an embodiment, the method may have the step of accommodating a variety of pin-outs without changing the modular boards. 
         [0015]    In an embodiment, the method may have the step of accommodating a variety of the board connector types to accommodate different modular board requirements. 
         [0016]    In an embodiment, the method may have the step of using one or more fixed board connector types for a specific modular board. 
         [0017]    In an embodiment, the board connector may be one or more of the following: a D-sub type connector, a nanominiature type connector, flex circuit, cable-to-board connector, surface mount connector, a direct solder connection, and/or coaxial connections. 
         [0018]    In an embodiment, the method may have the step of changing the interface between the ruggedized electrical connector and the board connectors with minimal design and/or manufacturing effort to accommodate different pin-outs in the ruggedized connector. 
         [0019]    In an embodiment, the method may have the step of press fitting a board to the pins of the ruggedized electrical connector in the interface between the ruggedized electrical connector and the board connectors. 
         [0020]    In an embodiment, the method may have the step of soldering a board to the pins of the ruggedized electrical connector in the interface between the ruggedized electrical connector and the board connectors. 
         [0021]    In an embodiment, the method may have the step of surface mounting connectors for the modular boards to the board that press fits to the pins of the ruggedized electrical connector. 
         [0022]    In an embodiment, the method may have the step of surface mounting connectors for the modular boards to the board that solders to the pins of the ruggedized electrical connector. 
         [0023]    In an embodiment, the method may have the step of connecting the board to the board connectors with a flex circuit. 
         [0024]    In an embodiment, the method may have the step of providing a flex circuit in the interface between the ruggedized electrical connector and the board connectors. 
         [0025]    In an embodiment, the method may have the step of providing power connections between the modular boards without being connected to a pin on the ruggedized electrical connector in the interface between the ruggedized electrical connector and the board connectors. 
         [0026]    In an embodiment, the method may have the step of providing ground connections between the modular boards without being connected to a pin on the ruggedized electrical connector in the interface between the ruggedized electrical connector and the board connectors. 
         [0027]    In an embodiment, the method may have the step of providing interconnections between the modular boards without being connected to a pin on the ruggedized electrical connector in the interface between the ruggedized electrical connector and the board connectors. 
         [0028]    In an embodiment, the method may have the step of providing microcontroller communication between the modular boards without being connected to pins on the ruggedized electrical connector in the interface between the ruggedized electrical connector and the board connectors. 
         [0029]    In an embodiment, the method may have the step of connecting the ruggedized electrical connector to frame ground. 
         [0030]    In an embodiment, the method may have the step of separating power and/or ground connections from other signal connections in the interface between the ruggedized electrical connector and the board connectors. 
         [0031]    In an embodiment, the method may have the step of enabling the modular boards to be used in different combinations to implement different active optical cable requirements. 
         [0032]    In an embodiment, the method may have the step of providing a fixed interface both optically and/or electrically to the hybrid cable assembly for a specific modular board. 
         [0033]    In an embodiment, the method may have the step of providing a fixed interface electrically to the hybrid cable assembly for a specific modular board. 
         [0034]    In an embodiment, the method may have the step of implementing subsets of the total functionality required by the multi-function active optical cables. 
         [0035]    In an embodiment, the method may have the step of communicating between the modular boards. 
         [0036]    In an embodiment, the method may have the step of implementing the communication between the modular boards using microcontrollers. 
         [0037]    In an embodiment, one of the microcontrollers may be the master microcontroller and/or the other microcontrollers may be slaves. 
         [0038]    In an embodiment, the method may have the step of communicating from one or more of the modular boards over the hybrid cable assembly to one or more of the modular boards on the other end of the active optical cable. 
         [0039]    In an embodiment, the method may have the step of implementing power management functions by one of the modular boards for other modular boards. 
         [0040]    In an embodiment, the power management may include power distribution over the hybrid cable assembly. 
         [0041]    In an embodiment, the power management may encompass surge protection, power isolation, voltage regulation, and/or noise filtering. 
         [0042]    In an embodiment, the method may have the step of providing one of the modular boards to be a mother board that implements common functions for other modular boards. 
         [0043]    In an embodiment, the common functions may have communication outside the active optical cable. 
         [0044]    In an embodiment, the method may have the step of implementing the communication outside the active optical cable using a two wire interface, three wire interface, I2C, SPI, and/or interfaces that may require more wires such as Ethernet and/or RS-422. 
         [0045]    In an embodiment, the method may have the step of implementing the communication with the other end of the active optical cable optically or electrically. 
         [0046]    In an embodiment, the common functions may encompass one or more of the following: built-in test, health monitoring, status reporting, communication with the other end of the active optical cable, providing an interface for field maintenance, providing an interface for firmware upgrades, and/or an interface for communicating with upstream components and/or systems. 
         [0047]    In an embodiment, the method may have the step of implementing other functions that may not be common functions with the mother board. 
         [0048]    In an embodiment, the method may have the step of implementing the interface for one or more electrical data types with the modular boards; and converting the incoming/outgoing electrical data to/from optical data for transmission over the hybrid cable assembly. 
         [0049]    In an embodiment, the method may have the step of providing more than one channel of a specific electrical data type. 
         [0050]    In an embodiment, the method may have the step of accommodating at least one of the following in the interface for electrical data types: RS-485, RS-422, RS-232, MIL-STD-1553, ARINC-429, CAN Bus, transistor-transistor logic (TTL) type data, CMOS type data, pulse width modulated (PWM) type data, interlock type data, 10/100/1000 Base-T Ethernet, analog video data, SDI video, CameraLink, FireWire, USB, high-speed differential signal data, and/or DVI video data. 
         [0051]    In an embodiment, the method may have the step of using health monitoring to enable optical data to be rolled over to an alternative optical channel if the primary optical channel degrades and/or fails. 
         [0052]    In an embodiment, the method may have the step of enabling a specific modular board to be used in an active optical cable even though not all functions implemented on the modular board may be required. 
         [0053]    In an embodiment, the method may have the step of enabling the modular boards to be manufactured in higher volumes than would be possible if custom boards were designed and/or manufactured for each customer requirement. 
         [0054]    In an embodiment, the method may have the step of performing verification and/or qualification of the modular boards once and applying the verification and/or qualification to different active optical cables. 
         [0055]    In an embodiment, the method may have the step of providing heat sinks for the mechanical assembly for the modular boards. 
         [0056]    In an embodiment, the method may have the step of providing mechanical support for mechanical shock and/or vibration for the mechanical assembly for the modular boards. 
         [0057]    In an embodiment, the heat sinks may be made of copper, aluminum, stainless steel, or other metal. 
         [0058]    In an embodiment, the method may have the step of attaching the heat sinks to the modular boards using a compliant material to compensate for differences in coefficient of thermal expansion (CTE). 
         [0059]    In an embodiment, the compliant material may be thermal grease. 
         [0060]    In an embodiment, the method may have the step of attaching the heat sinks to the modular boards and/or specific components on a modular board using thermally conductive epoxy. 
         [0061]    In an embodiment, the method may have the step of filling the enclosure and space between modular boards with a thermally conductive foam or injection molded material. In an embodiment, the method may have the step of bolting the mechanical assembly together. 
         [0062]    In an embodiment, the method may have the step of connecting the heat sinks to frame ground. 
         [0063]    In an embodiment, the method may have the step of attaching the heat sinks to the front and/or back sides of the modular boards. 
         [0064]    In an embodiment, the method may have the step of using a common set of firmware with a configuration file to specify the functions present in that specific active optical cable. 
         [0065]    In an embodiment, the method may have the step of using a common set of test equipment and/or procedures with a configuration file to specify the functions present in that specific active optical cable. 
         [0066]    In an embodiment, the method may have the step of providing the modular hybrid cable assemblies to meet the requirements of multiple users. 
         [0067]    In an embodiment, the method may have the step of providing the modular hybrid cable assemblies with optical fibers that may not be used by all users. 
         [0068]    In an embodiment, the method may have the step of providing the modular hybrid cable assemblies with conductors that may not be used by all users. 
         [0069]    In an embodiment, the method may have the step of providing the hybrid cable assemblies to support the distribution of power at different voltages, currents, and/or distances. 
         [0070]    In an embodiment, the method may have the step of terminating the optical fibers of the hybrid cable assembly in MT type connectors. 
         [0071]    In an embodiment, the method may have the step of terminating the optical fibers of the hybrid cable assembly in MT ferrules. 
         [0072]    In an embodiment, the method may have the step of terminating the optical fibers of the hybrid cable assembly in LC ferrules. 
         [0073]    In an embodiment, the method may have the step of shielding the conductors in the hybrid cable assembly with a grounded conductive sheath or other grounded shield. 
         [0074]    In an embodiment, the method may have the step of ruggedizing the hybrid cable assembly with a strength member. 
         [0075]    In an embodiment, the method may have the step of using the strength member for strain relief when attaching the hybrid cable assembly to the modular boards, frame for mounting the modular boards, and/or the ruggedized electrical connector. 
         [0076]    In an embodiment, the method may have the step of providing jacketing material to the hybrid cable assembly to provide environmental ruggedization. 
         [0077]    In an embodiment, the method may have the step of mechanically connecting the modular boards to the ruggedized electrical connector and/or the hybrid cable assembly with the enclosure for the modular boards and/or the frame for mounting the modular boards. 
         [0078]    In an embodiment, the method may have the step of providing environmental sealing with the enclosure for the modular boards. 
         [0079]    In an embodiment, the method may have the step of providing mechanical ruggedization with the enclosure for the modular boards. 
         [0080]    In an embodiment, the method may have the step of providing strain relief for the hybrid cable assembly with the enclosure for the modular boards and/or the frame for mounting the modular boards. 
         [0081]    In an embodiment, the method may have the step of providing electromagnetic interference (EMI) shielding with the enclosure for the modular boards. 
         [0082]    In an embodiment, the method may have the step of connecting the enclosure for the modular boards to frame ground. 
         [0083]    In an embodiment, the enclosure may have a backshell. 
         [0084]    In an embodiment, the backshell may be metal. 
         [0085]    In an embodiment, the enclosure may comprise overmolding. 
         [0086]    In an embodiment, the overmolding may encompass low-pressure injection molding and/or high-pressure injection molding. 
         [0087]    In an embodiment, the enclosure may have a backshell and/or overmolding. 
         [0088]    In an embodiment, the method may have the step of enabling the enclosure to be used for a variety of combinations of the modular boards. 
         [0089]    In an embodiment, the method may have the step of enabling the enclosure to be used with different numbers of the modular boards. 
         [0090]    In an embodiment, the method may have the step of enabling straight, right-angle and/or arbitrary-angle connections with only a change in the design and/or manufacturing of the enclosure and/or connectors to the ruggedized electrical connector. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0091]      FIG. 1  is a schematic diagram of multiple standardized boards connected to a ruggedized connector by a flexible cable with multiple board connectors in accordance with embodiments disclosed herein. The standardized boards may implement a variety of functions as shown, including: power management, mother board functions, and/or data conversion and/or transmission for a variety of different types of electrical data. 
           [0092]      FIG. 2  is a schematic diagram a standardized board for power management that may include power isolation, surge protection, voltage regulation, and/or power distribution in accordance with embodiments disclosed herein. 
           [0093]      FIG. 3  is a schematic diagram of a standardized board that may include mother board functions including health monitoring and/or control, and electronics and/or optoelectronics for the conversion of several types of electrical data to/from optical data for transmission over the hybrid cable in accordance with embodiments disclosed herein. 
           [0094]      FIG. 4  is a schematic diagram of a standardized daughter board that may include electronics and/or optoelectronics for the conversion of HD-SDI electrical data to/from optical data for transmission over the hybrid cable in accordance with embodiments disclosed herein. 
           [0095]      FIG. 5  is a schematic diagram of a stacked assembly of multiple standardized boards for the implementation of a combination of data types in accordance with embodiments disclosed herein. The board stack assembly may include thin heat sink layers that may reduce component junction temperatures and/or enable wider temperature operation, as well as providing mechanical support for mechanical shock and/or vibration. The schematic also shows connectors providing connections from the board to the ruggedized electrical connector and/or hybrid cable. 
           [0096]      FIG. 6  is a schematic diagram of standardized, modular test equipment that may be configured for testing customized active optical cables with a set-up and/or configuration file in accordance with embodiments disclosed herein. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0097]    A method for the modular design and/or manufacturing of multi-function active optical cables utilizes modular functional parts including ruggedized connectors, optoelectronic interface boards, and/or hybrid cable assemblies. By using the design and/or manufacturing method disclosed, the interchangeable parts may be combined in a large number of combinations to enable a wide variety of multi-function active optical cables that require limited design and/or qualification, enabling customized active optical cables to be manufactured profitably at small production volumes. 
         [0098]      FIG. 1  illustrates the use of a plurality of modular optoelectronic boards  10  useful in embodiments disclosed herein. The standardized boards  10  may implement a variety of functions as shown, including: power management, mother board functions, and/or data conversion and/or transmission for a variety of different types of electrical data. Connections from a ruggedized connector  20 , such as, for example, a MIL-DTL-38999, to the plurality of boards  10  may be accomplished using a flex circuit  30 . One end of the flex circuit  30  may be connected to one of the plurality of boards  10  that may be press fit to the pins of the ruggedized connector  20 . The other end of the flex circuit  30  may be connected to a plurality of board connectors that connect to the plurality of optoelectronic boards  10  as shown. The flex circuit  30  may act as a backplane enabling power distribution and/or MCU communication between the plurality of boards  10 . 
         [0099]    As  FIG. 1  illustrates, different boards may be used to implement different subsets of functions for a multi-function active optical cable. This may include a wide variety of functions that may be grouped together in many different ways.  FIG. 1  is an illustrative embodiment of such an implementation. As shown, Board 1—Power Board  40  may implement power management functions. The power management functions may include, for example: power distribution across the hybrid cable, surge protection, power isolation, noise filtering, and/or voltage regulation. Board 2—Mother Board  50  may implement electrical-optical/optical-electrical conversion of several different data types, including: RS-485, RS-422, RS-232, MIL-STD-1553, and/or ARINC-429. Board 2—Mother Board  50  may also function as a mother board. Board 2—Mother Board  50  may communicate with other boards on the same end of the active optical cable. Also, Board 2—Mother Board  50  may communicate with a mother board on the other end of the active optical cable. In such an embodiment, functions such as, for example: built-in test, health monitoring, self identification, channel rollover, external health reporting, firmware upgrades, and/or temperature compensation may be implemented. 
         [0100]    As shown, additional boards may be used to implement additional subsets of functions for the transmission of additional types of data. The illustrated embodiment also shows a Board 3—Interface Board  60  for TTL (transistor-transistor-logic), CMOS, PWM (pulse width modulation), interlock, and/or CAN bus data. Further, Board 4—Interface Board  70  may support 10/100/1000 Base-T electrical Ethernet data. In addition, Board 5—Interface Board  80  may support HD/3G SDI data. Moreover, Board 6—Interface Board  90  may support analog video data. Additional modular boards may support additional electrical data types, including: FireWire, USB, analog sensor, and/or high-speed differential signal data. 
         [0101]      FIG. 2  illustrates the functional schematic for an embodiment of the power management board, Board 1—Power Board  40 . In an embodiment, Board 1—Power Board  40  may be designed to support a wide variety of customer requirements thereby enabling the same board, namely Board 1—Power Board  40 , to be used for many different active optical cables that have different power supply voltages and/or power distribution requirements. Board 1—Power Board  40  may also isolate the power supply for the active optical cable boards from the distributed power and/or regulate the incoming power for use by the plurality of optoelectronic boards  10 . The Board 1—Power Board  40  may provide power distribution over the cable and/or between the plurality of boards  10 . Board 1—Power Board  40  may also provide surge protection, power regulation and/or filtering as well as power isolation and/or monitoring. Board 1—Power Board may provide more than one voltage for use by the plurality of boards  10 . 
         [0102]    In an embodiment, a 51 pin connector may be used. Two (2) pins may be used for an I 2 C buffer. The I 2 C buffer may connect to a MCU  100  to provide communication between the boards  10 . Three (3) of the pins may be connected for board power via a voltage regulator. Twenty-two (22) of the pins may be used for power and may connect to a surge stopper. Twenty-two (22) of the pins may be used for circuit ground. One (1) pin may be used for shield and/or frame ground. 
         [0103]      FIG. 3  illustrates the functional schematic for an embodiment of the Board 2—Mother Board  50 . In an embodiment, Board 2—Mother Board  50  may support the optical transmission of multiple channels of electrical data for each of the electrical interfaces (RS-485/RS-422, RS-232, MIL-STD-1553, and/or ARINC-429). In an embodiment, a 51 pin connector may be used. Sixteen (16) of the pins may be used for four channels of RS-485/RS-422. Eight (8) of the pins may be used for two channels of RS-232. Eight (8) of the pins may be used for four channels of MIL-STD-1553. Four (4) of the pins may be used for two channels of ARINC-429. Two (2) pins may be used for a first I 2 C buffer. The first I 2 C buffer may connect to a master MCU  100  to provide communication between the boards  10 . Two (2) pins may be used for a second I 2 C buffer. The second I 2 C buffer may connect to the master MCU  100  to provide external I 2 C for identification, health monitoring and/or maintenance. Three (3) pins may be used for connecting power, ground and/or frame ground. 
         [0104]    As  FIG. 3  also illustrates that low-speed data channels may be multiplexed onto a single optical channel. In addition,  FIG. 3  illustrates that back-up channels may be utilized thereby allowing data to be rolled over to the alternative channels in the event that an optical channel may degrade and/or fail. Moreover,  FIG. 3  illustrates that the Board 2—Mother Board  50  may have the master MCU  100  that may communicate with other boards on the same end of the active optical cable. The MCU  100  may also communicate with a master MCU on the other end of the active optical cable through a communication channel multiplexed with the other electrical data onto a single optical channel. Obviously, depending on the design of the modular boards and/or the number of data channels, the data may be multiplexed onto more than one optical channel. Multiplexing the data may enable consistent data rates for an optical engine, for example, a laser diode drive, a trans-impedance amplifier, a laser, and/or a photodetector. Multiplexing may also make a modular design easier to implement. However, multiplexing may not necessarily have to be implemented. In addition, while  FIG. 3  illustrates an implementation that may only multiplex low-speed (10 Mbps or less) data, the same implementation approach may be used for multiplexing higher speed data if the design requirements favor such an approach. 
         [0105]      FIG. 4  illustrates the functional schematic for an embodiment of Board 5—Interface Board  80  that may support the optical transmission of multiple channels of SDI video data including standard SDI, HD-SDI, and/or 3G SDI. In an embodiment, a 21 pin connector may be used. Sixteen (16) of the pins may be used for SDI convertors. Two (2) pins may be used for an I 2 C buffer. The I 2 C buffer may connect to an MCU to provide communication between the boards  10 . Three (3) pins may be used for connecting power, ground and/or frame ground. The higher speed data, for example, 1.5 Gbps or 3 Gbps per channel, may be allocated to an optical channel for every incoming/outgoing electrical channel. Consequently, the electrical data may not require multiplexing. Such an approach may be preferred due to the enhanced ability of achieving robust and/or reliable operation in harsh environments at lower data rates. 
         [0106]    While the functionality of each modular board may be different, the boards may all have the same dimensions and/or may utilize similar and/or identical connectors. As previously described with reference to  FIG. 1 , the boards  10  may be connected to the ruggedized connector  20  by small, low-profile board connectors such as D-Sub and/or nanominiature connectors. Depending of the requirements of the board  10 , the connectors may differ in the number of pins and/or the type of pins used. Such an embodiment may enable different, yet standardized connections for power, low-speed data, and/or high-speed data requiring coaxial connections. On the other side of the board, optical and/or electrical connections to the hybrid cable assembly may be standardized as well. In an embodiment, the optical connections may be made with MT-type connectors. The electrical power connections may be made with a connector, but the preferred connection may be made with a solder cup. 
         [0107]    The hybrid cable assembly may include optical fibers and zero or more conductors for transmission of electrical power and/or electrical data. If power distribution over the cable assembly may not be required, then the electrical conductors may be omitted. In an embodiment, the electrical conductors may be shielded with a grounded sheath. The optical fibers may be single and/or multimode fibers. In an embodiment, multimode fibers may be preferred. 
         [0108]      FIG. 5  is a schematic diagram of a stacked assembly of multiple standardized boards  10  for the implementation of a combination of data types in accordance with embodiments disclosed herein. The board stack assembly may include thin heat sink layers that may reduce component junction temperatures and/or enable wider temperature operation. The board stack assembly may provide mechanical support for mechanical shock and/or vibration. The schematic diagram also shows connectors providing connections from the boards  10  to the ruggedized electrical connector  20  and/or to the hybrid cable. 
         [0109]    Further,  FIG. 5  illustrates an embodiment of a method of assembling multiple modular boards  10  into a ruggedized assembly with integrated heat sinks  110 . As shown in  FIG. 5 , the boards  10  may be assembled between the copper heat sinks  110  with contact on both sides made using thermal grease  120 . The method may allow efficient heat sinking and/or spreading, minimizing the temperature rise above ambient for the components on the boards  10 . The method may enable higher operating temperatures and/or improved reliability. In addition, the copper heat sinks  110  may provide mechanical support for the boards  10 , significantly reducing their susceptibility to mechanical shock and/or vibration. The use of thermal grease  120  between the heat sinks  110  and/or the boards  10  may provide good thermal contact while remaining compliant. The use of the thermal grease  120  may enable the assembly to tolerate extreme temperature cycling despite a mismatch in coefficients of thermal expansion (CTE). To further improve the ruggedization of the assembly, the connectors may be potted with epoxy after the connections have been made. 
         [0110]    Using the modular boards  10  may enable the standardized boards  10  to be manufactured in volume even though the boards  10  may be made for different active optical cable requirements. In an embodiment, the boards  10  necessary to implement the required functionality of an active optical cable may be assembled. In an embodiment, the boards  10  may be fully populated even though a particular active optical cable may not require all the channels and/or functions on a board  10 . In an embodiment, the board for power management, Board 1—Power Board  40 , and/or the mother board, Board 2—Mother Board  50 , may be included, although these may obviously be omitted for certain sets of requirements. 
         [0111]    Using the flex circuit  30  to connect the ruggedized connector  20  (such as MIL-DTL-38999) to the boards  10  may enable the method to easily accommodate different connector types, pin arrangements, and/or pin-outs by only changing the flex circuit  30  while leaving the configuration of the boards  10  constant. For example,  FIG. 5  shows micro-D connectors and nano connectors on the flex circuit  30  connecting to the corresponding micro-D connectors and nano connectors on the stacked assembly of multiple standardized boards  10 . The schematic diagram of  FIG. 5  also shows connectors providing connections from the boards  10  to the hybrid cable. For example, MT-type connectors are illustrated. Power connections are also shown. 
         [0112]    The method may enable the boards  10  and/or other modular components of the active optical cable to be verified and/or qualified in an active optical cable as modular components that may be reconfigured to meet new customer configurations without significant additional design, verification and/or qualification. Reducing the non-recurring engineering (NRE) costs for a new cable configuration using this method may allow custom active optical cables to be manufactured in small volumes at costs that may not be substantially higher than the costs that may be achieved in the manufacture of high volumes. Such advantages may be possible because the design, verification, and/or qualification of the modular parts may be spread over high volumes consisting of numerous small volume custom configurations. 
         [0113]    As  FIG. 6  illustrates, a common test set-up  130  may be used for production testing. The test set-up  130  may have a fan-out cable connected via a flex circuit to a flex connector connected to each of the plurality of boards  10 . Each flex connector may connect to a corresponding board connector on each of the plurality of boards  10 . 
         [0114]    The test set-up  130  may have the ability to test all functionality for all channels on each of the plurality of boards  10 . The actual test run on a particular active optical cable may be determined by a configuration file that may define which functions and/or data channels may be present. Each of the plurality of boards  10  may have a fan-out for connecting to the test equipment. For example, the fan-out for Board 1—Power Board  40  may allow test equipment to analyze functionality, including: RS-485/RS-422, RS-232, MIL-STD-1553, ARINC-429, I 2 C and/or power. The fan-out for Board 2—Mother Board  50  may allow test equipment to analyze functionality, including: RS-485/RS-422, RS-232, MIL-STD-1553, ARINC-429, I 2 C and/or power. The fan-out for Board 3—Interface Board  60  may allow test equipment to analyze functionality, including: TTL (transistor-transistor-logic), CMOS, PWM (pulse width modulation), interlock, and/or CAN bus data. The fan-out for Board 4—Interface Board  70  may allow test equipment to analyze functionality, including: 10/100/1000 Base-T electrical Ethernet data. The fan-out for Board 5—Interface Board  80  may allow test equipment to analyze HD/3G SDI data. The fan-out for Board 6—Interface Board  90  may allow test equipment to analyze analog video data. 
         [0115]    Thus, the test set-up  130  may have the ability to test all functionality for all channels on each of the plurality of boards  10 , but the actual test run on a particular active optical cable may be determined by a configuration file that may define which functions and/or data channels may be present. A similar configuration file may be used to set-up the firmware during manufacturing, enabling a single version of the firmware to be developed that may include all functions, but may be configured to only implement those present in a particular active optical cable. 
         [0116]    It should be understood that various changes and/or modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and/or modifications may be made without departing from the spirit and/or scope of the present invention and without diminishing its attendant advantages. It is, therefore, intended that such changes and/or modifications be covered by the appended claims.