Abstract:
An integrated interface integrates a bus repeater and remote terminal into a single interface linking a main bus and an extended bus in a communication system. In one embodiment, the remote terminal communicates directly with the bus repeater to monitor bus repeater operation. By integrating the bus repeater and remote terminal together, the integrated interface can use only one set of input and output components for both the bus repeater and remote terminal, reducing the total number of components in the communication system.

Description:
TECHNICAL FIELD  
       [0001]     The present invention is related to communication systems, and more particularly to an architecture for a communication system.  
       BACKGROUND OF THE INVENTION  
       [0002]     Communication systems are used in many applications, including aircraft weapon control and status monitoring. The applications may include a main data bus that is directly connected to a central computer and an extended bus that carries data from the central computer to remote terminals  10  connected to the extended bus through a single electrical interface. In an aircraft weapons system, for example, the remote terminals may be associated with stores (e.g., weapons) carried on the aircraft.  
         [0003]     To ensure that the signals from the central computer reach the remote terminals, the signals are often sent to an electronic package that acts as a “black box” that retransmits the data received from the central computer to the extended bus remote terminals. The electronic package may also conduct additional computations, data changes, or other signal processing steps before sending the signals to the remote terminals.  
         [0004]      FIG. 3  illustrates one example of a prior art system that conforms with currently-used standard design requirements (e.g., Mil-Std-1553). Data traveling from a main bus  12  to an extended bus  14  travels through an electronic package  16  containing a bus repeater  18  connecting the two buses  12 ,  14 . To link the bus repeater  18  to the two buses  12 ,  14 , the bus repeater  18  uses two transceivers  20 ,  22 , with one transceiver  20  connected to the main bus  12  via a first isolation transformer  24  and the other transceiver  22  connected to the extended bus  14  via a second isolation transformer  26 . Depending on the distance between each transceiver and its corresponding bus connection, a coupling transformer  28  may be also be included between each isolation transformer  24 ,  26  and its corresponding bus  12 ,  14 . The bus repeater  18  sends signal traffic between the buses  12 ,  14  without acting on the signals themselves.  
         [0005]     Further, the electronic package  16  itself may need to monitor and control its own functions based on the data sent to the extended bus  14 . Thus, remote terminal interface control logic  30  may be included in the electronic package  16  and have its own associated transceiver  32  that is connected to its own corresponding isolation transformer  34 , which is in turn connected to a coupling transformer  28  that couples the isolation transformer  34  to the extended bus  14 . This additional remote terminal interface  30  receives and responds to messages from the extended bus  14  after converting the analog signals to a digital format. A subsystem  36  looks at the data in the signal traveling through the electronic package  16  and processes it from an input/output perspective. The received data may result in a decision to release a weapon from the aircraft in which the remote terminal  10  is located.  
         [0006]     The separate bus repeater  18  and remote terminal interface  30  form a configuration that provides reliable communication between two buses that increase the number of circuit elements in the electronic package  16 , thereby increasing product costs and circuit board area.  
         [0007]     There is a desire for a simpler, lower cost communication system that provides more direct communication between the main bus and extended bus through a single electrical interface.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention is directed to an integrated interface that links a main bus and an extended bus in a communication system. The integrated interface includes a bus repeater and remote terminal integrated into a single device. In one embodiment, the remote terminal interface in the electronic package communicates directly with the bus repeater to respond to central computer commands and monitors and controls bus repeater operation.  
         [0009]     By integrating the bus repeater and remote terminal together, the integrated interface can use only one set of input and output components, such as transceivers and coupling transformers, for both the bus repeater and remote terminal rather than providing separate components for the remote terminal alone. As a result, the remote terminal can tap directly into data going through the bus repeater rather than obtaining and converting data on its own. The integrated interface reduces the total number of components within the communication system. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]      FIG. 1  is a representative diagram of a system incorporating an electronic package according to one embodiment of the invention;  
         [0011]      FIG. 2  is a representative diagram of the electronic package of  FIG. 1  in more detail; and  
         [0012]      FIG. 3  is a representative diagram of a prior art system configuration. 
     
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS  
       [0013]      FIG. 1  is a representative general diagram of a communication system incorporating an electronic package  100  according to one embodiment of the invention. The examples described below focus on using the communication device in an aircraft weapons system, the electronic package  100  can be used in any desired application. In the illustrated example, the electronic package  100  acts as a pass-through between a main data bus  102  and an extended data bus  104  having multiple remote device terminals  106  associated with external devices (e.g., weapons) to be controlled. The main data bus  102  may be a primary bus that carries data to subsystems, including the electronic package  100 , throughout a main system (e.g., an aircraft) to and from is a central computer  107  to communicate with the subsystems, while the extended data bus  104  carries data from the electronic package  100  to the remote device terminals  106 .  
         [0014]     The electronic package  100  provides a virtually interface for data flow from the central computer  107  to more remote areas, such as the remote device terminals  106 . Rather than providing a bus repeater and a remote terminal that are separate and independent within the package and providing each with its own transceiver and coupling transformer like currently-known systems complying with design standards (e.g., Mil-Std-1553), the inventive system combines a bus repeater and remote terminal into a single integrated interface  108 . This integrated interface  108  allows the functions of both a bus repeater  110  and a remote terminal  112  ( FIG. 2 ) to be carried out using only two transceivers/isolation transformers  114 / 115 ,  116 / 117  and two associated coupling transformers  118 ,  120 , one transceiver  114  and coupling transformer  118  on the main bus  102  side and one transceiver  116  and coupling transformer  120  on the extended bus side of the bus repeater  110 . As shown in  FIG. 2 , the isolation transformers  115 ,  117  are part of the electronic package  100  while the coupling transformers  118 ,  120  act as bus connections. This structure therefore eliminates the need to provide a separate transceiver, isolation transformer and coupling transformer specifically for the remote terminal  112  alone.  
         [0015]     Signals from the central computer  107  can therefore travel between the main bus  102 , the extended bus  104 , and the remote terminals  106  via the bus repeater portion  110  through the integrated interface  108 . At the same time, the remote terminal portion  112  of the integrated interface  108  can tap data from the bus repeater  110  portion for operation of the electronic device  100 .  
         [0016]     In one embodiment, the analog data from the buses  102 ,  104  are converted into digital data by the bus repeater portion  110  by analog-to-digital conversion circuitry in the transceivers  114 ,  116 . The remote terminal portion  112  can then simply tap off the digital data from the bus repeater portion  110  directly rather than having to conduct its own separate conversion of analog data obtained from either bus  102 ,  104 . Similarly, digital data from the remote terminal  112  and the bus repeater  110  can both be converted by digital-to-analog conversion circuitry in the transceivers  114 ,  116 . By combining the bus repeater  110  and the remote terminal  112  functions into a single integrated interface  108 , the remote terminal  112  in the interface can simply transmit and receive already-converted digital data to and from the bus repeater  110  without conducting its own analog-to-digital conversion.  
         [0017]      FIG. 2  illustrates the electronic package  100  in greater detail. As noted above, the electronic package  100  includes an integrated interface  108  that includes a bus repeater portion  110  and a remote terminal portion  112 . As shown in  FIG. 2 , the bus repeater  110  and remote terminal  112  send digital signals to and from each other directly, allowing the remote terminal  112  to monitor the bus repeater  110  communication traffic operation in real time if desired. Because the signals going through the bus repeater  110  are already converted into digital data, the remote terminal  112  can tap directly into the bus repeater  110  to obtain the digital data without having to obtain and convert data from the extended bus  104  on its own. Thus, the remote terminal  112  in the electronic package  100  can rely on the bus repeater  110  to supply it with data and does not need its own transceiver or isolation/coupling transformers, reducing the total number of parts in the electronic package  100 . This single chip solution will require fewer components in the system, reduce power consumption, reduce data delay and data latency and also improves overall system reliability.  
         [0018]     In one embodiment, the electronic package  100  includes a programmable-type part device, such as a field-gate programmable array (FPGA), that can be programmed with code in a high-level language. This code can then be easily transferable to other devices. Making the electronic package  100  programmable eliminates part obsolescence, further improving system functionality.  
         [0019]     As shown in  FIG. 2 , the transceivers  114 ,  116  may form part of the bus repeater  110 . The bus repeater  110  also includes signal filtering and reconstruction control logic  122  that reconstructs data received by the bus repeater  110  in real time and controls the transmit/receive direction of data going through the bus repeater  110 . Signal filtering may include data validation, synchronization, and data bit extraction. Data reconstruction involves resynchronization and data bit insertion of data passing from the main bus  102  to the extended bus  104 . The control logic controls the transmit/receive direction by controlling the operating modes of the first and second transceivers  114 ,  116 . For example, the first transceiver  114  is in a receive mode and the second transceiver  116  is in a transmit mode when the system is first powered up and after any message transfer is complete to make them ready to carry a message from the central computer  107  to the remote terminal  106  (i.e., a transmit cycle). After receiving a valid command from the central computer  107 , the control logic  122  places the second transceiver  116  into a receive mode and the first transceiver  114  into a transmit mode to carry an acknowledgement from the remote terminal  106  (i.e., a receive cycle).  
         [0020]     The bus repeater  110  includes a bus idle detection circuit that determines bus activity as well as provides a fail-safe direction mechanism in case the remote terminal  106  fails to acknowledge receipt of the transmitted signal from the central computer  107  to the bus repeater  110 . More particularly, if the remote terminal  106  fails to respond within a predetermined amount of time, the control logic  122  reinitializes the transceivers  114 ,  116  to be ready for the next transmission from the central computer  107  by placing the first transceiver  114  back in the receive mode and the second transceiver  116  in the transmit mode.  
         [0021]     A subsystem  130  in the electronic package  100  may be used to process the data send through the bus repeater  110  from an input/output perspective and to control the device in which the remote terminal  106  resides. In one embodiment, the subsystem  130  an input/output  132 , a subsystem controller  134 , and a memory  136 . The subsystem  130  itself can be any subsystem appropriate for the system in which the electronic package  100  is used.  
         [0022]     The specific input and output characteristics of the electronic package  100  can include any characteristics (e.g., input waveform compatibility, common mode rejection, noise rejection, etc.) that ensure compatibility with other components in the communication system. In one embodiment, the architecture of the electronic package  100  supports a command/response system where the central computer  107  always initiates a transmission cycle with the remote terminals  106 . If the inventive electronic package  100  is used in, for example, a weapon-carrying aircraft, the remote terminals  106  may be configured to be responsible for controlling weapon stores. In this example, data entities, such as the time of store release, would be required by the remote terminal  106  before releasing the store from the aircraft.  
         [0023]     By encompassing the remote terminal in the electronic device within the bus repeater to form a single integrated interface, the invention eliminates the transceiver, isolation transformers and the coupling transformers normally associated with a standard configuration (e.g., a Mil-Std-1553 dual-redundant configuration), reducing the overall number of components in the system. Further, the bus repeater and remote terminal co-exist as a single part in the electronic package, creating a single chip solution for the interface between the main and extended buses. Note that the integrated interface can be in the form of a reprogrammable device that can be programmed with high-level code that is easily transferable to other devices in the system, eliminating part obsolescence.  
         [0024]     The inventive structure is therefore able to eliminate the isolation transformers used in previously-known systems, resulting in fewer parts, lowered system cost and improved reliability.  
         [0025]     It should be understood that various alternatives to the embodiments of the invention described herein may be employed in practicing the invention. It is intended that the following claims define the scope of the invention and that the method and apparatus within the scope of these claims and their equivalents be covered thereby.