GB2165379A - Configuration module for avionics signal processing units - Google Patents

Abstract

An apparatus for reducing the number of electrical connections required for remotely determining the operational configuration of an avionics system signal processing unit relative to optional sets of input and output signals. The reduction in the number of connections is attained by utilization of a configuration memory 32 that is mounted on the tray (36 Fig. 2) that receives the housing (34) containing the signal processing unit 12. Digitally encoded signals representative of the selected optional input and output signals are stored in a programmable nonvolatile memory 32 of configuration module 30 when the signal processing unit 12 is initially installed in the avionics system. The signals stored in the configuration module 30 are available for configuring replacement signal processing units. <IMAGE>

Description

SPECIFICATION Configuration module for avionics signal processing units Technical Field In general, this invention relates to methods and apparatus for configuring signal processing apparatus for operation with input and output devices of various types and configuration.

Although the invention has utility in various types of electrical and electronic systems, in its preferred form, it is particularly suited for configuring the signal processing unit of an avionics system for operation with signal sources and signal utilization devices that can alternatively be employed within that particular avionics system.

Background of the Invention Advances in the digital signal processing arts have made it possible to realize a wide range of electrical and electronic apparatus by utilizing a programmed digital signal processing unit in combination with various types of signal sources and signal utilization devices. In some such systems, it is necessary that the programmed digital signal processing unit be capable of operating in conjunction with alternative signal sources and/or alternative signal utilization devices that exhibit disparate signal characteristics. This requirement can be brought about for many reasons, including preferences of the system user or to facilitate the use of existing signal sources and utilization devices that serve as components of another electrical or electronic system that is installed at the same location or facility.In cases in which a substantial number of alternative signal sources or signal utilization devices must be accommodated and there is disparity between signals supplied by the signal sources and/or disparity between the signals required by the signal utilization devices, the problem of configuring the signal processing unit for operation with the alternative components can be substantial.

The problem of accommodating various signal sources and signal utilization devices has become especially troublesome with respect to signal processing units that are utilized in avionics systems of the type employed in commercial aircraft. In this regard, the air carrier or company that operates the aircraft generally determines what types of avionics systems will be installed on the various aircraft of that carrier's fleet, and further specifies the configuration of each system, including which particular signal sources and signal utilization devices are to be employed. Regardless of whether a particular signal utilization device is a cockpit display unit, an actuator, or another avionics system, several alternatives often are available to the carrier.In many cases, there is substantial disparity between the nature and characteristics of the drive signals required by the various alternative utilization devices. Moreover, modern transport aircraft include numerous avionics systems and oftentimes the drive signal required by a selected utilization device can be derived from different sets of input signals. Such alternative sets of input signals include signals provided by other avionics systems and signals supplied by various alternative transducers, sensors and actuators. Even further, in addition to the input signals required for deriving the system output signals, certain avionics system signal processors require input information that modifies or controls the manner in which the signal processor operates.A wide variety of this type of signal information can be required For example, it may be necessary to supply the signal processor with a signal representing the aircraft identification (i.e., "tail number") in situations wherein proper signal processor operation is dependent on the particular aircraft or type of aircraft. In some situations, even the language in which a system displays messages to the flight crew or passengers may be controlled by supplying a particular, seiected signal to the system signal processor.

For all these reasons, there is often substantial disparity between the nature and characteristics of the input signals that are supplied to the signal processing unit of an avionics system.

To facilitate the needs and desires of various air carriers, the manufacturers of aircraft and avionics systems have attempted to generically configure the signal processing unit of various avionics systems in a manner that provides easily selectable options which adapt a particular avionics system to a specified configuration. Generally speaking, these configuration options are made available by arranging the signal processing unit so that it is capable of supplying each type of alternative output signal and is capable of operating with each alternative input signal. In these arrangements, selection of the desired configuration is effected by alternative interconnection of various circuits and terminals that are contained in the signal processing unit.More specifically, the signal processing unit often includes a plurality of terminals that are electrically innerconnected with the signal processing unit circuitry so that innerconnecting the various terminals and/or connecting various terminals to a particular electrical potential (e.g., ground or another specified voltage) configures the signal processing unit in the desired manner. In effect, in such an arrangement, the signal processing unit is "informed" of the manner in which the avionics system is configured and is adapted to operate with the input and output signals that are associated with that particular configuration.

In prior art arrangements, the innerconnections that define the desired configuration have been established in a variety of manners.

For example, in some prior art arrangements, a plurality of switches that determine the operational characteristics of the signal processing unit are provided either within the signal processing unit or are mounted on the enclosure that houses the signal processing unit. In this type of arrangement, the switches are set to provide the desired configuration prior to the time at which the signal processing unit is installed on the aircraft.

This particular prior art approach presents at least one disadvantage or drawback. In particular, the signal processing units of avionics systems are generally packaged within a housing that slides into a tray that is mounted in equipment racks. Mating electrical connectors that are mounted on the tray and the signal processing unit allow rapid removal for service, repair or replacement. Since many carriers operate different types of aircraft and often configure a particular type of avionics system differently for the various types of aircraft, flightline personnel must set the switches of the signal processing unit to configure the unit for that particular type of aircraft and must test the signal processing unit for proper operation prior to installation. This can result in delays that prevent maximum utilization of the aircraft and disrupt scheduled departures and arrivals.

In a second prior art approach, which overcomes the abovediscussed replacement problem, each terminal of the signal processing unit that determines the operational configuration is connected to a pin (or receptacle) of the signal processing unit connector. In this arrangement, the operational configuration of the signal processing unit is established by electrically inner-connecting the mating receptacles (or pins) of the connector that is mounted on the tray that receives the signal processing unit. Although this particular prior art approach allows the aircraft wiring to define the configuration of the signal processing unit, the number of configuration options that must be accommodated has increased to the point where this technique is at least somewhat undesirable.In this regard, the availability of additional avionics systems and components that provide additional alternative input signals and require additional output signals has reached the point where it may be necessary that a particular signal processing unit provide a large number of configuration options. This means that a large number of electrical connections must be made at the connector that mates with the signal processing unit. Thus, a large number of connector pins must be dedicated to determining the operational configuration of the signal processing unit. This means that ralatively large connectors must be employed and a greater amount of labor is required to install the jumpers or straps that determine the signal processing unit configuration. The result is undesired increased cost, complexity and weight.

Summary of the Invention In accordance with this invention, the operating configuration of an avionics system signal processing unit is established by a memory unit that is contained in a separately packaged configuration module. Digitally encoded signals that characterize the desired configuration are stored in the memory unit either prior to initial installation of a signal processing unit or at the time at which the signal processing unit is installed in the avionics system. Preferably, signal codes that define each configuration variable (e.g., the type of signal sources and signal utilization devices employed by the system and various other system parameters) are stored in the memory unit in a predetermined sequence. Whenever the signal processing unit is replaced, the codes are supplied to the newly installed signal processing unit in a digital signal format.Thus, the mating electrical connectors that electrically innerconnect the signal processing unit with the remaining components with the avionics system need only include a small number of connections that are dedicated to configuring the signal processing unit.

In the currently preferred embodiments wherein the signal processing unit employs a programmed digital signal processor, the configuration module includes a serially accessed programmable nonvolatile memory unit and is mounted to the tray that receives the signal processor unit. In this arrangement, only six electrical connections are required between the signal processing unit and the configuration module.

In one realization of the currently preferred embodiment of the invention, the avionics system includes a control and display unit which is mounted in the crew compartment to facilitate keyboard entry of data and various system commands and to facilitate cathode ray tube display of system information and instructions. In this arrangement, the signal processing unit is programmed to provide a system installation procedure wherein the control and display unit is utilized to store the configuration codes in the configuration unit memory during the initial installation of a signal processing unit.

Additionally, in systems that employ a programmed digital signal processing unit, a signal that is identical to the signal stored in the configuration module is read into the nonvolatile memory of the signal processing unit during the initial installation procedure. This information is compared with the signal stored in the configuration module each time the avionics system is activated ("powered-up"), to verify proper configuration of the signal processing unit and to ensure that no changes have occurred in the signal stored in the confi guration module memory unit. Additionally, the configuration information stored in the nonvolatile memory of the signal processing unit serves as a back-up copy of the proper configuration data in the event of configuration module failure or removal.

Brief Description of the Drawing These and other aspects and advantages of the invention will be recognized by reference to the following detailed description of an illustrative embodiment, taken in conjunction with the drawing, in which: FIGURE 1 is a block diagram that illustrates an avionics system wherien the operational configuration of the system signal processing unit is established in accordance with this invention; FIGURE 2 is a perspective view of a signal processing unit and the mounting tray that receives the signal processing unit which illustrates a configuration module mounted to the mounting tray and electrically innerconnected with the signal processing unit in accordance with the principles of this invention; and FIGURE 3 is a chart that illustrates the installation procedure for the embodiment of the invention depicted in FIGURE 1.

Detailed Description Within reference to FIGURE 1, an avionics system of the type to which this invention primarily relates includes a programmed digital signal processing unit 12 that is connected to a plurality of signal sources 14 and is connected to a plurality of signal unit utilization devices 16. In operation, a central processing unit CPU 18 of the program med digital signal processing unit 12 sequentially samples the input signals provided by signal sources 14, processes the received signals and provides output signals to the signal utilization devices 16. In the arrangement depicted in FIGURE 1, each signal source 14 supplies data to CPU 18 via an associated input data port 20 that is connected to CPU 18 by means of an address and data bus 22.In a similar manner, the output signals supplied by CPU 18 are selectively coupled to each of the various signal utilization devices 16 via data bus 22 and an associated output data port 24.

As is known to those skilled in the art, the depicted arrangement of digital signal processing unit 12, input signal sources 14 and signal utilization devices 16 typifies a variety of avionics systems of the type that employ signal processing. Such avionics systems include, for example, navigation systems of various types and description, various types of com munication systems, various types of flight data recording systems, and various types of perform ance monitoring systems. As will be recognized by those skilled in the art, the configuration and nature of the signal sources 14 and signal utilization devices 16 of FIGURE 1 depend on the particular type of avionics system of interest. For example, signal sources 14 can be various conventional transducers or can be other avionics systems that are utilized on the aircraft employing the avionics system of interest.In a similar manner, the signal utilization devices depicted in FIGURE 1 can be conventional indicators that display information to the flight crew or can be another avionics system which requires a signal supplied by the avionics system of interest. Further, those skilled in the art will recognize that avionics systems that are typified by the block diagram of FIGURE 1 can include components not illustrated in FIGURE 1. For example, such systems may include apparatus such as signal acquisition units, digital to analog signal converters and other apparatus that, in effect, collect or preprocess the signals utilized in that particular avionics system.

Regardless of the type of avionics system and the particular signal input and signal output arrangement, those skilled in the art recognize that the CPU 18 of digital signal processing unit 12 includes an arithmetic/logic unit that is innerconnected with a random access memory (RAM) and a read only memory (ROM), none of which are shown in FIGURE 1.

In operation, the CPU is programmed by instructions stored in the ROM to sequentially access the data supplied by the signal sources 14; process the signal data in accordance with instructions stored in the ROM; and supply output signals to the signal utilization devices 16 in accordance with additional instructions stored in the ROM. During these operations, the RAM is utilized for temporary storage of calculation data and to provide various registers that are required for proper sequencing of CPU 18.

As is indicated in FIGURE 1, some avionics systems include a control and display unit 26, which serves as an interface between a member of the flight crew and digital signal processing unit 12. Although various arrangements are possible, control and display unit 26 of FIGURE 1 includes a keyboard 25 (which allows data to be transmitted to digital signal processing unit 12) and includes a cathode ray tube (or equivalent display) 27 (which permits the display of various information). As also is indicated in FIGURE 1, such a control and display unit can be coupled to the bus 22 of digital signal processing unit 12 by means of a dedicated data port (identified as CDU Data Port 28 in FIGURE 1).Additionally, in many cases, the digital signal processing unit 12 of an avionics system includes a power supply 31 for supplying electrical power to CPU 18 and various other active circuits contained in signal processing unit 12.

As previously mentioned, various kinds of signal sources 14 and signal unit utilization devices 16 are employed in realizing various types of avionics systems. Moreover, alterna tive signal sources and signal utilization devices often are available for a specific type of avionics system. That is, even though the avionics system of interest may be a particular type of navigation system that provides certain information to the flight crew, the signal utilization devices may include several alternative types of indicators and/or the navigation information provided by that specific navigation system may be supplied to alternative avionics systems.In a like manner, it may be possible to derive the required navigation information from various alternative signal sources, including signals provided by various other avionics systems and/or signals provided by various alternative transducers and sensors. For example, the invention disclosed and claimed herein is currently employed in a flight management computer, which provides many conventional navigation features and, in addition, provides additional valuable navigation information. That night management computer includes a large number of serial data ports that functionally correspond to data ports 20, 24 and 28 of FIGURE 1, with the data ports being of various types including ARIN C 429 serial data ports, RS 422 serial data ports and serial data ports utilizing other specific protocol.Although the nature and characteristics of the signals transmitted or received by a large number of the data ports are identical in each installation of the flight management computer, options must be provided relative to a certain number of the data ports so as to accommodate the various optional, alternative signal utilization devices and signal sources. In this regard, in the current flight management computer realization of the invention, four input ports are available for supplying aircraft position signals to the flight m anagement computer with there being three optional signal sources available for each of these data ports. In addition, eight radio-tuned ports are provided for receiving various alternative signal information and various fuel flow rate signals can be provided to any or all of four fuel flow rate ports.Further, there are numerous data ports wherein an option exists as to connection to one of two alternative signal sources or signal utilization devices.

In accordance with the present invention, configuring digital signal processing unit 12 for operation with the various possible sets of alternative signal sources and signal utilization devices is accommodated by a configuration module 30. As is indicated in FIGURE 1, the configuration module 30 includes a configuration memory 32 which is innerconnected with a programmable data port 34 of signal processing unit 12. In operation, CPU 18 of digital signal processing unit 12 is programmed to accommodate each of the optional sets of signal sources and signal utilization devices. A digital signal which represents the desired configuration (e.g., the selected alternative signal sources and signal utilization devices) is stored in configuration memory 32 either prior to or at the time of system installation.Each time the avionics system is subsequently activated, CPU 18 accesses the data stored in configuration memory 32. This information is utilized to configure digital signal processing unit 12 so that CPU 18 selectively executes signal processing appropriate to the signal sources and signal utilization devices being employed by the avionics system.

In accordance with the invention, and as is indicated in FIGURES 1 and 2, digital signal processing unit 12 and configuration memory unit 32 are separately packaged and mounted.

More specifically, in the arrangement of FIG URE 2, digital signal processing unit 12 is contained in a standard avionics enclosure 34, which slides into a tray 36. In most installations, tray 36 is mounted in a rack (not shown in FIGURE 2) that receives various other electrical and electronic equipment carried by the aircraft. Regardless of the manner in which tray 36 is mounted, configuration module 30 of the illustrated arrangement is mounted to the upper surface of a bracket assembly 38, which extends upwardly from the rear portion of tray 36. As the avionics enclosure 34 is slid rearwardly into rack 36, a connector 40 (which is mounted on a forward face of bracket 38), engages with a mating connector of the avionics enclosure (not shown in FIGURE 2).The electrical connections provided by connector 40 and the mating connector of avionics enclosure 34 provide electrical connection between digital signal processing unit 12 and configuration memory unit 32, the signal sources 14, the signal utilization devices 16, and control and display unit 26.

As is indicated in FIGURE 1, relatively few electrical connections are required between configuration memory 32 and digital signal processing unit 12, even though numerous options are specified by the data stored in configuration memory 32. For example, the configuration module 30 that is used in conjunction with the previously mentioned flight management computer, utilizes a type K MC9306/ COP 494, serially programmable nonvolatile memory, which is commercially available from National Semiconductor Corporation of Santa Clara, California, as configuration memory 32.

In this realization of the invention, only six electrical connections are required between configuration module 30 and digital signal processing unit 12. As is indicated in FIGURE 1, two of the required connections couple operating potential (V, and system ground) from power supply 31 of digital signal processing unit 12 to configuration module 30. Two of the remaining electrical connections serve as data input and data output connections to configuration memory 32.Clock signals are coupled from digital signal processing unit 12 to configuration memory 32 via one of the remaining electrical connections and the final electrical connection is used in conjunction with the clock and data input conections to select and control the operation of configuration memory 32 (i.e., write input data into memory, read data from memory, or erase a specified portion of memory).

Both the structure and operation of the invention can be further understood with reference to the proecedure employed in the currently employed embodiments of the invention relative to initially establishing the operational configuration of programmed signal processing unit 12. In this regard, in the previously mentioned flight management computer that employs the invention, one example of a utilization device that is subject to various alternatives or options is the system Horizon Situation Indicator. As is known in the avionics art, the Horizon Situation Indicator displays information including the aircraft heading and the aircraft bearing.As is further known in the art, several alternative types of Horizontal Situation Indicators exist, there are also various options as to the manner in which a Horizon Situation Indicator displays heading and bearing information and alternatives as to the type of signal that drives the bearing and course movements.

The manner in which the currently preferred embodiment of the invention establishes the configuration of digital signal processing unit 12 for operation with a particular Horizon Situation Indicator is illustrated in FIGURE 3.

As is indicated at block 40 of FIGURE 3, the first step of the procedure is to determine the reference for the course output. To facilitate this determination and all other configuration specifications, CPU 18 of the previously mentioned flight management computer is programmed to display "prompts" on cathode ray tube 27 of control and display unit 26, which requests that the installer specify a required configuration specification. With respect to specification of the course output reference, the flight management computer displsys the message "HSI COURSE OUTPUT IS RELATIVE TO: [ ]" across the top of cathode ray tube 27 and displays "1 Nose" and "2 North," directly below that message.To specify the course reference, the installer depresses the numeric key of keyboard 25 corresponding to either "north" or "nose" and then depresses an ENTER key. As is indicated by block 42 is FIGURE 3, CPU 18 is programmed to then display a message on cathode ray tube 27 which requests that the installer specify whether a resolver or synchro signal is employed in the system to drive the course indicating movement of the system Horizon Situation Indicator. When the installer has depressed the appropriate key of keyboard 25 and has pressed the ENTER key, the system sequences to the configuration determination indicated at block 44 of FIGURE 3.At this point, the system displays a message on cathode ray tube 27 requesting the installer to specify whether the bearing information displayed on the Horizon Situation Indicator being used in the system is relative to the aircraft "nose", or is relative to "North". When the appropriate information has been entered in the previously indicated manner, CPU 18 sequences to the step indicated at block 46, causing cathode ray tube 27 to display a message requesting that the installer indicate whether the bearing signal displayed on the Horizon Situation Indicator is offset by 0 (no offset) or is offset by 180 . Following entry of the appropriate configuration specification, CPU 18 causes cathode ray tube 27 to display a message requesting that the installer enter the type of bearing to be displayed by the Horizon Situation Indicator.During this step, which is indicated at block 48 of FIGURE 3, the installer specifies whether the bearing that will be displayed on the Horizon Situation Indicator is relative to: (1) a selected waypoint (e.g., a specified transmitter location of a navigation aid or a particular geographic location that is entered by longitude and lattitude); (2) the aircraft ground track; or, (3) a desired aircraft heading. During the final step of the Horizon Situation Indicator configuration specification, which is indicated at block 50 of FIGURE 3, CPU 18 causes cathode ray tube 27 to request entry of the type of signal that will drive the bearing mechanism of the Horizon Situation Indicator that provides bearing information.When the installer has entered an appropriate response (e.g., synchro or resolver), CPU 18 sequences to the next required configuration determination (indicated at block 62 of FIGURE 3).

As will be recognized by those skilled in the art, configuration specifications for each alternative signal service and signal utilization device can be determined in the manner indicated in FIGURE 3 and discussed above. In some cases, a particular configuration determination will require a series of steps such as those illustrated in FIGURE 3. In other cases, a single specification step will provide the required configuration information.For example, in the previously mentioned flight management computer that employs the invention, selection of the true airspeed input signal source is accomplished by a single inquiry wherein the system installer depresses one of seven indicated keys of keyboard 25 to indicate that either that no true airspeed input is utilized in that particular configuration, or to indicate which of six optional true airspeed input signals is to be provided to the system digital processor.

As is indicated by block 54 of FIGURE 3, when the installer has specified all configuration information necessary to implement a new installation or to change an existing in stallation, a binary signal code representative of the operational configuration of digital signal processing unit 12 is written into configuration memory 32 of configuration module 30.

In the currently preferred embodiments in the invention, such as the night management computer that is discussed herein, CPU 18 of digital signal processing unit 12 causes cathode ray tube 27 to display a message requesting the installer to depress a first key (e.g., "1") if the configuration data is not to be written into configuration memory 32 or to depress a second specified key (e.g., "2") if the data is to be written into configuration memory 32.

When the configuration data is to be written into configuration module 30, CPU 18 sequences to erase the appropriate memory registers of configuration memory 32 and to supply the configuration data as a serially formatted signal.

For example, the type NMC 9306/COP 494 programmable nonvolatile memory that is utilized in current realizations of the invention, is organized to store data in 16 registers, each containing 16 bits. To write the configuration code into one or more registers of this memory, CPU 18 sequences to supply the memory with operational codes that cause configuration memory 32 to erase the appropriate memory registers and cause the configuration data (which is stored in the random access memory of CPU 18 during the steps of the configuration specification) to be sequentially written into the registers of configuration memory 32. Once the configuration data is written into configuration memory 32, the data is read by digital signal processing unit 12 each time the avionics system is activated.

Thus, when digital signal processing unit 12 is replaced for normal maintenance or because of suspected malfunction, proper configuration data is supplied to the newly installed signal processing unit 12 without further action by malntenance personnel.

Although configuration memory 32 of the currently preferred embodim ents of the invention is organized as 16 16-bit registers, it should be noted that, in the preferred embodiments of the invention, the configuration data is organized as a single binary encoded instruction having a predetermined format. That is, the configuration data is organized as an ordered set of binary encoded signals wherein the selected configuration of each signal source 14 and each signal utilization device 16 is specified by a group of binary encoded signals. For example, in the implementation of the invention that is utilized in the previously mentioned flight management computer, the specification of the Horizontal Situation Indicator configuration data consists of a group of seven binary bits.To functionally associate the various parameters being specified, this group of seven binary bits is subdivided into three 2-bit characters and one 1-bit character.

In the particular organization employed, the 1bit character is the least significant bit of the Horizontal Situation Indicator 7-bit code and specifies whether the course output is relative to the aircraft nose or North. The 2-bit character that constitutes the next two least significant bits of the code specifies whether the Horizontal Situation Indicator bearing signal is: (1) relative to the aircraft nose with 1800 offset; (2) relative to North with 1800 offset; (3) relative to the aircraft nose with 0 offset; or (4) is relative to North with 0 offset. The character defined by the two next most significant bits specifies whether the aircraft bearing is relative to: (1) a waypoint; (2) the aircraft ground track; or (3) a desired heading.

The final character (i.e., the two most significant bits of the Horizontal Situtation Indicator code) specifies whether: (1) a resolver signal is utilized for both course and heading signals; (2) a synchro signal is utilized for aircraft course and a resolver signal is utilized for heading; (3) a resolver signal is utilized for aircraft course and a synchro signal is utilized for heading; or (4) a synchro signal is utilized for both aircraft heading and course.

It will be recognized by those skilled in the art that organizing the configuration data in the above-described manner, rather than organizing the signal into a plurality of data words having equal bit length, reduces the amount of memory required for storing the configuration data. Further, those skilled in the art will recognize that various other data compression techniques can be employed to further reduce the required amount of memory.

In addition to the above-discussed aspects and features of the invention, in the currently preferred embodiments, digital signal processing unit 12 is configured and arranged to periodically verify the configuration data stored in configuration memory 32. In this regard, and as previously mentioned, CPU 18 sequences digital signal processing unit 12 so that the configuration data is accessed each time that power is applied to the avionics system (i.e., the system is "powered-up"). In the previously mentioned flight management computer that employs the invention, CPU 18 includes nonvolatile random access memory and CPU 18 writes the configuration data into a predetermined portion of this memory whenever the configuration data is written into configuration memory 32 (e.g., initial installation or modification of the system). When the configuration data is subsequently accessed during each system power-up sequence, the data stored in the nonvolatile random access memory of CPU 18 is compared with the data supplied by configuration memory 32. In addition, in the currently preferred embodiments of the invention, conventional error detection (such as check-sum, parity, or Hamming code tests) is performed relative to both sets of data. If the two sets of data are identical and no errors are detected by either set of data, the system power-up sequence continues. On the other hand, if discrepancies are detected, a warning signal is supplied (e.g., to control and display unit 26 of FIGURE 1). This provides early detection of a malfunction within either configuration memory 32 or digital signal processing unit 12.

Those skilled in the art will recognize that the embodiments of the invention discussed herein are exemplary in nature and that various changes and modifications can be made without departing from the scope and the spirit of the invention. For example, although the invention has been described in terms of a digital signal processing unit, it can be recognized that the invention can be practiced with analog signal processors by providing dedicated digital circuitry for determining an appropriate digitally encoded signal and storing that signal in configuration memory 32. Further, although the input signal sources discussed relative to the illustrative embodiment of the invention are conventional sensors and transducers, the invention is applicable to all types of input signals and information. For example, the invention is well suited for providing input signals and codes such as the previously mentioned aircraft identification and other information that may control the operating characteristics of a particular signal processing unit.

Claims (12)

1. An avionics system comprising: a programmed signal processing means for processing one or more input signals and generating one or more output signals, said programmed signal processing means including means for processing digitally encoded signals end means for storing digitally encoded signals;; a set of signal devices including one or more signal sources electrically interconnected with said programmed signal processing means for supplying said input signals to said programmed signal processing means, and one or more signal utilization devices connected for receiving said output signals supplied by said programmed signal processing means, at least one of said signal devices being selected from a set of alternative signal sources and alternative signal utilization devices wherein the various signal sources of said set of alternative signal sources do not all exhibit identical signal characteristics and the signals required by the various ones of said utilization devices are not all identical; and configuration memory means for adapting said programmed signal processing means to a particular system configuration that includes at least one selected signal device of said set of signal devices formed by said alternative signal sources and said alternative signal utilization devices, said configuration memory means being external to said programmed signal processing means and being electrically interconnected therewith.

2. The avionics system of Claim 1 wherein said programmed signal processing means is mounted within an enclosure having at least one electrical connector that includes connections for supplying said one or more input signals to said program signal processing means and connections for supplying said one or more output signals, said avionics system further including a mounting tray for receiving said enclosure, said mounting tray including a connector for receiving said connector of said enclosure, said configuration memory means being mounted on said mounting tray and being electrically connectable to said connector of said mounting tray.

3. The avionics system of Claim 2 wherein said configuration memory means includes a programmable nonvolatile memory.

4. The avionics system of Claim 3 wherein said programmable nonvolatile memory is configured and arranged for supplying a stored digital signal, said stored digital signal being representative of said selected signal devices.

5. The avionics system of Claim 4 wherein said programmable nonvolatile memorry is further configured amd arranged for storing a signal supplied in serial digital format and wherein said programmed signal processing means is configured and arranged for supplying said digitally encoded serial format signal to said programmable nonvolatile memory when said progammed signal processing means is initially installed in said tray.

6. The avionics system of Claim 5 wherein said programmed signal processing means further includes nonvolatile memory means for storing a digitally encoded signal that is identical to said digitally encoded signal that is stored in said programmable nonvolatile memory of said configuration memory means, said digitally encoded signal being stored in said nonvolatile memory means of said programmed signal processing means when said signal processing means stores said digitally encoded signal in said programmable nonvolatile memory of said configuration memory means, said programmed signal processing means being further configured and arranged for comparing said digitally encoded signal stored in said nonvolatile memory means of said programmed signal processing means with said digitally encoded signal stored in said programmable nonvolatile memory of said configuration memory means each time operating power is supplied to said avionics system.

7. An avionics system of the type including a a programmed signal processing unit that is configured and arranged for processing a set of n received input signals (i" i2, i3...in) to provide a set of m output signals (o,, o,, Q...o#, wherein n and m are positive real integers and wherein at least one signal included in the entire collection of said n input signals and m output signals is selected from a plurality of signals that exhibit nonidentical signal characteristics, the system comprising: a system configuration module electrically connectable with said programmed signal processing unit, said system configuration module being packaged separately from said signal processing unit and including nonvolatile memory means for storing a digital signal that characterizes each one of said input and output signals that are selected from said plurality of nonidentical signals.

8. The avionics system of claim 7 hwerein said programmed signal processing unit includes an electrical connector for receiving said n input signals and transmitting said m output signals, said avionics system further including a mounting tray for receiving said programmed signal processing unit, said mounting tray including a connector for receiving said connector included with said programmed signal processing unit, said system configuration module being mounted on said mounting tray and being electrically connectable to said connector of said mounting tray.

9. The avionics system of claim 8 wherein said system conf iguration module is a programmable nonvolatile memory.

10. The avionics system of claim 9 wherein said programmed signal processing unit is configured and arranged for storing said digitally encoded configuration signal in said system configuration module when said programmed signal processing unit is initially installed in said tray.

11. The avionics system of claim 10 wherein said programmed signal processing unit further includes nonvolatile memory means for storing a digitally encoded signal that is identical to said digitally encoded configuration signal that is stored in said programmable nonvolatile memory means of said system configuration module, said digitally encoded signal being stored in said nonvolatile memory means of said programmed signal processing unit when said signal processing unit stores said digitally encoded configuration signal in said programmable nonvolatile memory means of said system configuration module, said programmed signal processing unit being further configured and arranged for comparing said digitally encoded signal stored in said nonvolatile memory means of said programmed signal processing unit with said digitally encoded configuration signal stored in said programmable nonvolatile memory means of said system configuration module each time operating power is supplied to said avionics system.

12. An avionics system comprising a separate programmed configuration module, substantially as described herein with reference to the drawings.