1、 ADIGITAL FREQUENCY/FUNCTIONSELECTION FOR AIRBORNEELECTRONIC EQUIPMENTARINC SPECIFICATION 720-1PUBLISHED: JULY 1, 1980AN A DOCUMENTPrepared byAIRLINES ELECTRONIC ENGINEERING COMMITTEEPublished byAERONAUTICAL RADIO, INCORPORATED2551 RIVA ROAD, ANNAPOLIS, MARYLAND 21401This document is based on materi
2、al submitted by variousparticipants during the drafting process. Neither AEEC nor ARINChas made any determination whether these materials could besubject to valid claims of patent, or other proprietary rights by thirdparties, and no representation or warranty, express or implied, ismade in this rega
3、rd. Any use of or reliance on this document shallconstitute an acceptance thereof “as is” and be subject to thisdisclaimer.REPLACEMENT PAGE REVISED: March 9, 1993Copyright 1993 byAERONAUTICAL RADIO, INC.2551 Riva RoadAnnapolis, Maryland 21401-7465 USAARINC SPECIFICATION 720-1 DIGITAL FREQUENCY/FUNCT
4、ION SELECTION (DFS)FOR AIRBORNE ELECTRONIC EQUIPMENTPublished: July 1, 1980Prepared by the Airlines Electronic Engineering CommitteeCharacteristic 720 Adopted by the Airlines Electronic Engineering Committee: August 30, 1979Characteristic 720 Adopted by Industry: November 16,197 9Characteristic 720-
5、1 Adopted by the Airlines Electronic Engineering Committee: June 19, 1980iiFOREWORDActivities of AERONAUTICAL RADIO, INC. (ARINC)and thePurpose of ARINC Reports and SpecificationsAeronautical Radio, Inc. is a corporation in which the United States scheduled airlines are theprincipal stockholders. Ot
6、her stockholders include a variety of other air transport companies, aircraftmanufacturers and foreign flag airlines.Activities of ARINC include the operation of an extensive system of domestic and overseasaeronautical land radio stations, the fulfillment of systems requirements to accomplish ground
7、 andairborne compatibility, the allocation and assignment of frequencies to meet those needs, thecoordination incident to standard airborne communications and electronics systems and the exchangeof technical information. ARINC sponsors the Airlines Electronic Engineering Committee (AEEC),composed of
8、 airline technical personnel. The AEEC formulates standards for electronic equipment andsystems for the airlines. The establishment of Equipment Characteristics is a principal function of thisCommittee.It is desirable to reference certain general ARINC Specifications and Reports which areapplicable
9、to more than one type of equipment. These general Specifications or Reports may beconsidered as supplementary to the Equipment Characteristics in which they are referenced. They areintended to set forth the desires of the airlines pertaining to components and general design,construction and test cri
10、teria, in order to insure satisfactory operation and the necessaryinterchangeability in airline service. The release of a Specification or Equipment Characteristic shouldnot be construed to obligate ARINC or any airline insofar as the purchase of any components orequipment is concerned. An ARINC Rep
11、ort (Specificatio n or Characteristic) has a twofold purpose, which is:(1) To indicate to the prospective manufacturers of airline electronic equipment theconsidered opinion of the airline technical people coordinated on an industry basisconcerning requisites of new equipment, and(2) To channel new
12、equipment designs in a direction which can result in the maximumpossible standardization of those physical and electrical characteristics which influenceinterchangeability of equipment without seriously hampering engineering initiative.ARINC CHARACTERISTIC 720TABLE OF CONTENTSITEM SUBJECT PAGEiii Pa
13、ge iv Intentionally left blank1.0 INTRODUCTION 11.1 Purpose of This Document 11.2 Relationship to ARINC Specification 429 11.3 Brief Description of the DFS System 11.3.1 Radio Configuration 11.3.2 Centralized DFS System 11.3.3 Federated DFS System 12.0 SYSTEM CONCEPTS 22.1 Centralized DFS System 22.
14、1.1 System Architecture 22.1.2 Aircrew Interface 22.1.3 Controlled Device Digital Data Input Ports 22.1.4 Controlled Device Control Source Selection 22.1.5 Remote Frequency Source Selection 22.1.6 DFS Su bsystem Crosstalk 22.1.7 Failure Effects Protection 32.1.8 Control of Additional Like Radios 32.
15、1.9 ILS Tune Inhibit 32.2 Federated DFS System 32.2.1 System Architecture 32.2.2 Aircrew Interface 42.2.3 Remote Frequency Source Selection 42.2.4 ILS Tune Inhibit 43.0 SYSTEM STANDARDS 53.1 Primary Power Input 53.1.1 Centralized DFS System 53.1.2 Federated DFS System 53.2 Digital Data Standards 53.
16、3 Selection Discretes 53.4 Nonvolatile Memory 54.0 SYSTEM DESIGN 64.1 D FS System Packaging 64.2 Desired System Capabilities 64.3 System Loading 65.0 APPLICATIONS NOTES 75.1 Radio/Electronic System Controls 75.1.1 ADF 75.1.2 DME 75.1.3 HF Communications 75.1.4 ILS 75.1.5 VOR 75.1.6 VHF Communicat io
17、ns 75.1.7 Transponder 75.2 DFS System Crew Station 85.2.1 Data Entry 85.2.1.1 Numeric Data Entry 85.2.1.2 Data Identification (Input Direction) 85.2.1.3 Switch Functions 85.2.1.4 Data Entry Operation 85.2.2 Status Display 8-95.2.3 External Program Inputs 95.3 Typical DFS Installations 9ATTACHMENTS1
18、Standards for Discrete Control Signals 10-112 Systems Concepts 123 Typical Installations 13APPENDIX1 Bibliography 14ARINC SPEC IFICATION 720 - Page 11.0 INTRODUCTION1.1 Purpose of this DocumentThis document sets forth the air transport industrysrecommended standards for a digital frequency selection
19、(DFS) system.Information transfer by means of ARINC Specification 429,“Mark 33 Digital Information Transfer System (DITS),” isassumed for the DFS System.With the exception of navigation receiver controls, most ofthe frequency and function selection systems in the pastwere federated systems, i.e., on
20、e control unit per receiver. Available technology and the 2X5 tuning method madefederated systems attractive. However, application ofdigital technology and interfaces permit various degrees ofcontrol integration in newer systems.This document addresses two opposite ends of the DFSintegration possibi
21、lities, i.e., a totally centralized and afederated system. This is necessary to assure that the radiointerface specifications are adequate to cover a range ofDFS integration.It is recognized that actual application of the DFS systemwill be between federated and centralized concepts. Typicalapplicati
22、ons deviating from the basic concepts of Figures 2-1 and 2-2 are illustrated in Attachment 2.1.2 Relationship to ARINC Specification 429ARINC Specification 429, “Mark 33 Digital InformationTransfer System (DITS),” describes how the transfer ofdigital data should be accomplished and, in Chapter 3, se
23、tsforth word formats for use in DFS applications. Thisdocument is concerned only with the system aspects ofdigital frequency/function selection and does not ventureinto DITS territory. Familiarity with both documents isnecessary, therefore, for a complete understanding of the airtransport industrys
24、DFS needs.1.3 Brief Description of the DFS System1.3.1 Radio ConfigurationEach radio is provided with two ARINC 429 low speed (12-14.5 KHz) input ports and one input port selection discrete.The radio will receive the control information on input portNo. 1 referred to as the “A” port when the port se
25、lectiondiscrete is in the “ground” state and on input port No. 2referred to as the “B” port when the port selection discreteis in “open” state.1.3.2 Centralized DFS SystemThe ARINC 720 DFS system, in the centralizedconfiguration, consists of two identical subsystems arrangedas shown in Figure 2-1. T
26、he solid lines in Figure 2-1represent digital data buses. The dashed lines representdiscrete control paths.1.3.2 Centralized DFS System (contd)It will be noted that this system architecture providesredundant information paths for protection against theeffects of failures and permits either subsystem
27、 to controlany radio. The radio determines, as described in Section1.3.1 from the binary state of the port selection discrete,which of the two input ports carries the control information.The frequency control may be transferred from DFS toeither of two remote sources such as a flight managementcompu
28、ter by setting the Automatic/Manual discrete to theproper state. A “ground” condition of the Automatic/Manual discrete will indicate manual control of frequencyand “open” state will indicate automatic control offrequency. During the remote control mode, automaticallyselected frequencies are transmit
29、ted to the radio through theDFS subsystem. This technique minimizes the number ofinput ports required in the radios and provides display ofautomatically selected frequencies in the DFS subsystem.1.3.3 Federated DFS SystemThe ARINC 720 DFS System in its federated configurationis shown in Figure 2-2.
30、The solid lines in Figure 2-2represent digital data buses. The dashed lines representdiscrete control paths.In a federated system a dedicated control is required foreach radio. Where Automatic/Manual operation is desired,the control unit is connected to the “A” port of the radio andthe remote tuning
31、 source is connected to the “B” port. Theinput port selection discrete is used as theAutomatic/Manual selection discrete. Where only manualoperation is desired, the control panel should be connectedto the “B” port and no connections are made to the “A” portand port selection discrete.Provisions are
32、made in the dedicated control units toreceive remotely selected frequencies for annunciation.ARINC SPECIFICATION 720 - Page 22.0 SYSTEM CONCEPTS2.1 Centralized DFS System2.1.1 System ArchitectureThe centralized DFS System consists of two identicalsubsystems as shown in Figure 2-1. These subsystems a
33、redesignated subsystem #1 and subsystem #2. Eachsubsystem provides two digital data output ports for radio orother electronic system control signals, two digital datainput ports for frequency selection information generated ina remote source such as a flight management computer, andone input and one
34、 output port for subsystem-to-subsystemtransfer of digital data. Additionally, each subsystemprovides one output discrete and one input discrete forsource selection discrete signals and one output discrete fora remote frequency source output command discrete(Automatic/Manual discrete) and three inpu
35、t discretes forILS tune inhibit function.2.1.2 Aircrew InterfaceThe ARINC 720 DFS System, in its centralized form,provides two cockpit control stations through which a crewmember can communicate with any of the radio or otherelectronic systems whose control functions are handled bythe system. These
36、control stations are designated“Captains” and “First Officers”. The Captains station isassociated with DFS Subsystem #1 and the First Officersstation is associated with DFS Subsystem #2.2.1.3 Controlled Device Digital Data Input PortsEach radio or other electronic system to be controlled by theDFS s
37、ystem should provide two digital data input portshaving the characteristics for low speed data bus receiversset forth in ARINC Specification 429. One of the portsshould be designated the “A” port and the other should bedesignated the “B” port. The “A” port of eachradio/electronic system should be co
38、nnected to the #1digital data output port of the DFS subsystem normallyassigned control of that system, while the “B” port shouldbe connected to the #2 digital output port of the other DFSsubsystem. Control is transferred to the #2 digital outputport in the event of normal subsystem failure.2.1.4 Co
39、ntrolled Device Control Source SelectionEach radio or electronic system under DFS Systemfrequency/function control should obey instructionscontained in the digital data entering via its “A” port andignore any information entering via its “B” side port whenthe signal reaching it via its selection dis
40、crete is in the“ground” state. This situation should be reversed when thesignal reaching it via its selection discrete input port is inthe “open” state. See Section 3.3 of this document fordefinitions of these valid and invalid states.2.1.5 Remote Frequency Source SelectionThe transfer of frequency
41、control of navigation sensorradios (DME and ILS) from the DFS system to a remotesource such as a flight management computer should beachieved by means of a manual-to-automatic selectionfunction provided at the crew members control stations.When “automatic” frequency selection is commanded, theDFS su
42、bsystem should change the state of the remotefrequency source data output command discrete from“ground” to “open” (so activating the remote source),remove from the data stream departing its digital dataoutput ports the frequency data for these radios derivedfrom the aircrew input, and insert in its
43、place the dataderived from the remote source(s). For example, note thatthe input of an “automatic” frequency selection command ateither crew station will result in both sets of navigationradios coming under flight management computer control,the #1 radio being controlled by the #1 computer and the #
44、2radios by the #2 computer. It should be made possible totune both radios from one computer in case of the failure orthe absence of one computer. This capability should beobtained without the help of computer crosstalk.Each DFS subsystem should be capable of providingremote frequency selection of co
45、mmunication radios fromdata link as described in ARINC Project Paper 724.2.1.6 DFS Subsystem CrosstalkIn order to permit overall radio/electronic system status tobe displayed at both crew stations, all #1 subsystem datashould be fed to the #2 subsystem and all #2 subsystem datashould be fed to the #
46、1 subsystem via the two subsystemcrosstalk digital data buses.DFS subsystem crosstalk capability should also be used tocontrol the #2 radios from the Captains control station andthe #1 radios from the First Officers control station. Whenthe Captains control station is used to make a #2 radio-related
47、 input, the information so derived is transferred fromthe #1 to the #2 subsystem via the crosstalk bus. The #2subsystem should replace its own word intended for thatradio in the data stream departing its digital data outputports with the word derived from the #1 subsystem. Thefrequency contained in
48、this word should also be thefrequency displayed to the crew for that radio. In likemanner, the First Officers control station may be used tocontrol the #1 radios via the second crosstalk bus.This concept permits any radio to be controlled from eithercrew station via its “A” digital data input port.
49、However,each DFS subsystem must be able to identify itself as #1 or#2. It may do this by reference to installation program pincoding.The characteristics of the crosstalk bus should correspondto ARINC 429 in its electrical, logic and timing elements inorder to minimize the risk of having to make special EMIprovisions in the aircraft.ARINC SPECIFICATION 720 - Page 32.0 SYSTEM CONCEPTS (contd)2.1.7 Failure Effects ProtectionIn normal operation of the DFS System, each subsystem willprovide appropriate data from both digital data output portstogether with a “ground” signal from its
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