1、 VHF DATA RADIO ARINC CHARACTERISTIC 750-4 PUBLISHED: August 11, 2004 AN DOCUMENT Prepared by AIRLINES ELECTRONIC ENGINEERING COMMITTEE Published by AERONAUTICAL RADIO, INC. 2551 RIVA ROAD, ANNAPOLIS, MARYLAND 21401 This document is based on material submitted by various participants during the draf
2、ting process. Neither AEEC nor ARINC has made any determination whether these materials could be subject to valid claims of patent, copyright or other proprietary rights by third parties, and no representation or warranty, express or implied, is made in this regard. Any use of or reliance on this do
3、cument shall constitute an acceptance thereof “as is” and be subject to this disclaimer. Copyright2004 by AERONAUTICAL RADIO, INC. 2551 Riva Road Annapolis, Maryland 21401-7465 USA ARINC CHARACTERISTIC 750-4VHF DATA RADIO Published: August 11, 2004 Prepared by the Airlines Electronic Engineering Com
4、mittee Characteristic 750 Adopted by the Airlines Electronic Engineering Committee: November 3, 1992 Summary of Document Supplements Supplement Adoption Date Published Characteristic 750-1 October 31, 1995 December 1, 1995 Characteristic 750-2 October 14, 1997 December 24, 1997 Characteristic 750-3
5、June 26, 2000 November 30, 2000 Characteristic 750-4 March 5, 2004 August 11, 2004 ii FOREWORD Aeronautical Radio, Inc., the AEEC, and ARINC Standards Aeronautical Radio, Inc. (ARINC) was incorporated in 1929 by four fledgling airlines in the United States as a privately-owned company dedicated to s
6、erving the communications needs of the air transport industry. Today, the major U.S. airlines remain the Companys principal shareholders. Other shareholders include a number of non-U.S. airlines and other aircraft operators. ARINC sponsors aviation industry committees and participates in related ind
7、ustry activities that benefit aviation at large by providing technical leadership and guidance and frequency management. These activities directly support airline goals: promote safety, efficiency, regularity, and cost-effectiveness in aircraft operations. The Airlines Electronic Engineering Committ
8、ee (AEEC) is an international body of airline technical professionals that leads the development of technical standards for airborne electronic equipment-including avionics and in-flight entertainment equipment-used in commercial, military, and business aviation. The AEEC establishes consensus-based
9、, voluntary form, fit, function, and interface standards that are published by ARINC and are known as ARINC Standards. The use of ARINC Standards results in substantial benefits to airlines by allowing avionics interchangeability and commonality and reducing avionics cost by promoting competition. T
10、here are three classes of ARINC Standards: a) ARINC Characteristics Define the form, fit, function, and interfaces of avionics and other airline electronic equipment. ARINC Characteristics indicate to prospective manufacturers of airline electronic equipment the considered and coordinated opinion of
11、 the airline technical community concerning the requisites of new equipment including standardized physical and electrical characteristics to foster interchangeability and competition. b) ARINC Specifications Are principally used to define either the physical packaging or mounting of avionics equipm
12、ent, data communication standards, or a high-level computer language. c) ARINC Reports Provide guidelines or general information found by the airlines to be good practices, often related to avionics maintenance and support. The release of an ARINC Standard does not obligate any airline or ARINC to p
13、urchase equipment so described, nor does it establish or indicate recognition or the existence of an operational requirement for such equipment, nor does it constitute endorsement of any manufacturers product designed or built to meet the ARINC Standard. In order to facilitate the continuous product
14、 improvement of this ARINC Standard, two items are included in the back of this volume: a) An Errata Report solicits any corrections to the text or diagrams in this ARINC Standard. b) An ARINC IA Project Initiation/Modification (APIM) form solicits any recommendations for addition of substantive mat
15、erial to this volume which would be the subject of a new Supplement. ARINC CHARACTERISTIC 750 TABLE OF CONTENTS iiiITEM SUBJECT PAGE 1.0 INTRODUCTION 1 1.1 Purpose of This Document 1 1.2 Airborne Subsystem Configuration 1 1.3 Interchangeability 1 1.3.1 General 1 1.3.2 Interchangeability Required for
16、 the ARINC 750 VHF Data Radio 1 1.4 Regulatory Approval 2 1.5 Relationship to ICAO Documents 2 1.6 Relationship to Other Documents 2 2.0 INTERCHANGEABILITY STANDARDS 3 2.1 Introduction 3 2.2 Form Factors, Antenna Considerations, Connectors (2) other manufacturers will implement only ARINC 429 BOP Ve
17、rsion 3 for both Mode A and Mode 2. It should be noted that these VDRs will not be interoperable with an early model CMU or ATSU that is only capable of VDR Mode A operation and can only communicate using ARINC 429 BOP Version 1. c-3 ARINC CHARACTERISTIC 750 - Page 9 3.0 MODES OF OPERATION 3.3 Mode
18、Determination At all times during operation, the VDR determines its current operating mode based on the content of the following three state variables: a. VD_STATUS state variable. b. CMU_STATUS state variable. c. A750_STATUS state variable. Table 3-1 summarizes these variables, their contents and t
19、he transition events. Table 3-1 - State Variables State Variables Content Transition Event NULL CMU is ABSENT or STANDBY See Section 3.3.2 PRIMARY CMU becomes ACTIVE or Unsuccessful ALOHA or receives an ALO word. See Section 3.3.2.1 CMU_STATUS See Section 3.3.2 BOP (transmit ALR) or (received ALR an
20、d version is supported) See Section 3.3.2.2 VOICE VD_STATUS See Section 3.3.1 DATA Determined by ARINC 429 Label 276 or Voice/Data discrete content. See Section 3.3.1 A716 Upon initialization or voice to data transition or VDR exits state S7. See Section 3.3.3.1 A750_STATUS See Section 3.3.3 A750 Co
21、mmand received from CMU. See Section 3.3.3.2 3.3.1 VD_STATUS State Variable The content of the VD_STATUS state variable is referenced in Table A8-17 VDR State Transition Table, and it can contain one of two values, VOICE or DATA. If this variable contains VOICE, the VDR executes in the ARINC 716 Voi
22、ce mode of operation, regardless of any other mode determining inputs. This voice priority feature is included to allow the pilot to select voice operation by manual override using for example, a switch mounted on the cockpit Radio Tuning Panel (RTP). If this variable contains DATA, the VDR executes
23、 one of the two data modes, ARINC 716 Data Mode or ARINC 750 Data Mode. The content of the VD_STATUS state variable is determined by two external signals: a. The ACTIVE/INACTIVE status and contents of the ARINC 429 Label 276 word received on the selected ARINC 429 tuning bus (low-speed). b. The stat
24、e of the Voice/Data Select rear connector discrete (MP7C). If the ARINC 429 Label 276 word is determined to be ACTIVE, then the content of the VD_STATUS state variable is determined by the ARINC 429 Label 276 word content. If the ARINC 429 Label 276 word is determined to be INACTIVE, then the conten
25、t of the VD_STATUS state variable is determined by the setting of the Voice/Data Select discrete. c-3ARINC CHARACTERISTIC 750 - Page 10 3.0 MODES OF OPERATION 3.3.1.1 ARINC 429 Label 276 Word The ARINC 429 Label 276 word may be present on the selected low-speed ARINC 429 tuning bus. The function of
26、this word was added to ARINC Characteristic 750 to provide aircraft manufacturers and airlines the ability to select the voice or data operation of the VDR without having the external Voice/Data select discrete wired in the airframe. If the Label 276 word is ACTIVE on the selected low-speed ARINC 42
27、9 tuning bus, then its content is used to determine the value of the VD_STATUS state variable in lieu of the value of the Voice/Data Select discrete. The choice of which of the two tuning buses is used is determined by the VDRs Frequency Control Port A-B Select rear connector discrete (MP11D). When
28、the Label 276 status is INACTIVE and the VDR receives Label 276 for 2 consecutive 500 msec intervals and each word has an SSM code value of NORMAL, then the VDR will change the Label 276 status from INACTIVE to ACTIVE. When the Label 276 status is ACTIVE and the VDR does NOT receive Label 276 OR eve
29、ry word has an SSM code value other than NORMAL for five consecutive 500 ms intervals, then the VDR will change the Label 276 status from ACTIVE to INACTIVE. If the VDR determines that the Label 276 word is ACTIVE, then the state of bit 11, 12, or 13 of the Label 276 word determines the value of the
30、 VD_STATUS state variable depending on the installed position of the VDR. The state of bits 11, 12, and 13 correspond to the selected Voice/Data state for VHF1, VHF2, and VHF3 respectively (see Attachment 8, Table A8-4). A bit value of 0 assigns the value VOICE to the VD_STATUS state variable. A bit
31、 value of 1 assigns the value DATA to the VD_STATUS state variable. When the selected tuning bus changes (can be caused by pin MP11D changing from open to ground or vice versa), then Label 276 will be considered INACTIVE until the criteria for ACTIVE status is met. 3.3.1.2 Voice/Data Select Discrete
32、 Input The Voice/Data Select discrete is the rear connector input MP7C and is used to determine the value of the VD_STATUS state variable when Label 276 is INACTIVE (see Section 3.3.1.1). When Label 276 is ACTIVE then the Voice/Data Select Discrete Input is ignored. If this input is floating (open)
33、and Label 276 is INACTIVE, then the VD_STATUS state variable is assigned the value VOICE. If the input is grounded and Label 276 is INACTIVE, then the VD_STATUS state variable is assigned the value DATA. 3.3.2 CMU_STATUS State Variable The CMU_STATUS state variable can contain one of three values, N
34、ULL, PRIMARY, and BOP, that indicate the state of the high-speed ARINC 429 data transfer bus between the CMU and the VDR. a. If the VDR has determined that a CMU is not present (absent) or not active (standby), then the content of the CMU_STATUS state variable is NULL. See Section 3.3.2.1. b. If the
35、 VDR has declared a CMU to be present and active, then the content of the CMU_STATUS state variable is PRIMARY. If an ALOHA event results in the CMU being declared “not bit oriented”, then the content of the CMU_STATUS state variable is PRIMARY. c. If the VDR has successfully negotiated a Williamsbu
36、rg protocol (Version 1 or 3) with the PRIMARY CMU using the ARINC 429 ALOHA mechanism, then the content of the CMU_STATUS state variable is BOP. These states are an indication of the sequential nature of the establishment of ARINC 429 data transfer between the CMU and the VDR. At system initializati
37、on the CMU_STATUS is NULL. After a CMU has been determined to be both PRESENT and ACTIVE, then the CMU_STATUS is PRIMARY. After a CMU is determined to be PRIMARY and the c-3 ARINC CHARACTERISTIC 750 - Page 11 3.0 MODES OF OPERATION Williamsburg version has been negotiated, then the CMU_STATUS is BOP
38、. The CMU_STATUS states and events are shown in the following state diagram: Figure 3-1 - CMU_STATUS State Diagram The events in Figure 3-1 are defined as follows: a. CMU becomes both PRESENT and ACTIVE (declared PRIMARY). See Section 3.3.2.1.1 and 3.3.2.1.2. b. VDR transmits or receives an ALOHA re
39、sponse containing a version number that is supported by the VDR. ALO/ALR handshake successful (CMU declared “bit oriented” BOP). May occur due to either a change of the supported Williamsburg version number or a change from PRIMARY to a supported version. c. CMU becomes ABSENT or PRESENT/STANDBY. Se
40、e Section 3.3.2.1.1 and 3.3.2.1.2. d. VDR transmits or receives an ALO word. ALOHA process started OR ALO/ALR handshake unsuccessful (CMU declared “not bit oriented”). May occur when a common Williamsburg version can not be found. 3.3.2.1 PRIMARY CMU Determination The VDR may be connected to one or
41、two CMUs. The VDR has a separate high-speed ARINC 429 input port for each CMU. The VDR provides one high-speed ARINC 429 output port which is connected to both CMUs. The VDR communicates with only one CMU at a time. The VDR communicates with the CMU which the VDR has determined to be the PRIMARY CMU
42、 according to the logic herein. A CMUs presence on an ARINC 429 bus can be represented by two state variables: ABSENT/PRESENT and STANDBY/ACTIVE. The state of these two variables for both CMUs will determine which CMU is considered PRIMARY by the VDR. 3.3.2.1.1 ABSENT/PRESENT Determination The VDR m
43、onitors both ARINC 429 inputs for Label 270 words. If the rate of the received Label 270 word is greater than once every second and the SSM code is set to “Normal” (00b) or “Functional Test” (10b), then that CMU is considered PRESENT. Else, its status is ABSENT. Its possible, and normal, for both CM
44、Us to be PRESENT. 3.3.2.1.2 ACTIVE/STANDBY Determination When the CMU is determined by the VDR to be PRESENT, then the VDR can determine whether the CMU is ACTIVE or STANDBY. If bit #20 (active/standby bit), of the CMUs Label 270 status word is set to “1” for five seconds, then the CMU is ACTIVE. If
45、 bit #20 of the CMUs Label 270 status word is set to “0” for five seconds, then the CMU is STANDBY. Normally only one CMU will indicate ACTIVE and only one will indicate STANDBY. c-3a,d NULL BOPPrimary c d b ca INIT ARINC CHARACTERISTIC 750 - Page 12 3.0 MODES OF OPERATION 3.3.2.1.3 Primary CMU Dete
46、rmination Algorithm The VDR uses the following procedure to determine the PRIMARY CMU: a. At VDR initialization both CMUs are declared to be ABSENT. b. If CMU1 is determined to be both PRESENT and ACTIVE, then CMU1 is declared to be PRIMARY. c. Else, if CMU2 is determined to be both PRESENT and ACTI
47、VE, then CMU2 is declared to be PRIMARY. d. Else, both CMUs are declared not PRIMARY and each CMU is periodically monitored for a change in status to ACTIVE and PRESENT. e. If the status of the PRIMARY CMU changes then the VDR resets to its initialization state. Once a CMU has been declared by the V
48、DR to be PRIMARY, the VDR uses that CMU for all communications until that CMUs ACTIVE/STANDBY or ABSENT/PRESENT status changes. 3.3.2.1.4 Primary CMU Notification When the VDR has declared a CMU to be PRIMARY, it broadcasts this information to both CMUs. The information is conveyed periodically in t
49、he VDRs Label 270 status word in Bits 15 and 16, the Primary CMU field. This field is used to indicate which CMU the VDR considers to be PRIMARY and should be set to the SDI code of the PRIMARY CMU. If neither CMU is declared to be PRIMARY, then both bits in the field should be set to “1”. The VDR should use the SDI codes as received from the CMUs even if the SDI codes are erroneous (reversed or identical). 3.3.2.2 BOP CMU Determination When the CMU_STATUS state variable becomes PRIMARY then the ARINC 429 BOP version is negotiated with the CMU. There is more than one v
