1、72 Rec. ITU-R M.492-6 RECOMMENDATION ITU-R M.492-6* OPERATIONAL PROCEDURES FOR THE USE OF DIRECT-PRINTING TELEGRAPH EQUIPMENT IN THE MARITIME MOBILE SERVICE (Question IT-R 5/8) (1974-1978-1982-1986-1990- 1992-1995) Summary The Recommendation provides in Annex 1 operational procedures for the use of
2、direct-printing telegraph equipment in communication between a ship and a coast station in the selective ARQ-mode on a fully automated or semi-automated basis and to a number of ship stations or a single ship in the broadcast FEC-mode. It also specifies interworking between equipments in accordance
3、with technical characteristics given in Recommendations ITU-R M.476 and ITU-R M.625. Appendix 1 contains procedures for setting up of calls. The ITU Radiocommunication Assembly, considering a) Recommendations ITU-R M.476, ITU-R M.625 and ITGR M.692; b) of using the 9-digit ship station identity is d
4、escribed in Recommendation ITU-R M.625; c) d) operational procedures may be required in frequency bands other than the HF and MF bands); e) f-) is required, at least for a transitionary period, that narrow-band direct-printing telegraph services are in operation using equipment as described in that
5、an improved narrow-band direct-printing telegraph system providing automatic identification and capable that the operational procedures necessary for such services should be agreed upon; that, as far as possible, these procedures should be similar for all services and for all frequency bands (differ
6、ent that a large number of equipments complying with Recommendation ITU-R M.476 exist; that interworking between equipments in accordance with Recommendations ITU-R M.476 and ITU-R M.625 recommends 1 that the operational procedures given in Annex 1 be observed for the use of narrow-band direct-print
7、ing telegraph equipment in accordance with either Recommendation ITU-RM.476 or ITU-R M.625 in the MF and HF bands of the maritime mobile service; 2 that when using direct-printing telegraphy or similar systems in any of the frequency bands allocated to the maritime mobile service, the call may, by p
8、rior arrangement, be made on a working frequency available for such systems. * This Recommendation should be brought to the attention of the International Maritime Organization (IMO) and the Telecommunication Standardization Sector (ITU-T). ITU-R RECMN*M. SERIES*PT*3 75 4855232 O527726 82T = Rec. IT
9、U-R M.492-6 ANNEX 1 73 Operational procedures 1 Mode A (ARQ) 1.1 Methods used for setting up narrow-band direct-printing telegraph communications between a ship station and a coast station in the ARQ-mode should be on a fully automatic or semi-automatic basis, insofar that a ship station should have
10、 direct access to a coast station on a coast station receiving frequency and a coast station should have direct access to a ship station on a coast station transmitting frequency. 1.2 However, where necessary, prior contact by Morse telegraphy, radiotelephony or other means is not precluded. 1.3 int
11、ernational telex network may be achieved by manual, semi-automatic or automatic means. Through connection to a remote teleprinter station over a dedicated circuit or to a subscriber of the NOTE 1 -Before an international automatic service can be introduced, agreement has to be reached on a numbering
12、 plan, traffk routing and charging. This should be considered by both the ITU-T and the ITU-R. NOTE 2 - Recommendations ITU-R M.476 (see Q 3.1.5) and ITU-R M.625 (see Q 3.8) make provision for automatic re- establishment of radio circuits by rephasing in the event of interruption. However, it has be
13、en reported that this procedure has, in some countries, resulted in technical and operational problems when radio circuits are extended into the public switched network or to certain types of automated switching or store-and-forward equipments. For this reason, some coast stations do not accept mess
14、ages if the rephasing procedure is used. NOTE 3 -When a connection is set up in the ARQ mode with the intemational telex network via a coast station, where practicable the general requirements specified in ITU-T Recommendation U.63 should be met. 1.4 When, by prior arrangement, unattended operation
15、is required for communication from a coast station to a ship station, or between two ship stations, the receiving ship station should have a receiver tuned to the other stations transmitting frequency and a transmitter tuned or a transmitter capable of being tuned automatically to the appropriate fr
16、equency and ready to transmit on this frequency. 1.5 For unattended operation a ship station should be called selectively by the initiating coast or ship station as provided for by Recommendations ITU-R M.476 and IT-R M.625. The ship station concerned could have available traffic stored ready for au
17、tomatic transmission on demand of the calling station. 1.6 transmitted. At the “over” signal, initiated by the calling station, any available traffic in the ships traffic store could be 1.7 ships equipment should automatically revert to the “stand-by” condition. At the end of the communication, an “
18、end of communication” signal should be transmitted, whereupon the 1.8 A “free channel” signal may be transmitted by a coast station where necessary to indicate when a channel is open for traffic. The “free channel” signals should preferably be restricted to only one channel per HF band and their dur
19、ation should be kept as short as possible. In accordance with Article 18 of the Radio Regulations and recognizing the heavy loading of the frequencies available for narrow-band direct printing in the HF bands, “free channel” signals should not be used in future planned systems. 1.9 The format of the
20、 “free channel” signal should be composed of signals in the 7-unit error detecting code as listed in Q 2 of Annex 1 to Recommendation ITU-R M.476 and Q 2 of Annex 1 to Recommendation ITU-R M.625. Three of these signals should be grouped into a block, the middle signal being the “signal repetition” (
21、RQ), the first signal of the block being any of the signals VXKMCF TBOZA and the third signal of the block being any of the signals VMPCYFS OIRZDA (see Recommendation IT-R M.491). These signals should be indicated in the IT List of Coast Stations. - ITU-R RECMN*U. SERIES*PT*3 95 W 4855232 0527927 7b
22、b 74 Rec ITU-R M.492-6 Selections of new signals should preferably be chosen to correspond to the first two digits of that coast stations 4-digit identification number. If this is not possible because the characters needed are not listed above, or if this is not desired because this combination is a
23、lready in use by another coast station, it is preferred that a combination of characters be selected from those listed above in the second part of each row, i.e. TBOZA for the first signal and OIRZDA for the third signal of the free channel block. The signals in the block are transmitted at a modula
24、tion rate of 100 Bd and the blocks are separated by pauses of 240 ms. For manual systems this “free channel” signal should be interrupted either by a period of no signal or by a signal or signals, that would enable an operator to recognize the “free channel” condition by ear. An aurally recognizable
25、 signal, e.g. a Morse signal, may be used alone as the “free channel” signal in manual systems. At least 8 blocks of the 7-unit signal should be transmitted before interruption. 1.10 signal should be interrupted by listening periods of at least 3 s. In the case of single frequency operation, as desc
26、ribed in Recommendation ITU-R M.692, the free channel 1.11 stations are given below and specific procedures are given in Appendix 1. General operational procedures for setting up calls between ship stations and between ship stations and coast 1.12 Manual procedures 1.12.1 Ship to coast station 1.12.
27、1.1 The operator of the ship station establishes communication with the coast station by A1A Morse telegraphy, telephony or by other means using normal calling procedures. The operator then requests direct-printing communication, exchanges information regarding the frequencies to be used and, when a
28、pplicable, gives the ship station the direct- printing selective call number assigned in accordance with Recommendation ITU-R M.476 or ITU-R M.625 as appropriate, or the ship station identity assigned in accordance with the Preface to List W A. 1.12.1.2 The operator of the coast station then establi
29、shes direct-printing communication on the frequency agreed, using the appropriate identification of the ship. 1.12.1.3 Alternatively the operator of the ship station, using the direct-printing equipment, calls the coast station on a predetermined coast station receive frequency using the identificat
30、ion of the coast station assigned in accordance with Recommendation ITU-R M.476 or ITU-R M.625 as appropriate, or the coast station identity assigned in accordance with the Preface to List W A. 1.12.1.4 The operator of the coast station then establishes direct-printing communication on the correspon
31、ding coast station transmit frequency. 1.12.2 Coast station to ship 1.12.2.1 The operator of the coast station calls the ship station by A1A Morse telegraphy, telephony or other means, using normal calling procedures. 1.12.2.2 The operator of the ship station then applies the procedures of 5 1.12.1.
32、1 or 0 1.12.1.3. 1.12.3 Intership 1.12.3.1 The operator of the calling ship station establishes communication with the called ship station by AIA Morse telegraphy, telephony, or by other means, using normal calling procedures. The operator then requests direct-printing communication, exchanges infor
33、mation regarding the frequencies to be used and, when applicable, gives the direct- printing selective call number of the calling ship station assigned in accordance with Recommendation -R M.476 or ITU-R M.625 as appropriate, or the ship station identity assigned in accordance with the Preface to Li
34、st VI1 A. 1.12.3.2 The operator of the called ship station then establishes direct-printing communication on the frequency agreed, using the appropriate identification of the calling ship. Rec ITU-R M.492-6 75 1.13 Procedures for automatic operation 1.13.1 Ship to coast station 1.13.1.1 The ship sta
35、tion calls the coast station on a predetermined coast station receive frequency, using the direct- printing equipment and the identification signal of the coast station assigned in accordance with Recommen- dation ITU-R M.476 or ITU-R M.625 as appropriate, or the coast station identity assigned in a
36、ccordance with the Preface to List W A. 1.13.1.2 The coast stations direct-printing equipment detects the call and the coast station responds directly on the corresponding coast station transmit frequency, either automatically or under manual control. 1.13.2 Coast station to ship 1.13.2.1 The coast
37、station calls the ship station on a predetermined coast station transmit frequency, using the direct- printing equipment and the ship station direct-printing selective call number assigned in accordance with Recommendation ITU-R M.476 or ITU-R M.625 as appropriate, or the ship station identity assig
38、ned in accordance with the Preface to List W A. 1.13.2.2 The ship stations direct-printing equipment tuned to receive the predetermined coast station transmit frequency detects the call, whereupon the reply is given in one of the following ways: a) the ship station replies either immediately on the
39、corresponding coast station receive frequency or at a later stage, using the procedure of 0 1.12.1.3; or the ship stations transmitter is automatically started on the corresponding coast station receive frequency and the direct-printing equipment responds by sending appropriate signals to indicate r
40、eadiness to receive traffic automatically. b) 1.14 Message format 1.14.1 network: Where the appropriate facilities are provided by the coast station, traffic may be exchanged with the telex a) in a conversational mode where the stations concerned are connected directly, either automatically or under
41、 manual control; or b) in a store-and-forward mode where traffk is stored at the coast station until the circuit to the called station can be set up, either automatically or under manual control. 1.14.2 Appendix 1, 0 2). In the shore-to-ship direction, the message format should conform to normal tel
42、ex network practice (see also 1.14.3 Appendix 1, 0 1. In the ship-to-shore direction, the message format should conform to the operational procedures specified in 2 Mode B (FEC) 2.1 of ships or to a single ship, preceded if desired by the selective call code of the ship) concerned where: Messages ma
43、y, by prior arrangement, be sent in the B mode from a coast station or a ship station to a number 2.1.1 a receiving ship station is not permitted or not able to use its transmitter, or 2.1.2 communications are intended for more than one ship, or 2.1.3 unattended reception of the B mode is required a
44、nd automatic acknowledgement is not necessary. In such cases, the ship station receivers should be tuned to the appropriate coast or ship station transmitting frequency. 76 Rec. ITU-R M.492-6 2.2 2.3 should stop automatically when reception of the emission ceases. 2.4 other means. All B mode message
45、s should start with “carriage return” and “line feed” signals. When the ship station receives phasing signals in the B mode, its teleprinter should start automatically and Ship stations may acknowledge the reception of B mode messages by AIA Morse telegraphy, telephony or by 3 Inter-working between
46、equipments in accordance with Recommendations ITU-R M.476 and ITU-R M.625 3.1 Recommendation ITU-R M.625 provides for automatic inter-working with equipment which is in accordance with Recommendation ITU-R M.476. The criteria for determining whether one or both stations are of the Recommendation ITU
47、-R M.476 type are the length of the call signal and the composition of the call blocks. 3.2 If both stations have equipment in accordance with Recommendation ITU-R M.625, automatic station identification is a part of the automatic call Set-up procedures. However, if one or both stations have equipme
48、nt in accordance with Recommendation ITU-R M.476, no automatic station identification takes place. For this reason, and because Recommendation ITU-R M.625 accommodates the use of the 9-digit ship station identity for the direct-printing equipment cai1 signal, it is desirable that all new equipment b
49、e in accordance with Recommendation ITU-R M.625 at the earliest practicable time. 3.3 In order to attain full compatibility with the large number of existing equipment, it will be necessary to assign both a 9-digit and a 5- (or 4-) digit identity (i.e. 7- and 4-signal call signals) to such new stations. Ship and coast station lists should contain both signals. Rec ITU-R M.492-6 APPENDIX 1 I QRC 1 Procedure for setting up a call in the ship-to-coast station direction 6 t + ? I Coast station I I I l Step I Ship station I Ship initiates the call 1 2 I Exchange answer-backs (
