1、 STD-ITU-R RECMN M-1082-L-ENGL II777 m it855212 0532758 781 m 266 Rec. ITU-R M.1082-1 RECOMMENDATION ITU-R M. 1082- 1 * INTERNATIONAL MARITIME MFMF RADIOTELEPHONE SYSTEM SELECTIVE CALLING SIGNALLING FORMAT (Question ITU-R 93/8) WITH AUTOMATIC FACILITIES BASED ON DIGITAL (1994-1997) Summary This Reco
2、mmendation provides for a means to establish a fully automatic radiotelephone service for vessels to send and receive calls via the public switched telephone network (PSTN) using MF/HF equipment. The Recommendation contains detailed operational procedures, timing diagrams for call Set-up sequences a
3、nd a description of factors which differ between MF/HF and VHF systems. The ITU Radiocommunication Assembly, considering that a maritime MF/HF radiotelephone system providing automatic connection with the public switched that a maritime VHF radiotelephone system providing automatic connection with t
4、he PSTN is described in a) telephone network (PSTN) would improve traffic handling and the efficiency of the use of the radio channels; b) Recommendation ITU-R M.689 and might, suitably modified, be used in MF and HF; c) d) in widespread use by ships and coast stations in the maritime mobile service
5、; e) working channels; f) can be used for signalling over the radio path for an automatic system using a DSC channel; g) use for manual operations from ships or coast stations, that international standardization is of great importance in the maritime mobile service; that the existing public correspo
6、ndence channels listed in Article 60 (S52) of the Radio Regulations (RR) are that FtR Articles 60 (S52) and 65 (S57) do not permit coast stations to emit signals on idle radiotelephone that the digital selective-calling (DSC) system described in Recommendations ITU-R M.493 and ITU-R M.541 that the e
7、xisting RR Article 60 (S52) channels can be used in such an automatic system without impairing their recommends 1 that the operational procedures described in Annex 1 be observed when operating an international radiotelephone system with automatic facilities based on the DSC signalling format and us
8、ing the public correspondence channels listed in RR Article 60 (S52); 2 that the same RR Article 60 (S52) channel can be used for both automatic and manual operation by the same coast station depending on the requirements of the ship stations; 3 that the technical characteristics of the ship and coa
9、st station equipment should be in accordance with Annex 2. * This Recommendation should be brought to the attention of the International Maritime Organization (IMO) and the Telecom- munication Standardization Sector (IW-T). COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLice
10、nsed by Information Handling ServicesRec. ITU-R M.1082-1 ANNEX 1 267 Operational procedures 1 Introduction These procedures are initiated by using DSC on an appropriate MF or HF paired DSC calling channel and based on the technical characteristics and operational procedures detailed in Recommendatio
11、ns ITU-R M.493 and ITU-R M.541. Connection to the PSTN is effected using any appropriate MF or HF public correspondence working channel listed in RR Article 60 (S52) without in any way impairing their use for manual operations. Appendix 1 illustrates the timing of the call Set-up, calling and acknow
12、ledgement sequences described by these procedures, in the ship-to-shore direction and in the shore-to-ship direction. Appendix 2 indicates the factors which are not the same in MF/HF as in VHF. 2 Operational procedures in the ship-to-shore direction 2.1 Ship station initiates caii 2.1.1 DSC equipmen
13、t as follows: The user aboard the ship (hereafter referred to as the user) composes the calling sequence (see Note 1) on his selects the format specifier 123 (individual station automatichemiautomatic service); enters 9-digit address (identification) of required coast station; selects the category r
14、outine (1 00); (the ship station self-identification is entered automatically); selects first and second telecommands as appropriate (for a normal radiotelephone call these would be 109 (J3E) and 126 (no information) respectively); the ships position should preferably be inserted so that the coast s
15、tation can use this information to select the working channel and/or directional antennas. In the absence of any information, the symbol 126 will be automatically inserted 6 times (see Recommendation ITU-R M.493, Annex 1, Q 8.2.2, Note and Table 7); inserts the required subscriber number (e.g. telep
16、hone number); selects “end of sequence” signal “RQ. NOTE 1 -It is assumed that commercial equipment will be produced which simplifies the composition of the calling sequence. In practice the user should only need to key the coast station address and the required subscriber number, all other informat
17、ion being inserted automatically. 2.1.2 The user selects the MF or HF DSC ship-to-shore calling frequency appropriate to the coast station and transmits the calling sequence, after checking as far as possible that there are no DSC calls in progress on that frequency. 2.1.3 DSC shore-to-ship frequenc
18、y (see $2.2) within 25 s, the user should: - If the ship station does not receive an error-free acknowledgement from the called coast station on the paired in the case of MF, repeat the transmission of the DSC call in accordance with 3 2.1.2; in the case of HF, either repeat the transmission of the
19、DSC call on the same frequency or initiate a call on another DSC frequency (which may prove better from the propagation standpoint than the frequency initially chosen). - COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD-ITU-R RECNN
20、N-3082-3-ENGL 3997 4855232 0532960 33T = 268 Rec. ITU-R M.1082-1 2.2 Coast station acknowledgement 2.2.1 The coast station can comply immediately with the call request 2.2.1.1 If, on receipt of an error-free calling sequence, the coast station can comply immediately with the call request, then it sh
21、ould, within 3 s of receiving it, transmit an acknowledgement sequence on the paired DSC shore-to-ship frequency. The acknowledgement sequence should contain the same information as in the call request, with the following exceptions: - - the address will be that of the ship, the self-identification
22、will be that of the coast station, - the working frequencylies or channel number will be included (see Recommendation ITU-R M.493, Annex 1, 0 8.2.2) and should be normally in the same band as that of the received DSC call, the “end of sequence” signal will be “BQ. - 2.2.1.2 After receiving the calli
23、ng sequence, the coast station should within 10 s switch to the working frequencylies indicated and then transmit an “engaged channel” signal on the working channel transmission frequency. In the case of an HF link, if the coast station uses directional antennas, it is possible to set up a transmiss
24、ion chain (one transmitter + one transmitting antenna and one receiver + one receiving antenna) corresponding to the geographical location of the ship station. 2.2.1.3 frequencyhes indicated. After receiving the acknowledgement sequence, the ship station should within 5 s switch to the working 2.2.2
25、 The coast station cannot comply immediately with the call request 2.2.2.1 If the appropriate working frequencylies or channel(s) are busy then the acknowledgement sequence should be as in Q 2.2.1.1, except that the first telecommand should be 104 (unable to comply) and the second telecommand should
26、 be 102 (busy) and no working frequencyhes or channel should be included in the acknowledgement. 2.2.2.2 except that the second telecommand signal should be one of symbol numbers 100-109 as appropriate. If the coast station cannot comply for other reasons, the acknowledgement sequence should be as i
27、n 9 2.2.2.1 2.2.3 The ship station, on receipt of an acknowledgement indicating “unable to comply” in accordance with 8 2.2.2.1 or 2.2.2.2 should, if an automatic connection is still required, initiate an appropriate new DSC call in accordance with 0 2.1. 2.2.4 0 2.2.2.1 or 2.2.2.2, then it should t
28、ake no further action with respect to the call request. If the coast station transmitted an acknowledgement indicating “unable to comply” in accordance with 2.3 Procedures subsequent to the exchange of initial DSC calls 2.3.1 ship-to-shore frequency of the working channel a DSC call identical to the
29、 initial call (see Q 2.1.1). Once tuned to the working frequencyhes indicated (see $ 2.2.1.3), the ship station transmits on the If a DSC call containing the same self-identification as that of the calling ship is received on the coast station receive frequency of the working channel within 25 s, th
30、e coast station may, on the receipt of an error-free calling sequence, automatically measure the signal-to-noise (S/N) ratio of the received DSC call and compare this to the SIN ratio required for the mode requested (see Note 1). NOTE 1 -Recommendation ITU-R F.339, Table 1 indicates that an RF SIN d
31、ensity ratio of 61 dBMz should be obtained for a J3E telephony call having a marginally commercial grade of service under non-diversity fading conditions. SIN density ratios applicable to other classes of emission can also be obtained from this table. The quality of the working channel may alternati
32、vely be estimated by other methods. 2.3.2 The coast station should then stop the transmission of the “engaged channel” signal, and initiate the transmission of a DSC acknowledgement, within 5 s after receiving the call, on the shore-to-ship frequency of that working channel. COPYRIGHT International
33、Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTDmITU-R RECMN M-LO82-L-ENGL 3997 4855232 0532963 276 Rec. ITU-R M.1082-1 269 2.3.2.1 If the working channel quality evaluation indicates that the communication on the working channel will be satisfactory, then
34、 the acknowledgement should be identical to that transmitted in accordance with 2.2.1.1. The coast station should then commence dialling the Subscriber number. 2.3.2.2 If the working channel quality evaluation indicates that the communication on the working channel will not be satisfactory, but the
35、coast station can offer an alternative working channel, then the acknowledgement should be identical to that transmitted in accordance with 0 2.2.1.1 except that the indicated frequency is the frequency corresponding to that alternative working channel and the procedure should be repeated from 8 2.3
36、.1. 2.3.2.3 If the working channel quality evaluation again indicates that the communication on the new working channel will not be satisfactory, and if the coast station cannot offer an alternative working frequency, then the acknowledgement should be the same as that transmitted in 8 2.2.1.1 excep
37、t that the first telecommand should be 104 (unable to comply) and the second telecommand should be 108 (unable to use proposed channel). 2.3.3 “engaged channel” signal from the working channel. If no such DSC call from the ship (8 2.3.1) is received within 25 s, then the coast station should remove
38、the 2.3.4 If the coast station transmitted an acknowledgement indicating “unable to comply” in accordance with 8 2.3.2.3, then it should remove the “engaged channel” signal from the working channel and take no further action with respect to the call request. 2.3.5 If the ship station receives an “un
39、able to comply” acknowledgement in accordance with 3 2.3.2.3 or if it receives no acknowledgement within 25 s from the start of transmission of the call described in 0 2.3.1 and hears no indication that the connection to the requested subscriber has been effected, then the ship station should clear
40、the call in accordance with 8 2.5.1. 2.4 Call connection 2.4.1 Once the coast station begins dialling the subscriber number it should connect the line circuit to the radio path. Timing of the call for billing purposes should commence after the subscriber answers, i.e. “off-hook” condition detected.
41、2.4.2 If the called subscriber does not answer within a period of 1 min from completion of dialling or if anything other than ringing tones are received (e.g. engaged, number unobtainable, etc.), then the call should be considered as not started and the coast station should clear the circuit by disc
42、onnecting the line and radio circuit. The user, on hearing the ringing tones stop or hearing anything other than “ringing” tones, should refrain from any further transmissions on the working channel. If a further call is required, the user should initiate a new call on a DSC calling channel. 2.5 Cal
43、l completion 2.5.1 When the ship station wishes to terminate the call connection to the subscriber it transmits an “end of call” DSC call on the ship-to-shore frequency of the working channel. The format of this call should be the same as that described in 0 2.1.1 except that the first telecommand s
44、hould be 105 (end of call) and the second telecommand should be 126. 2.5.2 On receipt of that call, if it contains the same self-identification as that of the calling ship, the landline is disconnected, the call timing is stopped and the coast station transmits a DSC acknowledgement on the shore-to-
45、ship frequency of the working channel within 1 s of receipt. The format of that acknowledgement should be the same as that described in 8 2.5.1 except that the “end of sequence” signal should be “BQ and: - the chargeable duration of the call should be inserted in the “frequency/channel” field by cod
46、ing the first three characters as hours, minutes, seconds and the remaining three characters as symbols 126: e.g. a chargeable duration of 6 min and 50 s would be coded as O0 06 50 126 126 126; - if the chargeable duration of the call is not available, then the “frequency/channel” field should conta
47、in six symbols 126. 2.5.3 of call” and consider the call to be complete. If the ship station does not receive an “end of call acknowledgement” within 20 s then it should repeat the “end COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services2
48、70 Rec. ITU-R M.1082-1 2.5.4 If the coast station does not receive the “end of call” as described in $ 2.5.1 then the call will be considered to be complete when the “on-hook” condition is detected from the PSTN (or if not reply within 1 min if anything other than ringing tones are received). When t
49、his indication is registered at the coast station the following action should take place: - call timing is stopped; - the line is cleared and disconnected from the radio circuit; - the coast station transmits an “end of call” DSC call whose format is the same as that of the acknowledgement described in 0 2.5.2 except that the “end of sequence” signal should be 127; - the coast station ceases transmissions on the working channel. The radio channel is now free to handle other traffic. 2.5.5 system operating on the line circuit to provide additional protection against call clear malfunc
