ITU-R M 632-3-1997 TRANSMISSION CHARACTERISTICS OF A SATELLITE EMERGENCY POSITION-INDICATING RADIO BEACON (SATELLITE EPIRB) SYSTEM OPERATING THROUGH GEOSTATIONARY SATELLITES IN THE.pdf

1、kTD.ITU-R RECMN Mmb32-3-ENGL 1997 4855222 0527435 O02 Rec. ITU-R M.632-3 401 RECOMMENDATION ITU-R M.632-3* TRANSMISSION CHARACTERISTICS OF A SATELLITE EMERGENCY POSITION-INDICATING RADIO BEACON (SATELLITE EPIRB) SYSTEM OPERATING THROUGH GEOSTATIONARY SATELLITES IN THE 1.6 GHz BAND (Question ITU-R 90

2、/8) ( 1986-1990- 1994- 1997) Summary This Recommendation contains the transmission characteristics of a satellite EPIRJ3 system operating through geostationary satellites in the 1.6 GHz band. This Recommendation is intended to facilitate the popularization of satellite EPIRB systems practically with

3、out sacrificing the system performance. The Radiocommunication Assembly, considering a) that satellite EPIRBs are one of the prime alerting means in the Global Maritime Distress and Safety System (GMDSS) adopted by the International Maritime Organization (IMO); b) that the satellite EPRB system oper

4、ating through geostationary satellites in the 1.6 GHz band is one of two satellite-based distress alerting systems developed for use in the GMDSS; c) that all ships to which Chapter IV of the Intemational Convention for the Safety of Life at Sea (SOLAS) 1974, as amended in 1988, applies are required

5、 by Regulation IV17.1.6 to carry a satellite EPIRB from 1 August 1993; d) that SOLAS Regulation N/7.1.6 permits the carriage of a satellite EPIRJ3 operating through the Inmarsat geostationary-satellite system, subject to the availability of appropriate receiving and processing ground facilities for

6、each ocean region covered by Inmarsat; e) f) operating through the geostationary Inmarsat satellite system on 1.6 GHz; g) satellite EPIRBs, some of which may not meet all of the requirements established by the IMO in Resolution A.661(16); h) remaining time-frame; j) k) onwards, will cover both the b

7、and 1 644.3-1 644.5 MHz and the band 1 645.5-1 646.5 MHz; 1) that pre-operational demonstrations have been satisfactorily completed; that the IMO has adopted Resolution A.661(16) - Performance standards for float-free satellite EPIRBs that ships to which the 1974 SOLAS Convention does not apply will

8、 use elements of the GMDSS, including the necessity to make available satellite EPIRB production units, and to gain operational experience within the that the frequency band for satellite EPms available through the first generation Inmarsat space segment is that the second generation Inmarsat space

9、segment, which is planned to commence operation from 1990 that the number of potential users, including non-Convention ships, cannot yet be estimated; 1644.3-1 644.5 MHz; * This Recommendation should be brought to the attention of the International Maritime Organization (IMO), the International Civi

10、l Aviation Organization (ICAO), and the International Mobile Satellite Organization (Inmarsat). Note by the Secretariat: The current version of this Recommendation has been incorporated by reference in the Radio Regulations (RR) as revised by the World Radiocommunication Conference, 1995 (WRC-95). A

11、ccording to resolves 1 of Resolution28 (WRC-93, the next Radiocommunication Assembly shall communicate to the WRC-97 the list of the ITU-R Recommendations incorporated by reference in the RR which have been revised and approved. COPYRIGHT International Telecommunications Union/ITU Radiocommunication

12、sLicensed by Information Handling ServicesSTDDITU-R RECMN Mmb32-3-ENGL 1797 M 9855212 0527Y3b T97 402 Rec. ITU-R M.632-3 m) operational capacity requirements is probably not greater than 200 kHz, that the amount of spectrum for the 1.6 GHz satellite EPIRB system necessary to meet the presently fores

13、een recommends 1 that the transmission characteristics of all types of satellite EPIRBs operating through geostationary satellites at 1.6 GHz should be in accordance with Annex 1; 2 that the transmission frequencies of satellite EPIRBs be distributed uniformly across the frequency band appropriate t

14、o the space segment in use; 3 that the operational implementation of the 1.6 GHz satellite EPIRB system as it applies to the second and subsequent generations of the Inmarsat space segment be initiated in the spectrum between 1 645.6 and 1 645.8 MHz; 4 that until all satellites of the Inmarsat first

15、 generation space segment (spare and operational) are completely replaced, all types of satellite EPIRBs in the 1.6 GHz band will transmit sequentially on both 1645.6-1 645.8 MHz and 1644.3-1 644.5 MHz. ANNEX 1 Transmission characteristics of a satellite emergency position-indicating radio beacon (s

16、atellite EPIRB) system operating through geostationary satellites in the 1.6 GHz band Modulation: Transmit frequency: * Deviation: Accuracy of clock frequency: Transmit frequency: - long-term accuracy (for 1 year): - short-term stability: FSK switching time: Transmit power (e.i.r.p.): Antenna: Anten

17、na axial ratio: Polarization: Frame length: - data: - synchronization: - parity bits: non-coherent binary frequency shift keying (FSK) within the bands 1644.3-1644.5 MHz (Inmarsat first generation space segment) and 1645.5-1 646.5 MHz (Inmarsat second generation space segment) -120 Hz (O) + 120 Hz (

18、1) tolerance Il% f2 x 104/year (This requires a clock accuracy of f2 x 10-7/year in the receiver processor) better than i 3 x lo4 2 x 10-8 for i min 80% transmit power within 1.5 ms O dBW with tolerance +2 to -3 dB Hemispherical in pattern I 5 dB for f90“ from zenith right-hand circular 100 bits (se

19、e Appendix 1) 20 bits (see Appendix 1) 40 bits (see Appendix 2) I * Until all satellites of the Inmarsat first generation space segment (spare and operational) are completely replaced, all types of satellite EPIRBs will transmit sequentially on both frequency bands of the Inmarsat first and subseque

20、nt generation space segments. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD-ITU-R RECMN M-b32-3-ENGL 1997 m Li855212 0529437 985 m Rec. ITU-R M.632-3 403 Code: NRZ-L Modulation rate: 32 Bd Total transmission duration: Number of t

21、ransmissions: NOTE 1 - The total transmission duration will be reduced to 20 min (75 min) (see 0 7 of Appendix 3) (see also 0 5 of Appendix 3) when all first generation satellites have been replaced. 40 min (150 min) (see 8 7 of Appendix 3) 4 (see Appendix 3) AFPENDIX 1 TO ANNEX 1 1 messages to the

22、extent practicable and necessary: The following items, listed in the preferred priority order for entry and read-out, should be included in distress TABLE 1 Content of distress message Item 1 2 2.1 2.2 2.3 3 4 5 6 7 Content of distress message Ship station identity Position coordinates and informati

23、on in the following order: Latitude in degrees and minuted) Longitude in degrees and minutes() Time of position up-dateo) Nature of distress Course speed Time of activatiod3) Assistance desired and any other information which might facilitate the rescue(4) Number of bits 30 14 15 11 4 9 6 11 (i) For

24、 implementation reasons the order in which items 2.1 and 2.2 are transmitted on the radio path is given in Tables 2 and 4 and Fig. 1. (2) (3) (4) The time of receipt of an alert is added by the digital receiver processor. Where a GPS receiver is built in as an integral part of the EPIRB, this field

25、may be omitted. The 11 bits thereby released may be used to enhance the accuracy of reported position as given in Table 4. Item 7 may be included with the data sent in item 3, if necessary. 2 The format of the transmitted message and string is shown in Table 2 and Fig. 1. COPYRIGHT International Tel

26、ecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD*ITU-R RECMN Hmb32-3-ENGL 1997 4855232 0529438 833 404 Synchronization bits . Xstress message Parity bits RW. ITU-R M.632-3 TABLE 2 Format of the transmitted message (see (i) Table 1) 20 bits 30 bits 1 bit 1 bit

27、 8 bits 6 bits 7 bits 6 bits 9 bits 5 bits 6 bits 5 bits 6 bits 6 bits 4 bits 40 bits Hex EDE20 ;hip station identity ange: 0-999.999.999 mgitude hemispherical symbol 1: East; 1: West atitude hemispherical symbol 1 North; 1: South Degrees of longitude ange: O- 180 Minutes of longitude :ange: 0-60 De

28、grees of latitude range: 0-90 Minutes of latitude range: 0-60 Course: degrees (true) range: 0-360 Time of position update: h (UTC) range: 0-24 Time of position update: min range: 0-60 Time of activation: h (UTC) range: 0-24 Time of activation: min range: 0-60 speed: knots range: 0-63 Nature of distr

29、ess (see Table 3) See Appendix 2 for composition In those systems where it is desirable to provide, on activation, a specific indication of the nature of distress, the indications of Table 3 should be used. TABLE 3 Nature of distress indications IMO indicator I Binary code 1 2 3 4 5 6 7 8 9 10 O001

30、0010 O01 1 0100 O101 o1 10 o111 m lo00 1111 Nature of distress Firdexplosion Flooding Collision Grounding Listing, in danger of capsizing Sinking Disabled and adrift Undesignated (unspecified distress) Abandoning ship Test(*) (1 Use of this indicator should be restricted to those applications where

31、transmission of the distress alert (or call) is required to ascertain that the system is operating properly. Provisions may be required to confirm that the complete system is functioning. Additional capacity should be provided if practical. COPYRIGHT International Telecommunications Union/ITU Radioc

32、ommunicationsLicensed by Information Handling ServicesSTD*ITU-R RECMN M-bI2-3-ENGL 1997 4855212 0529439 758 r Rec. ITU-R M.632-3 TABLE 4 Format of the transmitted message for “high resolution” mode* Synchronization bits Distress message Parity bits 20 bits 30 bits 1 bit 1 bit 8 bits 6 bits I bits 6

33、bits 9 bits 5 bits 6 bits 3 bits 4 bits 4 bits 6 bits 4 bits 40 bits Hex EDE20 System code ange: 0-999.999.999 Angitude hemispherical symbol 1: East; 1: West datitude hemispherical symbol 1: North; 1: South Degrees of longitude *ange: 0-180 Minutes of longitude range: 0-60 Degrees of latitude range:

34、 0-90 Minutes of latitude range: 0-60 Course: degrees (me) range: 0-360 Time of position update: h (UTC) range: 0-24 Time of position update: min range: 0-60 Mode selection (normal modelhigh resolution) (see NOTE 1) Latitude position enhancement (see Table 5) Longitude position enhancement (see Tabl

35、e 5) Speed: knots range: 0-63 Nature of distress (see Table 3) See Appendix 2 for composition 405 * For EPIRBs having an integral GPS receiver if a valid position fix has been provided, these 3 bits will be set to all ones to enable the digital receiver processor to recognize this and switch to “hig

36、h resolution” mode. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesSTD-ITU-R RECMN N*b32-3-ENGL 1797 M 4855232 0527g4D 47T 406 RC. ITU-R M.632-3 TABLE 5 Use of additional 4 bits to enhance latitude and longitude accuracy The additiona

37、l 4 bits enable increased accuracy by subdividing the minutes information into 5 equal steps, Le. intervals of 3.75 s or 0.0625 min. The binary representation of steps 1 to 15 is shown in Table 5. 2 3 1 Equivalent Decimal 1 Step I Binarynumber 0010 7.5 0.125 001 1 11.25 O. 1875 4 5 o100 15.00 0.25 O

38、101 18.75 0.3125 6 7 1 i I : 1 30.00 1 0.5 1 0.5625 33.75 1010 37.50 0.625 o1 10 22.50 0.375 o111 26.25 0.4375 11 12 101 1 41.25 0.6875 1100 45.00 0.75 13 14 1101 48.75 0.8125 1110 52.5 0.875 15 1111 56.25 0.9375 COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Inf

39、ormation Handling ServicesSTD-ITU-R RECMN M-b32-3-ENGL 1777 4855212 0527441 30b Rec. ITU-R M.632-3 407 APPENDIX 2 TO ANNEX 1 Forward error-correction code 40 parity bits for error-correcting purposes. A (140, 100, 5) BCH code is used resulting in a minimum code distance of 11. The input message Di the first of these additional bursts commencing 480 min after the commencement of transmissions from the EPIRB. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling Services