1、 Rec. ITU-R M.1458 1 RECOMMENDATION ITU-R M.1458*USE OF THE FREQUENCY BANDS BETWEEN 2.8-22 MHz BY THE AERONAUTICAL MOBILE (R) SERVICE FOR DATA TRANSMISSION USING CLASS OF EMISSION J2D (Question ITU-R 221/8) (2000) Rec. ITU-R M.1458 The ITU Radiocommunication Assembly, considering a) that the use of
2、the frequencies in the frequency bands allocated to the aeronautical mobile (R) service (AM(R)S) in the bands between 2.8-22 MHz is governed by the provisions of RR Appendix S27; b) the provisions of No. S27/15 of RR Appendix S27 on the use of frequencies with classes of emission other than J3E or H
3、2B; c) the operational need for the introduction of data link services in the HF band (HF data link) for messages related to the safety and regularity of flight for use by international civil aviation; d) that ICAO has completed standards and recommended practices (SARPs) for HF data link; and opera
4、tion in the frequency bands between 2.8-22 MHz, allocated to the AM(R)S; e) that the Radio Regulations Board (RRB) approved procedures concerning the use of the channels identified in RR Appendix S27 for various classes of emission other than J3E and H2B, recommends 1 that coordination between admin
5、istrations of frequency assignments to stations providing HF data link with class of emission J2D in the frequency bands between 2.8-22 MHz, allocated to the AM(R)S, be based on the technical characteristics contained in Annex 1; 2 that the technical and operational principles used for the establish
6、ment of the Plan of allotment of frequencies in the AM(R)S, as contained in RR Appendix S27, are also applicable for assignments with class of emission J2D that conform with the provisions of Annex 1. ANNEX 1 1 Frequency bands HF data link installations should be capable of operating at any single-s
7、ideband (SSB) carrier (reference) frequency available to the AM(R)S in the frequency bands between 2.8-22 MHz, and in compliance with the relevant provisions of the RR. 2 Channels Channel utilization should be in conformity with the table of carrier (reference) frequencies of No. S27/16 of RR Append
8、ix S27. _ * This Recommendation should be brought to the attention of the International Civil Aviation Organization (ICAO). 2 Rec. ITU-R M.1458 3 Sideband The sideband used for transmission should be on the higher side of its carrier (reference) frequency. 4 Modulation HF data link should employ M-a
9、ry phase shift keying (M-PSK) to modulate the radio-frequency carrier at the assigned frequency. M-PSK carrier The M-PSK carrier expressed mathematically should be defined as: s(t ) = A ( p(t k T ) cos 2 f0t + ( k ) for k = 0, 1., N 1 where: N: number of M-PSK symbols in transmitted physical layer p
10、rotocol data unit s(t ): analogue waveform or signal at time t A: peak amplitude f0: SSB carrier (reference) + 1 440 Hz T: M-PSK symbol period (1/1 800 s) ( k ): phase of k-th M-PSK symbol p( t k T ): pulse shape of k-th M-PSK symbol at time t. NOTE 1 The number of M-PSK symbols sent, N, defines the
11、 length (duration = N T s) of the physical layer protocol data unit. 5 Pulse shape The pulse shape, p( t ), should determine the spectral distribution of the transmitted signal. The Fourier transform of the pulse shape, P( f ), shall be defined by: P( f ) = 1 if 0 (1 + b)/2T where the spectral roll-
12、off parameter, b = 0.31, has been chosen so that the 20 dB points of the signal are at SSB carrier (reference) + 290 Hz and SSB carrier (reference) + 2 590 Hz and the peak-to-average power ratio of the waveform is less than 5 dB. 6 Frequency tolerance for high frequency data links (HFDL) The frequen
13、cy tolerance should be as follows: 20 Hz for HFDL aircraft station subsystems, and 10 Hz for HFDL ground station subsystems. 7 Protection A 15 dB desired to undesired signal ratio should apply for the protection of co-channel assignments for HFDL as follows: data versus data, data versus voice, and
14、voice versus data. NOTE 1 See also Nos. S27/25 and S27/28 of RR Appendix S27. Rec. ITU-R M.1458 3 8 Class of emission The class of emission should be J2DEN. 9 Assigned frequency The SSB assigned frequency should be 1 400 Hz higher than the SSB carrier (reference) frequency (see No. S27/75 of RR Appe
15、ndix S27). NOTE 1 The HFDL assigned frequency is offset from the channel carrier frequency by 1 400 Hz. The digital modulation is fully contained within the same overall channel bandwidth as the voice signal and complies with the provisions of RR Appendix S27. NOTE 2 In accordance with RR No. S1.148
16、 the assigned frequency is the centre of the frequency band assigned to a station. As the frequency band for HFDL is 2 800 Hz, relative to the carrier (reference) frequency the assigned frequency is 1 400 Hz higher than the carrier (reference) frequency. 10 Limits to the power level of recommended e
17、missions The tolerance for levels of emission outside the necessary bandwidth conform with Nos. S27/69 (suppressed carrier), S27/73 and S27/74 of RR Appendix S27. 11 Power The transmission power limits are in conformance with Nos. S27/60 and S27/68 of RR Appendix S27. 12 Undesired signal rejection F
18、or HFDL aircraft and ground station receivers, undesired input signals shall be attenuated in accordance with the following: on any frequency between fcand ( fc 300 Hz), or between ( fc+ 2 900 Hz) and ( fc+ 3 300 Hz): at least 35 dB below the peak of the desired signal level; and on any frequency below ( fc 300 Hz), or above ( fc+ 3 300 Hz): at least 60 dB below the peak of the desired signal level, where fcis the carrier (reference) frequency.
