Publication: Magyar Közlöny
Issue: MK-2009-104 (Year: 2009, Number: 104)
Era: 2004-2010
Section: 
Paragraph Index: 1947

c) Polarity: single channel circuits: the higher frequency corresponds to “position A” (start signal polarity). 8.3.2.2 Recommendation.— The variation of the mean between the radio frequencies representing respectively “position A” and “position Z” should not exceed 100 Hz during any two-hour period. 8.3.2.3 Recommendation.— The overall distortion of the teletypewriter signal, as monitored at the output of the radio transmitter or in its immediate vicinity, should not exceed 10 per cent. Note.— Such distortion means the displacement in time of the transitions between elements from their proper positions, expressed as a percentage of unit element time. 8.3.2.4 Recommendation.— Radioteletypewriter receivers concerned with F1B modulation should be capable of operating satisfactorily on signals having the characteristics set out in 8.3.2.1 and 8.3.2.2. 8.3.2.5 Recommendation.— The characteristics of multichannel transmission of teletypewriter signals over a radio circuit should be established by agreement between the Administrations concerned. 8.4 CHARACTERISTICS OF INTERREGIONAL AFS CIRCUITS 8.4.1 Recommendation.— Interregional AFS circuits being implemented or upgraded should employ high quality telecommunications service. Modulation rate should take into account traffic volumes expected under both normal and alternate route conditions. Annex 10 — Aeronautical Communications Volume III 22/11/07 I-8-4 8.5 TECHNICAL PROVISIONS RELATING TO ATS MESSAGE TRANSMISSION 8.5.1 Interconnection by direct or omnibus channels — low modulation rates — 5-unit code. Note.— See 8.6 for medium modulation rates. 8.5.1.1 Recommendation.— AFTN techniques (cf. 8.2) should be used. 8.6 TECHNICAL PROVISIONS RELATING TO INTERNATIONAL GROUND-GROUND DATA INTERCHANGE AT MEDIUM AND HIGHER SIGNALLING RATES Note.— Throughout this section in the context of coded character sets, the term “unit” means the unit of selective information and is essentially equivalent to the term “bit”. 8.6.1 General 8.6.1.1 Recommendation.— In international data interchange of characters, a 7-unit coded character set providing a repertoire of 128 characters and designated as International Alphabet No. 5 (IA-5) should be used. Compatibility with the 5-unit coded character set of International Telegraph Alphabet No. 2 (ITA-2) should be ensured where applicable. 8.6.1.2 When the provisions of 8.6.1.1 are applied, International Alphabet No. 5 (IA-5) contained in Table 8-2 shall be used. 8.6.1.2.1 The serial transmission of units comprising an individual character of IA-5 shall be with the low order unit (b1) transmitted first. 8.6.1.2.2 Recommendation.— When IA-5 is used, each character should include an additional unit for parity in the eighth level position. 8.6.1.2.3 When the provisions of 8.6.1.2.2 are applied, the sense of the character parity bit shall produce even parity in links which operate on the start-stop principle, and odd parity in links using end-to-end synchronous operations. 8.6.1.2.4 Character-for-character conversion shall be as listed in Tables 8-3 and 8-4 for all characters which are authorized in the AFTN format for transmission on the AFS in both IA-5 and ITA-2. 8.6.1.2.5 Characters which appear in only one code set, or which are not authorized for transmission on the AFS shall be as depicted in the code conversion tables. 8.6.2 Data transmission characteristics 8.6.2.1 Recommendation.— The data signalling rate should be chosen from among the following: 1 600 bits/s 4 800 bits/s 1 200 bits/s 9 600 bits/s 2 400 bits/s Part I Annex 10 — Aeronautical Communications I-8-5 22/11/07 8.6.2.2 Recommendation.— The type of transmission for each data signalling rate should be chosen as follows: Data signalling rate Type of transmission 1 600 bits/s Synchronous or asynchronous serial transmission 1 200 bits/s Synchronous or asynchronous serial transmission 2 400 bits/s Synchronous serial transmission 4 800 bits/s Synchronous serial transmission 9 600 bits/s Synchronous serial transmission 8.6.2.3 Recommendation.— The type of modulation for each data signalling rate should be chosen as follows: Data signalling rate Type of modulation 1 600 bits/s Frequency 1 200 bits/s Frequency 2 400 bits/s Phase 4 800 bits/s Phase 9 600 bits/s Phase-amplitude Note.— This recommendation does not necessarily apply to ground-ground extensions of air-ground links used exclusively for the transfer of air-ground data, inasmuch as such circuits may be considered as part of the air-ground link. 8.6.2.4 CHARACTER STRUCTURE ON DATA LINKS 8.6.2.4.1 Character parity shall not be used for error checking on CIDIN links. Parity appended to IA-5 coded characters per 8.6.1.2.2, prior to entry to the CIDIN shall be ignored. For messages exiting the CIDIN, parity shall be generated in accordance with 8.6.1.2.3. 8.6.2.4.2 Characters of less than eight bits in length shall be padded out to eight bits in length before transmission over any octet-based or bit-oriented communications network. The padding bits shall occupy the higher order end of the octet, i.e. bit 8, bit 7 as required, and shall have the binary values 0. 8.6.2.5 When exchanging data over CIDIN links using bit-oriented procedures, the entry centre address, exit centre addresses and destination addresses in the Transport and CIDIN Packet Headers shall be in the IA-5 character set contained in Table 8-2. 8.6.2.6 Recommendation.— When transmitting messages in AFTN format over CIDIN links using bit-oriented procedures, the messages should be in the IA-5 character set contained in Table 8-2. 8.6.3 Ground-ground character-oriented data link control procedures Note.— The provisions of this section pertain to ground-ground data interchange applications using IA-5 prescribed by 8.6.1 and which employ the ten transmission control characters (SOH, STX, ETX, EOT, ENQ, ACK, DLE, NAK, SYN, and ETB) for data link control, over synchronous or asynchronous transmission facilities. 8.6.3.1 Descriptions. The following descriptions shall apply to data link applications contained in this section: Annex 10 — Aeronautical Communications Volume III 22/11/07 I-8-6

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