Publication: Magyar Közlöny
Issue: MK-2009-104 (Year: 2009, Number: 104)
Era: 2004-2010
Section: 
Paragraph Index: 1944

b) For a parallel transmission with equal minimum intervals and equal number of significant conditions on each channel, it is m(1/T)log2n (m(1/T) in case of a two-condition modulation). Note 2.— In the above definition, the term “parallel channels” is interpreted to mean: channels, each of which carries an integral part of an information unit, e.g. the parallel transmission of bits forming a character. In the case of a circuit comprising a number of channels, each of which carries information “independently”, with the sole purpose of increasing the traffic handling capacity, these channels are not to be regarded as parallel channels in the context of this definition. Degree of standardized test distortion. The degree of distortion of the restitution measured during a specific period of time when the modulation is perfect and corresponds to a specific text. Effective margin. That margin of an individual apparatus which could be measured under actual operating conditions. Low modulation rates. Modulation rates up to and including 300 bauds. Margin. The maximum degree of distortion of the circuit at the end of which the apparatus is situated which is compatible with the correct translation of all the signals which it may possibly receive. Medium modulation rates. Modulation rates above 300 and up to and including 3 000 bauds. Modulation rate. The reciprocal of the unit interval measured in seconds. This rate is expressed in bauds. Note.— Telegraph signals are characterized by intervals of time of duration equal to or longer than the shortest or unit interval. The modulation rate (formerly telegraph speed) is therefore expressed as the inverse of the value of this unit interval. If, for example, the unit interval is 20 milliseconds, the modulation rate is 50 bauds. Synchronous operation. Operation in which the time interval between code units is a constant. Annex 10 — Aeronautical Communications Volume III 22/11/07 I-8-2 8.2 TECHNICAL PROVISIONS RELATING TO TELETYPEWRITER APPARATUS AND CIRCUITS USED IN THE AFTN 8.2.1 In international teletypewriter circuits of the AFTN, using a 5-unit code, the International Telegraph Alphabet No. 2 (see Table 8-1*) shall be used only to the extent prescribed in 4.1.2 of Volume II. 8.2.2 Recommendation.— The modulation rate should be determined by bilateral or multilateral agreement between administrations concerned, taking into account primarily traffic volume. 8.2.3 Recommendation.— The nominal duration of the transmitting cycle should be at least 7.4 units (preferably 7.5), the stop element lasting for at least 1.4 units (preferably 1.5). 8.2.3.1 Recommendation.— The receiver should be able to translate correctly in service the signals coming from a transmitter with a nominal transmitting cycle of 7 units. 8.2.4 Recommendation.— Apparatus in service should be maintained and adjusted in such a manner that its net effective margin is never less than 35 per cent. 8.2.5 Recommendation.— The number of characters which the textual line of the page-printing apparatus may contain should be fixed at 69. 8.2.6 Recommendation.— In start-stop apparatus fitted with automatic time delay switches, the disconnection of the power supply to the motor should not take place before the lapse of at least 45 seconds after the reception of the last signal. 8.2.7 Recommendation.— Arrangements should be made to avoid the mutilation of signals transmitted at the head of a message and received on start-stop reperforating apparatus. 8.2.7.1 Recommendation.— If the reperforating apparatus is provided with local means for feeding the paper, not more than one mutilated signal should be tolerated. 8.2.8 Recommendation.— Complete circuits should be so engineered and maintained that their degree of standardized test distortion does not exceed 28 per cent on the standardized text: THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG or VOYEZ LE BRICK GEANT QUE JEXAMINE PRES DU WHARF 8.2.9 Recommendation.— The degree of isochronous distortion on the standardized text of each of the parts of a complete circuit should be as low as possible, and in any case should not exceed 10 per cent. 8.2.10 Recommendation.— The overall distortion in transmitting equipment used on teletypewriter channels should not exceed 5 per cent. 8.2.11 Recommendation.— AFTN circuits should be equipped with a system of continuous check of channel condition. Additionally, controlled circuit protocols should be applied. * All tables and figures are located at the end of this chapter. Part I Annex 10 — Aeronautical Communications I-8-3 22/11/07 8.3 TERMINAL EQUIPMENT ASSOCIATED WITH AERONAUTICAL RADIOTELETYPEWRITER CHANNELS OPERATING IN THE BAND 2.5 – 30 MHz 8.3.1 Selection of type of modulation and code 8.3.1.1 Recommendation.— Frequency shift modulation (F1B) should be employed in radioteletypewriter systems used in the aeronautical fixed service (AFS), except where the characteristics of the independent sideband (ISB) method of operation are of advantage. Note.— F1B type of modulation is accomplished by shifting a radio frequency carrier between two frequencies representing “position A” (start signal polarity) and “position Z” (stop signal polarity) of the start-stop 5-unit telegraphic code. 8.3.2 System characteristics 8.3.2.1 Recommendation.— The characteristics of signals from radioteletypewriter transmitters utilizing F1B modulation should be as follows:

Source: https://magyarkozlony.hu/hivatalos-lapok/1f7c6b0e16b4b71a92e5ad24416008bbe2e26aab/dokumentumok/710811d1f7f958a2990684d0cbf918e84f5497e5/letoltes