Publication: Magyar Közlöny
Issue: MK-2009-104 (Year: 2009, Number: 104)
Era: 2004-2010
Section: 
Paragraph Index: 2347

b) provide indications to the flight crew identifying the approximate position of nearby aircraft as an aid to visual acquisition. Note.— ACAS I is intended to operate using Mode A/C interrogations only. Furthermore, it does not coordinate with other ACAS. Therefore, a Mode S transponder is not required as a part of an ACAS I installation. 4.2.2 Signal format. The RF characteristics of all ACAS I signals shall conform to the provisions of Chapter 3, 3.1.1.1 through 3.1.1.6 and 3.1.2.1 through 3.1.2.4. 4.2.3 Interference control 4.2.3.1 Maximum radiated RF power. The effective radiated power of an ACAS I transmission at 0 degree elevation relative to the longitudinal axis of the aircraft shall not exceed 24 dBW. 4.2.3.2 Unwanted radiated power. When ACAS I is not transmitting an interrogation, the effective radiated power in any direction shall not exceed –70 dBm. Note.— This requirement is to ensure that, when not transmitting an interrogation, ACAS I does not radiate RF energy that could interfere with, or reduce the sensitivity of, the SSR transponder or radio equipment in other nearby aircraft or ground facilities. 4.2.3.3 Interference limiting. Each ACAS I interrogator shall control its interrogation rate or power or both in all SSR modes to minimize interference effects (4.2.3.3.3 and 4.2.3.3.4). Annex 10 — Aeronautical Telecommunications Volume IV 22/11/07 4-4 Note.— These limits are a means of ensuring that all interference effects resulting from these interrogations, together with the interrogations from all other ACAS I, ACAS II and ACAS III interrogators in the vicinity are kept to a low level. 4.2.3.3.1 Determination of own transponder reply rate. ACAS I shall monitor the rate that own transponder replies to interrogations to ensure that the provisions in 4.2.3.3.3 are met. 4.2.3.3.2 Determination of the number of ACAS II and ACAS III interrogators. ACAS I shall count the number of ACAS II and ACAS III interrogators in the vicinity to ensure that the provisions in 4.2.3.3.3 or 4.2.3.3.4 are met. This count shall be obtained by monitoring ACAS broadcasts (UF = 16), (4.3.7.1.2.4) and shall be updated as the number of distinct ACAS aircraft addresses received within the previous 20-s period at a nominal frequency of at least 1 Hz. 4.2.3.3.3 Mode A/C ACAS I interference limits. The interrogator power shall not exceed the following limits: =1 { (k)} k a k Upper limit for P ∑ na If fr ≤ 240 If fr >240 ≥22 where: na = number of operating ACAS II and ACAS III equipped aircraft near own (based on ACAS broadcasts received with a transponder receiver threshold of –74 dBm); { } = average value of the expression within the brackets over last 8 interrogation cycles; Pa(k) = peak power radiated from the antenna in all directions of the pulse having the largest amplitude in the group of pulses comprising a single interrogation during the kth Mode A/C interrogation in a 1 s interrogation cycle, W; Chapter 4 Annex 10 — Aeronautical Telecommunications 4-5 22/11/07 k = index number for Mode A/C interrogations, k = 1, 2,..., kt; kt = number of Mode A/C interrogations transmitted in a 1 s interrogation cycle; fr = Mode A/C reply rate of own transponder. 4.2.3.3.4 Mode S ACAS I interference limits. An ACAS I that uses Mode S interrogations shall not cause greater interference effects than an ACAS I using Mode A/C interrogations only. 4.3 GENERAL PROVISIONS RELATING TO ACAS II AND ACAS III Note 1.— The acronym ACAS is used in this section to indicate either ACAS II or ACAS III. Note 2.— Carriage requirements for ACAS equipment are addressed in Annex 6, Part I, Chapter 6. Note 3.— The term “equipped threat” is used in this section to indicate a threat fitted with ACAS II or ACAS III. 4.3.1 Functional requirements 4.3.1.1 ACAS functions. ACAS shall perform the following functions:

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