Publication: Magyar Közlöny
Issue: MK-2009-104 (Year: 2009, Number: 104)
Era: 2004-2010
Section: 
Paragraph Index: 2326

b) no more than 10 per cent at signal input levels below –81 dBm. Note.— Transponder sensitivity and output power are described in this section in terms of signal level at the terminals of the antenna. This gives the designer freedom to arrange the installation, optimizing cable length and receiver-transmitter design, and does not exclude receiver and/or transmitter components from becoming an integral part of the antenna subassembly. 3.1.2.10.1.1 Reply ratio in the presence of interference Note.— The following paragraphs present measures of the performance of the Mode S transponder in the presence of interfering Mode A/C interrogation pulses and low-level in-band CW interference. 3.1.2.10.1.1.1 Reply ratio in the presence of an interfering pulse. Given a Mode S interrogation which requires a reply (3.1.2.4), the reply ratio of a transponder shall be at least 95 per cent in the presence of an interfering Mode A/C interrogation pulse if the level of the interfering pulse is 6 dB or more below the signal level for Mode S input signal levels between –68 dBm and –21 dBm and the interfering pulse overlaps the P6 pulse of the Mode S interrogation anywhere after the sync phase reversal. Under the same conditions, the reply ratio shall be at least 50 per cent if the interference pulse level is 3 dB or more below the signal level. 3.1.2.10.1.1.2 Reply ratio in the presence of pulse pair interference. Given an interrogation which requires a reply (3.1.2.4), the reply ratio of a transponder shall be at least 90 per cent in the presence of an interfering P1 – P2 pulse pair if the level of the interfering pulse pair is 9 dB or more below signal level for input signal levels between –68 dBm and –21 dBm and the P1 pulse of the interfering pair occurs no earlier than the P1 pulse of the Mode S signal. 3.1.2.10.1.1.3 Reply ratio in the presence of low level asynchronous interference. For all received signals between –65 dBm and –21 dBm and given a Mode S interrogation that requires a reply according to 3.1.2.4 and if no lockout condition is in effect, the transponder shall reply correctly with at least 95 per cent reply ratio in the presence of asynchronous interference. Asynchronous interference shall be taken to be a single Mode A/C interrogation pulse occurring at all repetition rates up to 10 000 Hz at a level 12 dB or more below the level of the Mode S signal. Note.— Such pulses may combine with the P1 and P2 pulses of the Mode S interrogation to form a valid Mode A/C-only all-call interrogation. The Mode S transponder does not respond to Mode A/C-only all-call interrogations. A preceding pulse Annex 10 — Aeronautical Telecommunications Volume IV 22/11/07 3-62 may also combine with the P2 of the Mode S interrogation to form a valid Mode A or Mode C interrogation. However, the P1 – P2 pair of the Mode S preamble takes precedence (3.1.2.4.1.1.1). The Mode S decoding process is independent of the Mode A/Mode C decoding process and the Mode S interrogation is accepted. 3.1.2.10.1.1.4 Reply ratio in the presence of low-level in-band CW interference. In the presence of non-coherent CW interference at a frequency of 1 030 ±0.2 MHz at signal levels of 20 dB or more below the desired Mode A/C or Mode S interrogation signal level, the transponder shall reply correctly to at least 90 per cent of the interrogations. 3.1.2.10.1.1.5 Spurious response Recommendation.— The response to signals not within the receiver pass band should be at least 60 dB below normal sensitivity. 3.1.2.10.2 Transponder peak pulse power. The peak power of each pulse of a reply shall:

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