A320飞机维护手册 AMM NAVIGATION 导航4(106)

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R  - Mode S all call interrogations 
R  - Mode S interrogations. 
R  1_  Mode A or C interrogation
R  A mode A or C interrogation consists of two pulses labelled P1 
R  and P3. A control pulse P2 is transmitted following the first 
R  interrogation pulse. P1 and P3 are radiated by a narrow 
R  rotating beam antenna. 
R  P2, also called the Side Lobe Suppression (SLS) pulse, is 
R  radiated by an omnidirectional antenna with an amplitude of 6 
R  dB below P1 and P2 within the main lobe. 
R  P1 amplitude is greater than or equal to P2 amplitude from the 
R  greatest side lobe transmission of the antenna radiating P1. 
R  2_  Mode S all call interrogation
R  (Ref. Fig. 007) 
R  A mode S all call interrogation consists of three transmitted 
R  pulses labelled P1, P3 and P4. A control pulse P2 (Side Lobe 
R  Suppression Pulse) is transmitted following P1. P1 amplitude 
R  is greater than or equal to P2 amplitude from the greatest 
R  side lobe transmission of the antenna radiating P1. 
R  P2 amplitude is at a level lower than 6 dB below P1 amplitude 
R  within the main lobe. 
R  P4 duration is 0.8 or 1.6 microseconds depending on the 
R  interrogation mode. 
R  If P4 is equal to 0.8 microseconds, this means that the 
R  interrogation only concerns conventional ATC mode A or C 
R  transponder, and consequently the Mode S transponder must not 
R  reply. 
R  If P4 is equal to 1.6 microseconds, this means that the mode S 
R  transponder must reply with mode S information. 
R  3_  Mode S interrogation
R  (Ref. Fig. 008) 
R  A mode S interrogation consists of a two-bit preamble followed 
R  by a data block. 
R  The preamble consists of two transmitted pulses labelled P1 
R  and P2. The characteristics of P1 and P2 are the same as for 

R 1EFF : 051-099, 1 34-52-00Page 44 1 1 May 01/05 1 1 1CES 1

R  the mode S all call interrogation, except that P2 amplitude is 
R  equal to P1. 
R  The data block consists of a single pulse P6 with a 
R  Differential Phase Shift Keying (DPSK) modulation. 
R  Pulse duration : short 15.5 microseconds, 
R  long  29.5 microseconds, 
R  Data block  : 56 or 112 bits. 
R  (b) Encoded reply 
R  1_  Mode A or C reply
R  A mode A or C reply consists of two framing pulses F1 and F2, 
R  separated by a 20.3 microseconds time interval. The encoding 
R  of the reply is done by means of the presence (1) or absence 
R  (0) of 13 reply pulses (12 pulses plus X pulse). 
R  2_  Mode S all-call reply
R  A mode S all-call reply consists of a four-bit preamble 
R  followed by a data block. 
R  The data block contains 56 position modulated pulses. 
R  3_  Mode S reply
R  A mode S reply occurs after a mode S interrogation or a mode S 
R  all call interrogation (P4 duration 1.6 microseconds). 
R  A mode S reply consists of a four-bit preamble followed by a 
R  data block. The data block contains 56 or 112 position 
R  modulated pulses. 
R  The replies are PPM coded. 
R  4_  Mode S message contents
R  The transponder must have the following Mode S message 
R  capabilities: 
R  - surveillance functions of both ATCRBS and Mode S ground 
R  sensors (UF=4.5 / DF=4.5) 
R  - surveillance functions of airborne interrogators (UF=0 
R  /DF=0) 
R  - bi-directional air-to-air information exchange, COMM-U/V 
R  (UF=16 / DF=16) 
R  - ground-to-air data uplink, COMM-A (UF=20.21) 
R  - air-to-ground data downlink, COMM-B (DF=20.21) 
R  - ground-to-air Uplink Extended length message (UELM), COMM-C 
R  (UF=24) (if external ADLP is installed) 
R  - air-to-ground Downlink Extended length message (DELM), 
R  COMM-D (DF=24). (if external ADLP is installed) 
R  All discrete Mode S interrogations and replies (except the 
R  all-call reply) contain the 24-bit discrete address of the 
R  Mode S transponder upon which 24 error detection parity check 
　
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