Mode S Flashcards
What is another name for Mode S?
Mode Select
How does Mode S enhance the operation of ATCRBS?
By adding a discrete interrogation capability and a data link feature as well as performance improvements
The ATCRBS/Mode S SSR interrogates the aircraft in the same way as the ATCRBS only ground station, except:
that when it interrogates an ATCRBS/Mode S equipped aircraft, that transponder will reply with a Mode S reply
The Mode S transponder may also function as part of an Airborne Separation Assurance (ASA) system when interfaced with what?
A Traffic Collision Avoidance System (TCAS)
The interrogator antenna uses what to determine the azimuth and bearing of the aircraft?
Mono-pulse processing from a single reply
As an aircraft equipped with a transponder enters the airspace served by a Mode S interrogator it:
Receives an ATCRBS/Mode S all-call interrogation which can be understood by both ATCRBS and Mode S transponders
ATCRBS transponders reply with ATCRBS reply format, while Mode S transponders reply with:
A mode S format that includes their discrete (24 bit) Mode S address
The discrete (24 bit) Mode S address and the location of the Mode S aircraft are entered into a file (put on roll-call) and then:
On the next scan the Mode S equipped aircraft is discreetly addressed
What happens once on roll-call?
All-call is locked out
Since azimuth and range are known for all aircraft on roll-call, they are interrogated according to a pre-computed schedule. Within this schedule are ATCRBS/Mode S All-Calls, which provide:
The tracking of known ATCRBS aircraft and the acquisition of additional ATCRBS and Mode S aircraft entering the served airspace
Mode S interrogation uses what format?
Uplink Format (UF)
The Mode S interrogation makes use of Differential Phase-Shift Keying (DPSK) modulation for the purpose of:
Transmitting the 4 million bits per second (4Mbps) data burst
The Mode S interrogation uses one of two general formats:
Short format with 56 bits of DPSK data
or
Long format with 112 bits of DPSK data
The P1-P2 pair preceding P6 suppresses replies from ATCRBS transponders to avoid what?
Synchronous garble caused by random triggering of the ATCRBS transponders by the Mode S interrogation
What prevents the trailing edge of P6 from interfering with the demodulation process?
a 0.5 microsecond guard interval after the last chip
