Mode S

[maxburner]

Is there anyone out there who can point me to some literature on Mode S addresses, what they are, what they do, etc?

Better still, is there anyone on this forum who can tell me something on the subject?

Thanks in anticipation,

M

[RaRadar]

The FAA and Eurocontrol web sites are good sources for information about Mode S.

The Mode S address is 24 bits long which means there are over 16 million possible values, enough to perminently allocate one to each aircraft. The addesses are allocated in blocks to each country, the US having the largest allocation! The full list of the country allocations is in ICAO Annex 10. It is then up to each registering authority to allocate the addresses to individual aircraft.

The Mode S address is fundamental to the way the Mode S (selective) radar system works. For example, an interrogation from the ground will contain the Mode S address of the target aircraft and it will only reply if the address matches.

Hope this helps

RR

[Flight Detent]

Hi all,
I'm currently doing some technical work on/around the B737-700/800 aircraft, and I remember Mode S as supporting the TCAS II system!

Hope this helps,Cheers
;)

[fixa24]

hi all...
mode s is reqired for TCAS resolution advisories only. a mode a or c will give traffic information but no RA... but u prob know that, just thought i'd add it. cheers..:=

[bids]

forgive me if these are going to be a silly questions but...

if the mode s is interrogated from the ground station, then how does the ground station receive the mode s address for the a/c in the first place.

And a kind of similar question...if the mode s address of the other a/c is required before interrogation, how can TCAS 2 use mode s to interrogate other a/c. i allways thought TCAS relied on mode C and A...or is this the older versions?



ta if anyone replies.

[RaRadar]

A fair question Bids!

As far as the Mode S ground station is concerned, it transmits a background All Call interrogation at regular intervals. Any Mode S equipped aircraft flying into coverage will respond with an All Call reply that contains its Mode S address. Once the ground station has detected the new target it will commence selective interrogations and lock-out the All Call - tell the aircraft to stop responding to All Call interrogations. If the aircraft stops receiving scheduled interrogations the lockout will time-out after 18 seconds.

A TCAS equipped aircraft continuosly transmits a Mode S 'squitter' reply once per second that also contains its Mode S address.

RR