transponder mode question
Thread Starter
Joined: Nov 2004
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From: Here, there, and everywhere
transponder mode question
ATC asked a military flight to try their second tx. They didn't have a second tx. The aircraft then asked if ATC could read mode 1 or 2. ATC said mode 3 only.
What are these modes?
What are these modes?
Joined: Mar 2007
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From: My
From what I remember, mode 3 gives squawk, altitude and speed, while the others are for mission use which filters what info is sent depending on what "source" is asking.
If I'm wrong then appologies, its been a while.
If I'm wrong then appologies, its been a while.
Joined: Jun 2001
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From: Blighty
IIRC, Mode 1 is similar to the original WW2 IFF (Identification Friend or Foe)which has 2 digits and therefore only 64 codes. It works on the same frequency as ATC transponders. Mode 2 has 4 digits and 4096 codes and is almost identical to ATC but uses a different frequency. Mode 3 is the same as ATC transponfers and has th ability to carry extra information such as Mode C - or altitude reporting. Mode 4 is encrypted and the codes can only be loaded with a data loader.
Typically, mode 3 will be used as the ATC transponder. Modes 1 and 2 are used for IFF purposes in tactical situations with possibly the squawk changing at regular intervals. Mode 4 is for tactical purposes and can give far more information than the other modes.
And a bit of SSR trivia - the wartime codename for IFF was "Parrot". Which is why when interrogated, it "Squawks".
Typically, mode 3 will be used as the ATC transponder. Modes 1 and 2 are used for IFF purposes in tactical situations with possibly the squawk changing at regular intervals. Mode 4 is for tactical purposes and can give far more information than the other modes.
And a bit of SSR trivia - the wartime codename for IFF was "Parrot". Which is why when interrogated, it "Squawks".
Joined: Nov 1999
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From: East side of OZ
And a bit of SSR trivia - the wartime codename for IFF was "Parrot". Which is why when interrogated, it "Squawks".
Often wondered why, now I know.
Makes perfect sense.
Thanks.
Often wondered why, now I know.
Makes perfect sense.
Thanks.
"Strangle your parrot"
To turn your IFF to OFF.
Regards,
BH.
Joined: Jan 2008
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From: Kabul, Afghanistan
well I was pretending when they say Mode C they are referring to the version capable of altitude reporting. but the other day the Mode S with different features (ident, level, with level or ident) grabbed my attention, then what is Modes S or what are the differences between mode C Mode S?
Joined: Aug 2007
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From: UK
The biggest difference between mode C and mode S would be the way transponders are interrogated. Mode C is interrogated in a general manner- i.e. the radar head asks all transponders to reply with their 4 digit code and altitude. The radar head then waits for the responses to get the distance to them. Mode S can send out a general roll-call like that, but it can also interrogate an individual transponder to get what information it needs (a rather large list of things potentially). The biggest advantage of mode S is that individual addressability. Mode C systems can get responses from transponders that were requested by another radar head- leading to them being in different places than expected.
