Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!att!cbnews!military
From: sampson@attctc.Dallas.TX.US (Steve Sampson)
Newsgroups: sci.military
Subject: Re: "Identify-Friend-or-Foe" questions
Message-ID: <12598@cbnews.ATT.COM>
Date: 27 Dec 89 03:40:40 GMT
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From: sampson@attctc.Dallas.TX.US (Steve Sampson)



> I would appreciate it if someone would post a description of how the "IFF"
> system works. Every way I can think of that it could work provides a way for an
> enemy to abuse the system. For instance, in a jet with such
> a system:
>
> 1. IFF broadcasts its signature continuously. In that case an enemy missile
>        could home in on the broadcast.

You're confusing IFF with SIF (Selective Identification Feature).  IFF is not
used 360 deg in war or even peacetime for that matter.  It is used only on a
particular azimuth.  The operator must aim his Stinger or hook a computer track
or push a button when the sweep gets near a radar target.  "Full Scan" is an
option, but you better be overwelmed when you use it.  For the reasons you
outlined above.  Even "Full Scan" only works for one scan.  An aircraft only
replies when interrogated.

> 2. IFF answers with its signature whenever someone else broadcasts a query.
>        A missile could be equipped with a query-broadcaster and then
>        home in on the answer.

The subject is classified.

> 3. A missile refuses to hit an enemy target because it identifies itself as
>        friendly, even though it isn't.

Would the military contractors give us a system that didn't work :-)  Actually
I don't think missles are that intelligent.  They merely are guided or track
on some feature.  The operator decides to abort.  With the speed of missles
though - there's not much chance of this.

> #1 and #2 are particularly a problem because Electronic Counter Measures can't
> be used to prevent this without nullifying the IFF system entirely. (That is,
> if a friendly system can use IFF to abort an attack, an enemy system can
> equally use it to complete an attack.)

If I was going to start a war I'd be jamming the piss out of the IFF frequency.
Say, send a data train of random alternating ones-n-zeros. IFF is a tool, the
bottom line is anything airborne in "my" area better be on the Frag or it dies.
This expains why alot of body bags come home marked "friendly fire".  If you
don't understand the rules, you better not get airborne.

> There were rumors after the Falklands war that HMS Sheffield didn't try to
> stop the incoming Exocet because IFF had identified it as friendly (French).
> This was denied, and then the whole subject was hushed up. I still wonder about
> this.

I've seen Exocets flying in the Gulf and never have seen them reply to IFF or
SIF, also, identification isn't confirmed with a squawk.  IFF is a crypto
secure system.  How would the Argentines know what the current code was?
The British weren't equipped to handle incomming Exocets so they tried to kill
targets before they got close enough to launch.  You might comment on what the
Sheffield had for defense systems for Exocets (either enroute or terminal)?
I saw an interesting video that showed most battles at or below 500 feet in the
Falklands.  My only comment would be - if the launch vehicle got close enough
to launch an Exocet, someone already screwed up, and the Argentines scored a
tactical victory.