Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!att!cbnews!military
From: tek@CS.UCLA.EDU (Ted Kim (Random Dude))
Newsgroups: sci.military
Subject: Re: "Identify-Friend-or-Foe" questions
Message-ID: <13041@cbnews.ATT.COM>
Date: 11 Jan 90 04:59:56 GMT
References: <12566@cbnews.ATT.COM> <12883@cbnews.ATT.COM> <12972@cbnews.ATT.COM>
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From: tek@CS.UCLA.EDU (Ted Kim (Random Dude))

In article <12972@cbnews.ATT.COM> denbeste@spdcc.com (Steven Den Beste) writes:
> ...
>
>   So my point is this: As long as one of our jets has IFF onboard and
>operating, there should be a relatively unsubtle way that a SAM can home in on
>that IFF system so as to destroy said jet. 
>
> ...

I will leave the theory discussion to others, but here is a summary of
some current IFF standards.

The current NATO IFF standard is Mk 10 (or Mk 10A). It is the standard
interrogate-response type setup. The response can be in one of a few
modes (civil/military/combined). In the military mode, the response
can include additional (encrypted) verification information. This type
of system has precisely the problem you mention. An enemy can send a
legal challenge and use the response (whether he understands it or
not) to track the target. Mk 10A expands the set of identifiers.

The US standard is Mk 12. The change here is that the interrogator
must send a coded sequence to get the transponder to respond. So, in
principle, unless the enemy knows the code, it can't use our
transponders to track our forces. (I don't know the nature of the code
and how keys and sequence numbers are distributed.) The Europeans did
not want to accept this standard due to cost.

A few years ago, the NATO IFF working group is said to have come up
with some new system which has the equivalent of Mk 12 capabilities in
it, though I don't know when systems using the new standard will come
out. Also the new standard allows interrogation in certain radar bands
also. In principle, this allows one to modify your radar to send IFF
interrogations (and not buy another transmitter). The response comes
back on the Mk 10 response frequency (backwards compatability). So you
still have to buy a separate receiver.

-ted

Ted Kim                           
UCLA Computer Science Department  Internet: tek@penzance.cs.ucla.edu
3804C Boelter Hall                UUCP:    ...!{uunet|ucbvax}!cs.ucla.edu!tek
Los Angeles, CA 90024		  Phone:   (213) 206-8696