On 2 Apr 2019 at 9:13, Bill Rutherford wrote:

> In canon, can a ship record another ship's transponder broadcast, and
> rebroadcast it, essentially taking over that ship's identity?

> So - back to my original question, would this work?
>
> One obstacle I can think of would be if the transponder sends some
> sort of authentication code based on a "seed" of some sort (kind of
> like the way a Symantec cybertoken uses a random number seed only
> elsewhere held on a Symantec server somewhere) which would be more
> difficult than most would be willing to deal with - to duplicate.
>
> What other obstacles, other than saying "That's now how they
> work!  You cannot rebroadcast somebody else's transponder signal
> because the Imperium, in their wisdom, incorporated handwavium into
> the transponder that precludes this sort of thing" might there be?

Consider what *real world* transponders are and do.

A transponder is *not* something that broadcasts an ID.

It's somethat TRANSmits a *resPONse* to a received radar pulse.

It *echoes back* the received pulse (thus making the vehicle mounting
the transponder show up *much* brighter on the transmitting vehicles
radar by changing things from an inverse 4th power law to an inverse
square situation) *plus* it adds ID info and other data (for
airplanes it adds altitude info as that's hard to determine
accurately from radar, for spaceships and starships, it'd probably
add other data and it addsd the transponder "squawk" which is the
3-digit code ATC assigned to the plane).

So recording another ships signal wouldn't work for the simple fact
that what you'd have a recording of is ship A's retransmission of a
radar pulse from ship B with ship A's data tacked on to the end.

Because of the huge distance involved, you need to be able to tell
*which* pulse is being echoed back to get an accurate distance. Which
means the outgoing pulses will have embedded time codes and ID codes.

Again, that's something *necessary* to make the radar disply the
proper distance to the target.

Time codes will be arbitrary, as they only need to be unique for the
period of time that covers the max range you care about. ID could be
simple numbers as all they need to be is differentiation the tracking
ship's pulses from those of othewr ships or installation using radar
in the area.

So the *tracking* ship's time & ID codes won't match the recording.
Nor will whatever added data the *tracked* ship added to the pulse.

For example, the return pulse might contain the ship's velocity &
acceleration. Which won't match what the PC's ship will be doing.

Oh yeah, note that recording a single pulse won't be any good,
because the pulses are all *different* except for the ID code of the
ship being tracked.

--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com