Transponder / IFF codes

[Mogul76]

First of all I would like to say hello to all of you!

I am a newly registered member of this forum but have been following it for quite some time.

I have a few questions regarding transponder / IFF codes (which seem to be two words for the same thing). The Cracken Rebel Field Guide gives a lot of information on these codes. However this information contradicts with descriptions from other sources.

According to the Cracken Rebel Field Guide “the [trandponder] code is created by giving slight variation to the frequency pattern of the ship’s engine. The engine itself sets the basic pattern, while the smaller elements, or “background” code, are created by a transmission device that transmits the code whenever the engine is on.” The “combined code” is unique to each ship and is registered with the Bureau of Ships and Services (BoSS). The guide does not mention that changing the “basic frequency pattern”, emitted by the ship’s engine, is possible. It seems to suggest that only the “background code” can be altered. In order to do this one needs to pick the transponder code of a ship very close or identical to the owner’s design.

wookieepedia mentions however that “Tycho Celchu chose to set his IFF transponder [mounted on a Thranta-class War Cruiser] to broadcast his starfighter as Another Chance's [an Alderaanian War Frigate] to honor his planet”.
Source: http://starwars.wikia.com/wiki/Another_Chance

Various sources indicate that the Millennium Falcon has an Imperial IFF transponder.
Source: http://starwars.wikia.com/wiki/Millennium_Falcon
(see the specifications)

In “The Isis Coordinates” the rebels carry a stolen Imperial transponder code that will be burned into a Corellian gunship called the Handree.

Page 31 of the d20 Starships of the Galaxy guide suggests that it is theoretically possible to claim an X-wing is a Y-wing by changing the transponder code (Wizards of the Coast do not seem to differentiate between the base and background codes).

My questions:
- What do you think? Is it possible to “change” the basic frequency pattern of a ship’s engine?
- Could an YT-1300 light freighter “impersonate” a Lambda-class shuttle or even a Star Destroyer (from a transponder perspective of course ) ? What are the limits?
- Does one need to install a second device simulating the new base frequency (in addition to the standard sensor transponder box, that takes care of altering the background code, as suggested in the Cracken Rebel Field Guide)? How would it be called?
- How would this measure affect sensors scanning the ship and at what ranges? Do sensors actually use the base frequency to identify a ship type / model (some of the Star Wars EU sources seem to suggest this)?
- Does modifying the ship’s engine speeds affect the base frequency? Do these kind of modifications need be registered with BoSS?

The Cracken Rebel Field Guide also says that a maximum of 3 additional background codes can be added otherwise the codes “bleed”. How come? Is it not possible to simply switch off a frequency altering the background code? I have always thought that the Millennium Falcon had about a dozen different ship ID's...

Thanks in advance for your answers.
I really need some suggestions, since this will be an important aspect of an adventure that I am creating (the heroes will need to break through an Imperial blockade after Tatooine has been put under quarantine, as (indirectly) described in Episode IV).

I have some house rule ideas regarding this issue, but would like to receive some feedback before posting them...

Mogul76

[Jedi Skyler]

I'm going to give you my own two cents. They may not fit with what everyone else thinks (or even what the books state), but it's my own take on it.

I believe the transponder code is a radio signal, plain and simple. I believe it is a broadcast device that does nothing more than identify your ship. I believe it conveys certain information about your ship, such as name, type, port of origin, etc. It might even perhaps give information about where you're flying from and to; but primarily it's so others know who and what's in the vicinity.

I also believe that a competent slicer can change the heck out of transponder information. I personally don't see any reason why a good slicer can't (or won't) have a whole file FULL of fake transponder codes hidden in the ship's computer somewhere, ready for access when that pesky Imperial flotilla just HAPPENS to drop into the same system, or when travelling to Nar Shadaa, or whatever. Sometimes you just want to go on vacation and not have everyone know you're Han Solo, smuggler extraordinaire. Know what I mean?

This technique does in fact allow one to disguise themselves as another vessel. That's why I say it needs a GOOD slicer, and also why it's so higly illegal. If just everybody could go around changing their codes at will there would be no use in having them. That might be why Cracken's tied it to the engine signature-to make it harder to change. I personally don't think it has ANYTHING to do with the engines, but I could be wrong; I have been twice before.

[Mogul76]

You may be right on that one, Jedi Skyler.
Nothing in the movies, books and comics directly says that the transponder code is linked to the frequency emitted by a ship’s engine.
But there is so much Star Wars material out there that I may have missed a thing or two regarding transponder codes.
Then again, isn’t all material that is released with the Star Wars logo reviewed and approved by Lucas Books or some other daughter company of Lucasfilm Ltd. before publication? That would also be the case for the Cracken Rebel Field Guide, wouldn’t it?
And I also kind of like the idea of the two things being interlinked (as well as the little graphs with the “waves”).
Like for so many things, WEG gave us players a detailed explanation for this technology.
I really do wonder what other GM’s think though, as “forging” transponder codes is an important thing in order for rebels and smugglers not to get into serious trouble and I want to get this right

[garhkal]

In the past, i have had the pcs who wanted to do this get not only a basic scan of the ship they wanted to imitate with the IFF, but actually get a full focus scan into their engineering area to find out what/why/how they have things configured to make it give off that freq. THEN they can put stuff in to imitate it when they wish, but they would also then need to get that data sliced into boss as well as get a forged licence with that posted on the datapad (or what ever the licence shows up on).. Most of the rolls for this are in the heroic+10 to +30 area to pull off without it looking like a patch job (which can be detected on a 25+ sensors roll)...

BUT woe betide anyone who gets caught with that, as iirc that level of forgery/imitating would be very high on the infraction list. In otherwods it would be best for a freighter to imitate freighters of its type if it was doing this as if say an imperial customs check point noted you were showing the IFF of a (say) HT-2400 but you are flying a Ghtroc 720, then no matter what your con/forgery roll is they WILL know something is wrong with this picture.
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[Jedi Skyler]

Yeah, it's best to resort to that level of fakery if A) You're fooling the Vong, or B) you stay at a very GREAT distance!

[masque]

[Esoomian]

[Mogul76]

Some pretty interesting theories, which all seem viable to me.

I'm not sure how to deal with transponder codes yet, though.

[vong]

I always figured transponders to be a separate thing. They are a piece of hardware that can emit a response to an IFF ping. For example. some ship goes [WHO IS OUT THERE] and then all the transponders report [I AM HERE]. And cracking this is difficult, it is not as hard as getting the frequency of your engines changed. But most ships do not scan for engine frequency, they simply look at IFF.

So, IMO i think that IFF's (transponders) can be changed, and you can have any number on board ready to switch. and your engines probably will never be changed in frequency, but thats fine, because no one is going to look until after your impounded.
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[ifurin]

when we did transponder codes it was essentially a box attached to the engines that emitted a code saying "i'm the players crap ship!" it gave information like what the ships name was, who it's affiliated with, where it came from, ect. the engine frequency was what identified the ship type. changing the changing the ship name and stuff was relatively easy, changing the code for the the type of ship was harder. my players never really tried to change the ship type transponder but it was common for them to change the "who am i" part quite frequently.

[Liam (Gunman) Kissane]

[Grimace]

Based on everything I read in Star Wars, Transponder codes are different from IFF and each work the following way.

Transponder codes are unique to each and every ship, as it's the "code" emitted by the operation of your engines. This is very similar to the modern day equivalency of identifying ships based on the "sounds" their engines make in the water. Computer can decode that sound and say that is "X" ship.

There are many levels and nuances of a transponder code and while some aspects of it might change when a pilot tweaks the engine, the overall identity of the ship will still be noticable even with tweaks to the engine. Completely replacing the engine would, obviously, change the transponder code, and as Esoomian, if you did this at a port with a legally purchased engine, it would be logged in BOSS. If you did this at some shadowport, or on some backwater planet, then you might be able to get away with being a "nobody" for a bit, but the moment you went to a port that used BOSS, they'd want your transponder to identify your ship.

Transponder codes are only picked up at closer ranges and if the engines of the craft are running. You can't just generally scan an area and get the transponder codes of ships. If you get a focus scan of a ship, you can get the transponder code.

At range, in order to identify ships, many ships have an IFF (Identify Friend or Foe) which broadcasts a signal identifying your ship so that other know who you are (or who you SAY you are). IFF is particularly helpful so you don't get shot down on your way from here to there, if people think you're a pirate or some other low-life. It also makes it so sides on a space battle can identify who is their friend and who is their foe. IFF CAN be turned off, which may cause people to be wary of you, and could lead to your craft being shot at as it approached another ship.

Now as far as modifying each of these goes, as you may be able to tell, modifying the IFF is easier, but it's also something that could get you shot at a lot quicker. While challenging to do so, IFF can be altered to read as something else. This could be to show that you're an "enemy" ship in hopes that the enemy would think you're one of them to let you sneak into their lair, or it could be to show that you're a different ship in hopes that they take your word for it until its too late. Changing the IFF signal of your ship could be dangerous, depending on what you do with it. Saying you're a Rebel X-Wing, when you're a Pirate, might make it so another Rebel X-Wing doesn't shoot you (assuming you're actually IN an X-Wing) but it won't protect you from the wave of Imperial TIE fighters coming in that want to kill all rebels. Likewise, saying you're the "Flying Zuz" freighter might be good most of the time, until you run across someone that has a grudge against the Flying Zuz, or actually run across the REAL Flying Zuz. Likewise, if you say you're the Flying Zuz, and a ship or station checks your transponder code and it says you're the "Oota Goota" then you're going to either have a lot of explaining to do, or you're going to have to get out of there in a hurry.

Changing the transponder code, however, isn't as easy as changing the IFF. You can tweak an engine, making it faster or some such, and while that will change a wave on your transponder, there will still be so much left in the transponder code that your ship will be easily identifiable as your ship. To mess with the transponder code, you basically need to make so many changes to your engine that reads as a different engine in MOST ways. Some people do this partly, and then match enough aspects of another ship's transponder code to cause confusion and doubt about a ship's transponder. If the transponder "sorta" matches the "Flying Zuz" and the IFF says it's the "Flying Zuz", it very well could be the Flying Zuz, but it could also be another ship who got a good reading on the Flying Zuz and spent a lot of time, effort and money to disguise their engines and IFF to pass themselves off as another ship.

Changing the engine changes the transponder code, and if the exchange was a legal purchase, the changes would be cataloged in BOSS. If you did it sneaky like, you can be a nobody for a while, as no one will be able to identify you for a while. Granted, the first military or authority ship you come across will want to catalog you, stop you, ask a bunch of questions and so on, so illegally change your engines at your own risk.

Turning off an IFF can get you accidentally shot, but isn't necessarily illegal. Changing your IFF to read something else is illegal in some parts, and may or may not get you in trouble. It can be used to simply go under a different name, but a transponder read might prove that the IFF is wrong and you get in trouble. It can be used to provide more than one name, so people might not be able to identify you readily. Again, when they get your transponder, it's all over unless you've taken steps to alter that as well.

Changing an IFF to read something different would be a Very Difficult action, and is illegal. Changing an IFF to be able to switch back and forth between real and fake names is a Heroic action, and is also illegal. Putting more than 3 fake names on the IFF can cause degradation in the signal, or "bleed over" of one signal to another. IFF isn't designed to hold more than one signal, so you're pushing things to have two in there, and pushing even more to have more than two. Bleed over of signals might lead a ship to think you're they "Flying Goota Zuz" or some such thing. Basically, they'll know based on the bleed through that something is up.

Changing the transponder codes on a ship can be done in small parts by altering the output of the engine (see associated cost for modifying engines). Your ship can still be identified by the transponder code this way, though, as you are still mostly the same engine.
Tweaking the engine to the extent that the transponder changes to something unidentifiable is extremely time consuming and expensive. It would require multiple engine tweaks, and the chance of engine malfunctions increase the more you change. An engine made completely unidentifiable would be a challenge to keep the engine online and in working order.

To change the transponder code to read as another ship, you need to acquire the detailed transponder code readings of a ship. This is Very Difficult and requires very close proximity to the craft or to steal the transponder codes from the BOSS computers aboard stations (Heroic +10). Then you need to work with a skilled, illegal mechanic to make appropriate changes to your engine so that the tweaks read similar to the engine of the craft you wish the mimic. Usually, this requires that your target have at least the same engine and roughly the same displacement as your ship, so that the transponder base signals will read close to the same. Each tweak will cost you in time and money, and with enough tweaks you should be able to get approximately half of your transponder signal to match your target's transponder code. Your engine will likely be partially unstable and filled with small problems, but ships or stations reading your transponder code will believe, with a corresponding IFF displaying the same name, that you are who you claim to be.

This process is expensive and highly illegal and will land you in jail or with super hefty fines if you get caught. Most times, it's easier to just get a new engine or a new ship and not get in trouble as quickly so that you can still get around. It's easier to get fake ID and buy a new ship under that name than it is to fake a transponder code and get the IFF changed.

As far as "Imperial" transponders go, that means that the ship is registered under the Imperial directory. Registering under the Imperial directory is one step better than BOSS in that the Empire will "trust" you since you are submitting yourself to them and making it so you can easily be identified by the Empire at any time.

Hope this helps.

[vong]

Wowzerz. Quite the post, and makes full sense to me

dont leave anything to the imagination
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[Mogul76]

Many thanks to all of you for your interesting answers.

During the last few days I have been doing some additional research and I have come to the following conclusions:

• Transponders, IFF’s and telesponders are the same thing.

• Definition: A kind of subspace radio wave generator used to provide a simple way to identify a starship. It provides a burst of information about the ownership and registry of a starship, including data on armament, ship's compliment, name and class, which can be analyzed by IFF receivers. If the codes check out, the starship is identified on targeting computers a friend. If not, then they are considered an enemy target. Many governments, military forces, and planetary traffic control systems have their own codes to mark their native ships. Smugglers usually have two or three IFF transponders on their ships, which can be swapped out for different identities. One of the more famous IFF transponder codes was the Alderaanian code used to link the Another Chance to its protective escort. Source: The Completely Unofficial Star Wars Encyclopedia Version 7.1, September 2005.

• Information sent out by a ship can be altered to anything one likes as long as the slicer has enough skill to create a key that matches the information contained in the transponder code (this key is called the transponder key). This key is validated against incoming data by the IFF receiver. During the “pinging” process the IFF receiver sends out a key (called the IFF key) to the target’s transponder (a. The IFF key is combined with the transponder key to create a unique combination which encrypts the transponder code and that can only be read by the pinging IFF receiver (the key which is initially transmitted by the IFF receiver has to match another key – called the base IFF key – that is stored in the IFF receiver and which is not broadcasted at all during the data exchange process; it is very hard for a slicer to obtain the base key).

In order to modify the information transmitted by a ship, additional transponders and a device that allows a captain to “flip” from one transponder to the other must be installed. This device could for example be called the “transponder switch”. This practice is considered highly illegal and if caught the ship’s crew must face punitive consequences (ranging from imprisonment and slave-like work in Kessel’s mines to on the spot execution without trial). Do note, however, that the transponder code, transponder key and the information included in a captain “papers” are stored in BoSS’s database.
It is possible to steal the information during the data exchange between the transponder and IFF receiver. This is very difficult, though, since 3 keys are involved in the data exchange process.
A slicer can of course also hack into BoSS’s computers in order to acquire an existing registry or create a new one, but this is considered even harder.
(Note: The process described in this bullet point purely results from my imagination and is not at all described in Star Wars lore).

• It is possible to switch off a transponder. This is the quickest way to get into trouble when travelling through Imperial or New Republic controlled space, though.

• Even though transponder – or IFF – code pinging is considered the easiest way to identify a ship, it is by all means not the only one. Each vessel’s engine is unique (although the signatures of identical ship models vary only very slightly). Hence, by making a very detailed scan of an engine the ship can be traced back to its owner as long as the collected data can be linked to information collected elsewhere or beforehand (by Imperial forces for example). The closer one is located to the target ship the more detailed the scan will be. There is, however, a degree of uncertainty associated with this. Engines tend to get damaged during space travel or (pirate) attacks. Events such as these – as well as (mostly illegal) upgrades – alter an engine’s unique signature. Therefore this method is generally not regarded as a viable way to identify a ship and its owner.

Engine signatures (amongst other elements) are used, however, by scanners to identify a ship’s model. The farther the range the les clear a signal emitted by an engine gets (it may still be possible to identify a ship’s presence, its type may remain unknown, though).

(a In some occasions the IFF key must match a specific code (not the standard / universal one developed by BoSS). Otherwise the target’s transponder will not feedback any information. This is mostly the case for military vessels that will only transmit the requested code to allied ships.

Please note that this may only be valid for my campaign. I am definitely not trying to impose my opinion on other Game Masters. This theory just represents my point of view.
There is no consensus amongst the various authors of Star Wars novels as to what a transponder or IFF code is. Each one of them seems to have a different opinion.


Some quotes from Star Wars novels supporting the above theories:

• "Son, I was swapping out IFF transponders on ships before your father even thought about having kids. As you know, IFF isn't the only way to identify a ship. The readings you got here were good enough that my people managed a spectral analysis of the ship's sublight ion exhaust. If you get a good reading, and these were very good, you can get a fairly unique analysis for the ship, and that can be matched against other ships' data to pick out a match." Source: I, Jedi.

• “Each ship had been equipped with a transponder that, when queried with the appropriate IFF code, would respond with its proper identification, thereby establishing that it was a friendly vessel, hopefully avoiding the kind of “friendly fire” incident that all too frequently occurred in the heat of battle.” Source: Jedi Trial.

• “He switched the navigator's display to tactical. None of the vessels in the usurpers' fleet was broadcasting a transponder code, but the Falcon's threat computer had used a combination of mass and energy bleed-off patterns to classify the contacts as Battle Dragons.” Source: Legacy of the Force, Tempest.

• “AFFIRMATIVE. TRAJECTORY is NOW CONFIRMED OUTBOUND.

"I mean about the efflux signature," Jaina growled. "Is that the Falcon or not?"

UNCERTAIN. CURRENT DATA YIELDS AN IDENTITY COEFFICIENT OF ONLY 94%.

Jaina sighed. For the R9 unit to be "sure," he would have to be plugged into one of the Falcon's data sockets, swapping data with the primary control brain.”

Source: Legacy of the Force, Tempest.


Some quotes speaking against these theories:

• “And now their trouble was his too, because the Infinity was still running under hot transponder codes. If the Imperials bothered to scan for its engines' unique emission signature – and they no doubt would – then they would know it was a smuggler's ship, wanted throughout the galaxy for tariff violation, tax evasion, gun-running, and dozens of other crimes.” Source: Tales from the Mos Eisley Cantina.

• "I didn't do a thing to your precious engines, Boo," said Deen, "all I did was add an ST box so the port will read our transponder signal as the Imperial driver's. Standard Operating Procedure, straight out of Cracken's Field Guide – I do it all the time." Source: Tales from the Empire.

• “Dengar instantly changed transponder frequencies so that his little Corellian JumpMaster showed up as an Imperial Scout. It was an older frequency, one that he'd used legally months before, but Dengar couldn't risk trying to shy away from the Imperial fleet.” Source: Tales of the Bounty Hunters.


Do note that the latter books were written during a time, when WEG was closely cooperating with Lucasfilm and a number of Star Wars lore authors. Ever since the license was withdrawn from WEG “opinions” on transponder / IFF technology have changed.


Reasons why I chose this path:

• Increased flexibility: Rebel PC’s can now send out Imperial transponder codes in order to break through blockades. Upon closer look, Imperial forces would quickly notice that it is a fraud, making this option not too "powerful".

• More in line with current Star Wars EU lore.

• To me it just makes more sense, since I am convinced that an engine’s base frequency will change over time or as a result of ship modifications, combat and accidents damaging the vessel.

[Mogul76]