Questions about sensors, comms, signals, etc.

[phavoc]

So, some more starship comms related questions, this time about a ship's ID:

- Assume a starship gives a call sign (Free Trader Beowulf) when it communicates with other starships, but also a more formal serial code and number (eg, the scout ship in High and Dry has SC000... or something). What kind of data would be available to another ship captain receiving that id (limitations of non-FTL transfer of information aside)? Make and model, I guess, but also current owner? registered crew? recent flight history?
- If a crew then wanted to change their ship's call sign, eg to avoid detection by the authorities, what kind of difficulty rating and timeframe would you give that? I'm thinking formidable (14+) but maybe even that is too easy.

Thanks again,

Dan.

I would assume starship transponders work the same way as ship transponders do today. There is something called AIS (Wiki entry here) that does something for ships. I believe the aircraft tracking version would be the same.

I don't see the need for registered crew, or flight history. The design of the Imperium, with it's multiple levels of independence preclude the idea that the state requires that level of details from all it's citizens all the time. If the Imperium were more autocratic and dictatorial then yeah, that might be more along the lines of what you would expect. Otherwise standard ship name, course, speed, & destination should be enough.

It gets me thinking, if a ship is in distress, are there going to be automated messages for medical emergencies, quarantine, hijacking, etc?

As for changing the transponder, I'm not sure if that would be formidable, probably difficult. Ships last for decades, even centuries. And some ships spend a lifetime on the fringes, away from the higher tech worlds, so they may never get a new transponder. Plus with the number of Free Traders lying around in the boneyard one could potentially just strip the transponder off that and it should work... though I've never seen anything in any version of the rules that talks about how a ship has unique fingerprints that could identify it as being something different than the transponder they are carrying. That would be up to the ref to determine for their universe.

 

[Condottiere]

Transponder signatures have to match up to a list of ship identities.

It's unlikely that starports allow ships to dock without a valid and verified one.

 

[xnet445]

What happens when a ship enters a system for the first time, before word of its presence in the sector makes its way to the port? It will have a new and unknown transponder signature by definition. Does it have to wait in quarantine until the next X-boat mail packet arrives?

 

[Condottiere]

Maybe not quarantine, if the ship register hasn't been updated, just an outlying terminal.

But databases should have a complete list of all commercial ships and private vessels, even if the information is out of date; so a forty year old freetrader that made it's way from the Solomani Rim to the Spinward Marches would be identifiable, though not updated on current ownership.

 

[xnet445]

But databases should have a complete list of all commercial ships and private vessels, even if the information is out of date; so a forty year old freetrader that made it's way from the Solomani Rim to the Spinward Marches would be identifiable, though not updated on current ownership.

Good point. That makes spoofing a tad more difficult, at least if you were trying to claim Imperium registry. I would think Sword Worlds or other beyond-the-border backwater empires would be popular as flags of convenience then.

 

[ochd]

Data broadcast by AIS

An AIS transceiver sends the following data every 2 to 10 seconds depending on a vessel's speed while underway, and every 3 minutes while a vessel is at anchor:

That's really interesting, thanks.

So, I guess starships would be broadcasting that data all the time, unless they chose not to. In which case a ship that wasn't would be immediately suspect to other ships?

Also, I'm thinking that likewise when a ship first jumps in system (and according to HG its jump flash is usually detected by the starport), it would automatically send these kinds of details to the starport.

Dan.

 

[Condottiere]

When I first moved to California, I was pretty surprised to discover that licence plates matched with the automobile type.

Much like your social security number had a sequence with year and place of birth.

 

[phavoc]

That's really interesting, thanks.

So, I guess starships would be broadcasting that data all the time, unless they chose not to. In which case a ship that wasn't would be immediately suspect to other ships?

Also, I'm thinking that likewise when a ship first jumps in system (and according to HG its jump flash is usually detected by the starport), it would automatically send these kinds of details to the starport.

Dan.

Yeah, in space their is no reason why their transponders wouldn't be squawking all the time. The reason would be the speeds at which they travel - accelerating even at a lowly 1G for 10hrs means you 've built up quite a velocity. It's even higher with interplanetary craft who are accelerating for days at a time. You wouldn't want it to be limited to interrogation only by other transmitters, or even done every 10 minutes.

Arrival should vary, depending on the arrival area. A busy starport should have traffic relay sats out at the 100D limit, broadcasting echo'es of local traffic patterns so inbound ships don't have to rely upon their sensors to detect other ships. Arriving ships should be contacting the traffic sats with their bonafides and crew/cargo/passenger manifest data. Then that would be relayed to the starport authorities so they can start processing it before the ship arrives at port. Based on this customs can determine to intercept them short of the port or just wait. And any cargo shippers would be notified of their cargo arriving in-system so they can make preparations if necessary.

Systems without an organized system might only have an automated traffic sat broadcasting location of the starport and maybe filed flight plans for any starship that bothered to let the satellite know where and when they were going.

Orbital facilities would more or less operate under the same rules, except ships would arrive much closer so they wouldn't need to use a traffic sat, they'd just contact the station directly.

Whether or not a ship is detected via its jump flash really depends on how you want to interpret that rule. Are flashes 'bigger' the faster a ship is traveling upon exiting jump space? Are the omni-directional, detectable only in the direction the ship is travelling, or some mix? And what kinds of sensors are required to detect them? Is it possible that a larger planetary sensor array could pick up a flash anywhere in the system, or only just in a very local area?

 

[Condottiere]

Transponders should also be able to be pinged, by normal spacecraft as to who do you say you are, and by authorities, as to what exactly are you.

 

[ochd]

Copying this post to this thread, where it's more on-topic:

Advanced sensors include densitometers and NAS. CRB says that, when close enough to provide full details, these sensors give (for densitometers) "fine details" and (for NAS) "individual brain activity".

For densitometers: What does "fine detail" mean? every nook and cranny in a ship will be seen? you can see how many individual people there are on a ship and where they are? you can verify how much and the type of cargo that's being carried? hidden pop-up turrets?
For NAS: does "individual brain activity" identify and locate anything that has any size brain (e.g. some sleeping chamax)? would it identify psionic capability?

Thanks,

Dan.

 

[Linwood]

Circling back to sensors - the conversation focused on visual sensing. What about gravitational - probably not for tracking the starship's mass but maybe for a gravity ripple or wave signifying a jump had occurred?

 

[Sigtrygg]

IIRC, all ships in Imperial space are required to have an Imperial transponder that is quite difficult to tamper with.

It might be possible to steal some other transponder and have several transponders, but only one turned on, giving you several identities to choose from...

Transponders should also be able to be pinged, by normal spacecraft as to who do you say you are, and by authorities, as to what exactly are you.

Pirates have access to this:

Notable features on the corsair are large cargo doors and variable identification
features. The large clamshell doors can open to reveal the entire cargo bay; the ship
can accept a 100 ton ship into its cargo bay. The ship has several centrally controlled
identification features which can alter the shape and configuration of the ship
at a moment's notice; fins retract or extend, modules appear or disappear, and
radio emissions alter frequency and content. The ship's transponders can be altered
to identify the vessel as having any of a variety of missions and identities.