Starship sensors

[Matt Wilson]

Hi there, not sure if this has been discussed previously, but I have a question about the sensors table on p. 144 of the core rulebook.

Visual and Thermal sensors, the type listed in the first and second columns, appear to be the most effective of all kinds, providing better detail than active radar/lidar.

But they're not listed as part of any electronics package in the ship design section (I have the pocket rulebook). Is that a mistake? Are they listed somewhere else?

 

[Old timer]

I think the intention was that all ships had thermal/EM/Visual, and the sensors list in the starship section of the CRB are the extra sensors that come with that tech level. So, as an example, basic military sensors (Tech level 10) have the above, plus radar, lidar and jammers. I do not know if there is any official errata on this.

 

[Matt Wilson]

Thanks. If thermal and visual are the most effective, what's the advantage of radar/lidar? Do they provide a benefit in certain situations?

 

[DickTurpin]

Visual and Thermal are passive sensors that are great for detecting objects but give little information other than that. Lidar and Radar are active sensors that can also give the distance and relative motion of the target.

In the game rules there is no distinction made as to what is needed to detect an object, gain sensor lock, or fire weapons at it. In the real world the active sensors would be far better for combat use or plotting an intercept but it doesn't matter in the game.

 

[dragoner]

Thanks. If thermal and visual are the most effective, what's the advantage of radar/lidar? Do they provide a benefit in certain situations?

Yes, in space, all you would need is visual: space is the real "severe clear", without any atmospheric distortion, it is the hardest to spoof; but it would be the computer seeing it. At range, active sensors would most likely be the most inaccurate, but would light yourself up like a Christmas display. Though maybe they would be good in an atmosphere or maybe a nebula, not so sure about that though, who knows what the effect of a nebula would be.

 

[Infojunky]

Hi there, not sure if this has been discussed previously, but I have a question about the sensors table on p. 144 of the core rulebook.

Visual and Thermal sensors, the type listed in the first and second columns, appear to be the most effective of all kinds, providing better detail than active radar/lidar.

But they're not listed as part of any electronics package in the ship design section (I have the pocket rulebook). Is that a mistake? Are they listed somewhere else?

Looking at the two sections in question I would assume that basic "visual and thermal" are part of the basic package and are controlled by the basic DM provided in the Ship construction section. Also note the Bit rules in the text for the table on pg.144.

Sidenote, previous editions tended to lump Passives and Actives into to distinct groups refer to Active and Passive EMS. Realistically in operation you will use you Active Array (Mostly Radar) identify presence of distant objects, then use you passives and Lidar to refine (identify) what the said distant objects are. (Note all of your passives and Lidar will have much smaller "areas of view" than your radar). Also note about 75% of what people say and assume is correct about real world sensors and detection here in this forum is functionally incorrect, but don't let that get in the way of having fun with the rules as written.

 

[Condottiere]

I like to think that there is a revolving telescope on top of the ship, connected to an object recognition application.

 

[dragoner]

I like to think that there is a revolving telescope on top of the ship, connected to an object recognition application.

Or just a 3cm aperture that does more than the hubble.

 

[Matt Wilson]

Thanks for all the replies, everyone. Very helpful.

 

[simonh]

Visual and thermal sensors, with sufficiently powerful optics, have the longest range and give a detailed image of the target, but at long ranges objects will be difficult to distinguish from the stellar background. They give next to no information about the distance to the target (hence the above limitation of distinguishing targets from background objects). Thermal sensors will give relatively low resolution images at long ranges though and aperture limitations will reduce the resolution of visual images at interplanetary distances.

Radar and Ladar are active sensors that have more limited range, but provide detailed information about the range to the target. Given range information you can calculate motion towards and away from you by measuring changes in range, and also from Doppler shifts in the reflected signal. Given range data you can also calculate lateral motion. So while active sensors reveal information about you, they're easily the best systems for targeting weapons. Radar is a low-detail area sweep system, while Ladar is a narrow beam sensor using low power lasers to paint and image the target more precisely. Absorption characteristics might even give some information about the texture and surface composition of a target.

Simon Hibbs

 

[Condottiere]

And yet I long to use a periscope.

 

[Condottiere]

There's still the possibility that metamaterials will make long distance visual observation hard, stealth features will absorb or deflect radar.

As for lidar, maybe ablative armour?

 

[Infojunky]

AFAIK it was the other way round in TNE and Mega (and 2300AD)

I never said they were right.....

You use passives to get the "something is out there" information, sneak up on it and than hit it with actives for an accurate firing solution. Basically "Red October" with the Sollies replacing Iwans and Vasily still using "only one ping"

Passives have the benefit that the other side is guessing as well what/if something is there while "going active" gives you away

That works with the Submarine analogy, but most commonly the Surface Ship/Aircraft model makes more sense.

 

[Infojunky]

I disagree with the Surface/Aircraft model in Traveller starships. While passiv detection can (or can not, depending on the In Universe physics as defined by the rule set used) give a "something is out there and around here" element quite reliable nothing beats a multi megawatt directed beacon to refine a target solution. And as more than one SAM operator coming into HARMs way has realized that works both ways. So I guess the run silent, listen and refine the solution until you are almost sure THAN do a quick active and fire setup as used by both subs and sub-hunters works better for Traveller. Even more for rules sets with more detailed sensor/stealth rules like Mega and TNE.

Actually the Passive sensor that replaces Actives (at least in terms of detecting fusion powered objects) in the wide field of view is the Neutrino Sensor which isn't specifically separated out in the Mongoose edition. In that it gives a angle of detection and a relative signal strength, thus a vector along which your passives and narrow field of view sensors can be focused. Though mind you even in this Passives Primacy mode you are still effectively in the Surface ship/Aircraft regime, unless great efforts (also Read this as Cost) are taken to provide your starcraft with the stealth equivalent of a submarine....

I might also point out that the tactics we are discussing will vary a great deal with the operation environment of said ships. Commercial ships will be using their actives for primary navigation operations, Single patrol/reconnaissance ships will be largely lurking on passives, Fleets probably will have a mixture of of Active and passives, Said fleets will probably have a few stand off pickets actively scanning with the combat core in passive/active mode i.e. using their passive to process the active returns of the ships that are radiating.