rgrove0172
SOC-12
What range would you give the standard navigational radar in 2300? I realize its more of a factor of time for the signal to return but functionally, how far out would another ship/object be detected?
Navigational Radar
- Thread starter rgrove0172
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shaunhilburn
SOC-12
It depends on the power of the nav radar and the reflected signature of the target. The simplest treatment is to create a handful of size categories with detection ranges and reaction times for each. If they're anything like active sensors in the space combat rules, then the detection range is several light-seconds and reaction time in minutes. You could treat nav radar as active sensors with a low rating, but then you're getting into space combat and all of its bookkeeping. I say "low rating" because I doubt nav radar exceeds the capability military search radar.
In the 2300 space combat framework, light has a movement rating of 30, and 15 hexes is the maximum round-trip travel distance for radar pulses that will fit within a space combat turn.
rgrove0172
SOC-12
Just read through Lone Wolf and there is a bit about Grav Scans and DSS but nothing on radar.
A little googling seems to indicate that a radar's effective range is a product of the strength and speed of the pulses, couple with the sensitivity of the reciever. Given that, we could have a whole host of different radar sets in 2300, similar to the varying quality of passive/active sensor arrays. I would have thought that a radio signal would have infinite range, only the delay in recieving a return making very remote objects such a long time in answering that the information would be useless.
With a light second being about 300,000km and an AU at 150,000,000 - a radar signal could go the distance and register on your screen in about 10 seconds. But then thats only in one general direction. I suppose if you are making a sweep you are only engaging one area every few seconds, or possibly minutes, further delaying the results. Then again, if you have the time, there is nothing wrong with making a sweep and finding out that there was something a couple AUs out there 5 minutes ago. At least you know!
Hmm, thoughts?
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shaunhilburn
SOC-12
Director's Guide say nav radar will sense all objects within 1 AU of the vessel, but will not normally identify them. Its used for maneuvering among close-set objects.
One AU is 499 light-seconds. It takes nearly 17 minutes for pulses to make that round-trip.
You need to know the solid angle of your scan. A 'general direction' seems like about 1 steradian = 3282.8 square degrees. The surface of a sphere, as seen from its center (in a all-sky sweep), has 4Pi or 12.5664 steradians = 41,252.96 square degrees.
rgrove0172
SOC-12
Geeze, thats why I shouldnt make post from my phone while screwing around in town. My mental math on that was catastrophic. Your right of course, something like 499 light seconds in an AU or 8.3 minutes so yeah, your right on the money.
Thanks for the tip on the Steradians, that will make a scan (partial or full etc.) a lot easier to detail and assign a required time to.
What would you suggest as terminology where these radii are concerned. Steradian just doesnt work... How would a Captain order a given area to be scanned? By sector? Bearing? Theres got to be a cool way of ordering a radar sweep in a given direction.
Thanks for the tip on the Steradians, that will make a scan (partial or full etc.) a lot easier to detail and assign a required time to.
What would you suggest as terminology where these radii are concerned. Steradian just doesnt work... How would a Captain order a given area to be scanned? By sector? Bearing? Theres got to be a cool way of ordering a radar sweep in a given direction.
Navigational radar today scans the whole circle several times a minute. Ask an OS (Operations Specialist) for better info, but scan is by bearing and range. From that, course, speed, and closest point of approach can be determined. Look of maneuvering board or mo-board manual. It's a pdf, freely available on google. Also try to google the Operations Specialist rate training manual and the Quartermaster NTM. Not sure what the navedtra numbers are off the top of my head, but google will tell you.
Since you're scanning up to 1 AU out, each pulse would be tagged so the system would recognize it when it came back as the pulse sent 314 seconds ago, or 692 seconds ago, etc, and would derive distance from that, bearing from the direction the sweep sent the pulse out at.
Range is more accurate for navigation than bearing when it comes to radar. Visual, however, is another story.
Since you're scanning up to 1 AU out, each pulse would be tagged so the system would recognize it when it came back as the pulse sent 314 seconds ago, or 692 seconds ago, etc, and would derive distance from that, bearing from the direction the sweep sent the pulse out at.
Range is more accurate for navigation than bearing when it comes to radar. Visual, however, is another story.
rgrove0172
SOC-12
Good stuff, thanks!
rgrove0172
SOC-12
I notice that military sensors are not actually described technology wise but only in game terms. Are they Radar? They seem to perform like radar (ie. Bistatic/Passive Coherent Radar for passive detection using some inert form of energy floating around out there instead of traditional signal sources, then a monostatic/collicated process for active scanning), or are they a superior type or radar, above that of the standard navigational variety, or are they a different technology altogether?
Speaking of passive detection. If it is radar, and utilizing bistatic/passive technology, would it be possible there is some sort of cosmic energy out there they are measuring when it reflects off a target? On earth there are sources aplenty but in space, especially deep space, what would a passive radar be detecting? Solar, natural electromagnetic?
OH, and where does infrared fit in? There are many comments on how heat is a dead give away in a vaccum, but no mention of what "sensor" detects it. Are we assuming all ships have infrared sensing equipment capable of detecting a trace heat signature anywhere in the system? Most civilian/commercial ships have only basic navigational radar, so are infrared detectors part of that suite?
Speaking of passive detection. If it is radar, and utilizing bistatic/passive technology, would it be possible there is some sort of cosmic energy out there they are measuring when it reflects off a target? On earth there are sources aplenty but in space, especially deep space, what would a passive radar be detecting? Solar, natural electromagnetic?
OH, and where does infrared fit in? There are many comments on how heat is a dead give away in a vaccum, but no mention of what "sensor" detects it. Are we assuming all ships have infrared sensing equipment capable of detecting a trace heat signature anywhere in the system? Most civilian/commercial ships have only basic navigational radar, so are infrared detectors part of that suite?
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rgrove0172
SOC-12
Laugh, sorry, but stumbled on an oddity.
The MT2300 book lists civilian sensor ranges as "0" on the range band chart. Range 1 = < 300,000km by the book. Not sure how to interpret that. The classic rules state that navigational radar can detect objects out to 1 AU, or 150,000,000km... which equates to LONG range in the new Mongoose Traveller rules... or range band 5, which they award to military sensors. Hmmm...
Similarly the MT2300 book claims that densitometers have been replaced with the Deep System Scans. The Sensors Table in Traveller Core Rules (page 144) lists their max range as Medium or about 10,000km. Thats not very Deep. Classic 2300AD claims they can detect and analyze objects throughout a system (30-40AU or more?) and can detect ship power emissions at 1 AU (150million km)
What happened here? Didnt anybody at GDW even read the orginal rules?
The MT2300 book lists civilian sensor ranges as "0" on the range band chart. Range 1 = < 300,000km by the book. Not sure how to interpret that. The classic rules state that navigational radar can detect objects out to 1 AU, or 150,000,000km... which equates to LONG range in the new Mongoose Traveller rules... or range band 5, which they award to military sensors. Hmmm...
Similarly the MT2300 book claims that densitometers have been replaced with the Deep System Scans. The Sensors Table in Traveller Core Rules (page 144) lists their max range as Medium or about 10,000km. Thats not very Deep. Classic 2300AD claims they can detect and analyze objects throughout a system (30-40AU or more?) and can detect ship power emissions at 1 AU (150million km)
What happened here? Didnt anybody at GDW even read the orginal rules?
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rgrove0172
SOC-12
Ok, a guy on the Mongoose forum explained the following;
The difference between the ranges given in the classic rules and those in the MT2300 variation of the Traveller Core Page 144 Sensor Table is in the strength of the sensor.
The sensor table shows the ability of the sensor to get good info on small objects, where ranges beyond that - reaching those listed in the classic rules, are for large planetoids and other major objects, where detection is automatic, but minimal in detail.
This falls from the Traveller Task system where some tasks (Like detecting Jupiter even at 30AU) is considered automatic for a sensor appropriately equipped. Trying to detect a ship by its power emissions is something else entirely and hense the smaller range scale.
For example, a Grav Scanner is said to be able to scan an entire system but only locate operating stutterdrives within an AU or so. Looking at the Traveller Sensor Table with the new 2300 Range bands (and assuming the densiometer is the equivalent of a grav scanner) it get minimal results when scanning at Medium range or about... well looky there - 1.5million Km
It seems he is on to something. Anyone agree or disagree.
The difference between the ranges given in the classic rules and those in the MT2300 variation of the Traveller Core Page 144 Sensor Table is in the strength of the sensor.
The sensor table shows the ability of the sensor to get good info on small objects, where ranges beyond that - reaching those listed in the classic rules, are for large planetoids and other major objects, where detection is automatic, but minimal in detail.
This falls from the Traveller Task system where some tasks (Like detecting Jupiter even at 30AU) is considered automatic for a sensor appropriately equipped. Trying to detect a ship by its power emissions is something else entirely and hense the smaller range scale.
For example, a Grav Scanner is said to be able to scan an entire system but only locate operating stutterdrives within an AU or so. Looking at the Traveller Sensor Table with the new 2300 Range bands (and assuming the densiometer is the equivalent of a grav scanner) it get minimal results when scanning at Medium range or about... well looky there - 1.5million Km
It seems he is on to something. Anyone agree or disagree.
There was a changing interpretation as time went on.
The listed ranges for DSS and Grav were for system survey work, i.e. finding planets. Now Jupiter is a much bigger brighter spot than a 150MW drive, so range is shorter.
David Neilsen changed this in Lone Wolf and Three Blind Mice, but it never made a huge amount of sense. The DSS was specifically defined as a neutrino detector, detecting nuclear reactors.
The grav scanner, as described, would be useless if the ship had a stutterwarp, as the grav wake of the scanning ship will swamp the detector. The same for DSS.
Even if superluminal, so you should be outrunning your own wake the waves within the field will propagate internally and swamp the sensor.
Hence realistically only the tactical sensors are useful for seeing things.
The listed ranges for DSS and Grav were for system survey work, i.e. finding planets. Now Jupiter is a much bigger brighter spot than a 150MW drive, so range is shorter.
David Neilsen changed this in Lone Wolf and Three Blind Mice, but it never made a huge amount of sense. The DSS was specifically defined as a neutrino detector, detecting nuclear reactors.
The grav scanner, as described, would be useless if the ship had a stutterwarp, as the grav wake of the scanning ship will swamp the detector. The same for DSS.
Even if superluminal, so you should be outrunning your own wake the waves within the field will propagate internally and swamp the sensor.
Hence realistically only the tactical sensors are useful for seeing things.
rgrove0172
SOC-12
Hmm, so your saying Deep System and Grav are scientific survey sensors, and shouldnt be permitted to detect shipping at all? We leave that up to Radar/Lidar only? What about EMF detection? Infrared?
rgrove0172
SOC-12
Perhaps ships have to disengage their stutterwarp before performing DSS and Grav scans. It would make a certain sense.
So if a DSS can detect a ship's powerplant at 150AU, how would you fit it into the Sensor table in the core rules? Does it gain FULL info out to the max 2300 range band of 4.8Million Km, or is it essentially a Minimal scanner no matter what the range?
So if a DSS can detect a ship's powerplant at 150AU, how would you fit it into the Sensor table in the core rules? Does it gain FULL info out to the max 2300 range band of 4.8Million Km, or is it essentially a Minimal scanner no matter what the range?
It's worth examining the space combat rules. "Black globe range" - range at which something can be detected but not targetted is 30 hexes - 1 light minute.
rgrove0172
SOC-12
Was that quote referring to DSS specifically?
rgrove0172
SOC-12
Help me put this question to rest and Ill drop this thread.
If a player asks what is the difference between navigational radar/lidar and the military scanner - I tell him..?
They can track and lock onto targets they detect? They are more powerful, better range etc. They have better passive capabilities?
If a player asks what is the difference between navigational radar/lidar and the military scanner - I tell him..?
They can track and lock onto targets they detect? They are more powerful, better range etc. They have better passive capabilities?
Range.
Sure, this is due to power/tech, but that is irrelevant unless mechanics focus on power requirements, which I would hope would only be at design time... As for tracking - the suite should do this regardless as a navigation system. 'Locking on' is a function of weapon systems - civilian systems might not interface with weapons, but that would seem silly if they have weapons.
Descriptively mil-spec would be just more powerful and sensitive, allowing for greater 'effective range'. Mechanically (rules wise), it would be nice if they had an edge against ECM/Jamming/Stealth - which, for simplicity could simply relate to reducing 'effective range'. TL modifiers should also apply, perhaps.
Sure, this is due to power/tech, but that is irrelevant unless mechanics focus on power requirements, which I would hope would only be at design time... As for tracking - the suite should do this regardless as a navigation system. 'Locking on' is a function of weapon systems - civilian systems might not interface with weapons, but that would seem silly if they have weapons.
Descriptively mil-spec would be just more powerful and sensitive, allowing for greater 'effective range'. Mechanically (rules wise), it would be nice if they had an edge against ECM/Jamming/Stealth - which, for simplicity could simply relate to reducing 'effective range'. TL modifiers should also apply, perhaps.
shaunhilburn
SOC-12
One of the booklets says its only used for navigating amongst close-set objects (I'm imagining debris fields, spaceship graveyards). It must be the 2nd edition Director's guide; I can't find it in 1st edition or Star Cruiser.
shaunhilburn
SOC-12
Navigation radar can't track & lock. Radars are generally dedicated to a particular role such as "search" or "fire control"; there are few multi-role radar sets.
Search radars (navigation radar) can locate a detect and locate a target, but a firing solution requires a narrower beam with much higher output than that provided by a search radar.
See http://en.wikipedia.org/wiki/Fire-control_radar
