My Gm being more or less puzzled as to how all this works, and by the amazing distances in play against any possible furtive approaches, count in that category.
My own imagination, still conflicting between modern nearly photographic radar imagining, oscilloscopes graphs of signatures, and that famous "cinematic green sea of dots on black screens" that can "go on the fritz"...
is also the happy proprietor of a Room for Improvements.
What we have :
Though never really stated as such, one can deduce from the Master Saga Sourcebook that radar ranges are made to be reduced to 30% on the ground. (Which is generally given for ground mecha, but one could rightly assume - as far as I know - that this would also be right for planes trying to detect something on the ground while doing a fly-by.) Considering the explanation for such being encumbered landscape and natural topography, and / or ground radio frequencies reflection, it would stand to reason that urban landscape would be worst than average ground level.
We also know, through diverse source of stealth and AEW jamming, that there can be some active penalty involved to read an echo in RT.
What could be added ?
By trying to fill-in the missing mechs, one might eventually find the works of previous fans which included not only radar ranges, but the mention "against 0 db", thus assuming (possibly rightly again) that RFI or obstacles (radar shadows) could reduce that range or affect the accuracy of the readings. But the sanctioned materials then lets us...
- Discover that there exists passive sources of interference,
- What they can be,
- Choose what kind of penalty to assign each occurrences.
Tired of repeating myself and sounding less clear than I wanted, and hoping this would help my Gm find his balance in SAR readouts narration, I finally decided to try to create some kind of scale for possible radio interference. Source 1. Source 2. And knowing that some people here are certainly more qualified in these things that I am, I was curious to know if my first draft held any value.
1[sup]st[/sup] Draft - Radar Penalties :
Radar Maximum Range Adjustment to Environment :
Radar are very less potent when trying to detect from ground level, even less in environments of reflective covers, and again even less in environments of heavily reflective / absorptive covers. Technically, only the target's surroundings needs to be taken in consideration. (Though obstacles between the detector and detected could become relevant if enough to cast a radar shadow.)
The exception to this would be a dense urban area, where reflections on the buildings could lead a radar to interfere with itself(?). In case of doubt, consider that the max range is conserved when scanning for the sky above a street (but not the reverse since the ground would limit a plane doing a fly-by).
The useful range can vary for an observer, for example; one that would be with his back to a city and nearby woods, while looking in direction of a nearby coast. The city would block its perception, the forest blurs it, its maximum range is diminished by being at ground level, but could remain at maximum air range in direction of the horizon above the water, where a boat would still lay against an empty background.
- LOS to Target is in clear sky / on an unobstructed horizon / space = 100% of written radar range available. (Some doubles in space?)
- LOS to target is at ground level / moderately encumbered (natural topography / light forests) = 30% of maximum listed radar range available.
- LOS to target in urban area = 7.5% of maximum listed radar range available, max 3km if the observer is also in an urban area.
Distance from Target :
The less a target blocks of the radar sensing ray / field of view, and the further away it is, the less it will reflects radio waves toward the array.
- Short Range ~ 00-30% of applied maximum radar range (Air or Ground) = 0%
- Medium Range ~ 31-60% of applied maximum radar range (Air or Ground) = -5%
- Long Range ~ 61-90% of applied maximum radar range (Air or Ground) = -10%
- Extreme Range ~ 91-100% of applied maximum radar range (Air or Ground) = -15%
Weather RFI :
A cloud of fine particulate matter becomes relevant according to which portion of the radar beam / field of view it occupies. Concentrated objects are always more visible and can dissimulate ambient noise coming from smaller objects. The image of a tank shouldn't be obstructed by some infantry passing in front of it. The image of a plane should technically remain clear under hail, but the same hail would hide surrounding rain.
This is why this modifier is counted at the observer's location, and not the target's. The radar under a weather condition is entirely occluded by it, and thus under the strongest influence of RFI from the phenomenon, which the returning radio waves must get through. On the other hand, a target in the distance will usually hide the weather in which it is.
One must assume that air turbulence augments with the percentage of penalty applied, and vice versa.
A character can attempt to identify a source of interference via a roll of sensory reading and use computer operation to try and correct its impact.
- Rain / Fog 0-5% base penalty.
- Heavy Rain 5-10% penalty.
- Snow 5-10% penalty.
- Heavy Snow to Blizzard 10-20% penalty.
- Hail 30-35% base penalty.
- Thunderstorms +5-10% penalty to above.
- Sun storms / Solar Flares +10-20% penalty to above.
Passive Jamming :
Passive Jamming enters the equation only when sufficiently packed emitted signals forms a "cloud of interference". (Most radar computers reduces these to nothing under normal conditions far from direct emitters.) A passive source should be under a 3km range to have any effect on a sensory reading, and should close at least to the hundreds of meters to make any major impact. Radar produced to work as a unit, such as the ones used by a fighter wing, should not be considered to interfere with one another... unless re-calibrated in the field, to compensate for other jamming sources. A battlefield might also become a cradle of passive RFI, if a lot of otherwise high powered jamming is going around the observer (even without targeting it directly).
Modifiers from this category are generally lower, because continuous noises tends to be more disruptive than pulsed massive events for interference dampeners.
A character can attempt to identify a source of interference via a roll of sensory reading and use computer operation to try and correct its impact.
- Proximity to High Powered Radio / Television / Radar towers = 5-25%.
- Proximity of large quantities of medium powered radio emitters = 0-5%. (Battlefield interference, densely communicating or electronic rich urban area.)
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What would you do differently, reinforce, or use as is?