Another newbie question, this one on radars

[Phoenix7786]

Heya all. Sorry to sort of flood the forum with so many questions, but I can't seem to see any of this info on the readme or changelog. Anyways, I see that having a large radar and small radar boosts the detection to 30%. It says that there is no way to increase the extra detection percentage by building more. However, what about the detection radius? I know the layers of circles represent what I can potentially detect, and given the changes/tweaks/fixes openXcom has made, exactly how many and what kinds of radars do I need to build for optimal radius for detection before I start wasting cash? Is it as simple as having a small, large, and then Hyper-wave decoder and that's all I need or has the openXcom source-port tweaked the mechanics? Sorry again to flood with questions but I'm not having luck seeing anything online other than vanilla Xcom.

[Dioxine]

Not 100% sure about that, but having many radars should increase your detection chance (it was bugged in the old game, not sure what the devs decided in the end). However the range cannot be increased in any way, it's tied to the radar (ie with small radar + large radar you get 30% chance within small radar's range, and 20% where only the large radar radius reaches). Hyper-Wave decoder makes all radars obsolete, you can safely scrap them (it has the largest radius & instant detection with 100% chance).

[7Saturn]

One thing I have experienced in the original game was, that an already identified object still disappeared, although found by hyperwave decoder. Especially when landet, hyperwave doesn't seem to be 100%. At least it can loose the object again. Not sure, how that applies to OpenXcom, but I believe to have experienced that as well with the reengineered version.

[yrizoud]

If your hyperwave decoder catches a flying UFO at 11:00 and it quickly lands outside your detection range, at 12:00, the game checks that none of your bases detectors or crafts are in range, and you lose track of it.

[7Saturn]

So hyperwave does have a range? That certainly would explain it.

[Hobbes]

Heya all. Sorry to sort of flood the forum with so many questions, but I can't seem to see any of this info on the readme or changelog.

Hello there and spam us with as many questions as you like

You should also check the wiki at https://www.ufopaedia.org/index.php?title=OpenXcom since you might find useful info there.

So hyperwave does have a range? That certainly would explain it.

The range of the decoder is the outermost circle when you're placing your initial base. It isn't much bigger than a Large Radar but the 100% chance more than makes up for it.

[mrxian]

The range of the decoder is the outermost circle when you're placing your initial base. It isn't much bigger than a Large Radar but the 100% chance more than makes up for it.

Makes up for it?
It's large enough to cover most continents, if it were much bigger it would be too big in my opinion.

[Phoenix7786]

Hello there and spam us with as many questions as you like

You should also check the wiki at https://www.ufopaedia.org/index.php?title=OpenXcom since you might find useful info there.

The range of the decoder is the outermost circle when you're placing your initial base. It isn't much bigger than a Large Radar but the 100% chance more than makes up for it.

Thanks for the patience! I just dog-earred that page. It does state that each radar facility contributes to the detection check, so having multiple Small Radar Systems and/or Large Radar Systems does improve your chances. The Hyperwave Decoder still makes all other facilities obsolete though since it has a 100% detection chance.

So is there still any reason to stack a small radar with large ones or is it better to just spam larges? Since a large is 20% can I just stack 5 until the Decoder or are the percentages from multiple radars not additive?

Thanks as always!

[yrizoud]

So is there still any reason to stack a small radar with large ones

The starting base already has a small radar, I systematically build a large one immediately. Of course I keep the small radar during construction. When large radar is complete, I don't *need* the small one anymore, but the monthly fee is small and it does increase the detection (in the smaller radius), so I keep it until I need room or complete a hyperwave decoder.

[ivandogovich]

As far as stacking goes, its not really additive  (5 does not equal 100%).  Each radar has its own, individual chance to detect at its detection rate, within its range.  So more is better, yes. Two radar double your chances, but each have the same chance to miss the ufo.  As Yrizoud said, Small + Large, then dismantle when you have HyperWave Decoder.  For Radar bases, most players just use a Large until the HyperWave Decoders come online.

Edit:  Ignore the above per Redv's explanation below

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[Phoenix7786]

Ok cool. So I know that a small+large is pretty much mandatory until the decoder is available. And thanks for clarifying they're ARE additive that tells me what I needed to know. At least this thread has been a learning experience for more than just me

[redv]

They're additive.
For example: Large radar vs Small scout at high altitude

1 Large radar: chance to detect is  20 * (100 - 15) / 100 = 17%
2 Large radars: chance to detect is  40 * (100 - 15) / 100 = 34%
...
6 Large radars: chance to detect is  120 * (100 - 15) / 100 = 102%

Chance to detect: https://github.com/SupSuper/OpenXcom/blob/master/src/Savegame/Base.cpp#L388
Visibility of UFOs is hardcoded: https://github.com/SupSuper/OpenXcom/blob/master/src/Savegame/Ufo.cpp#L593

[Dioxine]

Still, a single sweep takes 10 minutes, so if an UFO is present in your radar range for, say, 1 hour, you get 6 chances, so even a single Large radar is usually enough.

[redv]

An UFO can be detected one time per 30 min. https://github.com/SupSuper/OpenXcom/blob/master/src/Geoscape/GeoscapeState.cpp#L1254
The same example: Large radar vs Small scout at high altitude.

Chance to detect per 30 min = 17%
Chance to detect per 1 hour  = 100 - 100 * (1 - 17 / 100)^2 = 31.11%
Chance to detect per 2 hours = 100 - 100 * (1 - 17 / 100)^4 = 52.54%
Chance to detect per 3 hours (6 times) = 100 - 100 * (1 - 17 / 100)^6 = 67.31%
etc