Hearts of Iron IV - 39th Development Diary - 8th of January 2016

[Acaios]

radar waves are deflected by water surface by a large part. The other part that penetrate the water is refracted and change speed. it's impossible for a radar to spot a sub underwater. There's a reason if we're still using sonars.

Centimetrical radar used in that period could spot a periscope, but the resolution was really really bad and the signature can easily be confuse with a sea wave. All anti-submarine planes used eyesight to spot subs for that reason. Also, periscopes are used only during an attack, not during navigation.

A listening station with an appropriate RDF can spot the relative direction of the submarine at the moment of the radio transmission, but it cannot know the bearing, the distance or the speed of the submarine. it's impossible for anyone to find a submarine just drawing a line on a map and guessing the right point on that line.

Radar station spotting submarines is just wrong and it is also bad for gameplay.

 

[Secret Master]

radars to detect submarines.
are u serious?

A listening station with an appropriate RDF can spot the relative direction of the submarine at the moment of the radio transmission, but it cannot know the bearing, the distance or the speed of the submarine. it's impossible for anyone to find a submarine just drawing a line on a map and guessing the right point on that line.

Radar station spotting submarines is just wrong and it is also bad for gameplay.

I feel like there are key bits of information regarding WWII and SIGINT that need to be brought up.

Listening for subs by radio (and RADAR on mobile assets like planes), isn't just about detecting location using radio waves. That was certainly done sometimes (you can read on your own about how triangulation was used to locate wolf packs when they were chatty), and the German submarine service knew about it, and took measures during the war to avoid those problems (short transmission times for the win).

But the real reason you want to detect the transmissions form submarines is because you have broken the codes used by German naval ENIGMA machines, and therefore you know exactly what they are up to. Doenitz, in order to run the whole wolf pack thing, had the u-boats coordinated from both on land and with each other at sea. This meant you could know what they were doing regardless of whether you triangulated their actual location.

The impact of ULTRA and the program's decryption of naval ENIGMA was so significant that, when Doenitz found out about it in the 70s, he told a historian friend of his that they would literally have to rewrite the entire history of the war, starting from scratch.

 

[Acaios]

so, I have to suppose that even Iran has Enigma and it can spot uk subs just building a radar station. Make sense.

 

[misterbean]

so, I have to suppose that even Iran has Enigma and it can spot uk subs just building a radar station. Make sense.

Radar in the game is just an abstraction for all the electronic warfare going on behind the scenes. radio, radar, sonar, codebreaking, phone taps (if they had those back then), you name it. The name "radar" is just that. A name.

 

[Acaios]

or maybe it's an unknown alien technology.

 

[PGrob]

Seems good, except why is radio description linked to radar stations? Radio intercepts and decoding (Signals intelligence) did not require radar stations historically. All you needed was a radio receiver and smart guys code breaking. The fact that the radio detection feature was tied to radar sites in HoI3 really annoyed me, because in practice from 1936-39 there there was no decoding because Radar stations didn't exist, and after Radar sites were rarely built to a level large enough to take advantage of the radio decryption feature.

There hasn't been a DD on espionage yet, but it would seem to make sense to have radio intercepts be part of the intelligence mechanic. Let radar sites be just that, sites that detect incoming aircraft and coastal ships, aiding in making air interception more effective, while radio encryption and decryption be part of the general spying system (with higher levels of decryption allowing you to have a better chance of plotting the location of enemy forces anywhere on the map and uncovering battle plans.

 

[potski]

There is no "general spying system" as a separate feature in the game. That's why there has been no DD on espionage. Intelligence gathering is included in other features, such as from Radar stations, patrolling naval and air regions, and encryption/decryption levels. There are no spies like there was in HOI3.