Right, been reading a lot of threads by how it is "stupid" to could see enemy units as the small blobs on the map allthough you got no recon there and how stupid it is for radio silence RUSE to make units go invisible.
Frankly, people are stupid and know nothing of Electronic Warfare (EW henceforth)
In wartimes radio discipline, (speaking in short bursts, code etc.) is something that must always be maintained as the enemy is surely trying to listen.
You can spot units with no recon, but not identify them in the game.
Lets assume your HQ, and possibly your allies HQ if its larger than 1v1 tracks enemy radio communication.
Now this tracking can only occur when the enemy actually broadcasts something, as a radiosignal on most WWII radios does not have a directional signal (making it slightly harder to track)
Now when two or more trackers are active you can ping the radio transmission and have an approx. location of the enemy radio (and thus the enemy unit) and possible launch attacks, send scouts to confirm the threat etc. etc. what you do.
The Japanese Navy used a civilian radio airwave to find Pearl Harbor, the planes simply followed the trace for example. After this a general radio silence was ordered in the pacific to hinder such an incident again.
When you order your units to go in radio silent mode in RUSE, it have been said that they should not be able to receive orders or move. FALSE!
A unit not broadcasting / transmitting anything can still receive radio signals and thus, receive orders.
Like for example a german sub would never transmit as it would reveal it's location to the allies. And the allies did go into great length to obtain the fabled "Enigma" encryption machine as that would allow them to hunt german subs with greater efficiency as they would always know when a sub left harbor, but would have no idea where it went.
This gives an idea of why radio discipline is needed. If you simply talk freely, without codes and not in short burts (interrupting transmissions periodically even though you are not done broadcasting) you make it very easy for enemy EW divisions to find you, your capabilities, your combat strength and your intentions, making it quite easy to put up a counter move with a force dedicated to taking YOU out. NOT GOOD.
In wartime you allocate quite some manpower to track enemy radio, decrypt (opposite of encrypt) to try to figure out enemy intentions.
Now while RUSE doesn't sport EW units, assume they are in the HQ.
Which again makes "decryption" ruse understandable, for a short period of time your decrypters figured out the enemy radio code and thus knows enemy intentions and what orders they give. (untill enemy intel realizes this and switches codes, or it just happens to be that they switch encryption type every 24 hours for example)
Modern day radio equipment still suffers this although radios have become smarter, so has the countermeasures.
F.example you can get satelitte transmitters that records a message, compresses it into a very very small signal that takes less than a second to send, making it very hard for an enemy receiver to track as the radio signal is sent in less than the given time. They might be able to gather that something was sent, but not enough time to track from where.
However, they did not have ZIP files in WWII.
Hopefully this explains most.
Still hoping for a wargame where you have to invest in EW troops.