Signals and electronic warfare
Radio communications
Modern communications open up possibilities, but also create risks. Units equipped with radios can 
signal as their 
Action in a turn. Place a token on the unit signaling to indicate that it's signaled. This token is removed at the start of the same player's next turn.
Any unit with a radio can signal to provide one of the following:
- Situational awareness: A radio-using unit can use its Action to communicate to all other friendly units with radios, allowing them to target any unit the radio-using unit can see. The other units still need to be able to plausibly hit the target with their weapons (usually indirect fire weapons), but no longer require line of sight.
- Fires observation: A radio-using unit can use its Action to provide detailed observation of a single point or enemy target unit, giving all friendly units an
advantage to any attack against the targeted unit or point until this unit's next turn. Place a token on the targeted unit or point to indicate this. - Unmanned systems control: A radio-using unit can
focus to take control of a friendly unmanned platform. The platform can then take a move and action as if it was an independent unit using the platform's statistics.
Signals example
In this situation, the lone scout ahead of the rest can signal back. The receiving unit with a radio will automatically pass on the information to the mortarmen and the machine gunners within his own movement radius, but the heavy machine gun team further afield is too far away to receive the information.
Voice communication
Units with a radio can automatically communicate to any friendly unit within their own 
Movement distance, without signaling any further. This simulates shouting, speaking, or communications using local communication devices that are difficult to intercept. This occurs throughout a chain of units so long as they're within their Move distance of each other.
Signaling example
Steve the forward observer uses his Action to call in a situation report. This allows any friendly unit with a radio to see what Steve sees, including an enemy platoon in the open.
Dave the platoon commander, with a radio of his own, receives Steve's report. Dave can now use his M203 grenade launcher to target the enemy platoon if it's in range, even though he can't see it. While most of Dave's platoon is in his movement distance of 8 and can thus also attack the enemy platoon if they have a suitable weapon, Dave has one squad further away.
The closest member of that squad is within 8 of one of Dave's platoon members that can hear him directly, and so the rest of the squad can get the information passed to them automatically via word of mouth.
The two scouts Dave sent ahead, however, are more than 8 away from the rest of the platoon, and thus don't learn about the enemy platoon.
Electronic warfare
Units equipped with specialized electronic warfare (EW) equipment can do everything ordinary radio-using units can do, or use their Action to perform one of the following:
Signals intelligence
An EW unit can use its Action to analyze radio signatures in the area. This allows the EW unit to "see" any unit that has a signal token next to it. This action does not make the EW unit signal; however, as part of the same action, the unit can choose to signal for free and let every friendly unit with a radio know what they've picked up, similar to normal radio communication.
Jamming
An EW can use its Action to signal and jam any enemy radio users within 36. (Players may decide that certain forms of jamming equipment have a further range.) This means the enemy cannot use their own radios to provide situational awareness or fires observation. However, enemy EW units can still perform signals intelligence or jamming actions of their own. Enemy unmanned systems that are remotely controlled will also not operate within a jamming 
radius: flying ones will crash, and ground unmanned systems will stop moving and taking actions.