Gameplay Notes
This scenario models submarine communications; namely Extremely Low Frequency (ELF), Very High Frequency (VHF) and Link 11. It is also possible to communicate with the convoy NFSP-01 via Very High Frequency (VHF) burst transmission.
Extremely low frequency signals can be received at depths up to -1,000ft/-305m but are typically limited to a three or four character code. Your communications department will decipher the message and deliver you the relevant message. Usually this will be 'come to communications depth' in order to receive a more complete VHF message. If your submarine is deeper than -1,000ft/-305m the ELF signal will be repeated every 5 minutes until your submarine rises above -1,000ft/-305m and receives the signal. ELF signals tend to be very important, so it's a good idea to remain within ELF contact parameters.
Very high frequency signals can be received using a floating antenna from depths of up to -131ft/-40m, and are the primary method of tactical communication for your submarine. If your submarine is at communications depth (-131ft/-40m or shallower) when a VHF signal is sent it will automatically be received and displayed to you. If your submarine is deeper than communications depth the message will be stored and can be retrieved once your submarine returns to communications depth by activating the special action 'Stream VHF Antenna'. Urgent VHF messages that aren't received immediately will be followed by an ELF 'page' as described above. Routine VHF messages (for example, weather reports) will simply be stored waiting for you to return to communications depth and stream the VLF antenna. For this reason it is a good idea to come to communications depth and stream the VHF antenna occasionally when operating below communications depth.
Link 11 is a technology that allows units to share contacts and other information via ultra high frequency (UHF) datalink. While a great deal of data can be transmitted by UHF, the signals do not pass through water. This means that your submarine must be operating at periscope depth with the Link 11 antenna raised in order to enable this ability. To enable Link 11, come to periscope depth (-66ft/-20m) and activate the special action 'Raise the Link 11 Antenna'. While your submarine remains at periscope depth or shallower, contacts will be shared with friendly units. Once you dive deeper than periscope depth, the Link 11 connection will be lost after approximately 15 seconds. You can re-establish the connection later by following the steps above.
Very high frequency burst transmission allows you to pass course recommendations to offboard units. Your submarine is equipped with a floating antenna that allows VHF radio transmission from depths of up to -131ft/-40m. To send ourse recommendations to offboard units, open the special actions menu and select 'VHF Comms - ...' where ... represents the order you wish to give. While ELF, VHF (receive only) and Link 11 communications are passive and do not risk exposing your submarine, VHF burst transmission is an active process that involves emitting a signal. Enemy units within line of sight of your submarine may detect this signal and be able to determine the presence and location of your submarine. The chances of this happening are dependent on the range of the enemy unit to your submarine. For this reason is it advisable to minimise VHF radio use, and to do so only when you are certain that enemy units are not nearby or that the risk of detection is outweighed by the benefit of issuing an order.