ComSec is very important to the security of the operation. Wether that's a perimeter check or anything else you need Communications for.
Low power units like the FRS walkie talkies are very low powered and operating using simplex, both transmitting and receiving on the same channel/frequency. These definitely are useful for inclose communication such as between team members.
Operating Duplex involves the use of two frequencies and the difference between transmit and receive is refered to as the offset. 145.110/144.510 has a difference of 600kHz down and is called a negative (-) offset. Duplex normally is used with repeaters.
SPLIT- is another form of duplex with odd offset or nonstandard offset such as 146.535/147.505.
Cross-band- this is where your operation uses multiple frequencies and they are in different areas of the radio spectrum such as 223.415/147.480
Note: these operations do not extend the range of the communications. When you're transmitting to your partner it is still a simplex situation. Your radios must still be in range of each other. However, if a third party is also in range listening to your frequency, it's unlikely to be listening to your partner without knowing the frequency pair.
RedDog-one this is Lighthouse, report position over
Roger RedDog, Charlie Mike, lighthouse out
The other side of the conversation
Lighthouse this is RedDog-one, we are bullseye 215 1mike over
Bullseye is the last known fix. Could be the location of the camp 076545/457525 on an Azmith of 215° one mile away. You can now plot the location of RedDog-one.
Simplex as stated, both stations operators use the same frequency so any intercept is able to get both sides of the conversation.
Using map coordinates is a good SOP rather than latitude and longitude as the grid is map and scale specific. Using custom maps is highly advisable.
Always assume your communications are being monitored.