In CDMA, what is the primary technique utilized to encode and separate calls?

In Code Division Multiple Access (CDMA), the primary technique used to encode and separate calls is indeed based on Code Division. This method allows multiple users to share the same frequency channel simultaneously by assigning unique spreading codes to each user.

The core idea is that while all users transmit their signals at the same frequency and at the same time, each user's signal is combined with their unique code. This encoding process spreads the signal over a wider bandwidth, making it possible for multiple signals to coexist without causing interference. Each receiver, knowing its specific code, can differentiate its signal from others, effectively filtering out the unwanted signals and isolating the desired communication.

This approach contrasts sharply with other multiple access techniques. Time Division requires users to take turns transmitting, dividing available time slots among them, while Frequency Division assigns different frequencies to different users, allocating distinct bands of the spectrum. Packet Division, on the other hand, refers usually to data transmission methods that split data into packets for sending over a network but does not specifically pertain to the simultaneous access method that CDMA employs.

Thus, in the context of CDMA, the use of unique codes for encoding signals ensures efficient use of the communication channel and minimizes interference, making Code Division the correct choice.