Question $14$:

a$.$ State the types of mixers and draw one of them. $($Label all the information on the Figure and mention the function of each block or component$).$

b$.$ A special PCM system uses $16$ channels of data, one whose purpose is identification $($ID$)$ and synchronization. The sampling rate is $3\mathrm{.}2kHz.$ The word length is $6$ bits. Find $($a$)$ the number of available data channels, $($b$)$ the number of bits per frame, and $($c$)$ the serial data rate.

c$.$ ystems are used for analog information, and systems are used for digital information, although analog or digital signals may use either type of multiplexing$-$

d$.$ What is a direct$-$conversion receiver? What are its main advantages?