Digital To Analog Conversion and Transmission Tutorials Part I (D2A Conversion Introduction)

Digital to Analog conversion is the process of changing one of the characteristics of an Analog signal based on the information in digital data.

Digital to Analog Conversion:Digital data needs to be carried on an Analog signal.

A carrier signal (frequency fc) performs the function of transporting the digital data in an Analog waveform.

The analog carrier signal is manipulated to uniquely identify the digital data being carried.

Types of digital-to-analog conversion:

Amplitude Shift Keying (ASK)
Frequency Shift Keying(FSK)
Phase Shift Keying (PSK)
Constellation Diagrams

Quadrature amplitude modulation is a combination of ASK and PSK

In the Analog transmission of digital data, the signal or baud rate is less than or equal to the bit rate. 

S=Nx1/r bauds

Where r is the number of data bits per signal element.

Bit rate, N, is the number of bits per second (bps). Baud rate is the number of signal elements per second (bauds).

Problem Example-1
An Analog signal carries 4 bits per signal element. If 1000 signal elements are sent per second, find the bit rate.

Solution :

In this case, r = 4, S = 1000, and N is unknown. We can find the value of N from

Problem Example-2
An analog signal has a bit rate of 8000 bps and a baud rate of 1000 baud. How many data elements are carried by each signal element? How many signal elements do we need?

Solution :
In this example, S = 1000, N = 8000, and r and L are unknown. We find first the value of r and then the value of L.