swing from one state to another (0 to 1, or 1 to 0, depending on design) when the input voltage is equal to ( or greater than) the reference voltage. The encoder converts the number (represented by the comparator that are switch to the 1 or 0 states) to a digital word representing the level of each sample. BASIC D/A CONVERSION Figure 6 shows the basic circuit involve for D/A conversion . The digital decoder determine how many of the output inverters turn on (to 1 or 0, depending on design) for a given digital word. The familiar ladder or parallel resistor (having different value) convert the signal sample back to a staircase analog signal. As usual, the resistor value are multiples of the powers of 2. This corresponds to the value of each bit in the digital word. A larger sample produces a lower ladder output voltage. The output inverter correct this reverse relationship and produces the correct analog signal.Any sharp. level change in the signal from the ladder inverter are smoothed by LPF. The resultant analog output signal from the D/A converter is an exact reproduction of the input analog signal to the A/D converter. The LPF also function to eliminate unwanted harmonic produced by the sharp level change in the staircase signal.RESEARCH AND ANALYSIS:DIGITAL VERSUS CONVENTIONAL (ANALOG) TELEVISIONTo compare the basic functions of digital TV to a conventional TV the figure shows the basic block diagrams of both conventional and digital TV. as shown in figure 7 in digital television the central control unit (CCU) is a microprocessor that controls all operation in digital TV. There is no comparable circuit in an analog or conventional television. The detected video out put of the tuner/FIF stage supplies an analog signal to the A/D. Next, the digital Y/C circuit perform all necessary processing of the video component and generate the red, green, and blue (RGB) signals. The D/A converter supplies the processed signal to drive the cathode...
