Clock Controller

Figure 1.1 Hardware For The Clock Controller

Figure 1.2 Hardware For The Clock Controller

Analog-to-Digital Conversion (ADC) and Digital-to-Analog Conversion (DAC) are the processes that allow digital computers to interact with these everyday signals. Digital information is different from its continuous counterpart in two important respects: it is sampled, and it is quantized. Both of these restrict how much information a digital signal can contain.

Comparison Between Digital and Analog

DIGITAL	ANALOG
Digital system is used to process information. ·         Somehow need to convert an analog value into a digital value. ·         Perform digital operations on the data. ·         Somehow need to convert the digital results back into an analog quantity. ·         E.g. o   CD’s o   MP3’s o   DVD’S	Most value in nature: ·         Temperature ·         Speed ·         Position ·         Etc.

  QUANTIZATION

Quantization, in mathematics and digital signal processing, is the process of mapping a large set of input values to a smaller set – such as rounding values to some unit of precision.

Because quantization is a many-to-few mapping, it is an inherently non-linear and irreversible process (i.e., because the same output value is shared by multiple input values, it is impossible in general to recover the exact input value when given only the output value).

There are two substantially different classes of applications where quantization is used:

• The first type, which may simply be called rounding quantization, is the one employed for many applications, to enable the use of a simple approximate representation for some quantity that is to be measured and used in other calculations. This category includes the simple rounding approximations used in everyday arithmetic. This category also includes analog-digital conversion of a signal for a digital signal processing system (e.g., using a sound card of a personal computer to capture an audio signal) and the calculations performed within most digital filtering processes. Here the purpose is primarily to retain as much signal fidelity as possible while eliminating unnecessary precision and keeping the dynamic range of the signal within practical limits (to avoid signal clipping or arimethic overflow). In such uses, substantial loss of signal fidelity is often unacceptable, and the design often centers around managing the approximation error to ensure that very little distortion is introduced.

• The second type, which can be called rate–distortion optimized quantization, is encountered in the source coding for "lossy" data compression algorithms, where the purpose is to manage distortion within the limits of the bit rate supported by a communication channel or storage medium. In this second setting, the amount of introduced distortion may be managed carefully by sophisticated techniques, and introducing some significant amount of distortion may be unavoidable. A quantizer designed for this purpose may be quite different and more elaborate in design than an ordinary rounding operation. It is in this domain that subtantial rate distortion analysis theory is likely to be applied. However, the same concepts actually apply in both use cases.

DIGITAL

ANALOG

Digital system is used to process information.

·         Somehow need to convert an analog value into a digital value.

·         Perform digital operations on the data.

·         Somehow need to convert the digital results back into an analog quantity.

·         E.g.

o   CD’s

o   MP3’s

o   DVD’S

Most value in nature:

·         Temperature

·         Speed

·         Position

·         Etc.