Analogue vs Digital PDF

# Analogue vs Digital ## By Mohamed Nayel ### Digital Systems vs Analogue Systems - A signal is any kind of physical quantity that conveys information. - Audible speech is certainly a kind of signal, as it conveys the thoughts (information) of one person to another through the physical medium of...

# Analogue vs Digital ## By Mohamed Nayel ### Digital Systems vs Analogue Systems - A signal is any kind of physical quantity that conveys information. - Audible speech is certainly a kind of signal, as it conveys the thoughts (information) of one person to another through the physical medium of sound. - Signal will be used primarily in reference to an electrical quantity of voltage or current that is used to represent or signify some other physical quantity. - An analogue signal is a continuous signal that contains time-varying quantities. Unlike a digital signal, which has a discrete value at each sampling point, an analogue signal has constant fluctuations. ### Analog vs Digital - Any information may be conveyed by an analog signal; often such a signal is a measured response to changes in physical phenomena, such as sound, light, temperature, position, or pressure. The physical variable is converted to an analogue signal by a transducer. - A digital signal is a physical signal that is a representation of a sequence of discrete values. - Digital signals are signals that are represented by binary numbers, "1" or "0". The 1 and 0 values can correspond to different discrete voltage values. ### Analog vs digital - Analogy systems are less tolerant to noise, make good use of bandwidth, and are easy to manipulate mathematically. - However, analogy signals require hardware receivers and transmitters that are designed to perfectly fit the particular transmission. - If you are working on a new system, and you decide to change your analogue signal, you need to completely change your transmitters and receivers. ### Analog vs digital - Digital signals are more tolerant to noise, but digital signals can be completely corrupted in the presence of excess noise. - In digital signals, noise could cause a 1 to be interpreted as a 0 and vice versa, which makes the received data different than the original data. - There are systems in place to prevent this sort of scenario, such as checksums and CRCs, which tell the receiver when a bit has been corrupted and ask the transmitter to resend the data. ### Analog vs digital - The primary benefit of digital signals is that they can be handled by simple, standardized receivers and transmitters, and the signal can be then dealt with in software (which is comparatively cheap to change). - The difference between Digital and discrete - Digital quantity may be either 0 or 1, but discrete may be any numerical value i.e. 0,1....9. ### Analogue example A simple drawing of a violin with sound waves traveling through the air to an ear drum. The text below the drawing reads: - Violin - Air - Eardrum ### example - The first telephone was very analog, and in fact the wired phone in your house still works this way. - Person talks into microphone - Microphone converts sound waves into electrical waves - Electrical waves go down the wire to the other phone - At the other phone, speaker has magnets connected to a paper cone -- converts the incoming electrical wave back into sound waves - Analog! Simple drawing of a person speaking into a microphone, the wave traveling over a wire, and then to the other phone with a person listening ### Analog and Noise - Signal does not go through microphones, wires, magnets, etc. perfectly. - Each step - the wires, the magnets, etc. can introduce little errors. - "Noise"...like little random wiggles around the true signal. - Noise sounds like "hiss" - e.g. AM radio, cassette tapes. Image of a sine wave with no noise on top, and a sine wave with noise on the bottom. Text below image: - Pure signal, e.g. put into one end of the phone - Signal + noise as it comes out of the other end of the phone - All electronic circuits suffer from 'noise' which is unwanted signal mixed in with the desired signal ### Binary-Coded Decimal (BCD) - Four bits per digit A table with two columns: Digit and Bit pattern. - Digit column contains numbers 0-9 - Bit pattern column contains the 4 digit binary number representation of each number. Note: the following bit patterns are not used: - 1010 - 1011 - 1100 - 1101 - 1110 - 1111 ### Analog vs Digital A table with one row and two columns: Analog and Digital - **Technology** column: - Analog: Analog technology records waveforms as they are. - Digital: Samples analog waveforms into a limited set of numbers and records them. - **Uses** column: - Analog: Can be used in analog devices only. - Digital: Computing and digital electronics. - **Signal** column: - Analog: Analog signal is a continuous signal which represents physical measurements. - Digital: Digital signals are discrete time signals generated by digital modulation - **Representation** column: - Analog: Uses continuous range of values to represent information - Digital: Uses discrete or discontinuous values to represent information - **Applications** column: - Analog: Thermometer - Digital: PCs, PDAs - **Data transmissions** column: - Analog: Subjected to deterioration by noise during transmission and write/read cycle. - Digital: Can be noise-immune without deterioration during transmission and write/read cycle. - **Response to noise** column: - Analog: More likely to get affected reducing accuracy. - Digital: Less affected since noise response are analog in nature. - **Waves** column: - Analog: Denoted by sine waves - Digital: Denoted by square waves - **Example** column: - Analog: Human voice in air, analog electronic devices. - Digital: Computers, CDs, DVDs, and other digital electronic devices.