The purpose of this report is to describe some common data transmission terminology. Scope of Work:
This paper will discuss various data transmission (communication) protocols and how they are used in data communication. Synchronous and Asynchronous:
Asynchronous serial transmission is a technique used in serial RS232 communication. The data is framed by a series of control bits known as the start bit, stop bit(s), parity bits and error checking bits. A transmit clock signal is used to clock the data over the transmission line to the receiving end. At the receiver, a clock signal, known as the receive clock, which corresponds to the transmit clock is used to decode the transmitted data back to the original by stripping off the control bits.
Synchronous transmission sends data packets, in contrast to Asynchronous transmission, which sends data one bit at a time. The data is surrounded by start and end frames. The start frame tells the receiver to synchronize its internal clock and to expect the incoming packets. The end frame marks the end of the packet.
Low speed data transmission uses asynchronous transmission. Because asynchronous transmission does not include error checking, it is not very efficient. Synchronous transmission, on the other hand is very efficient. Data is transmitted in blocks. Synchronous communication is well suited for high speed data transmission. The protocol has error checking capabilities.
Analog and Digital:
Analog signals represent continuously changing signal such as sound wave emitted from a speaker or an alternating current (sine wave) traveling on a wire. Digital signal, on the other hand is a digital representation of an analog signal, it is either off or on.
AM - Amplitude modulation and FM Frequency modulations are means by which use to transmit analog signal. DM Digital modulation is used to transmit digital signal (Analog vs Digital Transmission, 2005)
X on and X off: