Tài liệu Data - Encoding and Transmission

What is Data?
Any meaningful information is data.
Otherwise it is noise or nonterrestrial data.

Data in Electronic form:
Any meaningful information can be represented into
Electrical,
Electromagnetic or
Optical form
for the purpose processing, storing and transmission.

Electronic Data can be of two kind:
Analogue and
Digital

Analogue Data - take on continuous values as time changes. E.g.,
Voice - uses microphone to convert to electrical form
Video - uses video camera
Temperature - uses sensor, like thermocouples
Pressure - uses piezoelectric crystals
Digital Data - take on discrete values, switching ON/OFF, text, integers, etc.
Can be grouped into
Bits - either a voltage or no voltage, 0 or 1
Bytes - group of 8 bits, like 0100 0001 is A in ASCII code

What is Data (2nd time)?
Normally we mean digital data processed by a computer.

Signals:
In a communication system, data are propagated from one point to another by means of electromagnetic signals. A signal is a series of analogue or digital data. That is a varying voltage (either continuous or discrete) with time in an electronic communication system.