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Data vs Signal | Difference between Data and Signal

This page compares Data vs Signal and mentions difference between Data and Signal used in data communication with examples.

Introduction: Data and signals are like two building blocks of computer networks. All the data transmitted over channel can either be in analog form or digital form. Data are manipulated in the signal form suitable for the transmission channel. Like data elements, signal can also either in analog form or digital form.

Hence four possible combinations of data and signal are as follows.
• Analog data converted into analog signal form, for example Telephone.
• Digital data converted to analog signal form, for example modem.
• Analog data converted to digital signal form, for example codec.
• Digital data converted to digital signal form, for example digital transmitter.

Data element vs Signal element

As shown in the figure, 1 data element is represented by two signal elements. Hence ratio 'r' which defines number of data elements carried by each signal element is 1/2. The right side depicts two data elements are represented by one signal element, which gives 'r' equals 2/1 (i.e. 2). QPSK signal has 'r' equals 2, as it maps two bits by one signal waveform.

If four data elements are represented by three signal elements, 'r' equals 4/3. The data rate and signal rate are related by following equation or formula.

Difference between Bit rate and Baud rate

Data can be numbers, text, image, audio or video which are stored in computer system. The digital data stored are usually stored as binary ones or zeros.

Signals have three basic parameters viz. amplitude, frequency, bandwidth and phase. Noise and attenuation affect the signal over medium. Signals can either be in electric form or in electromagnetic (EM) form or optical form. There will be continuous signal or discrete signal.

Line coding techniques such as unipolar, polar, bipolar are used to convert data elements (i.e. digital data) to signal elements (i.e. digital signal).

Tabular difference between data and signal

Following table mentions difference between data and signal with respect to various parameters.

Parameters Data Signal
• What is it ? Data is the information we want to transmit. Signal is the waveform format used to send data over channel.
• Function Acts as payload of carrier Acts as carrier which carries data or payload.
• Measurement quantity Bit rate in bps or Kbps or Mbps or Gbps Signal rate or baud rate in Baud, KBaud or Mbaud
• Affecting data communication parameter Speed, Higher the bit rate higher is the speed Bandwidth, lower the signal rate, lower is the bandwidth
• Format Analog (Continuous) or digital form (Binary or discrete) Analog (Electric, EM or Optical) or digital form (i.e. pulse such as NRZ or RZ )

Useful Links

echo canceller
exchange signaling types
EPABX basics
Erlang/Grade of Service

Line coding techniques

Difference between Unipolar Polar and Bipolar coding    RZ vs NRZ vs Manchester coding    RZ vs NRZ pulse shapes    Advantages and disadvantages of NRZ encoding    RZ encoding    2B1Q coding    8B6T coding    4D PAM5 coding    MLT-3 coding    4B/5B encoding    8B/10B encoding    R8ZS scrambling    HDB3 scrambling   

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