What are Analog & Digital Signals? Difference between these signals


Define Signals?

Signals are defined as a source of information which varies with respect to independent variable. Signals are used in communicating information in any form.

A data or information or message which is collected from one system is converted into electromagnetic wave and send to receiver end. The signals converted into electromagnetic wave can be of two types They are as follows

  1. Analog signal – information is in electric pulses or varying amplitude
  2. Digital Signal – information is in binary format either 0 or 1.

What are analog signals?

Analog signal is continuous signal for which time varying feature of the signal is representation of some other time varying quantity. Representation of analog signal is shown below.

It is defined as the type of signal that are used to express the quantities that are based on variability of time. The different type of time-based processes such as electrical, mechanical & hydraulic are called as the analog signals.

How Analog signals are transmitted?

The data /signal to be transmitted will be of varying voltage, current, phase with respect to time. The data are represented using two time-varying quantities. By modulating data (combining input signal with carrier signal), under specific frequency the transmission process is done.

Characteristics of Analog Signals:

  • These time-varying electrical signals are Positive or negative values at the minimum and maximum. It can either be regular or irregular.
  • Utilizing continuous data, analogue signals operate. It facilitates the measurement of physical or natural qualities.
  • The output form of an analogue signal is similar to a curve, line, or graph, thus not everyone will find it useful.

Examples of Analog Signals:

  • Conventional model transmitters
  • Video signals broadcast using outdated equipment 
  • Analog phones using wires which give high quality & good clarity of sound
  • Analog Watches, AM/FM Radio.

Advantages of Analog Signals:

  • Analog signal has power to define infinite amount of data.
  • Density of analog signals is much higher than digital signals.
  • Analog signals have easy processing.  
  • Cost effective & easily portable.
  • Bandwidth usage is limited and provide more accurate response.

Disadvantages of Analog Signals:

  • Unwanted noise in recording.
  • When transmitting data beyond certain distance the signal is affected by unwanted disturbance.
  • Generation loss.

What are Digital signals?

Digital signals are discrete in form. They are also discontinuous in nature. Digital signals are based on the sending information in binary values. These signals are more reliable in the computer field as it is used to transfers data. Digital signal representation is shown below. 

How Digital signals are transmitted?

The digital signal to be transmitted in binary bits form. For transferring the data between two systems, a message signal is passed through modulator circuit then transmit through a medium and finally it is passed through demodulator to receive the message signal at the other end.

Characteristics of Digital signals:

  • Digital signals are time-separated signals.
  • Because digital signals are flexible, they are frequently used.
  • The digital signal has greater accuracy than the analogue signal.

Examples of Digital signals:

  • Digital pen & Digital watches.
  • Digital images & video signals.
  • Computer, Mobile Phone, Digital Camera.

Advantages of Digital signals:

  • Transmitting speed is high.
  • Ability to transfer more data.

Disadvantages of Digital signals:

  • Greater bandwidth is essential.
  • Limited speed from processor side
  • Information will be lost because of sampling techniques.
  • Data processing is complex.

Difference between Analog and Digital signals:

ParametersAnalog SignalDigital Signal
Types of SignalsContinuous SignalDiscontinuous Signal
WavesSine wavesSquare waves
RepresentationInformation is represented in continuous range of values.Information is represented in discrete or binary values.
Circuit TechniquesAnalog technology (Modulation & Demodulation) is used. Circuit is not flexible.Sampling technique includes modulation & demodulation process. Implementation of circuit is easy.
NoiseMore response to noise leads to reducing accuracy of signal.Digital signals are less affected due to noise when compared to analog signals.
Power ConsumptionMore power consumed by analog signal.Less power consumption.
Bandwidth& impedanceBoth bandwidth & impedance is less.More bandwidth & higher order impedance of 100 Mega ohm.
CostCost effectiveHigh Cost when compared to analog signal
PropertiesAnalog signal does not require language and synchronization techniques.Requires specific synchronization, and Specific language for transferring data.
ErrorLess observational error.Error free signal transmission.

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