Fact Checked

What is an Analog Signal?

Jason C. Chavis
Jason C. Chavis

Analog signals are a representation of time varying quantities in a continuous signal. Basically, a time variance is presented in a manner in which some sort of information is passed using various types of methods, including electrical, mechanical, hydraulic, or pneumatic systems. Unlike digital signals, which use a numeric method of transmitting information, analog signals use small fluctuations in the signal itself to pass information.

These signals act essentially like simulations of a continuous time varying quantity. They duplicate the features of the actual quantity by presenting a different one. In other words, they use one method of recording information and transfer it to a different format that, in turn, presents the information in that medium.

Television rabbit ears to pick up analog signal.
Television rabbit ears to pick up analog signal.

Each analog signal uses a property of the final medium to convey the information for the signal. For example, a thermometer will use the heat of a particular object to determine its temperature. The heat is then transferred to mercury, which changes its position to display the temperature information on the gauge.

The most common analog form of transmission occurs electrically. In order for this to happen, a voltage must be sent at a specific frequency. The flow of this electrical charge is known as current. By controlling the frequency of the current, information can be transmitted to another medium and presented on that medium. For example, magnetic tape on a cassette conveys information to the stereo, which transmits it as electrical signals of specific frequencies, which in turn tell the speakers what noise to make.

Cassette tape.
Cassette tape.

Analog signals have a great advantage over digital signals in that they have a much higher density that can present more refined information. Essentially, there is the potential for the signal resolution to be infinite. In addition, the process to create this type of signal is achieved much more simply. By merely adjusting the time quantities, information can be presented.

Most speakers are designed to broadcast an analog signal.
Most speakers are designed to broadcast an analog signal.

Disadvantages of the system include the tendency to create unwanted variations in the information transmission such as noise, which can occur in random patterns. When a signal is copied and potentially re-copied, each subsequent version exhibits more of the random patterns, making information transmission harder and ultimately causes signal loss.

In order to avoid these disadvantages, or at least mitigate their effects, the concept of modulation can be used. The base signal is modified in some way to help retain the information as it is transmitted. An example of this is when the amplitude of a waveform is altered in what is known as amplitude modulation. Other options for retaining an electric signal over different generations are by using increased shielding or different cable types twisted together.

You might also Like

Discussion Comments


Analog signals transmit information for such things as what?


I think the difference in digital to analog signals is better expressed by comparing electronic input from one device to another, such as the difference between d-pad input and analog stick input.

Human ears can hardly discern the difference in well maintained and recorded vinyl records and today's lossless audio formats. Yes, there is some loss in the conversion, but with the right equipment, it's negligible to the senses.


I think CD's sound great. Technology has overcome any kind of barrier or loss of quality in signal that an analog to digital conversion could create.

Some audiophiles will say they can hear the difference between a vinyl record and a CD. I can't and I don't think most people do.


Analog signals are why records can sound better then compact discs. Whenever you break apart a solid waveform into digital pieces, no matter how small they might be, there is always loss in the quality of the curve.

Digital signals have revolutionized our world but it might be worth our time and effort to determine what kind of media is best presented over and analog or digital signal.

Post your comments
Forgot password?
    • Television rabbit ears to pick up analog signal.
      By: James Steidl
      Television rabbit ears to pick up analog signal.
    • Cassette tape.
      By: Radoslaw Maciejewski
      Cassette tape.
    • Most speakers are designed to broadcast an analog signal.
      By: kornienko
      Most speakers are designed to broadcast an analog signal.