Terminology » Data vs. Signal : Difference between Data and Signal

Data vs. Signal : Difference between Data and Signal

data communication signal digital signal analog signal data rate

All data transmitted over a channel exists either in analog or digital form. Data is manipulated into a signal form that’s suitable for the transmission channel. Just like data, signals can also be analog or digital. This leads to four possible combinations:

Analog data converted into an analog signal (e.g., telephone).
Digital data converted into an analog signal (e.g., modem).
Analog data converted into a digital signal (e.g., codec).
Digital data converted into a digital signal (e.g., digital transmitter).

Data element vs Signal element

As shown in the image above, one data element can be represented by two signal elements. The ratio ‘r’, which defines the number of data elements carried by each signal element, would be 1/2 in this case. Conversely, two data elements can be represented by one signal element, giving an ‘r’ value of 2/1 (i.e., 2). For example, QPSK modulation has an ‘r’ value of 2 because it maps two bits to 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 the following formula:

Difference between Bit rate and Baud rate

Data can take many forms, including numbers, text, images, audio, or video, and it’s stored in a computer system. Digital data is typically stored as binary ones or zeros. Signals, on the other hand, have three basic parameters: amplitude, frequency, bandwidth, and phase.

Noise and attenuation can affect the signal as it travels through the transmission medium. Signals can be electrical, electromagnetic (EM), or optical. They can also be continuous or discrete. Line coding techniques, like unipolar, polar, and bipolar, are used to convert data elements (digital data) to signal elements (digital signals).

We have understood how data is transformed into signals for transmission. Let us breaks down the fundamental difference between data and signal, two essential concepts for data communication in computer networks.

Data vs. Signal

The following table summarizes the key differences between data and signals across various parameters.

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

Conclusion: Data refers to raw information in the form of bits or symbols, while a signal is the physical form used to transmit that data over a medium. In essence, data is the content, and the signal is the carrier. Understanding both is essential for efficient communication system design.