Propagation Delay

Propagation delay is the time it takes for a signal (such as an electrical signal in a circuit or a data packet in a network) to travel from the source to the destination.  It is used in communication and networking systems, particularly in determining the performance and timing of data transfer. 

Several Factors Influence Propagation Delay

Distance  -  The farther the signal has to travel, the greater the propagation delay.
Transmission Medium  -  The material through which the signal is transmitted affects its speed.  For example, signals travel faster in optical fiber than in copper cables.
Speed of Signal  -  The speed at which the signal propagates depends on the medium and is often a fraction of the speed of light (in vacuum, around 299,792 km/s).
In Networks  -  Propagation delay is the time it takes for a packet to travel across a network from sender to receiver.  It's one of the factors contributing to network latency.
In Circuits  -  In digital circuits, propagation delay refers to the time it takes for a signal to propagate through a logic gate or circuit element.

Propagation delay is typically measured in nanoseconds (ns) or microseconds (µs), and minimizing it is important for high-speed systems.  The formula for propagation delay depends on the context in which it's used.  The most common contexts are networking and electronics (such as in digital circuits).

 

Propagation Delay formula
\( D_{prop} \;=\; D \;/\; S \)     (Propagation Delay) \( D \;=\; D_{prop} \; S \) \( S \;=\; D \;/\; D_{prop} \)
Symbol	English	Metric
\( D_{prop} \) = Propagation Delay	-	\(ms\)
\( D \) = Physical Distance Between the Source and Destination	-	\(m\)
\( S \) = Speed at which the Signal Travels Through the Medium	-	\(ms\)