What is Propagation Delay?

Malcolm Tatum

Propagation delay is the amount of time that is necessary for a digital signal to travel from a point of input to a point of output. Depending on how the delay is measured, the results may be reported in microseconds, nanoseconds, or picoseconds. Depending on the link length and the actual propagation speed, the amount of the delay will vary from one application or execution to the next. Both memory chips and microprocessors are subject to some degree of propagation delay.

Man holding computer
Man holding computer

The idea of propagation delay is found with just about any electronic device used for the conveyance of some type of data. With computers, the duration of a delay has a direct impact on the speed at which the system is able to process different commands. When it comes to providing wireless communications functions such as voice communications, propagation delay impacts the real time aspect of interactive communications. With all applications, the goal is to minimize the duration of the delay as much as possible, without placing an inordinate amount of stress on the circuits and equipment being used for the execution.

The level of propagation delay has a direct impact on the efficiency of data transfer and reception, in that the duration of the delay determines how quickly a recipient can begin to make use of the data and execute a follow-up action. For example, wireless communication options during the early to middle portion of the 20th century often involved a slight delay between the point of origin and the point of termination. This made it necessary for the recipient to wait for the entire message from the sender to arrive, then begin the task of providing a response. Over time, wireless communications became more efficient, allowing the propagation delay to be reduced significantly, eventually allowing for interactive voice communications today that are secure and in real time, with no perceptible delay.

Along with innovations in voice communications that virtually eliminate propagation delay, evolving computer technology has also made it possible to execute commands and complete tasks in a fraction of the time once required by the electronic brains of the middle 20th century. Searching databases or even browsing online for information often occurs with little to no apparent delays for individuals executing the search commands. The end result is that research that once took hours can now be managed within a matter of seconds or minutes, a factor that has aided many businesses in utilizing resources more effectively and increasing the chances of generating revenue without the need to expend additional resources.

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