Difference between revisions of "Time Delay"

Revision as of 14:38, 24 March 2010

Time delay is the amount of time it takes for a transmitted message to be received. There is always some time delay in any communication, however, the issue becomes more pronounced with distance, and becomes noticeable the further one ventures from the source of the message.

Calculating Time Delay

Radio transmissions do not travel instantaneously; they travel at the speed of light, which we will take to be the speed of light in a vacuum or approximately

<math>c = 300 000 000 m/s</math>

So if a radio transmission comes from a distance d away, it will take t seconds for the transmission to reach us, where

<math>t = \frac{d,c}</math>

which, as you can see is just a rearrangement of the basic definition that velocity is displacement over time.

Because this is a simulation, we have no need of exact values, so we will assume that the Earth is

<math>D_E = 150 000 000 000 \text{m} <\math>

from the Sun, and that Jupiter is

<math>D_J = 780 000 000 000 \text{m} <\math>

from the Sun such that the distance between the two planets is

<math>D = 630 000 000 000 \text{m} <\math>

[Sun]----De----[Earth]-------------D----------------[Jupiter]
     ---------------------Dj------------------------<\pre>

Using these numbers, we can calculate the maximum time delay for a transmission
coming from Jupiter to Earth in the arrangement shown above. Note that the delay would be greater if the Earth were
on the other side of the Sun from Jupiter.

The maximum time delay is then

<math>T = \frac{D,c}
      T = 2100 \text{s}
      T = 35 \text{min}<\math>