Today, signals are determined by state and local authorities and can vary from one region to another.

Each signal varies in terms of frequency and different signals are used to communicate different aspects.

A signal reflected by such meteor ionisation can vary in duration from fractions of a second up to several minutes for intensely ionized trails.

That doesn't look like a deep oscillation, otherwise the signal would vary even before the fadeout.

The signal will vary in strength depending on how far distant the viewer is from the Tygerberg site.

The signal never varied and was slowly picking up strength.

The second harmonic signal will vary with the azimuth angle of the sample due to the symmetry of the atomic and electronic structure (Figure 2).

Although signals vary widely between countries, and even between railways within a given country, a typical system of aspects would be:

The signal used for supervision varies depending on the type of trunk being used.

The size of place fields and their signal to noise ratio varies depending on the region of brain in consideration.