The direction of this line depends on the relative amplitudes of the two components.
The relative amplitudes of these peaks represent either a binary one or zero.
The eigenvectors (the columns of the matrix U) describe the vibrational direction and the relative amplitude in the different modes.
In other words, for each symbol a different carrier wave is sent with the relative amplitude.
If there is a phase shift between these two, then the combination will have a relative amplitude of (1 + cos φ).
By varying the relative amplitude of the signal sent to each speaker an artificial direction (relative to the listener) can be suggested.
The control which is used to vary this relative amplitude of the signal is known as a "pan-pot" (panoramic potentiometer).
The station identification would be heard once or twice, possibly with different relative amplitudes, depending on the aircraft location.
Its relative amplitude is of the order ΔT 0.13.
The relative amplitudes a and b may, of course, both be equated to unity when convenient.