In periodic analog signals, which of the following is NOT a parameter to…

Concept

A periodic analog signal is built from sine waves, and a single sine wave is completely described by exactly three independent parameters: peak amplitude (its maximum value, i.e. the strength of the signal), frequency (the number of cycles it completes per second, in hertz), and phase (its position in the cycle at time zero, measured in degrees or radians).

Wavelength is a derived, spatial quantity: it is the distance a single cycle occupies as the wave travels through a medium, and it equals propagation speed divided by frequency. Because it depends on the medium's speed rather than describing the time-domain waveform itself, it is not counted among the three defining parameters of a sine wave.

Applying it here

The question asks which option is NOT one of the parameters used to describe a sine wave. Matching each option against the three defining parameters:

• Peak amplitude — the maximum displacement from the centre line; one of the three defining parameters.

• Frequency — cycles per second; one of the three defining parameters.

• Phase — offset of the cycle at the time origin; one of the three defining parameters.

• Wavelength — a spatial distance derived from speed and frequency; it characterises the wave as it propagates through space, not the sine waveform itself, so it is NOT one of the three defining parameters.

Result

Three of the options (peak amplitude, frequency, phase) are the standard descriptors, so the one that is NOT a defining parameter is wavelength.