The nature of a photon is not solely defined by its frequency. While the frequency of a photon determines its energy and the corresponding color of light, it does not determine the specific shape or structure of the waveform that carries the signal.
When we talk about different types of signals, such as sawtooth, square, or pulse-shaped signals, we are referring to the modulation of a carrier wave. In radio communications, the carrier wave is usually an electromagnetic wave generated by an antenna. The information or signal to be transmitted is superimposed or modulated onto this carrier wave.
The modulation scheme determines how the signal is encoded onto the carrier wave. The different modulation techniques, such as amplitude modulation (AM), frequency modulation (FM), or pulse modulation, allow us to transmit various types of signals.
In these modulation schemes, the carrier wave remains at a fixed frequency, while the shape or pattern of the waveform varies to represent the information being transmitted. This variation can include changes in amplitude, frequency, or pulse duration.
When you transmit a signal using an antenna, the photons themselves do not change shape or waveform. The photons are carriers of energy, and their behavior is governed by the laws of quantum mechanics. However, the information encoded on the carrier wave can be recovered by a receiver and decoded based on the modulation scheme used.
In summary, the frequency of a photon determines its energy, but it is the modulation scheme applied to a carrier wave that allows us to transmit different types of signals, including sawtooth, square, or pulse-shaped signals. The photons themselves do not change shape; they simply carry the encoded information.