How do we use AM&FM for communiction when each signal has its unique amplitude,frequency & harmonics?

Question

Each signal is represented by its unique instantaneous amplitude,frequency & many harmonics i.e signal is a function of both amplitude & frequency simultaneously.So how can we just transmit a signal only by AM or only by FM(modulation of carrier wave according to instantaneous amplitude of modulating signal).
Why dont we consider the frequency of modulating signal 'also' during modulation(AM or FM).

Answer 1

You are much too confused to be able to answer your question. Go an review amplitude modulation and frequency modulation and what constitutes a "signal." A "carrier wave" is a "signal" that has only its wave characteristics as information (static and harmonics do not add information). To make it "carry" useful information, it must be modulated in a way that can be demodulated to extract the data.
"The frequency of modulating signal" is gibberish.

Answer 2

Amplitude modulation is the easiest modulation to grasp intuitively. While it is true that a signal is represented by its amplitude and frequency, the carrier is a constant amplitude and frequency until modulated by the signal we desire to transmit. In order to transmit the real signal which may have a complex variation in amplitude and frequency, we modify or modulate the carrier amplitude by this signal. When this is done, the sign wave of the carrier is still present at its higher frequency, but its amplitude or height will vary directly in proportion to the signal. The variation in the amplitude will reflect the lower frequency of the signal...it appears that the signal to be transmitted has been sampled by the carrier frequency...this is perhaps a more modern way of viewing this in this digital age. The "envelope" of the modulated carrier can be sketched and the original signal will be seen riding on top of the carrier.

In FM modulation, the same thing occurs except that the frequency is varied in proportion to the signal.

In terms of instantaneous amplitude, frequency, and harmonics...harmonics are taken care of by considering that the signal is already composed of the frequencies which make up its complex nature. This signal is completely encompassed by a bandwidth. The bandwidth of this signal must be much smaller than the carrier frequency to be successfully transmitted.

Hope this helps.