It isn't always.
Baseband analog signals have no carrier.
For transmission through a radiowave.
Carrier
When you convert digital signal to analog, it is called as an analog signal. The device used is called digital to analog converter.
Digital signal processing is the best compared to analog signal. It is because the digital signal is moreefficienterror freeimmune to noisethan an analog signal
An analog-to-digital converter is a device which converts an infinite resolution analog signal to a finite resolution digital signal.
Analog Modulation
For transmission through a radiowave.
In a analog transmitter the RF carrier have to be modulated with the analog signal either by AM or FM where in digital transmitter the carrier is simply switched on and off a off = a zero and on = a one
Frequency modulation and Phase modulation
Carrier
The most fundamental difference, I would say, is that Amplitude Modulation (AM) is a kind of Analog Modulation Technique (the modulation is applied continuously in response to the analog information signal) where Amplitude Shift Keying is a type of Digital Modulation Technique ( an analog carrier signal is modulated by a discrete signal, digital modulation methods can be considered as digital-to-analog conversion, and the corresponding demodulation or detection as analog-to-digital conversion. The changes in the carrier signal are chosen from a finite number of M alternative symbols).
A: A radio transmission signal has an envelope where the carrier frequency are enveloped by the analog signal before demodulation. it can easily be seen by an oscilloscope
In Analog communication, the analog message signal modulates some high carrier frequency inside the transmitter to produce modulated signal.this modulated signal is then transmitted with the help of a transmitting antenna to travel through the transmission channel. At the receiver, this modulated signal is received and processed to recover the original message signal. Example: AM , FM radio transmission an TV transmission.
An DAC convert digital signal to analog signal i.e Digital to Analog Converter. An ADC convert analog signal to digital signal i.e Analog to Digital Converter.
When you convert digital signal to analog, it is called as an analog signal. The device used is called digital to analog converter.
Digital signal processing is the best compared to analog signal. It is because the digital signal is moreefficienterror freeimmune to noisethan an analog signal
The frequency of the carrier of an analog signal can be anything you want it to be. Just be sure you notify the intended recipient of the frequency you're using to transmit, otherwise he won't be able to find your signal on his radio dial and receive your message.