Carrier is itself a High frequency signal,both are same my friend if you still have doubt your welcome.
A.m. can be applied to a carrier of any frequency.
FSK stands for Frequency Shift Keying, a method used in communication systems to encode information by varying the frequency of a carrier signal.
in frequency modulation, frequency of carrier signal changes. so frequency variations of carrier convey all the information in frequency modulation.
A carrier frequency is a single radio frequency with steady amplitude. Alone, it would sound like silence on a receiver. This is the frequency that a radio receiver is tuned into. To be of use in communication, this carrier wave has to be changed in time with another signal (usually audio), called 'Modulation' It can be turned on and off using a Morse key. It can be changed by shifting the frequency, FM. It can be changed by varying the amplitude, AM. It can be changed by adding or subtracting audio to the carrier. Single Side Band. It can have data applied by shifting between two carrier frequencies. FSK. (Frequency shift keying.) It's called a carrier, because it is the carrier of information without necessarily being the information itself.
to shift the frequency of information signal ,at the frequency domain to a higher frequency ...so the information can be transmitted to the receiver .
carrier is constant frequency information is a change from that constant
Carrier Wave: A carrier wave is a high-frequency electromagnetic wave that is used as the "carrier" or the base signal in a modulation process. It is typically a pure sine wave with a constant frequency and amplitude. The carrier wave by itself does not carry any information; it serves as a vehicle to carry the information from one location to another. In AM and FM radio broadcasting, the carrier wave is the primary signal transmitted by the radio station. Modulated Wave: A modulated wave is the result of combining the carrier wave with an information signal, such as an audio signal or data. Modulation is the process of varying the characteristics of the carrier wave (either its amplitude or frequency) in accordance with the information signal. There are two common types of modulation: Amplitude Modulation (AM) and Frequency Modulation (FM). In AM, the amplitude of the carrier wave is varied in proportion to the amplitude of the information signal. This variation encodes the information onto the carrier wave. In FM, the frequency of the carrier wave is varied in proportion to the amplitude of the information signal. This variation encodes the information onto the carrier wave. The modulated wave contains the information that needs to be transmitted, and it can be demodulated at the receiving end to retrieve the original information.
If you subtract from the carrier frequency the frequency of the tone that modulates it, then filter out the carrier frequency, then you have a lower sideband frequency. If you add to the carrier frequency, filter out the carrier, then you have an upper sideband frequency.
to shift the frequency of information signal ,at the frequency domain to a higher frequency ...so the information can be transmitted to the receiver.
recovering the information content from modulated carrier wave
Because in radio communication a signal is specified by its frequency, In AM the carrier frequency is fixed.. we cant limit or manipulate it as it will might switch us to another carrier in the atmosphere... manipulating however amplitude (as in FM) doesn't switch us to another channel... so remember in radio communication signal is specified by its frequency whether FM or AM..
Every information sent and received through satellite communication has to have an address to enable the communication process of signal delivery and reception. This naming of the signal is made in the form of a specific frequency. For example each TV channel operates on a unique frequency of it's own. When that frequency is called (tuned technically) out of a spectrum in that band, the chosen frequency gets selected. Since satellite transponders operate at very high frequency, modulation of the signal on to the carrier is difficult. Hence modulation is carried out at a much lower frequency. Such modulated signal is raised to the required frequency( name or address as stated above) that supports the satellite band and the transponder. The equipment used to elevate the frequency of the low frequency carrier (known as Intermediate Frequency) to the satellite transponder frequency is UP CONVERTER C.K.Vasudeva Bangalore