The carrier frequency, as the name implies, "carries" the actual signal to be transmitted. Exactly how this is done depends on the technology being used.
At the other end, the receiver subtracts out (don't take that too literally; again, it depends on the technology used) the carrier frequency, and what's left is the desired signal.
Larger bandwidth and high data rate
probably (the carrier frequency +- the maximum frequency of the pulse train)/(the carrier frequency) but pulses have a lot of harmonics
when the frequency is low , energy will be obviously low. To increase the energy of the signal we need to increase the frequency. This is achieved by multiplying the message signal with the carrier signal (with high frequency).
The process of changing the amplitude of the "carrier" so as to add information to it (modulation) doesn't change the frequency of the carrier. But it does create energy at two other newfrequencies.The new frequencies are equal to (carrier frequency) plus and minus (the modulating frequency). These are referred to as the upper and lower sidebands.The upper sideband is an exact copy of the modulating signal, but with every component of it shifted up by an amount equal to the carrier frequency. The lower sideband is a mirror image of the upper sideband, with every frequency component in it reflected about the carrier frequency.
In FM the carrier is still present and the power is still there, at a constant amplitude at the transmitter. It's only the frequency of the carrier that alters, in time with the audio applied to it. The louder the sound the further the frequency shifts.
If the modulating system is AM (Amplitude Modulation) then the amplitude of the carrier wave changes with the amplitude of the modulation. On a specrum analyser that shows up as frequency sidebands. If the frequency of the carrier waves depends on the amplitude of the modulating signal that is called FM (frequency modulation). On a spectrum analyser that shows up as sidebands also.
to make available carrier frequency at the receiver
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.
for colour sub carrier frequency
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.
in frequency modulation, frequency of carrier signal changes. so frequency variations of carrier convey all the information in frequency modulation.
Explain the need for carrier frequency stability in radio transmitters?
If your Motorola phone is unlocked, then yes, you can use it abroad. You just have to make sure that the carrier that you are going to use the phone on can support the Motorola L6. By this it means that, the frequency that the carrier run on is compatible to the frequency of the phone.
probably (the carrier frequency +- the maximum frequency of the pulse train)/(the carrier frequency) but pulses have a lot of harmonics
Upper sideband = Carrier frequency + modulating frequencyLower sideband = Carrier frequency - modulating frequency
FM stands for frequency modulation. The definition is: when the frequency of the carrier wave is changed in accordance with the intensity of the signal, it is called frequency modulation. In frequency modulation, only the frequency of the carrier wave is changed in accordance with the signal. However, the amplitude of the carrier wave remains unchanged.
The Carrier....
Following are the 3 parameter by which high Frequency carrier can be varied by low frequency intelligence signal 1) Amplitude 2) Phase 3) Frequency