Explain the need for carrier frequency stability in radio transmitters?
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.
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 three frequency components of an amplitude modulation (AM) wave are the carrier frequency, the upper sideband frequency (carrier frequency + modulating frequency), and the lower sideband frequency (carrier frequency - modulating frequency). These components are responsible for carrying the signal information in an AM wave.
in frequency modulation, frequency of carrier signal changes. so frequency variations of carrier convey all the information in frequency modulation.
Low frequency signal are not able to get propagated throught longer distance. So it is to be carried by a carrier wave. Hence high frequency carrier wave is to be generated by the help of an oscillator. So we need an oscillator here a crystal oscillator to produce high frequency carrier waves.
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
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
typically the carrier frequency has to be at least double the signal frequency but in order to get better results you want to choose a frequency that is at least 5 times the highest frequency you are designing for.
A.m. can be applied to a carrier of any frequency.
A carrier is a high-frequency signal that carries information on a radio wave. The carrier frequency is modulated to encode audio signals, which are then transmitted and decoded by the radio receiver to produce sound. The carrier frequency determines the station you're tuning into on the radio.