0
Which component of an AM transmitter generates the carrier frequency?
Wiki User
∙ 8y ago
The oscillator circuit, which is usually quartz crystal controlled with the quartz crystal in a temperature regulated oven to stabilize its resonant frequency.
Wiki User
∙ 8y ago
Add your answer:
Earn +20 pts
Why the strength of the carrier in FM spectrum is not constant?
You can think of it this way: When the FM carrier is modulated, you know that "sidebands" appear in the frequency spectrum, at frequencies both above and below the carrier frequency. These are new signals, with energy being transmitted at each sideband frequency. But the power out of the transmitting hardware hasn't changed. Unlike the case with AM, the modulation process most likely takes place in a low-level stage of the transmitter, and the modulator supplies no RF power. Since new signal energy appears at new frequencies separated from the carrier frequency, the energy has to come from somewhere. No RF energy is added in the transmitter, so the sideband energy comes out of the carrier signal. That's a very unscientific and un-mathematical way to look at it, but I don't think it's essentially inaccurate.
Is it true that information can be carried on a carrier wave by changing or modulating either the amplitude or frequency?
in frequency modulation, frequency of carrier signal changes. so frequency variations of carrier convey all the information in frequency modulation.
How do you choose carrier frequency value?
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.
Why do you need a carrier wave?
In radio transmission, you could theoretically transmit radio signals at audio frequencies. However, because the wavelength of electromagnetism at audio-like frequencies is Huge and the frequency of a radio transmitter dictates the size of the antenna and the power requirement, you would need A Very Big Antenna and a Very Big Power Supply to do this. So, we've learned to transmit at higher "carrier" frequencies, modulating either the amplitude or frequency of the carrier signal with our audio and subtracting the carrier at the receiver end.
What is a SSBSC signal?
Single Side Band Suppressed Carrier. This is a modification of AM (Amplitude Modulation) that both reduces required transmitter power and signal bandwidth. The carrier is first modulated by the signal the same as in ordinary AM, then is sent through a bandpass filter to remove one sideband and the carrier. To demodulate it and recover the original signal the receiver must reinsert the carrier using a BFO (Beat Frequency Oscillator) and Mixer.
What component of an AM transmitter generates the carrier frequency?
The classic AM transmitter layout is a master oscillator, followed by a "pen", or penultimate amplifier, followed by a PA or power amplifier. The master oscillator, which is probably crystal controlled, generates the carrier frequency.
What is master oscillator?
it generates the carrier frequency of the output after passing a signal.
How does the frequency change in a FM transmitter?
-- the modulation index varies -- the instantaneous deviation varies -- the amplitude of the carrier component varies -- the spectrum of sidebands varies -- the total occupied bandwidth varies
What happens to the power in the carrier after frequency modulation?
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 frequency in AM does not change then how are these sidebands formed?
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 transmitter the rate of frequency swing is determined by the?
The frequency with which the carrier frequency is deviated is exactly the modulating frequency, i.e. the frequency of the sound that makes up the music or voice announcement, stereo pilot, SCA subcarrier, etc.
Why oscillator is needed in transmitter circuit?
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.
What is the technical difference when it comes to the implementation of AM and FM?
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
What causes sideband frequency?
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.
What is FM transmitter and what are the different FM transmitters?
FM transmitter : In this case the frequency of a carrier signal is modulated/altered in accordance with that of frequency of modulating signal. TYPES OF FM TRANSMITTER: 1> directly modulated FM transmitter. 2>indirectly modulated FM transmitter. an FM transmitter is a portable device that plugs into the headphone jack or proprietary output port of a portable audio or video device, such as a portable media player, CD player, or satellite radio system. The sound is then broadcast through the transmitter, and plays through an FM broadcast band frequency. Purposes for an FM transmitter include playing music from a device through a car stereo, or any radio.
What is coherent and non coherent detection reception?
1AnswerA coherent detector uses the knowledge of the phase of the carrier wave to demoduleate the signal.it's simply a product device , which multiply the AM signal by a sinusoidal signal having the same carrier frequency , followed by a low pass filter ( LPF). The product will shift the AM signal to 0 Hz and double carrier frequency , and the LPF will eliminate the later component.2ANSWER:Coherent detectioninCoherent detectionrequires carrier phase recovery at the receiver and hence, circuits to perform phase estimation.Sources of carrier-phase mismatch at the receiver:inPropagationtalking causes carrier-phase offset in the received signal.inThe oscillators at the receiver which generate the carrier signal, are not usually phased locked to the transmitted carrier.coherent detection: Huge need for a reference in phase with the received carrierinLess complexity compared to incoherent detection at the price of higher error rate.Coherent ( synchronous ) detection: in coherent detection , the local carrier generated at the receiver in phase locked with the carrier at transmitter .Non coherent ( envelope ) detection : this type of detection does not need receiver carrier to be phase locked with transmitter carrier
What is the difference between analog and digital transmitter?
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
