0
There are three major types of modulation:
AM, Amplitude Modulation, where the modulation signal is altering the amplitude of the carrier according to its own amplitude, normally this is done in the output stage. Therefor a strong audio signal is necessary at the same or a little less than the power of the carrier, never higher, because that will over modulate the carrier that will resort in distortion of the receiver output. AM is used in the lower band of the RF spectrum.
FM, Frequency Modulation, where the frequency of the carrier is altered by the audio signal. When the amplitude of the audio is going higher the frequency go lower. Modulation happen at the oscillator stage, therefor a small audio signal is used to modulate the frequency. FM is normally used in the higher frequency range of the RF spectrum, 50MHz and up.
FSK, Frequency-shift keying, used for data transmission, this type of modulation is simply, switching the carrier on and of, a high bit will switch the oscillator on and a low bit will switch it off, in some designs a low will be on and a high off.
Wiki User
∙ 11y ago
Add your answer:
Earn +20 pts
Why is the intelligence signal not in the AM envelope?
The intelligence signal is in the AM envelope.In AM modulation, the carrier is amplitude modulated by the signal. This signal appears as the envelope of the carrier. You can demodulate it by following the peaks on each cycle of the carrier. You can either follow the positive peaks or the negative peaks - it does not matter if the original modulation is symmetrical.
Why carrier signal is always in analog signal?
It isn't always. Baseband analog signals have no carrier.
Discussion about amplitude demodulator?
A modulator modulates the carrier frequency, while a demodulator detects the modulation on the carrier wave and recovers the original lower frequency waveform at the destination. For many years the modulated carrier wave was converted to a radio signal. Now it is often an electrical signal which is sent down a teleohone line; the information is usually a set of pulses going between computers. When computers are connected to each other in a two-way conversation, the MOdulator and DEModulator are combined into a single device called a MODEM.
What is signal modulation?
modulating signal is the message to be carried by the carrier signal.
What is the frequency and wave form of old land line phone carrier?
First answer.The landline phone has no carrier frequency it is a baseband signal with a 3KHz bandwidth.Correction:So there is a signal that can handle a 3KHz bandwidth, what do you call that signal? I call it a carrier, if you don't have a carrier, you will need to amplify the audio every 30 meters else you will end up with no audio at the end of the line. So there is a carrier on all phone lines. Note the carrier signal are up to 90 VPP and is AM modulated at the instrument, but in digital systems the carrier are switched on and of, FSK modulation.
Why is the intelligence signal not in the AM envelope?
The intelligence signal is in the AM envelope.In AM modulation, the carrier is amplitude modulated by the signal. This signal appears as the envelope of the carrier. You can demodulate it by following the peaks on each cycle of the carrier. You can either follow the positive peaks or the negative peaks - it does not matter if the original modulation is symmetrical.
Could Light be used as carrier for intelligence signal?
Absolutely
What do modem stand for?
MODEM stands for MOulator/DEModulator. It is a device that translates a data bit stream from a digital device into a modulation signal and modulates a carrier for transmission over wires. Since it can also receive data streams it must be able to demodulate the carrier and translate the modulated intelligence back into a data bit stream.
What extracts the intelligence from a high frequency carrier in FM receivers?
One method to extract the intelligence (signal) from a high frequency carrier in FM receivers is with a phase locked loop.
What a modems used for?
A modem is a modulator and demodulator device that modulates the analog carrier signal to encode the digital information and demodulates the signal to decode the transmitted information. The modem usually produces a signal that can be transmitted easily and decoded to reproduce the original data.
How the modem change the analog signal?
MODEM stands for modulator/demodulator. Outgoing it modulates a carrier wave with information and transmits this data on a wire or through the air. When it receives a modulated signal it demodulates the signal and separates out the information.
How does a modem work on osi physical layer?
Modem (from modulator-demodulator) is a device that modulates an analog carrier signal to encode digital information, and also demodulates such a carrier signal to decode the transmitted information. The goal is to produce a signal that can be transmitted easily and decoded to reproduce the original digital data. That is the definition of Layer 1.
What are the parameters of high frequency carrier that may be varied by a lower frequency intelligence?
Following are the 3 parameter by which high Frequency carrier can be varied by low frequency intelligence signal 1) Amplitude 2) Phase 3) Frequency
What are 'definitions'?
aural modulator used to extend the audio information and aural modulator also modulates visual carrier signal.
What does a radio wave transform radio waves into?
Sound.More informationAfter a modulated carrier signal has been received through the radio's aerial, the radio de-modulates it to release the live sound as picked-up from microphones in the radio studio (or was taken from recordings), which was then used to modulate the carrier signal at the transmitter.De-modulation that is done by a radio receiver can be described very simply as "removing the carrier signal to produce the sound".
What does a radio transform waves into?
Sound.More informationAfter a modulated carrier signal has been received through the radio's aerial, the radio de-modulates it to release the live sound as picked-up from microphones in the radio studio (or was taken from recordings), which was then used to modulate the carrier signal at the transmitter.De-modulation that is done by a radio receiver can be described very simply as "removing the carrier signal to produce the sound".
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.
