In older Microwave link systems they used basic FM or Phase Modulation, modern MW radio links use complex modulation protocols, i.e. 64 QAM, 256 QAM among several other modern modulation types which nowadays enable very large bandwidths and also enables a much more error free end to end signal. These new modulation techniques are also used by your computers Wi-Fi which also operate in the Microwave bands.
Amplitude modulation for video and frequency modulation for audio
frequency modulation
It is a type of Pulse modulation as in PPM the position of pulse of carrier pulse train is varied in accordance with the modulating signal.
in order to transmit the video signal amplitude modulation is used. the composite video signal has distinct polarity of black and white levels in the picture.1.positive modulation :- in this type of modulation, increase of brightness toward white causes increase in carrier amplitude peak white has 100% modulation while black and sync level have lower and minimum modulation respectively2.negative modulation :-in this type of modulation,the sync tip level are at 100%.blanking level correspond to black is at 75%and increase in brightness toward white causes decrease in carrier amplitudeNegative modulation is preferred over positive modulation because impulse interference is difficult to deal with and random increase in signal is similar to existing sync pulse.these interference result in generation of black spot and white blobs.
Pulse-Amplitude Modulation
Amplitude Modulation, the method of sending information through radio frequencies.
amplitude modulation
depends on type of modulation and other variables
The Role of modulation in signal transmission varies because of what type of signal should be modulated.Then how long it should be travel in air.All these points are considered, when we go before modulation.Suppose we are transmitting vedio signal means it should be only Amplitude Modulated signal.If we transmitting audio signal means it should be Frequency Modulated Signals.So the Role of the modulation is varies in signal transmission.
Amplitude Modulation (AM) is used for the picture portion of a television transmission while Frequency Modulation (FM) is used for the audio portion.
The most fundamental difference, I would say, is that Amplitude Modulation (AM) is a kind of Analog Modulation Technique (the modulation is applied continuously in response to the analog information signal) where Amplitude Shift Keying is a type of Digital Modulation Technique ( an analog carrier signal is modulated by a discrete signal, digital modulation methods can be considered as digital-to-analog conversion, and the corresponding demodulation or detection as analog-to-digital conversion. The changes in the carrier signal are chosen from a finite number of M alternative symbols).
Double-sideband modulation is a type of amplitude modulation where both upper and lower sidebands are present with the carrier signal. The dynamic characteristic of double-sideband modulation is that it allows for efficient use of bandwidth but is susceptible to fading and interference.
A transmitter takes in a signal and modulates a carrier wave to send that signal out. A mixer takes the signal and modifies it according to the type of transmission being done. AM means amplitude modulation. The signal determines the intensity of the transmitter signal. FM means frequency modulation. The transmitters frequency is changed by the incoming signal.There are several ways of sending a signal. Side band and other methods you can read about.
Aplitude ModulationAn AM transmitter is a Amplitude Modulated transmitter where the amplitude of the Radio Frequency signal is modulated, usually used in the lower frequency bands where the frequency is to low for Frequency Modulation (FM), it was the first type of modulation used in radio communication FM was developed in the late 1950's and is not sensitive to static interference as AM AnswerAM is Amplitude Modulation that is the RF signals amplitude is modulated with the audio signal. this modulation is done because the audio signal being of low frequency cannot be transmitted to longer distance so the audio signal is amplitude modulated with RF signal and then transmitted into the air