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What is lowlevel amplitude modulation and highlevel amplitude modulation?
low level amplitude modulation occurs when the carrier signal is first modulated and then amplified,whereas in high level modulation,the carrier signal is first amplified and then is modulated.
What is high level modulator?
High level AM modulation is a type of modulation using class c (90 percent) amplifiers. The system uses medium power tubes or transistors and is bulky.
In what stage modulation is done on high power amplitude modulation transmission?
In high power AM transmission, modulation is done at
Compare high level modulation and low level modulation?
IN LOW LEVEL MODULATION THE MODULATING SIGNAL IS APPLIED NEARER THE CARRIER OSCILLATOR N IN HGH LEVEL MODULATION MODULATING SIGNAL IS APPLIED AT OUTPUT OF FINAL POWER AMPLIFIER OR FAR FROM CARRIER OSCILLATOR... IN OTHER WORDS :::: IN HAIGH LEVEL MODULATION THE AF SIGNAL IS APPLIED TO COLLECTOR OR PLATE AS THEIR RESPECTIVE DEVICES..... N IN LOW LEVEL MODULATION AF SIGNAL IS APPLIED AT BASE OR GRID IN TRANSISTOR AND TUBES RESPECTIVILY IN LOW LEVEL MODULATION THE MODULATING SIGNAL IS APPLIED NEARER THE CARRIER OSCILLATOR N IN HGH LEVEL MODULATION MODULATING SIGNAL IS APPLIED AT OUTPUT OF FINAL POWER AMPLIFIER OR FAR FROM CARRIER OSCILLATOR... IN OTHER WORDS :::: IN HAIGH LEVEL MODULATION THE AF SIGNAL IS APPLIED TO COLLECTOR OR PLATE AS THEIR RESPECTIVE DEVICES..... N IN LOW LEVEL MODULATION AF SIGNAL IS APPLIED AT BASE OR GRID IN TRANSISTOR AND TUBES RESPECTIVILY
What is the advantage of high level modulation over low level modulation?
Low level modulation: Class B (75%max) power amplifiers are used which offers better quality modulation i.e low distortion probability. Minimize generation of harmonics. The advantage of using a linear RF LP amplifier is that the smaller early stages can be modulated, which only requires a small audio amplifier to drive the modulator. High level modulation: Class C (90%max) power amplifiers are utilized which improves greatly the efficiency of the transmitter but low in quality i.e higher distortion level is expected. A large audio amplifer will be needed for the modulation stage, at least equal to the power of the transmitter output itself. Traditionally the modulation is applied using an audio transformer, and this can be bulky. Direct coupling from the audio amplifier is also possible (known as a cascode arrangement), though this usually requires quite a high DC supply voltage (say 30V or more), which is not suitable for mobile units.
What is the unit for modulation index?
Modulation index is also called as Modulation depth. The modulation index of a modulation scheme describes by how much the modulated variable of the carrier signal varies around its unmodulated level.
What are the advantages frequency modulation amplitude modulation?
Frequency modulation have some advantages over amplitude modulation, FM is not sensitive to the amplitude noise, and have high efficient use of transmitted power
What is the two level digital puse amplitude modulation?
In Pulse Amplitude Modulation, amplitude of pulse varies with signal. Theoretically in analog modulation there infinite levels of amplitudes or continuous amplitude. Two level PAM is digital modulation where only 2 number of levels are there. Thus signal is quantized to two discrete levels.
What is positive and negative modulation?
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.
What is c4fm?
The C4FM is the Constant Envelope 4-Level Frequency Modulation.
What are the advantages of pulse position modulation?
Pulse position modulation offers high noise immunity, efficient use of bandwidth, and easy implementation with digital circuits. This modulation technique is particularly useful in applications requiring high data transmission rates and reliable communication in noisy environments.
How velocity modulation is different from normal modulation?
As we know normal modulation is superimposing the wave with another carrier signal but the concept of velocity modulation is totally different, as The modulation in velocity of a beam of electrons or ions caused by passing the beam through a high-frequency electric field, as in a cavity resonator there is no concept of superimposition.
