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How does differential pulse code modulation lower the bit rate of transmitted signals?
Wiki User
∙ 14y ago
It signals the difference between successive sample sizes
Wiki User
∙ 14y ago
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What is need of space vector pulse width modulation?
due to space vector modulation we can eliminate the lower order harmonics
What is difference between modulator and demodulator?
Modulation is used when information is available in analog form that varies the frequency and/or amplitude of a lower frequency wave, depending on the information it carries. The role of modulation is to place this information onto a carrier frequency that can be transmitted more readily and with least loss of information. There are three fundamental types of modulation - frequency modulation, amplitude modulation and phase modulation. In each of these, a carrier frequency is modulated by a lower frequency, to form a modulated carrier wave. 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 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 signal bandwidth?
Every line has an upper limit and a lower limit on the frequency of signals it can carry. This limited range is called the bandwidth. The signals ranging within the upper limit & lower limit are called bandwidth signals.
What are the advantages and disadvantages of phase modulation?
Advantage - 1. Phase modulation & demodulation is easy compared to Frequency modulation. 2. Phase modulator is used in determining velocity of moving target by extracting Doppler information. Doppler information needs stable carrier which is possible in phase modulation but not in frequency modulation. Disadvantage - 1. Phase ambiguity comes if we exceed its modulation index pi radian(180 degree). 2. we need frequency multiplier to increase phase modulation index. Visit my website http://harshit.org
When you do modulation in time domain you get modulated waveform of modulating signal information and carrier. How can you recognize the upper and lower side bands in time domain modulated waveform?
You need modulation signal(carrier) which is a required signal in order to make envelope of time domained signal(target signal). The modulating signal is imposed on modulation signal.This creates envelope of waveform which is modulated(desired) signal. Now, the desired signals uper and lower sideband of signal strictly depends on modulation signal's bandwidth. Max. peak of that signal is uper sideband and min. peak is lower sideband for this modulated signal.
What is an AM transmitter?
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
What type of transmission is indicated by the term NTSC?
NTSC was the standard used in the US (and some other countries) for transmitting analog color television signals in a backward compatible manner with the original US black and white television signals (developed in 1939 by RCA). It has been superseded by the ATSC digital television standard.It uses the following systems of modulation:vestigial lower sideband amplitude modulation of main carrier with the black and white video signalfrequency modulation of a 4.5MHz subcarrier with the audio signalphase modulation of a 3.58MHz subcarrier with the color signal
What is modulation why do we need modulation?
Sometimes we have to send low frequency information, like the tone of the voice of someone talking on a telephone, over a specific channel that only permits a specific high frequency, such as radio frequencies (RF). So how do we do that? One simple, cost effective, and bandwidth efficient method is to change, or modulate, a known RF signal a certain way. Some common ways of modulating such a high frequency signal are Amplitude Modulation and Frequency Modulation. Each of these modulation techniques has its own advantages and disadvantages and are therefore more useful in certain applications.
What is need of space vector pulse width modulation?
due to space vector modulation we can eliminate the lower order harmonics
What is an infection transmitted by a hypodermic needle transmitted by?
lower down
Do microwaves carry am signals?
They can - any "radio waves" can carry any kind of modulation, so long's the frequency is a few hundred kilohertz or more - lower frequnecies can be modulated, but the rate of data is so slow it may not be worth the effort.
3 How is digital radio different than the types of radio that came before It?
The way the signal is transmitted and processed. FM radios are transmitted via signal generators and amplifiers on the ground while digital radio like Sirius or AM are transmitted via satellites. The digital signals are sent in packets vs. lower frequency radio waves.
What are the amplitude modulation application?
Amplitude modulation is one way to carry information on a carrier, such as a radio signal. Another way is FM (Frequency Modulation). While FM offers greater clarity for audio, and the higher frequencies that FM use offer a wider bandwidth, allowing for more information to be transmitted, one application where FM and digital are not suitable are Aviation communication, which to this day still use AM analogue. This is because weaker signals can be heard over stronger, closer ones with AM, allowing for emergency transmissions to have more chance of being heard over other traffic. Also, AM uses a narrower bandwidth than FM, allowing more users in a smaller space. This is important for the lower frequencies of Radio, where space is at a premium (ie shortwave bands).
What is the dynamic characteristic of a double-sideband?
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.
How do you lower turbine differential expansion?
by controlling main steam flow
What is difference between modulator and demodulator?
Modulation is used when information is available in analog form that varies the frequency and/or amplitude of a lower frequency wave, depending on the information it carries. The role of modulation is to place this information onto a carrier frequency that can be transmitted more readily and with least loss of information. There are three fundamental types of modulation - frequency modulation, amplitude modulation and phase modulation. In each of these, a carrier frequency is modulated by a lower frequency, to form a modulated carrier wave. 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.
