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What is the difference between pulse duration modulation and pulse density modulation?
Both reproduce analog waveforms by switching between 2 values at a much higher rate than the signal itself changes.Pulse duration modulation is a synonym for pulse-width modulation or PWM. The switching frequency is usually constant, and the width or duration of the "high" state determines the output. For instance, if the width is 100%, it is always high, and produces the highest analog value possible. If the width is 50%, it spends half of its time high and half low, producing a halfway voltage. If the width is 0%, it stays low all the time, producing the lowest possible voltage.Pulse density modulation uses a feedback loop to track the analog output voltage, switching low when the output is too high and high when the output is too low.To produce a 50% voltage, with an equivalent resolution of 8-bits, a PWM waveform will turn on for 128 clock cycles and then off for 128 cycles. A PDM waveform with the same clock rate would alternate between on and off every other cycle. The average of both waveforms is 50%, but the PDM waveform switches more often. For 100% output or 0% output, they are identical.
Does a period effect the frequency of a soundwave?
Period and frequency are 'locked' together, not independent numbers. They're simply the reciprocals of each other.Period = 1 / (frequency).Frequency = 1 / (period).So definitely, if one changes, the other changes. Their product is always [ 1 ].
A mass oscillates on the end of a spring with a period of four seconds what is the frequency of the oscillator?
Period, T , and frequency, f , are always the inverse of each other; f = 1/T
What are 3 forms of Electromagnetic Radiation with a wavelength less than visible light?
The wavelength of electromagnetic radiation is a measure of the frequency; multiply the frequency times the wavelength, and the answer is ALWAYS the "Speed of Light", which we abbreviate as "c". All of these are different "bands" of electromagnetic energy. Radio is the longest wavelength and lowest frequency. "Low Frequency" is the lowest, followed by "high frequency", "very high frequency" or VHF, "ultra-high frequency" or UHF. Beyond that are microwaves, and then heat, then "infrared", and then visible light. Higher frequency (and shorter wavelengths) than light are "ultra-violet", then X-rays, and then "gamma rays".
Difference between narrow band angle modulation and wide band frequency modulation?
Preface:In communications, modulation is the process of "mixing" one signal (the one you intend to transmit, called the "message" and often simplified as being a simple sinusoid) with another (called the "carrier" and also often simplified as being a sinusoid) in some form. In Amplitude Modulation (AM), the two are simply linearly multiplied, ie:u(t) = Ac(1 + k*m(t))*cos(2*pi*fc*t)where Ac represents the amplitude of the carrier signal, k is a modulation index, fc is the carrier frequency, and u(t) represents the modulated signal. Through the trigonometric properties of sinusoids, it is possible (and in the case of AM fairly straightforward) to recover the original message signal m(t) in the absence of noise.Both Frequency Modulation (FM) and Phase Modulation (PM) are forms of Angle Modulation, in which your signal of interest m(t) modulates the angle of the carrier wave, which is a type of nonlinear modulation. This can be generalized as:u(t) = Ac*cos(2*pi*fc*t + p(t))where p(t) is linearly related to m(t), your message, and itself represents an angle shift. (For now it doesn't matter whether p(t) is modulating frequency or phase.)Assume p(t) described above is a sinusoid out of phase with the carrier by 90 degrees, specifically that the carrier is a cosine wave and the angle modulating message p(t) is a sine wave. Using the simple trigonometric identitycos(a + b) = cos(a)cos(b) - sin(a)sin(b)we can rewrite u(t) in its in-phase quadrature formu(t) = Ac[ cos(p(t))*cos(2*pi*fc*t) - sin(p(t))*sin(2*pi*fc*t) ]Trigonometrically speaking (see first-order Taylor Series approximation for further reading), for very small (close to zero) values of t in cos(t), cos(t) is almost 1, and sin(t) is almost t. If we assume that p(t), the angle modulating signal message, always has a very small value (nearly zero), we can reasonably simplify the modulated signal to the form:u(t) Ac[ cos(2*pi*fc*t) - p(t)*sin(2*pi*fc*t) ]which, if you compare with the form of the AM signal, is very similar. In fact, this "narrowband" angle modulation, which assumes a narrow range of angles possible, is nearly identical to the functionality of AM and therefore consumes almost the same amount of signal bandwidth and is analyzed in a very similar manner. This is because a first-order approximation (which narrowband is an example of) is linear and therefore is fundamentally the same as AM.Physically speaking, however, using a narrowband angle modulation technique is not reliable and provides little benefit over an AM technique. It consumes the same amount of signal bandwidth as AM and is just as susceptible to noise. (Consider some additive spectral noise variable, taken with our assumption that p(t) was extremely small, will indicate that the received signal will be unrecognizably different than the transmitted signal.)Wide band angle modulation, on the other hand, does not make this simplifying assumption that angles are small (first-order approximation). Without these assumptions, signal analysis is much more complex, and involves solving Bessel functions for multiple values of the message signal across the intended spectrum. However, because of its true nonlinearity, wide band angle modulation is much more resilient to noise than is narrowband/AM and consumes much more bandwidth.
Which modulation your radio stations are using now?
Hi, Same as always. AM (amplitude modulation). FM (frequency modulation) and some FM's are now adding a digital component to their signal at the sacrifice of some transmitted volume. Hope that helps, Cubby
In frequency modulation the ratio of the maximum deviation from the idling frequency to the audio modulating frequecy is what?
it is some kind of vegetable with can be found easily in south africa, where villagers always use it to cook soup.
Sinusoidal pwm generation using modulation index?
Not sure what type of modulation you are looking for, but there are two that can be manipulated, either individually or in conjunction:Frequency modulation index refers to the relation between the sine wave frequency (sine_freq) and the triangle (or saw-tooth) wave frequency (triang_freq).The frequency modulation index is equal to ((triang_freq)/(sine_freq)).Amplitude modulation index refers to the relation between the sine wave amplitude (sine_amp) and the triangle (or saw-tooth) wave amplitude (triang_amp).The amplitude modulation index is equal to ((sine_amp)/(triang_amp)).Varying the modulation index (normally by varying the frequency or amplitude of the triangle wave form) changes that respective modulation index.From personal experience, an appropriate amplitude modulation index for an SPWM waveform should be around 0.8(that is, if the triangle has an amplitude of 10, the sine would have an amplitude of 8). This index should never be equal to 1 (one); it should always be less. A.K.A.: the triangle-wave amplitude should always be greater than the sine-wave.On the other hand, a triangle-wave frequency much greaterthan the sine-wave frequency makes an SPWM that in turn generates a "cleaner" synthesized sine-wave in the H-bridge you are probably using. Try different freq. modulation indexes, but an index of at least 10 should be used (preferably somewhere around 100 if you want a good SPWM). That is, if the sine-wave frequency is 60 Hz, the triangle-wave frequency should be above 600, preferably 6,000 or more. Complications in the filter design in the "output" of the H-bridge will vary greatly when playing around with the frequency modulation index. That being said, keeping the amplitude modulation index at a static 0.8, and playing around with the triangle-wave frequency should be your best bet.
Why do you think a rainbow is always the same order of colors?
It goes in order from highest frequency beam, violet, to lowest frequency, red.
What polarization are AM antennas?
It depends on the frequency, not the type of modulation. However, in view of the wavelength of medium waveband transmissions and h.f. transmissions the antennas are always horizontal and therefore so is the polarisation.
How Frequency Modulation Have Higher Bandwidth then AM?
Bandwidth is defined as difference between two frequencies.In AM only amplitude is modulated or changed to transmit the data at the given fixed frequency. In FM the frequency of the signal is changed to transmit the data. Since we will need a range of frequency to transmit the data using FM (say frequencies from f1 to f2), the bandwidth of FM signal will be higher than AM signal which can transmit at a fixed frequency.But.....The above answer does not address the issue of "strength of modulation", that is, modulation index.A.M. will always have a bandwidth of twice its highest modulating frequency regardless of the strength of modulation.For voice comms with about a 3 kHz maximum frequency, A.M. will demand (3+3) = 6 kHz of bandwidth.Because F.M. modulates the frequency swing of the transmitter, low modulation indexes with F.M. can give a bandwidth LESS than the maximum modulating frequency. Narrow-Band F.M. (NBFM) can have a bandwidth of *less than* 3 kHz, indeed it can have a bandwidth of only a few hundred hertz, in theory.In practice, very narrow NBFM suffers from worsening signal-to-noise ratios, and one of F.M.'s chief advantages over A.M. is the superior signal-to-noise of F.M. when it is allowed sufficient bandwidth.
Why should be the voltage of the modulating signal greater than that of the carriers in the nonlinear modulators?
When the modulating signal is greater than the carrier it can cause over modulation, that will cut of the peaks of the modulating signal and when detected by the receiver the final audio signal will also show the flat peaks and the results will be a distorted sound at the speaker. A 90% modulation is always better than a 100% modulation. In the case of frequency modulation it will cause the frequency to shift to much and will result in a to wide band and will cause adjacent channel interference, it can be so severe that a transmitter can occupy the whole spectrum of the band that is allocated for FM broadcasting.
Why is that amplitude modulation is mostly affected by man made interference than frequency modulation?
since man made devices always produce noise for other electronic devices and noise always add at the amplitudes of any wave.in the am,amplitude is varying w.r.t. the information or modulating signal so it is most prone to noise and hence affected most by man made devices
FM is better than AM?
FM is frequency modulation. The amplitude is held constant and the carrier frequency is varied. AM is amplitude modulation. The amplitude is varied and the carrier frequency is held constant.
Why digital modulation is not enough for radio transmission and what are the general goals for digital modulation?
Worldwide regulation always uses FDM for separating different systems (TV, WLAN, radio, satellite …). Thus, all radio systems must modulate the digital signal onto a carrier frequency using analogue modulation. The most prominent system is the traditional radio: all music and voice use frequencies between, e.g., 10 Hz and 22 kHz. However, many different radio stations want to transmit at the same time. Therefore, all the original signals (which use the same frequency range) must be modulated onto different carrier frequencies. Other motivations for digital modulation are antenna and medium characteristics. Important characteristics for digital modulation are spectral efficiency, power efficiency and robustness. Typical schemes are ASK, PSK, FSK.
What is the highest frequency sound wave an adult can hear?
An adult can hear up to 10 kHz, but it depends always on the level this frequency has. The sensitivity of hearing goes slowly down with age. If there is no level given in the question. the answer is really useless.
What is the adverb in- we should always speak the truth?
The adverb is always, it is an adverb of frequency
