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In frequency modulation what happens to the bandwidth when you increase the modulating frequency?
Wiki User
∙ 14y ago
Bandwidth increases as a function of both modulating frequencyand deviation. As deviation increases, pairs of sidebands are generated, each equal to fc+m and fc-m, fc+2m, fc-2m etc. where fc = the carrier frequency and m = the modulating frequency. Increasing modulation (frequency deviation) will change the level of each of the sideband pairs - and the carrier, which at times falls to zero.
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∙ 14y ago
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Is The carrier frequency is usually lower than the modulating frequency?
when the frequency is low , energy will be obviously low. To increase the energy of the signal we need to increase the frequency. This is achieved by multiplying the message signal with the carrier signal (with high frequency).
Why high frequency signal is more affected by noise compare to low frquency signal?
AS FREQUENCY INCREASE THE BANDWIDTH INCREASE. AS WE KNOW NOISE HAVE LARGER BANDWIDTH. SO ITS AFFECT HIGH FREQUENCY SIGNAL. BUT LOW FREQUENCY SIGNAL HAVE LOW BANDWIDTH SO IT IS LESS AFFECTED BY NOISE. ALSO WE KNOW QUALITY FACTOR= CUTOFF FREQUENCY / BANDWIDTH. SO AS FREQUENCY INCREASE B.W. INCREASE SO QUALITY DEGRADE. CUTOFF FREQUNCY AND THE TERM FREQUENCY (USED HERE) IS DIFFERENT. CUTTOFF FREQUNCY IS USED IN FILTER. PRABIR KUMAR SETHY prabirsethy.05@gmail.com
Principle of peak AGC system?
A peak-based AGC system, such as is required for SSB, will reduce the receiver gain by 6 dB as the modulating percentage increases from 0% to 100%. A receiver with a peak-responding AGC system will, in theory, cause a gain reduction as modulation percentage increases and a gain increase as the modulation level decreases. (Thanks to Clifton Laboratories 7236 Clifton Road Clifton VA 20124 tel: (703) 830 0368 fax: (703) 830 0711 E-mail: Jack.Smith@cliftonlaboratories.com)
Why use dc motor not stepper motor in robot?
DC motors use PWM (pulse width modulation), which can easily increase or decrease the power to the motor, thereby increasing or decreasing the motor speed by modulating the width of the pulse. Stepper motors have fixed frequencies, thereby having fixed motor speeds. As a result, the speed of the stepper motor cannot be controlled when the load is increased.
Why the entire frequency range of 20hz-20khz is not used in telephony?
Because it is not necessary, and providing that bandwidth would increase cost and complexity. While the full range of 20Hz-20KHz is required for proper rendering of music, telephony, by standard, only requires a 3.5KHz bandwidth. You can hear and understand the spoken voice with only this range. You do not need the extended musical range.
Is The carrier frequency is usually lower than the modulating frequency?
when the frequency is low , energy will be obviously low. To increase the energy of the signal we need to increase the frequency. This is achieved by multiplying the message signal with the carrier signal (with high frequency).
Why high frequency signal is more affected by noise compare to low frquency signal?
AS FREQUENCY INCREASE THE BANDWIDTH INCREASE. AS WE KNOW NOISE HAVE LARGER BANDWIDTH. SO ITS AFFECT HIGH FREQUENCY SIGNAL. BUT LOW FREQUENCY SIGNAL HAVE LOW BANDWIDTH SO IT IS LESS AFFECTED BY NOISE. ALSO WE KNOW QUALITY FACTOR= CUTOFF FREQUENCY / BANDWIDTH. SO AS FREQUENCY INCREASE B.W. INCREASE SO QUALITY DEGRADE. CUTOFF FREQUNCY AND THE TERM FREQUENCY (USED HERE) IS DIFFERENT. CUTTOFF FREQUNCY IS USED IN FILTER. PRABIR KUMAR SETHY prabirsethy.05@gmail.com
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
Why FM have infinte number of sidebands?
It can't. FM (like broadcast AM) has two *sidebands*, one at a higher frequency than the transmitter's carrier, one at a lower frequency. The modulating signal (voice, music, etc) of any trasnmitter creates one or more pairs of side frequencies within the two sidebands. A broadcast AM signal can only produce two side frequencies, so an AM transmitter at 1.5 MHz, with a 1 kHz modulating tone (fm), would put out its carrier (fc) at 1.5 MHz, a lower side frequncy at (1.5 - 0.001) = 1.499 MHz, then its carrier at 1.5 MHz, and then the upper side frequency at (1.5 + 0.001) = 1.501 MHz. The AM signal can never be wider than twice the highest modulating frequency (fm), spanning from (fc - fm) to (fc + fm), a span of 2 x fm. Be aware that special-purpose AM systems can generate just *one* sideband - we won't go into that amount of detail apart from noting it. FM signals can be wider than twice the highest modulating frequency. The complete analysis needs the mathematical Fourier Transform, but we can think of it this way. Stronger frequency modulation shows up as a larger change in the transmitted signal frequency. An FM signal at 100 MHz, modulated by a 1 KHz tone, *can* put out a lower side frequency at (100 - 0.001) = 99.999 MHz and an upper side frequency at (100 + 0.001) = 100.001 MHz. You could receive this just fine, but it would sound "weak" compared to normal broadcasts. It's possible to increase the frequency shift to (say) five times. Now, the sidebands must extend from (100 - 5x0.001) = 99.995 MHz to (100 + 5x0.001) = 100.005 MHz. How do we account for the original 1 KHz tone creating a bandwidth of 2x5 kHz? The answer is that we actually have *five* lower side frequencies, at -5, -4, -3, -2, -1 kHz below the carrier, and *five* upper side frequencies at +1, +2, +3 +4 and +5 kHz above the carrier. Notice that they are multiples of the original 1 kHz modulating frequency. These can, in fact, be shown on the instrument called a spectrum analyser. Your question? As with broadcast AM, an FM signal has only two sidebands. In FM, the strength of modulation (the modulation index) controls the number of individual side frequencies, and thus the total bandwidth of the signal. Can an FM signal have *infinite* numbers of side frequencies? Not really. It can have a *very large* number of side frequencies with very great modulation strength. In practice, this would take up *a lot* of the FM radio band, so broadcast FM commonly uses a maximum modulation index of 5.0. This means that a fully-modulating 15 kHz signal would give a bandwidth of -(15 x 5) to +(15 x 5) kHz, which is +/- 75 kHz.
How can the Doppler effect cause broadening of a spectral line?
The Doppler effect causes broadening of a spectral line by shifting the wavelength of emitted light from a moving source. Faster moving atoms within a gas cloud emit light at slightly different wavelengths due to their relative motion, leading to a broader range of wavelengths in the observed spectral line.
How control dc motor using micro controller?
The speed of the motor depends on load, voltage and current. The speed can be maintain by using a method called Pulse code modulation (PWM). By changing (modulating) the width of the pulse applied to the DC motor we can increase or decrease the amount of power provided to the motor, there by increasing or decreasing the motor speed. mean we have to just change the duty cycle of modulating output.
How to increase the bandwidth on an Android phone?
You cannot increase the bandwidth on an Android phone.
How do you reduce congestion?
Increase the bandwidth.
How do you increase bandwidth speed for xp home edition?
http://dummy-essentials.blogspot.com/2009/07/increase-bandwidth-by-20.html
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.
How do you reduce traffic congestion?
Increase the bandwidth.
What is relationship between gain and bandwidth of an op amp is?
An op amp can have a very large gain, but a limited bandwidth. If you decrease the gain, you can increase the bandwidth.
