40
Transmission bandwidth depends on modulating signal frequency and carrier frequency
75khz
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.
I believe the bandwidth of ANY signal is defined as the range of frequencies that encompasses 99% of the signal's power. For an AM signal at anything less than 100% modulation, it's 2 x the highest modulating frequency. FM signals aren't that simple to characterize. "Cramer's Rule" says that the bandwidth is 2 x (peak deviation + highest modulating frequency), but as the 'modulation index' increases, that rule becomes a poorer approximation.
Upper sideband = Carrier frequency + modulating frequencyLower sideband = Carrier frequency - modulating frequency
modulating signal is the low frequency signal .so we cant transmit for a long distance.so we go for modulating the signal either by modulating the amplitude or frequency or phase of the signal.
Perhaps this broadening of the spectral line might be due to different propogation speeds under Doppler conditions when the emitting object is moving towards us? Therefore increasing the frequency shift and spreading the spectrum over a wider bandwidth. Or perhaps Take an amplitude modulated carrier wave with a fixed modulating frequency. Un-shifted the sidebands would remain constant in width. If the signal source was moving towards us the modulating frequency would also increase. The increased modulating frequency would move the sidebands further away from the carrier, increasing bandwidth or broadening the spectrum.
increases
When the frequency sensitivity of the modulating signal is small,the bandwidth of the FM is narrow. The narrowband FM has one carrier term two sideband terms.The modulation index is also small compared to one radian.
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.
It is a device or electronic circuit that changes the frequency of an oscillator according to the amplitude of modulating signal. For instance, if the modulation is linear, the modulator changes the frequency proportional to the amplitude of the modulating voltage.
It is a device or electronic circuit that changes the frequency of an oscillator according to the amplitude of modulating signal. For instance, if the modulation is linear, the modulator changes the frequency proportional to the amplitude of the modulating voltage.