ANGLE MODULATION
Chapter Objectives
This chapter will help you to:
1. Define and explain the processes of frequency modulation (FM) and phase modulation (PM) and state their differences.
2. Calculate the modulation index given the maximum deviation and maximum modulating frequency, determine the significant number of sidebands in an FM signal, and calculate the bandwidth of an FM signal.
3. Define pre-emphasis and de-emphasis, state their benefits, and show how they are accomplished.
4. Name the advantages and disadvantages of FM and PM compared to AM.
Angle modulation is a technique in which the angle of the carrier wave is varied according to the instantaneous amplitude of the modulating signal. There are two types of angle modulation.
1. Frequency Modulation
2. Phase Modulation
Frequency Modulation: (Definition & Introduction)
FM is a technique in which the instantaneous frequency of the carrier wave is varied according to the instantaneous amplitude of the modulating signal. In other words if the amplitude of the modulating signal increases, then there will be a corresponding increase in the frequency of the modulated wave, similarly if the amplitude of the modulating signal decreases, then there will be a corresponding
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As can be seen in Figure 3.1 (a) the modulating signal increases from its negative peak value during this quarter, and at time t3 it becomes zero. This sinusoidal increase in the amplitude of the modulating signal is mapped on to the carrier signal by increasing its frequency. At time T3, the amplitude of the modulating signal is zero and hence there will not be any deviation in the carrier frequency from its original value. Thus between time T2 and T3, the frequency of the modulated carrier increases from its minimum value attained at time t2. This is shown in Figure 3.l(c) by inserting more cycles during quarter III as compared to the number of cycles that occurred during the quarter
The stream of complex numbers is rearranged so that the pilots can be inserted. In each OFDM symbol, four pilot signals are inserted in order to make the coherent detection robust against frequency offsets and phase noise. The pilots are BPSK modulated by a pseudo binary sequence to prevent the generation of spectral lines [18]. A zero padded block adds zeros, in the right places, to adjust the IFFT bin size to length N. Selector block rearranges the sub-carriers so that real signal output can be generated. The IFFT block then computes the Inverse Fast Fourier Transform (IFFT) of length N, where, for ease of implementation, N is a power of
This process of Fourier transform and back-transform establishes the essential frequency components of the temporal data while eliminating high-frequency noise. This is a powerful technique to:
Single sideband modulation may be viewed as the removal or reduction of the amplitude modulation signal component. In order to see how the SSB is created, it is necessary to use an amplitude modulated signal as a starting point. (Rosu, NA)
A composite signal can be decomposed into individual sine waves called harmonies.Fourier analsis is done to decompose a signal.the decomposed signals have different amplitude,frequency and phase.A periodic signal has
Calculate each of the five measurements in the project by performing every step in sequence. In your own words, summarize what you have learned concerning RF behavior.
It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects.
letting t ¼ nTs, where Ts is the sample interval, the digitalmulti-carrier transmitter output is now
strating the energy transformations involved in the process * outlines what frequency modulation or amplitude modulation is
13. Next, adjust tension back to high, change it to a fixed end, pulse, and reset the wave. Send a pulse and when it has traveled about half way to the end send a second. When the first pulse is on its way back and the second is moving toward it pause the simulation and then step it while you observe the
Describe why a manager needs to understand the characteristics and importance of financial markets including their liquidity, competitiveness, and efficiency.
ANS: The entire process is performed by multiplying a radio frequency carrier and a pseudo-noise (PN) digital signal. The PN code is modulated onto an information signal using several modulation techniques such as quadrature phase-shift keying (QPSK), binary phase-shift keying (BPSK), etc. A doubly-balanced mixer then multiplies the PN modulated
This helps with transmitting only when there is no traffic in the air. This helps with slow transmission and get better performance overall. The RTS is request to send it sends out to a node and then the CTS is clear to send the requested information when the air is clear and is able to send data with interruption. The throughput is also reduced with the extra frames. (Ciampa, 2013)
Record the amplitude and corresponding period of vibration for one oscillation, followed by the sixth oscillation.
1) The study of communications in the early twentieth century solidified in to which two approaches?
On old radios the antenna was detrimental to the radio’s operation. Today, the antenna is not necessary. AM radio does not have as good of quality as FM but it can travel farther distances. FM signals can be interfered by things such as mountains or other barrier