Modulation in physics is the time alteration of the chosen properties of the regular physical processes. The practical application of modulation is the overlay of the low-frequency information signal on high-frequency signal carrier for the long-distance transmission.
For example, with an alphabet consisting of 16 alternative symbols, each symbol represents 4 bits. Thus, the data rate is four times the baud rate.
In the case of PSK, ASK or QAM, where the carrier frequency of the modulated signal is constant, the modulation alphabet is often conveniently represented on a constellation diagramshowing the amplitude of the I signal at the x-axis, and the amplitude of the Q signal at the y-axis, for each symbol.
The resulting so called equivalent lowpass signal or equivalent baseband signal is a complex-valued representation of the real-valued modulated physical signal the so-called passband signal or RF signal.
These are the general steps used by the modulator to transmit data: Group the incoming data bits into codewords, one for each symbol that will be transmitted.
Map the codewords to attributes, for example, amplitudes of the I and Q signals the equivalent low pass signalor frequency or phase values. Adapt pulse shaping or some other filtering to limit the bandwidth and form the spectrum of the equivalent low pass signal, typically using digital signal processing.
Perform digital to analog conversion DAC of the I and Q signals since today all of the above is normally achieved using digital signal processingDSP. Generate a high-frequency sine carrier waveform, and perhaps also a cosine quadrature component. Carry out the modulation, for example by multiplying the sine and cosine waveform with the I and Q signals, resulting in the equivalent low pass signal being frequency shifted to the modulated passband signal or RF signal.
Sometimes this is achieved using DSP technology, for example direct digital synthesis using a waveform tableinstead of analog signal processing.
In that case, the above DAC step should be done after this step. Amplification and analog bandpass filtering to avoid harmonic distortion and periodic spectrum. At the receiver side, the demodulator typically performs: Automatic gain controlAGC to compensate for attenuationfor example fading.
Frequency shifting of the RF signal to the equivalent baseband I and Q signals, or to an intermediate frequency IF signal, by multiplying the RF signal with a local oscillator sine wave and cosine wave frequency see the superheterodyne receiver principle.
Sampling and analog-to-digital conversion ADC sometimes before or instead of the above point, for example by means of undersampling. Equalization filtering, for example, a matched filtercompensation for multipath propagation, time spreading, phase distortion and frequency selective fading, to avoid intersymbol interference and symbol distortion.
Detection of the amplitudes of the I and Q signals, or the frequency or phase of the IF signal. Quantization of the amplitudes, frequencies or phases to the nearest allowed symbol values.
Mapping of the quantized amplitudes, frequencies or phases to codewords bit groups. Parallel-to-serial conversion of the codewords into a bit stream. Pass the resultant bit stream on for further processing such as removal of any error-correcting codes.Modulation for Analog Communication ©Yao Wang, EE Analog Communications 2 frequency/phase modulation • Frequency division multiplexing • Application of modulation • Demo of AM and QAM ©Yao Wang, EE Analog Communications 3 Baseband Communications • Signal strength attenuates with distance.
term. second the. Applications of Phase Modulation: Phase modulation application is not different from frequency modulation. In the pulse code modulation, Analog Signal is reconstructed to digital signal for ease of transmission by using the analog signal samples.
It is the base for all digital modulation techniques and it is simple process for both. Application of Analog Modulation Techniques Term Paper: Modulation in physics is the time alteration of the chosen properties of the regular physical processes. The practical application of modulation is the overlay of the low-frequency information signal on high-frequency signal carrier for .
Analog Modulation Techniques. PSK Presentation. on the applications of phase modulation, the topic of the term paper for the current 3rd semester. I. II. Documents Similar To Application of Phase Modulation. Analog Modulation Techniques. Uploaded by. pawan. PSK Presentation.5/5(3). This application note introduces the concepts of digital modulation used in new digital modulation techniques.
Examples of digital modulation include • QPSK (Quadrature Phase Shift Keying) Frequency Modulation (FM) is the most popular analog modulation technique used in mobile communications systems.
In FM, the amplitude. Modulation Techniques for Communication via Diffusion in Nanonetworks In this paper, novel modulation techniques called Concentration Shift Keying (CSK) and Molecule Shift Keying (MoSK) are The second term can be calculated.