More on quantizationNow, each sample will be represented by 4-bits, consequently we would have high data rates, improved signal quality or fidelity.In real time communication message must not be delayed, and bits must move faster.This is how one can generally obtain better fidelity at the cost of more transmission bandwidthNext Fig.2.18 compares the quantization of a strong versus a weak signal for uniform and non-uniform quantization.The staircase like waveforms represents approximation to the analog waveforms (after quantization distortion has been introduced. Thus increasing the number of levels will reduce the quantization noise.If we double the number of levels to 16, what supposed to be the benifit? qpsk modulation and demodulation using python, Quadrature Phase Shift Keying (QPSK) is a modulation technique which is widely used in wireless communication system due to its ability to transmit twice the data rate for a given bandwidth.
These modulation schemes can be characterized by their transmitted symbols which consist of a discrete set of values occurring at gradually spaced intervals. This paper mainly discusses about three basic digital modulation process ASK, FSK, PSK. This paper mainly discusses about three basic digital modulation process ASK, FSK, PSK. What could we do to improve the fidelity?We know that process of quantization replaces the true signal with an approximation (i.e., adds quantization noise). Implementation of ASK, FSK and PSK with BER vs. More on quantizationSuppose that analog signal is a musical, which is sample at a Nyquist rate (fs 2fm).Also suppose that when we listen to the music in digital form, its quality is not good.
Ask fsk psk modulation code#
More on quantizationThe ordinate in fig.2.16 is labeled with quantization levels and their code numbers.Each sample of the analog signal is assigned to the quantization level closest to the value of sample.Beneath the analog waveform x(t) are seen four representations of x(t) as follows:-The natural sample values, quantized sample values, the code numbers and the PCM sequence.Note that each sample is assigned to one of eight levels or a three bit PCM sequence. More on quantizationBlock diagram of formatting and transmission of baseband signals Fig.2.2. M-ary orthogonal pulsesCross correlation between any two rows is zero for e.g. M-ary orthogonal pulsesFig.3.34 shows one possible set of M orthogonal signals For example we may use M orthogonal pulses 1(t), 2(t),, M(t), with the following property:- ASK FSK PSK Digital Modulation Techniques BSNL JTO GATE Digital Communication Tutorials - YouTube. M-ary orthogonal pulsesFig.3.33 shows just one possible M-ary scheme (multi-amplitude signaling).There are other possible ways to structure M waveforms. Power spectral density (PSD)of ASK,PSK and FSK Note that the bandwidth of FSK is higher than ASK or PSK.Conclusion is that polar signaling is the most efficient scheme from the point of view of the noise immunity.The PSK, being polar, requires 3dB less power than ASK or FSK for the same noise immunity i.e.
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