16 psk constellation diagram

16 psk constellation diagram插图

How do I set the parameters for 16-PSK modulation?

Set the parameters for 16-PSK modulation with no phase offset and binary symbol mapping. Construct the modulator object. Plot the constellation. This example shows how to plot a QAM constellation having 32 points.

What is a constellation diagram?

What is a Constellation Diagram? A constellation diagram is a diagram that shows how the information in a digital modulation scheme such as phase shift keying (PSK) is represented in a modulated carrier.

What is the distance between the constellation points in 16QAM modulation?

The distance between the constellation points fo 16QAM modulation is around 1.6x the value for 16PSK modulation. Expressing in dB’s, this comes to around . More the distance between the constellation, lesser is the chance of a constellation point getting decoded incorrectly.

How do you plot a QAM constellation with no phase offset?

Set the parameters for 16-PSK modulation with no phase offset and binary symbol mapping. Construct the modulator object. Plot the constellation. This example shows how to plot a QAM constellation having 32 points. Use the qammod function to generate the 32-QAM symbols with binary symbol ordering. Plot the constellation.

What is constellation diagram?

A constellation diagram is a diagram that shows how the information in a digital modulation scheme such as phase shift keying (PSK) is represented in a modulated carrier. This article is a bit of an experiment; instead of introducing the constellation diagram by simply presenting it, I’m going to try to have it emerge from the formulas of PSK modulation.

What is QAM in modems?

In application such as cable or DSL modems for broadband internet, more elaborate constellations such as Quadrature Amplitude Modulation ( QAM) are used. In QAM, both the phase and the amplitude of the signal are adapted in order to be able to send more bits per symbol. An example is 16-QAM (4 bits per symbol), as shown in Figure 3. Cable modems typically use 64-QAM or 256-QAM, and, for DSL, constellations as large as 32768-QAM (15 bits per symbol) are used routinely.

What is the waveform for MPSK?

by applying Euler’s formula. Because the waveform for MPSK is simply a cosine with a phase offset , the calculation of the analytic signal is the same as in the mentioned article on analytic signals.

What is the formula for m = 0?

for m = 0, …, M ? 1. In this equation, A is the amplitude of the carrier, f c is the frequency of the carrier, and M is the number of phase offsets. This formula represents a carrier wave of which the phase is suddenly shifted for each new symbol (if that symbol is different from the previous one, of course). This is a digital modulation scheme, because the phase is changed in fixed steps instead of continuously as for analog modulation techniques.

What is QAM modulation?

Quadrature Amplitude Modulation (QAM) conveys two bit streams by changing the amplitude of two carrier waves that have the same frequency and a 90° shift. The most common type of QAM modulation is rectangular QAM, were the constellation points are arranged in a square grid. Depending on the desired number of bits per symbol (4, 5, 6 …), we have 16QAM, 32QAM, 64 QAM, etc.…

What is QAM.slx?

Open the file named QAM.slx. This file contains a simulated QAM communication system. The system is shown in Figure 4.

How many bits per symbol in AWGN?

In the AWGN block, set the Symbol period parameter to 1e-6 (i.e. 1 µs) and the Number of bits per symbol parameter to 4 (since 16 QAM uses 4 bits per symbol).

What are the distortions in a transmission?

In real transmissions, the transmitted signal may suffer from different types of distortions such as phase errors, amplitude errors, frequency errors, and time jitter. Note that for the previous modulation schemes (BPSK and QPSK) amplitude errors do not make much difference since the information is contained in the phase. However, for 16 QAM, since it is both phase and amplitude modulations, it is sensitive to amplitude errors and DC offset. In this part, you will simulate the effect of these distortions on the transmitted signal and how to correct them.

How to change the size of a random integer generator?

Double-click on the Random Integer Generator and adjust the set size to a proper value (Remember that the input to the 16 QAM modulator should be from the set {0, 1, 2, …, 15}).

How to set sample time for BPSK?

Double click on the Bernoulli generator for the BPSK part. Set the sample time to 1e-6 and the Samples per frame to 1024.

How many carriers are used in QAM?

Since in QAM modulation two carriers are used, the Symbol Error Rate per carrier is given by:

How much arond does 16QAM need?

As can be observed, at a symbol error rate of , 16QAM requires only arond 19dB whereas 16PSK requires around 23dB of .

What is rate in coding?

The parameter called rate in coding (1/2, rate 3/4 etc) convey the level of redundancy added. For eg rate 1/2 means we send out 2 coded bits for every 1 data bit.

Can you define constellation points on the IQ plane?

And just to add, we cannot define a constellation point on the IQ plane by knowing the angle alone. We need both angle and magnitude and angle to define a point in the plane.