User manual MATLAB COMMUNICATIONS BLOCKSET 4

[. . . ] Communications BlocksetTM 4 User's Guide How to Contact The MathWorks Web Newsgroup www. mathworks. com/contact_TS. html Technical Support www. mathworks. com comp. soft-sys. matlab suggest@mathworks. com bugs@mathworks. com doc@mathworks. com service@mathworks. com info@mathworks. com Product enhancement suggestions Bug reports Documentation error reports Order status, license renewals, passcodes Sales, pricing, and general information 508-647-7000 (Phone) 508-647-7001 (Fax) The MathWorks, Inc. 3 Apple Hill Drive Natick, MA 01760-2098 For contact information about worldwide offices, see the MathWorks Web site. Communications BlocksetTM User's Guide © COPYRIGHT 2001­2010 by The MathWorks, Inc. The software described in this document is furnished under a license agreement. The software may be used or copied only under the terms of the license agreement. [. . . ] The situation is analogous for demodulators. General and Specific Blocks General Modulator General QAM Modulator Baseband M-PSK Modulator Baseband Specific Modulator Rectangular QAM Modulator Baseband BPSK Modulator Baseband QPSK Modulator Baseband M-DPSK Modulator Baseband CPM Modulator Baseband DBPSK Modulator Baseband DQPSK Modulator Baseband GMSK Modulator Baseband Specific Conditions Predefined constellation containing 2K points on a rectangular lattice M-ary number parameter is 2. M-ary number parameter is 2, Frequency pulse shape parameter is Gaussian. M-ary number parameter is 2, Frequency pulse shape parameter is Rectangular, Pulse length parameter is 1. Frequency pulse shape parameter is Rectangular, Pulse length parameter is 1. MSK Modulator Baseband CPFSK Modulator Baseband 1-100 Digital Modulation General and Specific Blocks (Continued) General Modulator General TCM Encoder Specific Modulator Rectangular QAM TCM Encoder Specific Conditions Predefined signal constellation containing 2K points on a rectangular lattice Predefined signal constellation containing 2K points on a circle M-PSK TCM Encoder Furthermore, the CPFSK Modulator Baseband block is similar to the M-FSK Modulator Baseband block, when the M-FSK block uses continuous phase transitions. However, the M-FSK features of this blockset differ from the CPFSK features in their mask interfaces and in the demodulator implementations. Baseband Modulated Signals For a given modulation technique, two ways to simulate modulation techniques are called baseband and passband. This blockset supports baseband simulation for digital modulation. Baseband simulation, also known as the lowpass equivalent method, requires less computation compared to passband simulation. This is because modeling a high-frequency carrier signal is computationally intensive. For the mathematical expressions that define baseband signals, see the baseband signal section in the Communications Toolbox documentation. 1-101 1 Using the Libraries Representing Signals for Digital Modulation All digital modulation blocks process only discrete-time signals and use the baseband representation. The data types of inputs and outputs are depicted in the following figure. real Digital Modulator complex Digital Demodulator real Note If you want to separate the in-phase and quadrature components of the complex modulated signal, use the Complex to Real-Imag block in the Simulink Math Operations library. Binary-Valued and Integer-Valued Signals Some digital modulation blocks can accept either integers or binary representations of such integers. The corresponding demodulation blocks can output either integers or their binary representations. This section describes how modulation blocks process binary inputs; the case for demodulation blocks is the reverse. If a modulator block's Input type parameter is set to Bit, the block accepts binary representations of integers between 0 and M-1. It modulates each group of K bits, called a binary word. Also, the input vector length must be an integer multiple of K. If the input is frame-based, then it must be a column vector. In binary input mode, the Constellation ordering (or Symbol set ordering, depending on the type of modulation) parameter indicates how the block maps a group of K input bits to a corresponding integer. If this parameter is set to Binary, the block maps [u(1) u(2) . . . u(K)] to the integer u(i)2 i =1 K K -i 1-102 Digital Modulation and subsequently behaves as if this integer were the input value. For example, if M = 8, Constellation ordering (or Symbol set ordering) is set to Binary, and the binary input word is [1 1 0], the block internally converts [1 1 0] to the integer 6. The block produces the same output as in the case when the input is 6 and the Input type parameter is Integer. [. . . ] The I/Q Imbalance block simulates transmitter impairments. This block adds rotation to the signal, simulating a defect in the transmitter under test. The I/Q amplitude imbalance is 0. 5 dB, and I/Q phase imbalance is 1°. Receiver Impairments In this model, the Receiver Thermal Noise block represents receiver impairments. This model assumes 290 K of thermal noise, representing imperfections of the hardware under test. EVM Calculation The EVM calculation relies upon the following blocks: · Digital Filter · Selector · EVM Measurement · Display 2-36 Measuring Modulator Accuracy The EVM measurement block computes the vector difference between an ideal reference signal and an impaired signal. 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