Communications

Features

• Stream-Driven System Design and Test
• Modulators and Demodulators: Costas Loop Demodulator, MFSK, MPSK, PPM, PWD, PWM, QAM, and More
• Supports Analog, Digital and Mixed-Mode System Simulation
• Supports End-to-End System BER Analysis
• Complete Filter Design Package: FIR, IIR, Custom, Laplace
• Channel Models: Jakes, Rayleigh, Rician, Rummler, and Multipath
• Encoders and Decoders: Block (Including BCH, Reed Solomon, Golay), Convolutional (Including Viterbi Decoders), Gray Encoder
• Baseband Pulse Shaping Filters, Raised Cosine, Root Raised Cosine, Gaussian, Bit Interleavers and Deinterleavers, and More

Overview

The optional Communications Library enhances the SystemVue core libraries with key models required for system-level communications design. This library contains all of the tools necessary to develop modern wired and wireless communications systems. Typical applications include PCS/cellular radios (GSM, CDMA, TDMA, pi/4 DQPSK); cordless phones, pagers, and modems (wired and wireless); satellite systems (GPS, DBS, LEOS); and spread-spectrum systems.

16 QAM I/Q signal constellation

All of the elements required to perform complete end-to-end system simulations are available. This library includes error-correcting codes, baseband pulse shaping (raised cosine, etc.), Gray encoding, modulation and demodulation, channel models, and data recovery. Complex models such as the Reed Solomon (RS) error-correction encoder/decoder, the Costas Loop, and the PLL demodulator are provided as individual functional blocks. Using SystemVue’s stream-driven engine, your simulation can combine both the baseband or digital operations with the RF portions of the transmitter and receiver.

Phase plane trajectory as a PLL achieves lock

In addition to the basic communications channel, you may add the requisite system synchronization loops. A baseband bit sync token is included in the library, and all standard synchronization loop architectures can be implemented. The early/late gate tracking loop and sliding loop correlators used in PN type CDMA spread-spectrum systems can also be added to the simulation.

Complete BER curves can be produced in a single run, and can be optimized so that the run time at a particular Eb/No is proportional to that value. In this way time and accuracy are preserved as the system SNR changes from point to point.

Design Example

An end-to-end communications system, created in SystemVue, is shown above. This system includes a BCH coder, Gray coder, differential coder, root- raised cosine filters, BPSK modulation, Rician fading channel, and AWGN.

The SystemVue block diagram shown above is an example communications system simulation containing all of the real world processing elements required to optimize system performance. The source data is first encoded with a [15,11,1] BCH code. The modulation is Differential 8-ary PSK (D8PSK) with Gray encoding. A root-raised cosine filter is used to compact the signal bandwidth. The channel model is a Rician flat fade combined with standard additive white Gaussian noise. The demodulator chain recovers the data. To recover the data, the PSK demodulator makes hard decisions on the transmitted symbol. These symbols are then Gray decoded into bits, which serve as the input to the BCH decoder. The BCH decoder outputs the recovered data, which is then compared to the original data to produce the BER curve. Other features, such as synchronization loops, can be easily added to the simulation.

A typical BER plot is shown above. For each value of Eb/No, the simulation can be run until a fixed number of errors occur.

By using SystemVue’s global parameter variation feature, a complete BER curve can be generated in a single run. For each value of Eb/No, the simulation can be run until a fixed number of errors occur. This allows the user to optimize the simulation run time.

Library Tokens:

Channel Models

• Fading Channel Models
• Jakes Mobile Channel
• Multipath Channel
• Narrow Band Interferer
• Rice Fading Channel
• Rummler Fading Channel

Encoders/Decoders

• Bit Error Rate (BER) Counter
• Bit to Symbol Converter
• Block Error Correcting Coder
• Block Error Correcting Decoder
• Convolutional Error Correcting Coder
• Convolutional Error Correcting Decoder
• Depuncture
• Gold Code Generator
• Gray Encoder/Decoder
• Puncture
• Symbol to Bit

Filters

• Constant Modulus Algorithm (CMA) Equalizer
• Integrate and Dump Filter
• Inverse Sinc Function

Modulators/Demodulators

• Costas Loop
• Double Sideband AM Modulator
• Frequency Controlled Pulse Train
• Frequency Modulated Pulse Train
• M-ary Frequency Modulator
• Non-Coherent FSK Demodulator
• Orthogonal Frequency Division Modulator
• Orthogonal Frequency Division Demodulator
• Phase Lock Loop
• Pulse Position Demodulator
• Pulse Position Modulator
• Pulse Width Demodulator
• Pulse Width Modulator
• PSK Demodulator
• Quadrature Amplitude Modulator
• Quadrature Amplitude Modulation Detector

Processors

• Bit Synchronizer
• Compander
• Divide by N
• Error Vector Magnitude
• Interleaver
• Inverse Compander
• I-Q Downconverter
• Numerically Controlled Oscillator
• PN Generator
• Pulse Shape
• Time Division Mux
• Time Division Demux
• Quadrature Amplitude Modulation Demapper
• Quadrature Amplitude Modulation Mapper

Additional Resources

• Read the manual ( 1.2MB)

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