Part 1: Baseband Communications Link with Integrated RF Receiver Model

以下模型包括基带信号发生器，一个简单的通道，一个RF接收器最初使用RF预算分析仪设计如下所述RF建模入门，一种模数转换，解调方案和符号错误率的计算块。

model ='simrfv2_comms_rf_example'; open_system(model);

对于此模型，通信工具箱和DSP System Toolbox™的块用于执行基带信号处理。非标准符合符合的基带信号具有矩形QAM星座，其余弦滤波和基带接收器不包括载波/时钟同步。基带信号生成的参数定义Model Properties- >模型回调PreLoadFcn, which sets these parameters in the MATLAB workspace when the model is loaded:

Sample time用于基带信号和Step sizeRF阻滞接收器配置块具有相同的值。这确保了RF模拟带宽与输入信号的采样率一致。RF模块化接收器具有输入和输出端口，可将Simulink信号转换为RF域数量，并将其功率扩展到50欧姆参考阻抗。万博1manbetx输入端口以2.45 GHz的指定中心频率将基带信号集中，并且RF IQ解调器将输入信号降低到单个正交阶段。

bdclose(model);

第2部分：包括带外干扰器信号

The modelsimrfV2_comms_rf_interferer展示如何添加以2.5 GHz为中心的带外干扰素的高功率。该阻滞剂通过将其驱动到非线性区域来影响RF接收器。使用以下步骤完成此任务。

model ='simrfv2_comms_rf_interferer'; open_system(model);

Add an 8-PSK Modulator Baseband block source to include a blocking signal with a higher power level than the transmitter signal. Using the Vector Concatenate block, combine the baseband and blocker signals. The input signal to the RF receiver is now composed of two complex baseband signals. It is important that the two baseband sources use the same sample rate to insure equal simulation bandwidths for each signal (same envelope bandwidth). If the two signals don't have the same sample time, they need to be resampled before combining. This is the recommended best practice for simulating blocker signals when they are "far away" from the desired signal in the frequency spectrum and cannot be included in the same envelope for a particular carrier. To display the spectral positioning of the two input signals in the Spectrum Analyzer block, theOffset选项具有两个基带信号指定的两个频率。

The input port of the RF receiver has been modified to include the two carrier (载体频率）信号（2.45 GHz和2.5 GHz）。最初，我们将配置块自动选择基本音调和谐波顺序。

bdclose(model);

Part 3: Add Imperfections to the RF Receiver

The modelSIMRFV2_COMMS_RF_IMPAIRMENTS展示了如何将损伤添加到RF接收器中最初未在RF预算分析仪的链接预算中估算的。

model ='simrfv2_comms_rf_impairments'; open_system(model);

在RF接收器的掩码下，修改RF解调器以添加将由阻塞信号驱动的缺陷。在智商解调剂的面具中，会更改以下参数：

Each of these imperfections separately increases the bit error rate. These imperfections cause finite image rejection and a DC offset that is removed in the baseband domain. As observed, the DC offset correction requires time to integrate the signal power and remove the DC component. To further modify the structure of the I/Q demodulator system, you can click on the "Edit System" button. With this operation you disable the link to the library, inline the value of the parameters, and have the ability to manually modify the block parameters as well as the block architecture.

bdclose(model);

第4部分：如何减少模拟时间

The modelSIMRFV2_COMMS_RF_SPEEDshows how to decrease the simulation time of the previous model described in this example. Follow these steps to speed up the simulation of the model.

model ='simrfv2_comms_rf_speed'; open_system(model);

In Simulink, selectAccelerator模式的速度up the simulation by leveraging automatic C code generation.

In the RF Blockset section, to speed up simulation reduce theHarmonic orderof the Circuit Envelope configuration block. UncheckAutomatically select fundamental tones and harmonic order并设置Harmonic orderequal to 3. The总仿真频率is reduced from 61 to 25, equivalent to an approximate 2.5 times speed up. After reducing the Harmonic order, verify that simulation results do not change.

为了进一步提高模拟速度，请使用频域modeling instead ofTime domainmodeling for the S-parameters SAW filter block. You need to verify that when changing theCompare Time and Frequency Domain Simulation Options for S-parameters方法模拟传输函数仍然正确，并且模型使用足够长的脉冲响应持续时间.

通过上述修改，模拟的速度约为五倍，而不会显着影响仿真结果。

bdclose(model); clearmodel;

相关话题

RF建模入门