In this letter we experimentally verify a real-time implementation of the ‘better-than-Nyquist’ pulse shape in carrier-less amplitude and phase (CAP) modulation in the context of a visible light communications system. We use two National Instruments universal software radio peripherals (USRPs) as a transmitter and receiver working independently. Previously reported experimental work on pulse shaping in CAP is also verified in real time, showing lower error vector magnitudes (EVM) can be obtained at shorter filter lengths using the better-than-Nyquist pulses in place of the conventionally used square-root raised cosine as the basis function of the signal. We show that a real time EVM penalty is an additional 3% EVM in the worst case and is a result of synchronisation offset at the receiver.

中文翻译：

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在可见光通信中使用“优于奈奎斯特”的脉冲整形实时实现 CAP 调制

在这封信中，我们通过实验验证了在可见光通信系统环境中在无载波幅度和相位 (CAP) 调制中“优于奈奎斯特”脉冲形状的实时实现。我们使用两个 National Instruments 通用软件无线电外设 (USRP) 作为独立工作的发送器和接收器。先前报道的关于 CAP 中脉冲整形的实验工作也得到了实时验证，表明使用优于 Nyquist 的脉冲代替传统使用的平方根升余弦可以在较短的滤波器长度下获得较低的误差矢量幅度 (EVM)作为信号的基函数。我们表明，在最坏的情况下，实时 EVM 惩罚是额外的 3% EVM，并且是接收器同步偏移的结果。