We present a flexible software defined radio (SDR) receiver design for the reception and demodulation of satellite signals. The proposed SDR performs an online Doppler search, as well as a code-rate and code-phase search online. The use of graphics processing units (GPUs) allows the radio to compensate Doppler offsets and achieve symbol synchronization in real time. This eliminates the need for a priori information on the satellites position and velocity to perform Doppler compensation on the downlink. To successfully utilize the enhanced computational power of graphics processing units (GPUs) and achieve real-time performance, we utilize acausal batch based signal processing, which allows for the use of fast convolution algorithms. These can efficiently be parallalized and run on GPUs. The Doppler search and demodulation is done by using matched filters. This allows one to adapt the demodulator to work for many modulation schemes by merely changing the set of filters. The demodulator itself essentially works as a batched correlation receiver. Additionally, the proposed SDR can decode signals from multiple antennas that are located at geographically spread ground stations simultaneously. The decoded bits are compared using soft decisions. This can greatly increase the rejection of local burst interference as well as polarized interference and tracking signals that rotate in polarization.

中文翻译：

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用于卫星通信的多普勒校正软件定义无线电接收机设计

我们提出了一种灵活的软件定义无线电 (SDR) 接收器设计，用于接收和解调卫星信号。建议的 SDR 执行在线多普勒搜索，以及在线码率和码相位搜索。图形处理单元 (GPU) 的使用允许无线电补偿多普勒偏移并实时实现符号同步。这消除了在下行链路上执行多普勒补偿时需要有关卫星位置和速度的先验信息的需要。为了成功利用图形处理单元 (GPU) 的增强计算能力并实现实时性能，我们利用基于非因果批处理的信号处理，允许使用快速卷积算法。这些可以有效地并行化并在 GPU 上运行。多普勒搜索和解调是通过使用匹配滤波器完成的。这允许仅通过改变一组滤波器来使解调器适用于许多调制方案。解调器本身本质上用作批处理相关接收器。此外，提议的 SDR 可以同时解码来自多个天线的信号，这些天线位于地理上分散的地面站。解码后的比特使用软判决进行比较。这可以大大提高对本地突发干扰以及极化干扰和极化旋转的跟踪信号的抑制。提议的 SDR 可以同时解码来自多个天线的信号，这些天线位于地理上分散的地面站。解码后的比特使用软判决进行比较。这可以大大提高对本地突发干扰以及极化干扰和极化旋转的跟踪信号的抑制。提议的 SDR 可以同时解码来自多个天线的信号，这些天线位于地理上分散的地面站。解码后的比特使用软判决进行比较。这可以大大提高对本地突发干扰以及极化干扰和极化旋转的跟踪信号的抑制。