当前,移动通信技术的迅猛发展,促使传统的基于专用硬件的通信设备所固有的功能单一、不易升级改造的缺点突显出来,导致多种通信协议在兼容和版本升级方面的问题日益严重.而软件无线电技术由于自身的灵活性和开放性,可以很好地解决这些问题.在此基础上,对多速率数字中频系统中的关键技术进行了研究和实现.系统设计为全双工模式,支持多速率收发处理,可根据实际应用的需要进行配置,从而实现多种数据速率的转换.系统主要包括混频器模块、采样率变换(插值和抽取)模块、低通滤波器模块.功能上实现了32、96、480倍的降/升采样处理和240 kHz的信号下变频处理,且阻带衰减可以达到60 dB,有效地对杂散信号进行了抑制.在灵活配置的系统前提下,对模块进行了优化和复用,不仅节省了硬件开销,而且提高了系统性能.%As the mobile communication technology develops rapidly,traditional communication devices based on proprietary hardware have limited function and are hard to upgrade,which cause a compatibility issue for a variety of communication protocols and software versions.Software defined radio technology has the advantage of flexibility and openness,and can solve these problems easily.We present a multi-rate digital intermediate frequency (IF) system implemented by FPGA.The system is designed in a full duplex mode and supports multi-rate transceiver;it can also be configured according to specific applications in order to achieve a variety of data conversion rates.The system includes a mixer module,a sample rate conversion (interpolation and decimation) module,and a low-pass filter module.It realizes 32,96,480 times down/up sampling and 240kHz down conversion process.The spurious signals are effectively suppressed while the signal stopband attenuation can reach 60dB.With flexible system configuration,the module is optimized and reused,which can save hardware cost and improve the performance.
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