双模对讲机中数字编码静噪系统如何实现
摘要：由于数字对讲机的頻谱利用率比模拟对讲机高得多，还由于数字对讲机能够提供模拟对讲机无法达到的数据处理种类及灵活性，因此模拟对讲机的数字化改造进程已势不可挡。在 这个过渡时期，需要开发数模兼容的双模对讲机，以满足市场需要并实现平缓过渡。双模对讲 机的数字基带信号处理系统已经用数字信号处理器（DSP)实现，以往使用专用芯片实现的数字编码静噪系统也需要集成到DSP当中，这样不仅能够简化整个系统的硬件电路，提高集成度， 而且可以简约成本，降低功耗。介绍了如何在以DSP为核心的双模对讲机硬件平台上实现数字 编码静噪系统。经测试，本系统在接收机输出信噪比为OdB的条件下可以可靠地工作，完全符合电子工业协会(EIA)标准的要求。 关键词：数字编码静噪；数模兼容；双模对讲机；数字信号处理器 Implementation of digital coded squelch system in Abstract： Because the digital two way radio’s spectrum efficiency is much higher than analog one, and also the digital one can provide more kinds of data processing and flexibility, so analog two way radio’s digital transformation process has been overwhelming. In this transitional period，development of dualmode two way radio should meet the market needs to achieve smooth transition. The digital baseband signal processing system in dual-mode two way radio has been implemented on digital signal processor (DSP) , then, the digital coded squelch system which used to be implemented on ASIC also needs to transplant onto the DSP, as this can not only simplify the system hardware and improve the integration, but also reduce costs and power consumption. This article describes how to develop digital coded squelch system on hardware platform based DSP. After testing, the digital coded squelch system works reliably when the output SNR of the receiver is OdB, which is fiill compliance with the Electronic Industries Alliance (EIA) standards. Key words： digital coded squelch； digital-analog-compatible； dual-mode two way radio； digital signal processor 引言
