【摘要】 频偏的存在相当于对带限信号的频谱进行了搬移,使解扩信号经过带限滤波器后能量受到损失,从而降低了系统的误码性能。本文首先详细分析了零中频非相干解扩解调器误码性能的影响,推导出误码率表达式,然后提出了改进型非相干解扩解调器,并分析了它的误码性能,最后对这两种解扩解调器误码特性进行了比较。更多还原

【Abstract】 Frequency-offset would shift the central frequency of band-limited signal, as the result, signal energy lost would happen during the signal despreading and band-limited filtering. In this case, the performance of spread spectrum communication system will be declined. In this paper, the effect of frequency-offset for zero-IF noncoherent despread/demodulator is firstly investigated in detail as to derive a bit-error-rate (BER) formula. Secondly, an improved noncoherent despread/demodulator is presented and its performance is analyzed. Finally, comparison for the BER performance of the two kinds of noncoherent despread/demodulator is conducted. It is concluded from the result that conventional zero-IF noncoherent despread/demodulator was very sensitive to frequency-offset, while the improved noncoherent despread/demodulator proposed in this paper can provide more toleration to frequency-offset.更多还原