BOC調制信號體制下多址干擾對偽碼跟蹤偏差影響分析

BOC調制信號體制下多址干擾對偽碼跟蹤偏差影響分析

周傳宇,李井源,黃新明,黃仰博,孫廣富

(國防科技大學電子科學與工程學院衛星導航定位技術工程研究中心,長沙 410073)

摘要：在遠近問題嚴重的偽衛星或導航戰功率區域增強典型場景下,用戶機接收到的不同衛星信號功率不均衡,對于衛星信號監測的高精度偽碼測距接收機,多址干擾成為必須考慮的誤差因素之一,即使在導航現代化的新體制下影響也十分顯著。本文在BOC調制信號體制下基于偽碼跟蹤非相干延遲鎖定環路,對多址干擾影響偽碼跟蹤偏差的機理展開,從碼跟蹤環鑒別函數出發推導出偽碼跟蹤偏差的近似解析表達式,其后對BOC(1,1)調制信號體制下存在一路多址干擾時偽碼跟蹤偏差的影響進行分析和仿真驗證,得出只有在偽碼相位及載波相位差變化至特定位置時多址干擾影響明顯,否則影響微弱;多址干擾影響與碼跟蹤相關器間隔變化較小,與多址干擾功率變化較大;在多址干擾功率高于期望信號功率20 dB時,跟蹤偏差達到0.1個碼片。

關鍵詞：偽衛星;多址干擾;二進制偏移載波調制;非相干延遲鎖定環;跟蹤偏差

doi:10.13442/j.gnss.1008-9268.2015.05.011

中圖分類號：P228.4

文獻標志碼：A

文章編號：1008-9268(2015)05-0058-07

收稿日期：2015-07-17

作者簡介

Abstract:In the scenario of pseudo satellites which facing a serious near-far problem or power region enhancement in navigation warfare, user receive different signals with various power levels, as a result, the impact of multiple access interference for high precision PN code ranging signal detection receiver is one of the major factors that must be considered,even for the new generation navigation system. In this paper the principle of multiple access interference effects on the noncoherent delay locked loop PN code tracking deviation is analyzed, based on the binary offset carrier (BOC) modulated signal system. An approximate analytical expression of the pseudo code tracking deviation is derived from the phase detector function, then the effect of single multiple access interference on the pseudo code tracking deviation and simulation analysis is carried out for BOC(1,1) modulated signal, concluding that the effect of multiple access interference is obvious only when the carrier phase difference and the phase difference of the PN code is changed to a specific position, and is a little influenced by the correlator spacing, while much influenced by multiple access interference power. The pseudo code tracking deviation reaches 0.1 chips when the multiple access interference power is 20 dB higher than the expected signal power.

0引言

衛星導航系統的高速發展對導航性能提出了更高的要求,偽距跟蹤偏差受到多種因素的影響,由于擴頻偽碼互相關峰值相對自相關峰值較小,傳統觀點認為多址干擾引起的偽碼跟……