公开(公告)号：US06002710A

公开(公告)日：1999-12-14

申请号：US175052

申请日：1998-10-19

申请人： Alan F. Hendrickson ,  Ken M. Tallo

发明人： Alan F. Hendrickson ,  Ken M. Tallo

IPC分类号： H04L1/24 ,  H04L7/02 ,  H04L7/033 ,  H04B15/00 ,  H04K1/00 ,  H04L7/00 ,  H04L27/30

CPC分类号： H04L7/0054 ,  H04L1/24 ,  H04L7/0334

摘要： In a digital communication system for voice signals, a system and method for recovering the timing of a pseudo-random noise (PN) sequence used for direct-sequence spreading and despreading of the communicated signals. In one embodiment, a received signal is a time-division duplexing (TDD) or time-division multiple access (TDMA) signal, and a receiver performs a complete "sliding correlator" examination of the received signal in a fixed time by using the timing of the TDMA or TDD frames. This examination allows a rapid initial acquisition of the PN synchronization. In another embodiment of the receiver, the initially acquired PN phase is verified by reading a SYNC field from the received signal and by checking that shifting the receiver's local PN phase results in a degraded correlation between the local PN sequence and the received signal. A fast tracking procedure finely synchronizes the receiver's PN sequence with the received PN sequence by repeatedly testing the effects of dithering the receiver's PN phase. The fast tracking is preferably performed for a fixed duration of time and is followed by a slow tracking that continues the dithering to maintain the fine synchronization. In the slow tracking procedure, the receiver preferably adjusts its PN phase only if repeated tests consistently indicate a lag or lead in the synchronization. The slow tracking procedure preferably also includes a second-order correction in the PN phase to allow for frequency differences between a PN clock in the receiver and a PN clock in a remote transmitter.

摘要翻译： 在用于语音信号的数字通信系统中，用于恢复用于所传送的信号的直接序列扩展和解扩的伪随机噪声（PN）序列的定时的系统和方法。 在一个实施例中，接收信号是时分双工（TDD）或时分多址（TDMA）信号，并且接收机通过使用定时对固定时间对接收信号进行完整的“滑动相关器”检查 的TDMA或TDD帧。 该检查允许快速初始获取PN同步。 在接收机的另一个实施例中，通过从接收信号读取SYNC字段并且通过检查接收机的本地PN相位的移位导致本地PN序列与接收信号之间的相关性降低来验证初始获取的PN相位。 快速跟踪程序通过重复测试抖动接收机的PN相的效果，将接收机的PN序列与接收到的PN序列进行精细同步。 快速跟踪优选地在固定的持续时间内执行，并且之后是慢速跟踪，其继续抖动以保持精细同步。 在慢速跟踪过程中，只有在重复测试一致地指示同步中的滞后或引导时，接收器才优选地调整其PN相位。 慢跟踪程序优选地还包括PN阶段中的二阶校正以允许接收机中的PN时钟和远程发射机中的PN时钟之间的频率差。

公开(公告)号：US06256337B1

公开(公告)日：2001-07-03

申请号：US09148607

申请日：1998-09-04

申请人： Alan F. Hendrickson ,  Ken M. Tallo

发明人： Alan F. Hendrickson ,  Ken M. Tallo

IPC分类号： H04L2730

CPC分类号： H04L1/24 ,  H04L7/0054 ,  H04L7/0334

摘要： In a direct sequence spread spectrum communication system, a system and method for recovering the timing of a pseudo-random noise (PN) sequence used for despreading the received signals. In one embodiment, the communication system is a time-division duplexing (TDD) or a time-division multiple-access (TDMA) system. A receiver in the communication system uses a “sliding correlator” maximal-likelihood (ML) detection system to scan through a range of possible PN phases to determine the correct one. In one embodiment of a method for performing the synchronization, a receiver acquires the PN phase by repeating the ML detection for a time greater than or equal to the period of the TDD or TDMA frames, with a sufficiently high repetition rate to ensure that the correct PN phase is examined at least once during a received frame. The acquisition is thereby completed within a fixed amount of time. One embodiment of a system for performing the synchronization includes an input for the received signal, a receiver PN clock, and an ML detection logic. The ML detection logic repeats the ML detection so that at least one complete set of PN phases is examined during a time when the received signal is active. In another embodiment of the method, the receiver acquires the PN phase by performing the ML detection during a timeslot in which a received frame is expected. Again, the acquisition is completed within a fixed amount of time.

摘要翻译： 在直接序列扩频通信系统中，用于恢复用于解扩接收信号的伪随机噪声（PN）序列的定时的系统和方法。 在一个实施例中，通信系统是时分双工（TDD）或时分多址（TDMA）系统。 通信系统中的接收机使用“滑动相关器”最大似然（ML）检测系统来扫描可能的PN相的范围以确定正确的PN相位。 在用于执行同步的方法的一个实施例中，接收机通过以足够高的重复率重复ML检测大于或等于TDD或TDMA帧的周期的时间来获取PN相位，以确保正确的 PN帧在接收帧期间至少检查一次。 因此，在一段固定的时间内完成收购。 用于执行同步的系统的一个实施例包括用于接收信号的输入，接收机PN时钟和ML检测逻辑。 ML检测逻辑重复ML检测，使得在接收信号有效的时间期间检查至少一个完整的PN相组。 在该方法的另一实施例中，接收机通过在期望接收帧的时隙中执行ML检测来获取PN相位。 同样，收购在固定的时间内完成。