CN103401583A

CN103401583A - Clock recovery and calibration method based on identification of pseudo-random sequence characteristics

Info

Publication number: CN103401583A
Application number: CN2013102545412A
Authority: CN
Inventors: 钱海峰
Original assignee: BEIJING YIMEI SIFANG SOFTWARE TECHNOLOGY Co Ltd
Current assignee: BEIJING YIMEI SIFANG SOFTWARE TECHNOLOGY Co Ltd
Priority date: 2013-06-25
Filing date: 2013-06-25
Publication date: 2013-11-20
Anticipated expiration: 2033-06-25
Also published as: CN103401583B

Abstract

The invention discloses a clock recovery and calibration method based on identification of pseudo-random sequence characteristics. The method comprises that a base station and a terminal are reset and then initialized, the base station and the terminal respectively employ clock sources thereof, and the terminal initializes a local counter to carry out free counting; the base station regularly sends wireless signals consisting of synchronous information of the pseudo-random sequence characteristics; and according to the received wireless signals consisting of the synchronous information of the pseudo-random sequence characteristics, the base station calculates frequency deviation and calibrates a local clock. According to the method, the wireless signals consisting of the pseudo-random sequence characteristics are employed to synchronize the terminal with the base station, thereby avoiding the disadvantage that insufficient precision of cheap local devices leads to synchronism loss of signals, and enabling low-cost information transmission of the wireless communication system.

Description

A kind of clock recovery based on the identification of pseudo random sequence feature and calibration implementation method

Technical field

The present invention relates to a kind of clock recovery based on the identification of pseudo random sequence feature and calibration implementation method in frequency hopping wireless communication system, belong to the frequency hopping wireless communication system field.

Background technology

Frequency hopping wireless communication (FHSS:Frequency-Hopping Spread Spectrum) technology is basic frequency multiplexing technique commonly used in a kind of communication, in the situation that the synchronous and while, accept two ends and transmit signal with the narrow frequency carrier wave of specific pattern, for a unspecific recipient, the runout signal that FHSS produces, for it, is only also impulsive noise.The signal that FHSS launches can be evaded according to special design the non-repetitive channel of noise or One-to-Many, and these frequency hopping signals must be observed the requirement of FCC, uses frequency hopping signal more than 75 and frequency hopping extremely the maximum time interval (Dwell Time) of next frequency be 400ms.

Frequency-hopping spread spectrum is exactly to go to carry out frequency shift keying (FSK) modulation with the code sequence of spread spectrum, makes the constantly saltus step of frequency of carrier wave.The jump frequency of frequency-hopping system has a plurality of, nearly tens even thousands of.The information that transmits and the combination of these spreading codes are selected to control, constantly saltus step in transmission.At receiving terminal, need to have with the identical spreading code of the identical local generator generation of transmitting terminal and carry out despreading, then by demodulation, could correctly recover original information.The clock source that uses due to base station and terminal is subjected to the restriction of cost, and running precision is tens of ppm ranks often, and in running, the clock jitter of accumulative total can cause the synchronizing signal step-out, and then affects the correct reception of wireless message.

So, design a kind of clock recovery and calibration implementation method, wireless message transport process is accurately controlled, want with regard to becoming the present invention the problem that solves.

Summary of the invention

In view of above-mentioned existing situation, the present invention aims to provide a kind of clock recovery based on the identification of pseudo random sequence feature and calibration implementation method, to solve the synchronizing signal step-out phenomenon that causes due to the clock cumulative departure, guarantee delivery quality, realize the Frequency Synchronization of frequency hopping wireless communication system.

For achieving the above object, the present invention is achieved through the following technical solutions:

A kind of clock recovery based on the identification of pseudo random sequence feature and calibration implementation method comprise the following steps:

Step 1, to the rear initialization that resets of base station and terminal, set base station and terminal and adopt the clock source of self, the local counter of terminal initialization carries out free counting;

Step 2, base station timed sending comprise the wireless signal of pseudo random sequence feature synchronizing information;

The wireless signal calculated rate deviation that comprises pseudo random sequence feature synchronizing information that step 3, terminal basis receive, and carry out the local clock calibration.

Described step 3 specifically comprises: terminal after receiving synchronizing signal, records local rolling counters forward value, then starts again the synchronizing signal checking,, waiting in the concluding time point, checks whether confirmation signal arrives; If confirmation signal arrives, according to the local clock rolling counters forward value that the pseudorandom feature sequence in confirmation signal receives in conjunction with twice of front and back message, the clock alignment factor of computing terminal and base station, produce local clock according to calibration factor, completes clock synchronous; Otherwise, proceed the terminal synchronizes signal and receive.

Utilization of the present invention comprises pseudorandom feature sequence wireless signal and realizes the synchronous of terminal and base station, can avoid because the puzzlement of the signal step-out that cheap local clock devices timekeeping performance causes not, provide condition for realizing that wireless communication system information transmits cheaply, had advantages of that applicability is good, with low cost.

Embodiment

Below in conjunction with real process, the inventive method is described in further detail.

The invention provides a kind of clock recovery based on the identification of pseudo random sequence feature and calibration implementation method, concrete steps comprise:

Step 1, to the rear initialization that resets of base station and terminal, set base station and terminal and adopt the clock source of self, the local counter of terminal initialization carries out free counting.

Wherein, base station and terminal reset after rear initialization and enter respectively the init state, and base station arranges the radio channel initial value according to the parameter of self configuration, and terminal is carried out free counting after the local counter of initialization.

Step 2, base station timed sending comprise the wireless signal of pseudo random sequence feature synchronizing information.

Whether step 3, terminal after receiving synchronizing signal, record local rolling counters forward value, start again the checking of synchronizing signal,, waiting in the concluding time point, watch confirmation signal and arrive.If confirmation signal arrives, according to the local clock rolling counters forward value that the pseudorandom feature sequence in confirmation signal receives in conjunction with twice of front and back message, the clock alignment factor of computing terminal and base station, produce local clock according to calibration factor, completes clock synchronous; Otherwise, proceed the terminal synchronizes signal and receive.

Wherein, the specific works flow process of terminal comprises:

(1) terminal is under synchronous regime not, periodic slow scanning mode attempts receiving or waiting for the wireless signal of the base station timed sending that includes the sync_detect feature, if it is effective sync_detect to be detected, record the count value of local counter, enter the resync_wait state;

(2) then, wait for the validation signal with resync_detect, start timing and verify whether this packet that receives is effectively correct;

Wherein, sync_detect, resync_detect are the input signs of physical layer, when equipment, receive a string known synchronizing signal, just think and wireless signal detected, sync_detect, resync_detect are set to effectively, and simultaneously flip-flop number is caught passage and is carried out count value and catch.Resync_wait is the terminal synchronizes tracking mode, is in the situation that terminal is not synchronous, and terminal utilizes the scanning of local clock source to receive aerial message, and determines whether the state of sync packet.

(3) if this packet is incorrect or be in disarmed state, return to step (1) relaying continued access and receive or wait for, otherwise, enter step (4);

(4) according to the local Counter Value of the information in synchronization packets and step (1), step (2) record, calculate the deviate of local clock and base station clock, adjust the local clock benchmark, the local clock after the output compensation, the clock synchronous adjustment is completed.

Produce radiofrequency signal according to adjusting the local clock source of completing, just can control transceiver and carry out radio communication, guaranteed the delivery quality of wireless signal and transmitted synchronism, eliminated the drawback of the signal step-out that causes not because of the local clock devices timekeeping performance of cheapness, for wireless telecommunication system signal transmission cheaply provides realizability condition.

Claims

1. the clock recovery based on pseudo random sequence feature identification and calibration implementation method is characterized in that:

2. a kind of clock recovery based on the identification of pseudo random sequence feature according to claim 1 and calibration implementation method, is characterized in that, described step 3 specifically comprises:

Described terminal after receiving synchronizing signal, records local rolling counters forward value, then starts again the synchronizing signal checking,, waiting in the concluding time point, checks whether confirmation signal arrives;

If confirmation signal arrives, according to the local clock rolling counters forward value that the pseudorandom feature sequence in confirmation signal receives in conjunction with twice of front and back message, the clock alignment factor of computing terminal and base station, produce local clock according to calibration factor, completes clock synchronous; Otherwise, proceed the terminal synchronizes signal and receive.