CN102378354A - Synchronization method for short-term burst communication - Google Patents

Abstract

The invention relates to a synchronization method for short-term burst communication. The synchronization method is characterized in that: 0 Phi phase modulation is carried out on carrier signals with the frequency of 70MHz with a binary sequence, and the carrier signals are transmitted; a receiving end conducts real-time related detection on the received signals and noise; when a related peak value exceeds a set threshold value, the received data are adopted as effective data frames to fulfill coarse acquisition segment processing; the data of a synchronization segment are adopted to carry out timing recovery and carrier recovery; related operation is adopted to judge a precise acquisition segment, the subsequently received data are effective data when a related peak value exceeds a set threshold value, and thereby the synchronization of short-term burst communication is realized. A burst communication system which is designed by adopting the method has lower complexity, better error rate property and shorter timing synchronization and carrier synchronization recovery time, and can assist a transmission device to fulfill a secondary radar ranging function.

Description

A kind of method for synchronous that is used for short-term burst communication

Technical field

The present invention relates to a kind of method for synchronous that is used for short-term burst communication, belong to communication technical field, particularly the communication system of short-term burst data communication.

Background technology

Most wireless communication systems are operated under the continual state of wireless signal, and in a single day communication set up in this type communication system, and signal transmits continuously, just can disappear up to an end of communication signal.The carrier synchronization time to signal in this type systematic does not have strict demand with timing lock in time, can sacrifice a part of communication data up to regularly synchronous and carrier synchronization completion, just begins active data communication then.But in some communication environment; Data volume is less but real-time and security requirement are very high; Use the burst communication mode to transmit data, call duration time is short in this case, sends frame data at every turn; Communication frame length is generally slightly long than valid data, and regularly sync carrier is deciphered and must in frame data of limited length, be solved with data demodulates synchronously.

The transmission of short-term burst communication pattern has been compared tangible difference with reception with continuous system:

The catching of burst communication, regularly synchronously and the carrier synchronization time to lack with respect to the continuous communiction pattern, could improve overall system efficiency like this.Generally use phase-locked loop to carry out timing and carrier track in the continuous system, if according to traditional loop-locking time to short-term burst frame operation, loop parameter locking time will be much larger than the time span of burst frame so; And burst communication system is data-aided for being based on synchronously of packet, uses the loop parameter of broad auxiliary data to be locked the locking time that can reduce loop simultaneously.

Under the situation of continuous communiction intermediate ring road locking, the local parameter of receiver is slowly followed the parameter that receives signal and is changed; And in the burst communication; Effective duty ratio of communication is lower; Make the channel parameter of two adjacent communication frames alter a great deal, the timing of this synchronization gain and carrier parameter can not must be caught and tracking processing the signal that each communication is received as messaging parameter use next time again.

Common continuous communiction system pays attention to separating of data and is in harmonious proportion decoding, and the short-term burst system of this paper also requires accurately to measure the moment of arriving signal, is used for auxiliary transmitting apparatus to accomplish the secondary radar distance measurement function, and obvious traditional continuous communiction can't be accomplished this function.

Summary of the invention

The technical problem that solves

For fear of the weak point of prior art, the present invention proposes a kind of method for synchronous that is used for short-term burst communication, is applicable to the forward error correction communication system of short-term burst.

Technical scheme

A kind of method for synchronous that is used for short-term burst communication is characterized in that step is following:

Step 1: is that the carrier signal of 70 megahertzes is carried out 0 π phase modulated and sent with binary sequence to frequency; The bit rate of described binary sequence is 5 megabit per seconds, successively according to slightly the section of catching, sync section, the essence section of catching and data segment are exported in proper order; The said segment encode word of slightly catching is: 0010010110011110001101110101000; Said sync section code word is 91 10 sequences; Said essence is caught the segment encode word: 0011100100010100001001011001111; Said data segment is the actual required information transmitted data of system;

Step 2: receiving terminal is done real-time coherent detection to the signal and the noise employing

of receiving; Wherein: x (k) is the baseband signal of input; H (m-k) is for slightly catching the segment encode word, and L is for slightly catching the length of segment encode word;

Step 3: when correlation peak surpasses the setting threshold value, the data that receive are accomplished the slightly section of catching processing as effective data frame; Said threshold value is 1/2～1/3 of a theoretical correlation; Said effective data frame comprises sync section, the essence section of catching and the data segment data of input successively;

Step 4: adopt the data of sync section to carry out timing recovery and carrier wave recovery;

Step 5: adopt related operation to judge in the essence section of catching; When correlation peak surpasses the setting threshold value; The data of follow-up reception are valid data, realize the synchronous of short-term burst communication.

Beneficial effect

A kind of method for synchronous that is used for short-term burst communication that the present invention proposes has following advantage:

1, used ' 0 ' ' 1 ' targeting sequencing that replace in the sequence, make and regularly recover the locking process quickening that recovers with carrier wave.

2, to compare with traditional single synchronous head structure, the three stage structure of the top slightly section of catching, sync section and the smart section of catching can effectively improve the false-alarm and the false dismissal performance of system.The section of catching comparison threshold can reduce false dismissal probability greatly by reducing slightly, but has improved false-alarm probability simultaneously, and is consistent with received signal through the timing parameters carrier parameter of system behind the sync section.Under the condition of accomplishing synchronously, essence is caught and can effectively be rejected when slightly catching because comparison threshold is crossed the false-alarm signal of low entering system.From alarm dismissal probability and the false alarm probability that has reduced system.

3; In the essence section of catching, the timing of receiver is consistent with the reception signal with carrier parameter, and this moment is through improving the clock cycle of related operation; Receiver can provide accurate smart sync section signal due in, can accomplish the distance measurement function of secondary radar through this due in.

Adopt the burst communication system of the inventive method design to have lower complexity, better error ratio characteristic, faster regularly synchronously with carrier synchronization recovery time, and can assist transmitting apparatus completion secondary radar distance measurement function.

Description of drawings

Fig. 1: binary sequence

Preceding 31 bit M sequences of the first behavior difference wherein, the targeting sequencing that second behavior ' 0 ' ' 1 ' replaces, the third line are 31 bit M sequences behind the calculus of differences.

Fig. 2: for receiving the handling process sketch map, Fig. 2 has reflected the treatment mechanism to Fig. 1 frame signal.

Embodiment

Combine embodiment, accompanying drawing that the present invention is further described at present:

The embodiment of the invention realizes as follows:

Step 1: is that the carrier signal of 70 megahertzes is carried out 0 π phase modulated and sent with binary sequence shown in Figure 1 to frequency; The bit rate of described binary sequence is 5 megabit per seconds, successively according to slightly the section of catching, sync section, the essence section of catching and data segment are exported in proper order; The said segment encode word of slightly catching is: 0010010110011110001101110101000; Said sync section code word is 91 10 sequences; Said essence is caught the segment encode word: 0011100100010100001001011001111; Said data segment is the actual required information transmitted data of system;

Step 2: the receiving terminal of communication is done real-time coherent detection to signal and the noise received; Adopt

and do real-time coherent detection; Wherein: x (k) is the baseband signal of input; H (m-k) is for slightly catching the segment encode word, and L is for slightly catching the length of segment encode word;

Set thresholding in case correlation peak surpasses, think that then effective data frame arrives, carry out immediately synchronously and demodulation work.We are called the related operation of this step and slightly catch operation, and corresponding signal segment is called the slightly section of catching.Slightly the binary sequence of the section of catching is as shown in Figure 1.Related detecting method is through a window with the discrete series value after the digital to analog conversion that receives; The length of window is with slightly the section of catching sequence length is consistent; Reception data in the window and local acquisition sequence are carried out related calculation, and the content of local acquisition sequence is consistent with the slightly section of the catching content of signal.The thresholding of an operation result and a setting is done comparison.If operation result a continuous bit in the time all greater than threshold value, just think that the signal that arrives is an effective data frame.

Step 3: when correlation peak surpasses the setting threshold value, the data that receive are accomplished the slightly section of catching processing as effective data frame; Said threshold value is 1/2～1/3 of a theoretical correlation; Said effective data frame comprises sync section, the essence section of catching and the data segment data of input successively;

Step 4: adopt the data of sync section to carry out timing recovery and carrier wave recovery; The sync section binary sequence adopts 0 yard and 1 yard composition alternately, variable-length, and selecting length here for use is 90 bits, contains abundant timing information and carrier information.In the step 2 slightly catch completion after, receiver starts and regularly to recover and carrier recovery loop, and the sync section data are sent into timing recovery loop and carrier recovery loop.The broader bandwidth of phase-locked loop can reduce the time overhead of clock synchronization and carrier synchronization greatly.The timing and the carrier track of receiver were accomplished after sync section was handled.

Step 5: be the essence section of catching after the sync section; The essence section of catching adopts and the identical binary sequence of the section of catching slightly; But slightly the sign indicating number sequence of the section of catching and the smart section of catching is different in adopting differential modulation system system; Slightly the section of catching is the original series that does not carry out differential coding, and the essence section of catching is the sequence through differential coding.Thick sync section is a carrier wave and regularly do not have to carry out under the synchronous state, so the amplitude of coherent detection and time are not too accurate; And the timing of carrier wave has all been accomplished synchronously when carrying out the operation of smart sync section, and therefore the amplitude and the time precision of smart synchronization gain improve greatly, particularly in native system, utilizes this time information to return a radio-frequency pulse as the secondary radar pulse of finding range.

Adopt related operation to judge in the essence section of catching; When correlation peak surpasses the setting threshold value; The data of follow-up reception are valid data, realize the synchronous of short-term burst communication.

The receiving terminal utilization of communication is done time reference to the coherent pulse of the synchronous computing of essence, returns a radio-frequency pulse to data sending terminal, accomplishes distance measurement function.Receiver is accomplished the synchronous working that this frame receives signal, and next step task is that the data of data segment are carried out demodulation, decoding and output services, and then accomplishes communication task one time.

Embodiment:

Quadrature demodulator output I road and Q road Low Medium Frequency signal are sent the IQ two paths of signals into analog to digital converter respectively.The digital IQ signal of analog to digital converter output is sent into correlation detector; Correlation detector carries out related calculation input signal respectively with the 31 bit correlated serieses of this locality; The computing peak value thinks that arriving signal is effective coarse synchronization signal after surpassing the comparison threshold of setting, and the output frame lock-on signal is synchronous and carrier synchronization module to timing, if correlation peak is less than comparison threshold; The output frame lock-on signal does not continue the detection of burst.The related operation formula is following:

$R\left(k\right)=\underset{m=1}{\overset{L}{\mathrm{\Σ}}}x\left(k\right)h^{*}(m-k)---\left(1\right)$

In the formula (1), x (k) is the baseband signal of input, and h (m-k) is local M sequence, and L is the length of local correlated series.

In case catch completion, input signal is sent into the matched filtering module, utilize timing information that input signal is carried out integration and clean, improve the signal to noise ratio of input signal.It is 1/10 symbol time length that integration cleans stepping length, and the integration duration is 1 symbol time, finishes from the initial code element that is added to of code element.

The data that integration cleans after accomplishing enter into regularly recovery and carrier recovery loop, and timing error is extracted as door extracting mode sooner or later, and carrier error is extracted and adopted the realization of cross product inspection frequency method.

After regularly recovering completion with carrier wave, receiver reuses related operation to input signal to carry out essence and catches, and the related operation formula is identical with formula (1).The result who slightly catches does comparison in amplitude with on the time with predefined thresholding, and requirement is higher but essence is caught the result, and the amplitude information that essence is caught the result is necessary equal with predefined comparison value, otherwise abandons this frame data, waits for and catching next time.The temporal information of catching the result is exactly the moment that this frame signal arrives, and returns pulse with this time basic point transmission and just can accomplish the secondary radar distance measurement function.

Claims (1)

1. one kind is used for the method for synchronous that short-term burst is communicated by letter, and it is characterized in that step is following:

Step 1: is that the carrier signal of 70 megahertzes is carried out 0 π phase modulated and sent with binary sequence to frequency; The bit rate of described binary sequence is 5 megabit per seconds, successively according to slightly the section of catching, sync section, the essence section of catching and data segment are exported in proper order; The said segment encode word of slightly catching is: 0010010110011110001101110101000; Said sync section code word is 91 10 sequences; Said essence is caught the segment encode word: 0011100100010100001001011001111; Said data segment is the actual required information transmitted data of system;

Step 2: receiving terminal is done real-time coherent detection to the signal and the noise employing

of receiving; Wherein: x (k) is the baseband signal of input; H (m-k) is for slightly catching the segment encode word, and L is for slightly catching the length of segment encode word;

Step 3: when correlation peak surpasses the setting threshold value, the data that receive are accomplished the slightly section of catching processing as effective data frame; Said threshold value is 1/2～1/3 of a theoretical correlation; Said effective data frame comprises sync section, the essence section of catching and the data segment data of input successively;

Step 4: adopt the data of sync section to carry out timing recovery and carrier wave recovery;

Step 5: adopt related operation to judge in the essence section of catching; When correlation peak surpasses the setting threshold value; The data of follow-up reception are valid data, realize the synchronous of short-term burst communication.

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