CN1117151A - Short-wave timing digital correlated detecting technique and short-wave self-correcting time-keeping clock - Google Patents

Abstract

The shortwave timing digital correlated detection techn utilizes the principle that the time-keeping second signal and the local clock second signal have the same period, digitalizes every analog time signal for correlated analysis and sectional statistics, and thus obtains high time signal tracking precision and time-keeping reliability. The shortwave self-correcting time-keeping clock based on the above-said techn can automatically recognize, analyze and track several time signals, and correct the transmission time delay, so that it is an ideal timing equipment.

Description

Shortwave timing digital correlation detection technology and the shortwave self-correcting clock of keeping time

The invention belongs to radio time service and timing technology field.Short-wave radio regularly is the hf time signal of radiothermy time service platform broadcast, after being handled by the remote user reception, obtains and the synchronous standard time of transmitting station.Handle for the reception of short-wave radio time signal, mainly contain at present that narrow-band filtering, pulse thresholding, width are differentiated, technology such as time gated; To the control of local clock, methods such as synchronous mode, comparison time difference recording, Continuous Tracking formula once.The development of Japanese RRL radio research laboratories is arranged abroad, is used for the JJY time signal synchronizer of the oblique synchronizing detection in ionosphere, the DGS-256 numeral altimeter WWV that U.S. LoweLL university arranged to the time equipment etc.

Because Dispersive Channels when short wave channel is, ionosphere can cause the various propagation phenomenons such as chromatic dispersion, absorption, decline, Doppler shift, multimode propagation and signal interruption of time signal to the reflection of short-wave signal, and shortwave frequency range channel is very crowded, all kinds of dried scratching seriously.In addition, existing shortwave time service time signal form is simple, all is the gradual amplitude modulation by tone signal in arrowband generally, this for anti-dried scratch with accurate timing also totally unfavorable.Above-mentioned just reason has caused the serious distortion and the phase jitter (maximum can reach the several milliseconds of orders of magnitude) of hf time signal waveform.

Relevant studies show that; The propagation delay of hf time signal can change in time, this mainly is because the conventional radio wave attenuation height change and the time signal that cause of changing in ionosphere causes what the travel path variation was caused through different communication modes [as F layer, E (Es) layer, various paths such as a jumping, multi-hop].Newest research results also shows, sometimes there is the unusual time signal of a kind of so-called shortwave, its propagation delay is many greatly than the time delay of regular reflection time signal, reach several milliseconds even tens milliseconds, it is actually a kind of hf time signal that arrives acceptance point along non-Da Yuan path through ionosphere secondary focusing, a ground scatter propagation.

Above-mentioned propagation characteristic in view of hf time signal, adopt the timing accuracy lower (generally at several milliseconds to tens milliseconds) of the shortwave timing device of prior art design, reliability relatively poor (often causing timing error) because of signal dropout, capable and experienced scratching, and a kind of shortwave timing device often can only be to a kind of time signal regularly, and in timing, need manual intervention, need handle or artificial calculating and setting the propagation delay of time signal afterwards.

But it should be noted that the BPM hf time signal timing instrument of being developed by Shaanxi Astronomical Observatory, Chinese Academy of Sciences is the regularly outstanding representative of instrument of modern shortwave, this instrument adopts midpoint detection technique (to apply for China's patent of invention, the patent No.: 88103184) and in conjunction with four-dimensional gating (is frequency domain, time domain, width, amplitude) method, make this instrument shortwave timing accuracy more in the past the shortwave timing device improve a lot, the automatic tracking accuracy of its time signal reaches ± 1.5ms, accused as 363-6 number record skin books and newspapers of time-frequency research new development income nineteen ninety degree CCIR the 7th seminar by International Telecommunication Association, made significant contribution for improving the shortwave timing technology.But, it is symmetrical that midpoint detection technique requires the time signal waveform, but in the ionosphere of reality time signal was propagated, owing to decline, driedly the requirement that the time signal wave form distortion that causes often can not be satisfied symmetry such as scratch, this just caused determining that the time signal due in can occur than serious mistake.In addition, midpoint detection technique can't obtain the various ionospheres information that hf time signal carries, thereby fully overcomes the influence that propagate time signal in ionosphere.For example: the differentiation of time signal waveform distortion, the variation of communication mode, the identification of unusual time signal etc., thereby also just the absolute timing accuracy of shortwave can't be guaranteed in 1ms.Utilize digital circuit hardware to finish because mid point detects,, can't utilize external various time-signal station signal, limited its usable range and timing efficient so BPM shortwave timing instrument can only be discerned BPM timing signal regularly (other method generally also is a time-signal station).This BPM timing instrument also needs artificial rough search to differ second to instrument internal second and time signal just to enter in the 10ms scope from the motion tracking method of synchronization, also need manually table look-up to preset in advance to the correction of the propagation delay of time signal and revise, can not revise in real time according to the propagation characteristic of time signal, so time delay correction precision is also lower.

The objective of the invention is to disclose a kind of shortwave timing digital correlation detection technology, so that solve the problems referred to above that exist in the existing shortwave timing technology effectively.And to provide a kind of be the punctual clock of shortwave self-correcting of foundation development with shortwave timing digital correlation detection technology, it is a kind of real time clock of energy Continuous Tracking shortwave time signal, because it can discern automatically, analyze, follow the tracks of time signal, and revise propagation delay automatically, thereby obtain higher timing accuracy and reliability.

The object of the present invention is achieved like this, utilize time service signal second and local clock to have this characteristic of identical cycle in inner second, with each simulation laggard line correlation analysis of time signal digitizing and classified statistics, thereby obtain higher time signal tracking accuracy and timing reliability.Principle of work of the present invention is as follows:

Fig. 1 is a shortwave timing digital correlation detection technology schematic diagram.

Fig. 2 is the short timing digital correlation detection technology electrical schematic diagram that drapes over one's shoulders.

Fig. 3 is the punctual clock electrical schematic diagram of shortwave self-correcting.

Wherein: a---emission time signal waveform second, b---the inner second waveform of punctual clock, c---receive time signal waveform second, d---sample range, e---a standard output second waveform, 1---time signal second, 2---the A/D sampling thief, 3---microcomputer (8031 Single Chip Microcomputer (SCM) system), 4---program storage, 5---data-carrier store, 6---the crystal oscillator frequency source, but 7---the phase shift division chain, 8---the variable time delay counter, 9---standard second, 10---digital tuning point frequency receiver, 11---bandpass filter, 12---audiomonitor, but 13---the phase shift digital clock, 14---2 * 9 keyboards, 15---keyboard display controller, 16---6 light-emitting diode displays.

1, see Fig. 1 (a) second by the standard time signal of shortwave time service platform broadcast, it is made of several audio frequency sine waves, and its starting point and UTC Universal Time Coordinated are synchronous, and second is long accurately to be 1 second.See that Fig. 1 (b), it and time service platform standard second have the unknown time difference second at acceptance point by the inside that punctual clock frequency source frequency division produces, but the second long of them also is 1 second much at one.The time signal of time service platform arrives acceptance point through ionospheric propagation and sees Fig. 1 (c) second through the time signal of short-wave receiver detection output, and launching time signal relatively has 1 time difference

), it comprises the receiver time delay 1 and the time signal propagation delay

2, wherein, 1 is that constant also can be measured in advance,

2 change with the time signal travel path.With the inner pulse per second (PPS) of local clock is with reference to starting point, trigger the A/D sampling thief and gather a period of time with constant sampling interval △ t, make it cover each time signal second, see Fig. 1 (d), that is to say that the analog waveform of each time signal second is converted into digital quantity and sends into the microcomputer internal memory, carries out coherent detection and analysis then, to obtain time signal due in second accurately, to be actually the time difference value T of the time signal second that obtains inner pulse per second (PPS) of punctual clock and reception ₁

Digital correlation detects with analytical approach as follows:

If the time series of sampling is X ₀, X ₁, X ₂X _nThe standard time signal waveform data is Y ₀, Y ₁, Y ₂..., Y _m, m＜n, their sampling interval is △ t, and then related function is: $C\left(R\right)=\frac{\underset{i=R}{\overset{R+m}{\mathrm{\Σ}}}[X\left(i\right)-\stackrel{\‾}{X}\left(R\right)]\·[y(i-R)-\stackrel{\‾}{Y}]}{\sqrt{\underset{i=R}{\overset{R+m}{\mathrm{\Σ}}}[X\left(i\right)-\stackrel{\‾}{X}\left(R\right){]}^2\·\underset{i=R}{\overset{R+m}{\mathrm{\Σ}}}[y(i-R)-\stackrel{\‾}{Y}{]}^2}}$ $\stackrel{\‾}{X}\left(R\right)=\frac{1}{m}\underset{i=R}{\overset{R+m}{\mathrm{\Σ}}}x\left(i\right),\stackrel{\‾}{Y}=\frac{1}{m}\underset{i=0}{\overset{m}{\mathrm{\Σ}}}y\left(i\right)$

From following formula as seen, C (R) is the standard related function, when sample waveform overlaps and intends mutually with reference waveform, and C (R)=1, other situation is all less than 1.That is to say that we utilize following formula pointwise mobile computing C (R), obtain maximal value C (R _m), with C (R _m) be worth and judge the distortion degree that receives the time signal waveform.In actual applications, as C (R _m)＞0.55 thinks that then this waveform can be as timing; Use R _m△ t represents inner second of the punctual clock of a waveform measurement and this time signal time difference position t of second _iAccording to the factors such as die-away time of time signal, with 30 time signal waveform measurement value t ₁, t ₂T _p(p≤30) are one group of statistical study, obtain time signal phase jitter rate and the most probable time difference value T of second ₁As time goes on, will obtain a series of T ₁, T ₂, T ₃, promptly constitute the time delay change curve.Notice that the variation of time lag curve is just because ionosphere changes and the clock frequency source shakiness of keeping time causes, when the frequency source degree of stability is higher (10 ^-8), the ionospheric situation of change of then basic reflection.

Obtaining T ₁After, because each receiver time delay L ₁Can measure in advance, then according to receiving and dispatching the propagation delay value L that point big garden distance and communication mode can calculate time signal ₂(referring to KDavies, Ionospheric Radio, Peter Peregrinus Ltd, London, 1989), inner second of then punctual clock and the time service standard time signal time difference P of second ₁=T ₁-L can obtain.But utilize the phase shift clock, produces one and differed P in inner second with punctual clock ₁Fig. 1 is seen in pulse per second (PPS) ^-(e), this pulse is exactly the standard second signal that obtains.

Can see that from top principle this technology is diverse with shortwave timing technology in the past.On the one hand, the quality of its energy analysis to measure time signal waveform, the decline size, the phase jitter rate, eliminate the distortion of time signal first cycle second that chromatic dispersion causes and last cycle and the serious distortion of waveform influence, and utilize the statistical property of time signal to improve shortwave reliability regularly the time signal tracking accuracy.On the other hand, the curve that the time delay of acquisition changes helps the correction of time signal propagation delay value and eliminates the influence of unusual time signal, improves absolute timing accuracy.In addition, this technology is easy to realize the automatic search of different time-signal stations, regularly (only needs conversion reference waveform data) and the automatic calculating and the correction of propagation delay, generally speaking, this technology is according to the characteristics of ionospheric reflection time signal, utilize the full detail of time signal, the time-varying characteristics that suppressed ionospheric channel most effectively are to shortwave influence regularly.

2, as shown in Figure 2, provided the electrical schematic diagram that the digital correlation detection technique realizes.A/D sampling thief (2), microcomputer (3) and program storage (4), data-carrier store (5) are connected successively; Crystal oscillator frequency source (6) but phase shift division chain (7), variable time delay counter (8) connect successively; Again microcomputer (3) but respectively and phase shift division chain (7), variable time delay counter (8) connects, time signal second (1) is from A/D sampling thief (2) input, standard second (9) is exported from variable time delay counter (8).A/D sampling thief (2) begins to sample by microcomputer (3) control at inner second rising edge constantly, sampling interval 0.1ms, time signal waveform (1) is become digital signal sends in the data memory (5), by the front introduce carry out the coherent detection statistical study after, obtain a time difference value T ₁, obtain P through microcomputer (3) ₁Value is controlled a variable time delay counter (8) and is produced one and inner second hysteresis P ₁Standard second pulse (9), variable time delay counter (8) only obtains new P at microcomputer (3) ₁Just revise after the value.In addition, obtained by crystal oscillator frequency source (6) frequency division in inner second, overlapping situation appears for preventing punctual clock inner second and receiving time signal second (1), and make the sampling period can cover time signal (the general per second sampling time is not more than 400ms), be movably but adopt phase shift division chain (7) to make inner second phase place of punctual clock.

3, short-wave signal digital correlation detection technique software flow is down: microcomputer under starting in inner second, control A/D sampling thief is with the sampling interval sampling 400ms of 0.1ms, digital waveform after the digitizing is through low-pass digital filter, eliminate impulse disturbances, then desire is received time signal and carry out the coherent detection analysis, if detecting time signal then enters definition status, searched for time signal otherwise carried out new round coherent detection behind the phase shift 300ms again in inner second.In definition status, for improving timing accuracy and reducing the computational analysis time, the sampling time of A/D sampling thief has only 30ms, carries out the coherent detection except that the same with search condition, also maximum correlation C (Rm) is carried out the parabolic interpolation, makes T ₁Temporal resolution bring up to 0.01ms from 0.1ms.In addition, but statistical study also carry out in definition status.

4, as shown in Figure 3, provided the electrical schematic diagram of the punctual clock of shortwave self-correcting.Digital tuning point frequency receiver (10), bandpass filter (11), A/D sampling thief (2), 8031 Single Chip Microcomputer (SCM) system (3), but phase shift digital clock (13) connects successively; Frequency source (7) respectively with 8031 Single Chip Microcomputer (SCM) system (3) but be connected with phase shift digital clock (13); Keyboard shows that control apparatus (15) interface is connected with Single Chip Microcomputer (SCM) system (3) with 6 light-emitting diode displays (16) back in 2 * 9 keyboards (14); On digital tuning point frequency receiver (10), be connected with audiomonitor (12); Time signal second (1) is from a frequency receiver (10) output, standard second (9) but export from phase shift digital clock (13).Point frequency receiver (10) adopts that phase-locked loop frequency is synthetic, digital tuning and monolithic integrated optical circuit technology, and has guaranteed need not tuningly also can accurately receive time signal for a long time with the crystal oscillator frequency source.Time signal second of receiver detection output is after bandpass filter (11), under punctual clock started in inner second, eight A/D sampling thiefs (2) are with the 10KHz frequency sampling, digitized time signal waveform is sent into single-chip microcomputer RAM district, finish in real time each time signal coherent detection and the analysis to measure of second by 8031 Single Chip Microcomputer (SCM) system (3), and with one group of Measurement and analysis result (30 time signal second) statistical study obtain inner second with the reception time signal time difference T of second ₁,, can calculate time signal propagation delay modified value according to communication mode and transmitting-receiving point Da Yuan path

2.But phase shift digital clock (9) is controlled by Single Chip Microcomputer (SCM) system (3), exports a relative interior P1 second (P1=T1- ) standard UTC second.Keyboard and 6 light-emitting diode displays of being used for one 2 * 9 interface in the keyboard display controller among the figure (15) are finished time service platform number, the isoparametric input of acceptance point longitude and latitude, and the calibration of Hour Minute Second and demonstration.

The punctual clock of shortwave self-correcting is compared with existing shortwave timing device, its time signal autotracking error is 0.1ms (punctual clock signal second that this index reflection ionosphere random fluctuation and radio interference cause, from the motion tracking hf time signal matching measurement error of second), absolute timing accuracy is better than 1ms (having reflected the accuracy of the standard second that the clock of keeping time after propagation is revised provides in real time), the timing accuracy of the BPM timing instrument that this technical indicator is the highest with current precision improved a new step (the automatic tracking accuracy of BPM timing instrument for ± 1.5ms), shortwave potentiality are regularly given full play to.In addition, the punctual clock of shortwave self-correcting also has FAS full automatic search, follows the tracks of time signal, input longitude and latitude and revise propagation delay automatically and can be to domestic and international multiple time-signal station outstanding advantage regularly, and these all are that existing shortwave timing device does not have or incomplete.

Shortwave timing digital correlation detection technology has than universal significance, in the timing of the gradual timing signal in arrowband that transmits in the Dispersive Channels when it can be applicable to.Because this technology is carried out many reference amounts analyses such as digital correlation to timing waveform, improved timing accuracy and reliability effectively.

Based on punctual clock the key technical indexes of the shortwave self-correcting of digital correlation detection technique and performance be:

Time signal tracking error: 0.1ms

Absolute timing accuracy: be not more than 1ms

Time signal search tracking mode: automatically discern and follow the tracks of time signal.Optionally be: BPM, JJY, BSF, WWV, WWVH etc. with time-signal station;

Input mode: with the longitude and latitude of little key input time service platform number, acceptance point, timing every minute and second demonstration etc.;

The way of output: output Transistor-Transistor Logic level standard UTC pulse, positive polarity two tunnel, forward position＜1 μ s is when LED shows, minute, second;

Frequency source: be equipped with 5 * 10 in the machine ^-6Crystal oscillator;

The punctual user of high precision can connect the 5MHz or the outer frequency marking of 1MHz of corresponding degree of stability;

Interior dress number is transferred receiver performance: receive frequency is 2.5,5.0,8.0,10.0,15.0,20.0MHz etc.;

Sensitivity: 10 μ V (signal to noise ratio (S/N ratio) is not less than 20dB) can external receiver and antenna;

Power consumption: 2 watts.

Claims (3)

1, a kind of shortwave timing digital correlation detection technology, after the reception of hf time signal is handled, obtain the standard time synchronous with it, it is characterized in that, utilize time service signal second and endemic species to have this characteristic of identical cycle inner second,, obtain the relative time error of two seconds the laggard line correlation analysis of each simulation time signal digitizing, and to its classified statistics, its related function is: $C\left(R\right)=\frac{\underset{i=R}{\overset{R+m}{\mathrm{\Σ}}}[X\left(i\right)-\stackrel{\‾}{X}\left(R\right)]\·[y(i-R)-\stackrel{\‾}{Y}]}{\sqrt{\underset{i=R}{\overset{R+m}{\mathrm{\Σ}}}{[X\left(i\right)-\stackrel{\‾}{X}\left(R\right)]}^2\·\underset{i=R}{\overset{R+m}{\mathrm{\Σ}}}{[y(i-R)-\stackrel{\‾}{Y}]}^2}}$ $\stackrel{\‾}{X}\left(R\right)=\frac{1}{m}\underset{i=R}{\overset{R+m}{\mathrm{\Σ}}}x\left(i\right),\stackrel{\‾}{Y}=\frac{1}{m}\underset{i=0}{\overset{m}{\mathrm{\Σ}}}y\left(i\right)$

2, by the described shortwave timing digital of claim 1 correlation detection technology, it is characterized in that electrical schematic diagram is as follows: A/D sampling thief (2), microcomputer (3) and program storage (4), data-carrier store (5) are connected successively; Crystal oscillator frequency source (6) but phase shift division chain (7), variable time delay counter (8) connect successively; Again microcomputer (3) but respectively and phase shift division chain (7), variable time delay counter (8) connects; Time signal second (1) is from A/D sampling thief (2) input, and standard second (9) is exported from variable time delay counter (8).

3, a kind of punctual clock of shortwave self-correcting of implementing claim 1, it is characterized in that electrical schematic diagram is as follows: digital tuning point frequency receiver (10), bandpass filter (11), A/D sampling thief (2), 8031 Single Chip Microcomputer (SCM) system (3) but phase shift digital clock (13) connect successively; Crystal oscillator frequency source (6) respectively with 8031 Single Chip Microcomputer (SCM) system (3) but be connected with phase shift digital clock (13); Keyboard display controller (15) interface is connected with Single Chip Microcomputer (SCM) system (3) with 6 light-emitting diode displays (16) back in 2 * 9 keyboards (14); On digital tuning point frequency receiver (10), be connected with audiomonitor (12); Time signal second (1) is from digital tuning point frequency receiver (10) output, standard second (9) but export from phase shift digital clock (13).

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