CN104202041A - Phase-locked loop based downhole tool signal clock recovery method - Google Patents
Phase-locked loop based downhole tool signal clock recovery method Download PDFInfo
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- CN104202041A CN104202041A CN201410371463.9A CN201410371463A CN104202041A CN 104202041 A CN104202041 A CN 104202041A CN 201410371463 A CN201410371463 A CN 201410371463A CN 104202041 A CN104202041 A CN 104202041A
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Abstract
The invention discloses a phase-locked loop based downhole tool signal clock recovery method. The method comprises the steps of collecting true data of a downhole tool, and filtering for the first time to obtain signals to be decoded; carrying out square function on each signal to be decoded, and filtering for the second time to obtain signals needing following by a clock; following the signal through phase locking by a phase-locked loop; and carrying out two divided-frequency on the signal which is locked and followed to obtain the clock of an original downhole tool signal. Through adoption of the method, clock recovery is rapid, and the filtered signal can be decoded conveniently. Compared with a conventional phase-locked loop based downhole tool signal clock recovery method, the method is not supported by hardware but software, thereby saving cost and improving anti-interference performance.
Description
Technical field
The present invention relates to the signal process field in oil logging while drilling technology field, particularly a kind of underground instrument signal clock recovery method based on phase-locked loop.
Background technology
Wireless drilling measuring system is a kind of advanced measuring instrument generally adopting in current drilling well in the world.It can measure in real time geologic parameter, well track parameter in drillng operation, and draws various types of logs, for next step construction provides foundation.
Drilling well signal, in transmitting procedure, is very easily subject to the interference of ambient noise, increases the error rate, affects data accuracy.Generally speaking, conventional signal filtering is to be completed by hardware circuit, generally adopts passive filter circuit or active filter circuit, and this method realizes simple.But when existing filtering technique is applied to well logging during mud pressure pulse signal, because its transmission frequency is lower, and comparatively approaching with the frequency of interference source, the method for employing hardware filtering cannot meet the requirement of precision and effect.
Along with the progress of electronics technology, the calculation process ability of computer is more and more faster, and it is more simple and convenient and rapid for realizing with hardware circuit that Applied Digital phase-locked loop carries out signal clock recovery.Phase-locked loop (PLL:Phase-locked loops) is the frequency of a kind of utilization feedback (Feedback) control principle realization and the simultaneous techniques of phase place, and its effect is that the clock of the circuit output reference clock outside with it kept synchronizeing.When the frequency of reference clock or phase place change, phase-locked loop can detect this variation, and carrys out regulation output frequency by its inner reponse system, until both re-synchronizations, is thisly synchronously called again " phase-locked " (Phase-locked).
Phase-locked loop is widely used in fields such as radio communication, Digital Television, broadcast at present, phase-locked loop circuit conventionally as shown in Figure 1, by following module composition: phase frequency detector (PFD) (or phase discriminator PD), low pass filter (LPF), voltage controlled oscillator (VCO), feedback loop (conventionally being realized by a frequency divider (Frequency divider)).Signal f
refbe input to phase discriminator PD, then output signal f after VCO
out.Phase frequency detector or phase discriminator, for the reference signal of input and the signal of feedback loop are carried out to the comparison of frequency and phase place, are exported a signal that represents both differences to low pass filter.Low pass filter, for by the radio-frequency component filtering of input signal, retains direct current component and delivers to voltage controlled oscillator.Voltage controlled oscillator is used for exporting one-period signal, and its frequency is controlled by input voltage.Feedback loop is for returning to phase frequency detector by the signal of voltage controlled oscillator output.Conventionally the frequency of the output signal of voltage controlled oscillator is greater than the frequency of reference signal, therefore need add frequency divider to reduce frequency at this.
Therefore, how phase-locked loop is applied to oil logging while drilling technology field, makes underground instrument signal clock accurate, save hardware cost simultaneously, improve precision, there is important research and be worth.
Summary of the invention
Main purpose of the present invention is that the shortcoming that overcomes prior art is with not enough, a kind of underground instrument signal clock recovery method based on phase-locked loop is provided, the method can be carried out clock recovery fast, facilitate the decoding of filtering signal, simultaneously can be cost-saving for hardware circuit is realized, simple and convenient.
Object of the present invention realizes by following technical scheme: a kind of underground instrument signal clock recovery method based on phase-locked loop, comprises step:
(1) gather the True Data of downhole instrument, and carry out filtering for the first time, obtain needing the signal of decoding;
(2) each signal of needs decoding is carried out to square operation, then carry out filtering for the second time, obtain carrying out the signal of time clock tracking;
(3) utilizing phase-locked loop to carry out phase place locking to the signal of step (2) gained follows;
(4) locking is followed to signal and carry out the clock that two divided-frequency obtains original underground instrument signal.
Concrete, in described step (1), be filtered into for the first time low-pass filtering.
The object of in described step (2), signal being carried out to square processing is the phase hit causing in order to eliminate Synchronization, facilitates the use sinusoidal signal and follows the trail of.
Concrete, in described step (2), be filtered into for the second time bandpass filtering, band pass filter centre frequency is the twice of Synchronization frequency.Thereby can extract the sinusoidal signal of signal transmission rate twice, object is to remove high and low frequency noise, make the signal sublimate that need to follow follow effect to improve clock.
Concrete, in described step (3), phase-locked loop circuit comprises phase discriminator, loop filter, NCO (numerically-controlled oscillator), and the feature according to input signal, arranges loop filter, utilizes the mode of feedback iteration to constantly update the frequency of tracking.
Compared with prior art, tool has the following advantages and beneficial effect in the present invention:
1, compared with prior art, the present invention utilizes phase-locked loop to carry out clock and finds the cost of having saved hardware circuit, and filtering simultaneously and clock recovery are all to realize by software, for hardware is realized, can respond fast and revise, and have greater flexibility.
2, the inventive method can be carried out clock recovery fast, conveniently signal after filtering is decoded, and realizes with respect to conventional phase locked loops, and this method does not need hardware circuit support, only need to realize with software, cost-saved and raising anti-interference.
Accompanying drawing explanation
Fig. 1 is phase-locked loop circuit structural representation in prior art.
Fig. 2 is the flow chart of method described in embodiment 1.
Embodiment
Below in conjunction with embodiment and accompanying drawing, the present invention is described in further detail, but embodiments of the present invention are not limited to this.
Embodiment 1
As shown in Figure 2, the underground instrument signal clock recovery method based on phase-locked loop described in the present embodiment, comprises step:
Step 1: the True Data that gathers downhole instrument.
Step 2: True Data is carried out to low-pass filtering.
Step 3: filtered each signal is carried out to a square processing.The object of square processing is the phase hit causing in order to eliminate Synchronization, facilitates the use sinusoidal signal and follows the trail of.
Step 4: utilize the band pass filter that centre frequency is Synchronization frequency twice to carry out bandpass filtering treatment, extract the sinusoidal signal of signal transmission rate twice.
Step 5: utilize phase-locked loop to carry out phase place track lock to this signal.
Phase-locked loop circuit in the present embodiment comprises phase discriminator, loop filter, NCO (digital oscillator) as shown in Figure 2.According to the feature of input signal, design suitable loop filter, utilize the mode of feedback iteration to constantly update the frequency of tracking.
Phase-locked loop circuit in the present embodiment comprises phase discriminator, loop filter, NCO (numerically-controlled oscillator) as shown in Figure 2.According to the feature of input signal, design suitable loop filter, utilize the mode of feedback iteration to constantly update the frequency of tracking.
Wherein applied mathematical formulae is
W in formula (n) is the n angular frequency of NCO constantly, and f is 2 times of Manchester code frequency, f
sfor sample frequency, m is feedback factor, u
outoutput valve for loop filter.
Step 6: the frequency tracking is carried out to two divided-frequency, can obtain the clock of primary signal.
Above-described embodiment is preferably execution mode of the present invention; but embodiments of the present invention are not restricted to the described embodiments; other any do not deviate from change, the modification done under Spirit Essence of the present invention and principle, substitutes, combination, simplify; all should be equivalent substitute mode, within being included in protection scope of the present invention.
Claims (4)
1. the underground instrument signal clock recovery method based on phase-locked loop, is characterized in that, comprises step:
(1) gather the True Data of downhole instrument, and carry out filtering for the first time, obtain needing the signal of decoding;
(2) each signal of needs decoding is carried out to square operation, then carry out filtering for the second time, obtain carrying out the signal of time clock tracking;
(3) utilizing phase-locked loop to carry out phase place locking to the signal of step (2) gained follows;
(4) locking is followed to signal and carry out the clock that two divided-frequency obtains original underground instrument signal.
2. the underground instrument signal clock recovery method based on phase-locked loop according to claim 1, is characterized in that, in described step (1), is filtered into for the first time low-pass filtering.
3. the underground instrument signal clock recovery method based on phase-locked loop according to claim 1, is characterized in that, in described step (2), is filtered into for the second time bandpass filtering, and band pass filter centre frequency is the twice of Synchronization frequency.
4. the underground instrument signal clock recovery method based on phase-locked loop according to claim 1, it is characterized in that, in described step (3), phase-locked loop circuit comprises phase discriminator, loop filter, NCO, according to the feature of input signal, loop filter is set, utilizes the mode of feedback iteration to constantly update the frequency of tracking.
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| CN201410371463.9A CN104202041A (en) | 2014-07-30 | 2014-07-30 | Phase-locked loop based downhole tool signal clock recovery method |
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| CN201410371463.9A CN104202041A (en) | 2014-07-30 | 2014-07-30 | Phase-locked loop based downhole tool signal clock recovery method |
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Cited By (1)
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| CN109361501A (en) * | 2018-12-10 | 2019-02-19 | 重庆思柏高科技有限公司 | A kind of clock and data recovery circuit and method for visible light communication |
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| US20130136283A1 (en) * | 2010-02-24 | 2013-05-30 | Audiunt Holding B.V. | Hearing instrument |
| CN103152036A (en) * | 2011-12-07 | 2013-06-12 | 珠海扬智电子科技有限公司 | Phase discrimination wave filter and digital phase-locked loop circuit and clock generating method |
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| US20130136283A1 (en) * | 2010-02-24 | 2013-05-30 | Audiunt Holding B.V. | Hearing instrument |
| CN103152036A (en) * | 2011-12-07 | 2013-06-12 | 珠海扬智电子科技有限公司 | Phase discrimination wave filter and digital phase-locked loop circuit and clock generating method |
| CN102539892A (en) * | 2012-01-16 | 2012-07-04 | 南京磐能电力科技股份有限公司 | Method for obtaining true effective values of AC (alternating current) signals |
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| CN109361501A (en) * | 2018-12-10 | 2019-02-19 | 重庆思柏高科技有限公司 | A kind of clock and data recovery circuit and method for visible light communication |
| CN109361501B (en) * | 2018-12-10 | 2021-04-27 | 重庆思柏高科技有限公司 | Clock and data recovery circuit and method for visible light communication |
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