CN108196307A - Sine wave phase swashs the technical solution of electricity - Google Patents

Abstract

"Technical scheme of sine wave phase IP" is a new technology development of geophysical prospecting for geological exploration in the field of scientific methods and applied research in land resources. It belongs to the phase IP branch of frequency domain induced polarization method. The measurement parameters are single frequency or multiple Absolute phase at frequency and apparent resistivity. This scheme is based on the characteristics that narrowband filtering can attenuate interference signals by a large decibel and the physical phase shift of single-frequency sine wave filtering can be compensated. The sine wave signal is locked by a single-chip microcomputer, the phase is directly engraved, and the amplitude is simulated at the peak of the sine wave. It is simple, fast and It is economical and efficient, suitable for geological survey and detailed survey of various non-ferrous metals, and suitable for mine geophysical prospecting with strong power frequency interference and strong stray DC interference. The application of this solution solves the disadvantages of high cost and low benefit, unsuitable for geological survey, and unsuitable for mine geophysical prospecting at present, and can be used as a fast and convenient means for the application of existing frequency-domain IP technology. Geological exploration and mine production.

Description

The technical scheme of sine wave phase IP

1. Technical field

The "technical scheme of sine wave phase IP" of the present invention belongs to the technical development and application research field of land and resources scientific methods, is a new method for the application of geophysical prospecting technology in geological exploration, and belongs to the phase IP branch of the frequency domain induced polarization method.

2. Technical background

"Technical scheme of sine wave phase IP", referred to as sine wave phase IP, measuring apparent absolute phase ψs(mrad) and apparent resistivity ρs(Ωm), is a new method independently researched by the inventor and has independent property rights. Frequency-domain IP, including two branches of spectrum IP and phase IP, is a new technology that has been gradually promoted in recent years, but the current application is not mature enough, and it is only suitable for indoor research and geological surveys, and for other geophysical anomalies. Evaluation; sine wave phase IP can solve the disadvantages of high cost and low benefit, unsuitable for geological census and unsuitable for mine geophysical prospecting, and will be used as a rapid application of existing frequency domain IP technology. And convenient means, used in geological exploration and mine production.

(1) Time domain IP (TDIP)

Time-domain IP is to use equally spaced pulse square waves to transmit power in forward and reverse directions. The receiver measures the primary field of the power supply, calculates the resistivity ρs (Ωm), and then measures the secondary induced by the geological body at the moment when the primary field disappears. In the secondary electric field, after normalization processing relative to the amplitude of the primary field, the excitation parameter ηs (%) is obtained; in the early time domain excitation, the A and B electrodes are powered to transmit signals with a pulse width of 10S (seconds) and a period of 40S. Due to the influence of the earth electric field and natural potential SP, the receiver receives the △U _MN signal, and manual compensation is required during operation. Therefore, the operation of the instrument for single-point measurement takes 1 minute at the fastest, and the power supply pulse width can be 2S/4S/8S in the later stage. , The instrument with a period of 8S/16S/32S, the receiver manually compensates and automatically compensates, and the field measurement speed is correspondingly accelerated.

Time-domain IP provides a large number of IP anomalies for geological exploration, and is effective in non-ferrous metal prospecting. However, due to the interference of graphitization (carbonaceous metamorphism through magmatic hydrothermal fluid), there are still a considerable number of IP anomalies. When it is suspected to be sulfide ore such as copper, lead, zinc, etc., the verification fails, so the application of time-domain IP encounters a bottleneck in mineral prospecting.

(2) Spectrum Induced Electricity (SIP)

The principle of spectrum IP originates from the complex resistivity of rock ore formations. According to W.H.Pelton et al. through the measurement of a large number of rock ore specimens and outcrops, and the description of the frequency characteristics of the IP effect by the Cole-Cole model, the complex resistance The rate expression is:

Among them: _ρ0 represents the resistivity at zero frequency, m, τ, and c represent the polarizability (or charge rate), time constant and frequency correlation coefficient, respectively.

Theoretically, the Spectrum Induced Potential (SIP) should be observed in a wide area of 10 ^-3 --n10 ² Hz, but in practical application, the signal source can only transmit a limited number of frequency points, and the domestic common V-6/V- 8 Multifunctional IP instrument (Phoenix Company in Canada) and GDP-32Ⅱ multifunctional IP instrument (Chung Company in the United States) are representatives. When working in the field with spectrum IP, generally choose 18-- 27 frequency points for transmission and reception, the receiver first processes the received signal through the notch filter of the power frequency interference signal, and then performs signal amplification and A/D in the wide frequency range according to the logical timing of the square wave transmission Acquisition, after Fourier transform and DSP operation, the zero-frequency resistivity ρs ₀ and the resistivity ρs, charging rate (stimulation rate) ms, time constant τs, and frequency correlation coefficient cs of each frequency point are obtained.

According to the experiment and field practice of spectrum IP, metal sulfide ore and mineralization are geologically highly polarized, low resistivity, medium time constant (τs=0.1-2s), small frequency correlation coefficient (cs<0.2), dense Rich ore time constant (τs=2－10s), graphite is low resistance, high intensification, large time constant (τs>n10s), larger frequency correlation coefficient (cs>0.3), as the basis for geophysical prospecting interpretation, Good results have been achieved in practice, and it is effective for distinguishing between copper, lead, zinc and other ore body anomalies and graphite interference methods, and solves the bottleneck problem of time-domain IP. Among them, the time constant τs is related to the crystal particle size of the ore body , the smaller and denser the crystalline particles, the greater the value of τs, and the two-dimensional section with abnormal τs contour of the electric sounding can correspond well to the occurrence of the ore body, and the indication effect is obvious.

Due to the complex spectrum IP technology, the signal channel of the instrument requires precision and low drift, the signal A/D acquisition requires high precision, and the digital signal processing requires DSP operation, so the equipment cost is relatively high; the signal channel uses a notch filter to filter out power frequency interference, Not only the suppression of power frequency interference is not complete (V-8 instrument suppresses power frequency 50Hz/60Hz attenuation -40dB), but also filtering will cause physical phase shift at similar frequency points, resulting in increased measurement error; Taking the V-8 instrument sweeping 25 frequency points as an example, it takes 35 minutes to automatically collect a cycle of data, plus auxiliary work such as pole running, to complete a single point measurement, it takes 35--60 minutes; and the receiver collects extremely low frequencies The signal is affected by the earth's electric field and natural potential. The electrode grounding conditions are stricter than the time-domain IP and phase IP, and the construction is extremely difficult; many factors make the spectrum IP suitable for indoor research and geological surveys, not suitable for large areas. geophysical survey.

(3) The status quo of existing phase IP in China

The complex resistivity formula of Cole theory has two parts: real number and imaginary number. In the alternating electric field, there is a phase difference between the real part and the imaginary part. In the field IP geophysical prospecting, the potential difference △U measured on the geological body Compared with the emission current _IAB , _MN has a certain phase lag ψ. When the frequency is constant, the stronger the excitation effect, the greater the delay phase ψ; the delay phase of a certain frequency is measured by geophysical detection, which is called the (absolute) phase excitation of a certain frequency. Measurement, measuring the relative difference of different frequency phases, is called relative phase difference IP measurement.

At present, the commonly used phase excitation in China, such as FX-1 phase induction instrument, measures the absolute phase, and WSJ-3 phase induction instrument, measures the relative phase difference. They all use frequency coherent technology, that is, use the form of constant current source to synchronize the pulse emission source. signal, the receiver multiplies the synchronous signal (sine wave) and synchronous quadrature signal (cosine wave) of the current with the measurement signal respectively and then integrates and filters to obtain the DC real variable and DC imaginary variable of the complex variable, and then divides the virtual and real components and then Calculate the arc tangent to get the phase, and calculate the root mean square of the real and imaginary variables to get the complex amplitude. The formula is as follows:

The FX-1 Fu phase meter is an intermediate example of the development from time-domain IP to frequency-domain IP. It continuously transmits a single-frequency rectangular wave (symmetrical square wave) with a frequency less than 0.25 Hz, because there is no blackout interval for time-domain IP. , the time efficiency of the measurement has been improved, and the measurement parameters are the excitation rate ηs in the time domain, the resistivity ρs, and the absolute phase ψs at a frequency point of the excitation in the frequency domain. Since FX-1 is measured in the 10 ^-1 Hz frequency band, the properties of the measured excitation rate ηs and phase ψs are similar, the useful information is not improved much, and it faces the same bottleneck problem as the time-domain excitation. Interference is meaningless.

WSJ-3 phase-induced electrical instrument is currently a relatively advanced new phase-induced electrical instrument in China. It divides 9 frequency points within the range of 0.03125--8Hz, namely {8Hz, 4Hz, 2Hz, 1Hz, 0.5Hz, 0.25Hz, 0.125 Hz, 0.0625Hz, 0.03125Hz}, and divided into five groups, each group is composed of five adjacent frequency points, combined in a pseudo-random order, and pulsed in the form of positive and negative constant current square waves. After the receiving signal channel is filtered for the power frequency interference signal, the five-frequency wideband signal is divided into ten channels for coherent detection processing, and each frequency point has its own synchronous and orthogonal coherent signals. D acquisition, division of virtual and real variables and arctangent operation to obtain the phase and amplitude of five frequency points. The measurement results of WSJ phase IP can distinguish the sulfide anomaly and graphite interference through the relative phase difference of the high-frequency band and the relative phase difference of the low-frequency band, which solves the bottleneck problem of time-domain IP. Better; but because the WSJ IP instrument is the same as the spectrum IP instrument, it needs to collect extremely low frequency and other multi-frequency aliasing signals in a wide frequency band, the main shortcomings of poor electrode grounding conditions and high labor intensity on site have not been improved, and the instrument needs to be used Integral filtering eliminates the frequency-coherent AC signal. This method has a long measurement period due to extremely low-frequency signal processing, and the slow measurement speed of geophysical detection has little room for improvement. Although the cost of the instrument is slightly reduced, it has no technical advantage compared with the spectrum IP. Compared with the time-domain IP, the phase IP represented by WJS is still complex in principle, poor in anti-power frequency interference, poor in grounding conditions, and long in the measurement point period. The field practicability needs to be further improved.

(4) References from foreign phase induced electrical instruments

At present, there are domestically imported instruments for phase induced electrical measurement, such as V-8 and GDP-32Ⅱ multifunctional electrical instrument. In fact, although they do phase induced electrical measurement, they are still called CR (complex resistivity) or SIP. (Spectrum induced excitation) measurement, because whether it is measuring the phase induced excitation of ψs, or measuring the spectrum induced excitation of ρ _, m, τ, c, the data acquisition method is the same as the data processing, and the output spectrum induced excitation or phase excitation Electricity, only because of the different output methods of the software, there is no difference in equipment cost and engineering cost. For example, the V-8 instrument, the fastest single-measurement of the phase of 1 Hz at a frequency point takes 1 minute, and it needs to measure multiple frequencies in actual use. Point, the cumulative total time-consuming is the same as that of spectrum IP, so it is not economically cost-effective to use imported multi-functional electrical instrument for phase IP measurement of geological survey nature.

In the 1960s, the former Soviet Union was the first to develop phase-induced electrical instruments. The "Kazakh Geophysical Instrument" factory once developed the ИНφA3 BЛ vehicle-mounted base station and the BЛ-Ф portable base station. The former can complete the absolute phase measurement of the electric field and magnetic field, and the two The relative phase measurement of two frequencies, the latter can only complete the relative phase measurement of two frequencies.

The IP emission of the Soviets uses silicon controlled silicon single-frequency pulse square wave emission, and the first and third harmonics of the square wave are used in the measurement, whether it is the measurement device of the vehicle-mounted base station, or the BЛ-Ф portable receiver (external portable frequency selection Oscillators) have two signal channels, and filter and select two frequency points at the same time, one selects the fundamental frequency of the square wave and suppresses the third harmonic of the square wave, and the other selects the third harmonic and suppresses the fundamental frequency. The result signal of frequency selection can be respectively connected to the detection circuit (such as diode rectification and filtering) with a manual switch, and can be displayed and read by an analog pointer meter, which can be used for signal monitoring and calculation of resistivity.

When measuring the relative phase difference, the Soviets used an approximate calculation method, under the condition that the cosine value of the fundamental frequency is approximately equal to 1, and the sine value of the fundamental frequency is approximately equal to the chord angle of the frequency, using a special method to calculate three times The relative phase difference between the harmonic and the first harmonic of the fundamental frequency. The two frequency-selective signals are first shaped into square waves, and then the timing of the respective square wave edges is compared with each other. The relative phase is measured under the conditions of a quartz oscillator and pulse analog counting; When measuring the relative phase difference, it is not necessary to transmit a synchronous reference. When the vehicle-mounted base station performs absolute phase measurement, one frequency point is measured each time. For the square wave fundamental frequency or the third harmonic, the synchronization logic of wireless transmission is processed by the frequency selection process of sampling the transmission current at the transmitting base station; the receiver is measuring the absolute phase When the wireless synchronization is first introduced into the receiving channel, the frequency selection output is compared with the synchronous signal to measure the base of the phase, and then the signal of the measuring point is introduced into the receiving channel to measure the absolute phase after base compensation.

The method used by the Soviets for phase IP measurement is based on the analog counting of quartz crystal oscillators, and the tedious switching of mechanical manual switches. Under the electronic technology conditions of that era, relatively advanced equipment was made, and a lot of success was carried out in the field. The practice, and in the transmission and reception of the phase excitation, a variety of power supply measurement device methods, carried out systematic research, A.B. Kulikov and E.A. Shemyakin co-authored "Phase Induced Polarization Method", on The development of phase IP in our country has played an important role in promoting it. The principle of Soviet phase IP is clear, the method is simple, the equipment is cumbersome, the measurement is guided by empirical formulas, and the use of very backward electronic technology, due to the different times, is still behind the current time domain IP, which is completely out of date now. Adaptation; but the method is simple, consistent with the idea of sine wave phase IP, and the results of its field practice have an important reference for sine wave phase IP.

(5) Novelty search conclusion

"Technical scheme of sine wave phase induction", except that the inventor himself newly contributed an introduction to "sine wave phase induction" in the "Geophysical and Geochemical Exploration" periodical, there is no relevant report in other documents.

"Technical scheme of sine wave phase IP", including the sub-project of 'sine wave transmission and single-channel phase IP device reception', and the sub-project of 'symmetrical square wave transmission and three-channel sine wave phase IP device reception', former Soviet Union The method of phase excitation is similar to the second sub-program of the present invention, and has no intersection with the first sub-program. The method of the Soviets is to compare and approximate processing by double signals. The present invention is a single-chip microcomputer frequency locking and accurate engraving. The former can only process two relative signals, and only one phase parameter can be obtained from one measurement. The latter can process three signals at the same time. Three absolute phase parameters are measured; the former has neither the important feature of narrow-band filtering and large-decibel attenuation of interference signals, nor the concept of "sine wave phase induction", and the latter is based on advanced and mature electronic technology. The measurement method of sine wave phase excitation is mainly characterized by single frequency sine wave, especially the characteristics of the first sub-plan of sine wave transmission and reception are obvious; "Technical scheme of sine wave phase excitation" is aimed at the current domestic Electric application, the improvement and improvement measures invented in the aspects of rapid measurement and convenient application, belong to the development of new technology, and the technology difference from the former Soviet Union is very obvious.

3. Contents of patented inventions

According to the current situation of spectrum IP and phase IP, the problems to be solved by the "technical solution of sine wave phase IP" are: <1> Simplify the measurement principle, reduce the cost of equipment, <2> Reduce the labor intensity of geophysical prospecting and improve production Efficiency, <3> excavate the phase spectrum change law of phase IP, find more geophysical information with minimum investment, <4> expand the application range of phase IP, and increase the potential economic benefits of the scheme application.

At present, there are many deficiencies in spectrum induced excitation and phase induced excitation, but the focus of the contradiction is mainly reflected in the "extremely low frequency signal measurement", because of the extremely low frequency, resulting in: ① a large number of interference signals cannot be ruled out (including earth electric field, natural potential, industrial travel Scattering DC interference, uneven electrode excitation, etc.), ②Poor grounding conditions, arranging electrodes requires deep digging and pouring salt water, which is labor-intensive, ③The operation and measurement cycle of the instrument is long, ④The instrument requires precision and low drift, and the cost is high. Therefore frequency research is the working focus of the present invention.

According to previous studies, the complex resistivity ρ decreases with the increase of the frequency f of the alternating electric field, while the delay phase ψ approaches zero at low and high frequencies. On the logarithmic coordinate of the frequency, with different Different shapes of crystalline grains of geological bodies have different values of τ and c, and the frequency fc corresponding to the delayed phase peak ψmax is different. On both sides of the peak, the phase value changes like a normal distribution; The fc of the ore is greater than 10Hz, the fc of the veinlet or massive infested sulfide ore body is about 1Hz--10Hz, the fc of the massive sulfide ore is about 1Hz, and the fc of the dense massive sulfide-rich ore body It is around 0.5Hz, and the frequency of graphite phase peak fc is less than 10 ^-2 Hz. In the frequency range available for excitation, the phase of graphite always decreases with the increase of frequency. When the frequency is around 10 ^-1 Hz , the phase size difference between graphite and other metal sulfide ore bodies is not large, and when ≥ 1 Hz, the phase of graphite decreases significantly. Therefore, according to different prospecting targets, the actual geophysical prospecting in the field can be targeted, and the frequency point of phase IP measurement can work near the fc of the corresponding target geological body, and the measurement of other frequency points can be greatly reduced on site, especially Avoiding the frequency point measurement of extremely low frequency can not only improve the work efficiency, but also reduce the cost of the instrument, reduce the grounding conditions of the electrodes, and reduce the labor intensity of field work. This is to improve the shortcomings of the current spectrum excitation and phase excitation. Breakthrough direction.

According to the theoretical calculations and experiments of Central South University of Technology, see the accompanying drawings, in which Figure 2 is the theoretical calculation spectrum curve of a sulfide ore, Figure 3 is the theoretical calculation spectrum curve of graphite, and Figure 4 is the test spectrum of a certain pyrite sulfide Figure 5 is the test spectrum curve of graphite. In the frequency range below 32Hz, the absolute value of the delayed phase of the metal sulfide ore body excitation spectrum increases with the increase of frequency, while the absolute value of the delayed phase of graphite increases with the increase of frequency. When the frequency is about 0.1Hz, the two are almost equal. When the frequency is greater than 10Hz, the contrast is huge; in the past, conventional time-domain IP, using equal interval pulse square wave forward and reverse power supply, the width is 2S, 4S respectively , 10S, because the amplitude of the fundamental frequency in the square wave dominates, and these fundamental frequencies are around 0.1Hz, the results of geophysical prospecting cannot effectively distinguish the sulfide ore body from the graphite carbonaceous non-mineral, and the results are also the same as those shown in Figure 2, Figure 3, and Figure 3. 4. Figure 5 shows the same.

Therefore, in the case of avoiding graphite interference and reducing the labor intensity of field geophysical exploration, the measurement frequency range of phase IP should be between 1Hz--50Hz, and the lower the frequency, the greater the signal-to-noise ratio of the measurement signal. The higher the frequency, the lower the efficiency of field work; the higher the frequency, the greater the electromagnetic interference in the measurement. "Technical scheme of sine wave phase IP", the selected frequency range is 1Hz--12.5Hz, which meets the theoretical requirements and is in line with the actual field geophysical prospecting. Although the frequency of phase IP selection tends to fc of the predicted target, it is not necessarily fc, which is determined comprehensively according to the prospecting target, geological environment, and work efficiency; a lower frequency is suitable for searching for massive metal sulfides, but the frequency is too low , will reduce work efficiency and increase labor intensity, and the frequency is higher, which is suitable for searching for precious metals such as infested sulfide and gold and silver associated with pyrite; according to the distribution law of IP phase spectrum, through the three For the phase measurement of the above frequency points, the indoor calculation of fc and ψmax by mathematical means can achieve the geophysical effect close to the spectrum IP with the least workload and the most labor-saving way.

At present, there is no simple and reliable absolute phase IP measuring instrument in our country. In addition to the complicated principle of traditional coherent technology, there is actually a key problem, that is, broadband measurement, which has not been solved and handled well. It is necessary to reduce the 50Hz power frequency interference. , It is also necessary to avoid the contradictory problem of signal physical phase shift caused by filtering. In order to safely reduce power frequency interference, phase IP can only work in a lower frequency range. The core of the sine wave phase excitation is that the signal acquisition channel recognizes the single-frequency sine wave. Using narrow-band filtering technology, it can attenuate other useless signals by a large decibel, and the single-frequency signal, when the filter channel parameters are fixed, the channel The physical phase shift generated inside is also fixed and can be compensated and eliminated. Therefore, the scheme of using sine wave phase excitation completely solves the contradiction between the physical phase shift of the signal channel and the large decibel reduction of power frequency interference. On this basis, The working frequency of phase IP can be freely designed according to geological needs and field construction needs.

The main content of the sine wave phase IP invention, its logical relationship schematic diagram is shown in Figure 1, wherein, it is affected by the inductive load of the earth between the AB electrodes, the inductance of the long power supply wire, and the change of the grounding conditions of the A and B electrodes. There is a phase delay ψ _AB between the current signal I _AB and the supply voltage signal V _AB in the AB power supply circuit, and the excitation phase ψs between the potential difference △U _MN of the measuring point MN and the supply current I _AB is locked by a single-chip microcomputer I _AB synchronous signal as the reference, and then lock the △ U _MN signal, ψs parameter can be read directly with the time counter on the microcontroller, and the signal amplitude can be positioned at the sine wave peak of the locked frequency signal for A/D acquisition. "Sine wave phase induction" is neither DSP operation of broadband Fourier transform, nor synchronous coherent detection plus arc tangent operation, nor is its amplitude acquisition the root mean square operation of real and imaginary variables, so it is a simple and direct principle Program.

The scheme design of sine wave phase IP signal transmission and reception is divided into two sub-schemes: sine wave inverter transmission and single-channel reception, and symmetrical square wave transmission and three-channel simultaneous reception. In order to reduce the cost of transmitting equipment, and also to reduce the electromagnetic interference radiation generated by the system, different from other spectrum excitation and phase excitation, the signal transmission of sine wave phase excitation is in the form of a stabilized voltage source, and the actual emission current The size and signal synchronization are obtained by actual measurement of the transmitter. When the sine wave waveform signal is transmitted, no high-frequency signal is generated. When the symmetrical square wave is transmitted, the transmitter does not deliberately require the current signals of each harmonic to be consistent and synchronized. The transmitter synchronizes the 1/3/5/three harmonic current signals Measured separately and transmitted to the receiver through multiple channels; because no other exciting constant current source is used for pulse emission, when the voltage direction of the pulse changes, the voltage spike radiation caused by the sudden change of current and the electromagnetic interference caused by radiation Significantly reduced.

The characteristics of the sine wave phase IP are:

① The receiving signal channel is suitable for single-frequency sine waves. Due to the narrow frequency band, the system adopts large-decibel filter attenuation for strong power frequency interference and strong stray DC interference. The physical phase shift of single-frequency sine waves caused by channel filtering can be compensated. The IP instrument does not care about or be affected by other frequencies passing through this channel.

② The absolute phase and frequency amplitude of the sine wave phase induction instrument are directly measured after the frequency is locked by the single-chip microcomputer, which is simple and fast in principle.

③ Sine wave phase IP receiving, there are single-channel phase IP device with sine wave transmission, and three-channel sine wave phase IP device with symmetrical square wave transmission, a total of two sub-plan models, the former serially receive single frequency or multi-frequency sine wave signal, using a common signal filter channel; the latter collects signals of three frequency points in parallel at the same time, each frequency point has its own signal filter, and the signal processing method of each channel is the same as that of a single-channel receiver. In exactly the same way.

④ Sine wave inverter transmission, the transmitter transmits a standard sine wave, which can be a single frequency continuous transmission, or a multi-frequency combination sequential transmission. When the symmetrical square wave is continuously transmitted, according to the Fourier transform of the square wave, the transmitter synthesizes and transmits the sine wave of the 1/3/5th harmonic of the fundamental frequency signal at the same time, satisfying the three-channel sine wave phase excitation instrument that can simultaneously complete three Absolute phase and frequency amplitude measurements of frequency points.

⑤ The operating frequency of sine wave phase IP is designed within the range of 1Hz--12.5Hz on the basis of analyzing the target of IP, reducing the difficulty of on-site operation, and reducing the cost of equipment. The time of single-point multi-frequency measurement can be within Complete in seconds.

⑥ According to the distribution law of the IP phase spectrum, through the measurement of the phase ψs of more than three frequency points, the approximate calculation of fc and ψmax by mathematical means (Gaussian normal curve inversion or simple quadratic equation inversion) can be performed with a minimum of work In the most cost-effective and labor-saving way, the geophysical prospecting effect close to that of spectrum induced electricity can be realized.

⑦ The sine wave phase-induced electrical instrument has a strong ability to resist power frequency interference and stray DC interference. It is especially suitable for mine (area) geophysical prospecting, and can operate in deep tunnels and command mining production on site.

4. The principle of sine wave phase IP implementation

(1) Geophysical signal transmission of sine wave phase IP

There are two forms of sine wave phase IP signal transmission, one is the standard sine wave waveform transmission, which can be transmitted continuously at a single frequency, or sequentially and circularly transmitted at multiple frequencies, and the available frequency range is 1Hz--12.5Hz. Point continuous transmission of 3 cycles, for example, 1248 four-frequency sine wave transmission is: 1Hz, 1Hz, 1Hz, 2Hz, 2Hz, 2Hz, 4Hz, 4Hz, 4Hz, 8Hz, 8Hz, 8Hz, 1Hz, 1Hz..., each cycle is in There is no gap between 360° and 0°. The other is continuous transmission of fixed-frequency symmetrical square waves, with a square wave fundamental frequency of 1Hz-2.5Hz.

The principle block diagram of the IP transmitter for sine wave waveform emission is shown in Figure 6, in which the transmitter group consists of two stages of switching power supply, the front stage is the input and output high-frequency transformer isolation and boosting type, which controls the output voltage range of the sine wave, and the rear stage The first-stage switching power supply is responsible for the inversion of the sine wave waveform, which is a four-tube bridge type, in which the switching tubes {S1, S1'} switch simultaneously, and {S2, S2'} switch simultaneously, and the change of the switching duty cycle is shown in Figure 7, the sine wave In the inverter, the switching tubes {S1, S1'} and {S2, S2'} switch alternately, {S1, S1'} is on and {S2, S2'} is off at 0--180°, and {S2, S2'} tubes Integrated reverse diode freewheeling, {S2, S2'} open {S1, S1'} closed at 180°-360°, {S1,S1'} integrated reverse diode freewheeling. The output of the switching power supply in the latter stage is filtered by two stages of LC to filter out the high-frequency switching signal of the switching power supply and turn it into a low-frequency sine wave.

The transmitter inverts the sine wave, and its waveform correction is controlled by a single-chip microcomputer. The sine wave output of the inverter is sampled by non-inductive resistor voltage division, isolated from the ISO122 op amp, and then connected to the A/D signal input terminal of the single-chip microcomputer. After the single-chip microcomputer collects data, it is compared with the standard sine wave signal. As a result, the duty cycle of the inverter output of the subsequent switching power supply can be changed and controlled at any time to achieve and maintain the integrity of the output sine wave signal without deformation.

The synchronization signal of the output current of the transmitter is sampled by a shunt meter. After being transformed into a small sine wave voltage signal by an isolated operational amplifier, it is driven by a large current operational amplifier on the one hand and output to a small synchronous cable. On the other hand, it is passed through a zero comparison , get the square wave logic pulse of the emission current, the pulse is sent to the wireless emission synchronization, the absolute value converter of the current signal, and the single-chip microcomputer, and the amplitude of the emission current signal is collected by the single-chip microcomputer control A/D, according to the actual measurement Current size, compared with the output current set by the system, real-time feedback control and adjustment of the output voltage of the pre-stage switching power supply, to maintain the stability of the inverter output current, and at the same time, the single-chip microcomputer continuously corrects the output sine wave through the zero-crossing pulse and GPS timing The starting phase ensures that the output current synchronization is consistent with the GPS timing in real time.

The principle block diagram of IP transmitter with symmetrical square wave emission is shown in Figure 8. Since this kind of transmitter is generally of high power, which can reach tens of kilowatts, and the output is greater than ±1000V, from the perspective of system heat dissipation, convenient maintenance and cost reduction Considering that the pre-stage switching power supply can be connected in series with two switching power supplies of general-purpose commercial products with 0--600V DC regulated output, and the output voltage is controlled by the binary 12-bit PWM signal output by the single-chip microcomputer. The rear stage of the symmetrical square wave output is a general IGBT full-bridge inverter, and the inverter switching frequency is 1Hz--2.5Hz, which is controlled by a single-chip microcomputer.

The wireless synchronization or GPS synchronization of symmetrical square wave IP transmission corresponds to the pulse voltage signal output by the transmitter; while the small cable output is the shunt measurement of the transmitter output current signal and the current synchronization of the isolated operational amplifier drive output Signal.

(2) Signal reception of sine wave phase IP

A. Single-channel sine wave phase IP instrument receiver for receiving sine wave transmission signals:

Single-channel sine wave phase IP receiver, its core is a high-speed and low-power 16-bit or 32-bit single-chip microcomputer, such as dsPIC30Fxxxx series, STM32F103xx series, etc., requiring I ² C/SPI/USART/USB and other interfaces, with The ability to capture the upper and lower edges of the high-speed wide pulse can accurately capture the phase time of the zero-crossing comparator. It has the ability to locate the sine wave peak for A/D sampling. The A/D resolution is not less than 12 bits in binary, with 32/32 Or 32/16 hardware division command, which can instantly calculate the resistivity, phase and other parameters of each measuring point under the complicated geophysical detection device. The operating frequency of the sine wave phase IP can be manually input by the keyboard, or it can be actually measured during the measurement synchronization according to the transmission frequency. The parameters measured by the receiver are apparent resistivity ρs (Ωm) and absolute phase ψs (mrad), MN interface input Impedance 10MΩ, △U _MN receiving signal range ±0.01mV--±2000mV (peak value), which allows the maximum superimposed power frequency interference to exceed ±1000mV, phase measurement range 0--±1500mrad, phase resolution less than 0.01mrad.

In order to ensure that the receiver can work normally in various harsh environments in the field, the temperature index of each component of the receiver circuit is selected in line with the automotive-grade standard, that is, when working at a temperature of -40°C-+125°C, each The parameter performance does not change. In actual use, the minimum conditions of each parameter must meet the temperature requirements of the industrial grade -40°C--+85°C, including each chip, resistor, capacitor, quartz crystal, etc., as well as the printed board and solder used , and the components in it must go through parameter screening and aging treatment before welding, and all components in the inventory before welding must be sealed and kept at a constant temperature; this can ensure that the working parameters of the final instrument product will not be affected by the ambient temperature during use. change due to influence.

The circuit principle of the single-channel phase IP receiver, as shown in Figure 9, the differential signal ΔU _MN of the measuring electrodes M and N, when connected to the receiver signal introduction end, first passes through C ₀ and R ₀ , and the entrance will be 1Hz The following DC signals are blocked outside. When entering the first-stage operational amplifier U0A, there is a fixed gain of 2 times, and then the linear digital potentiometer RW1 divides the voltage, and then enters the second-stage fixed-gain operational amplifier U0B. The digital potentiometer RW1 is controlled by the microcontroller. Through the I ² C bus control, it can be divided into 256 levels of changes, and together with the fixed gain operational amplifier, it forms the pre-stage control of the programmable automatic gain. The system is divided into front and rear programmable gains. The rear programmable gain is composed of a digital potentiometer RW2 and a fixed gain operational amplifier U4B. The method is the same as that of the previous stage. Gain to ensure a sufficient signal-to-noise ratio, but if the amplitude of the power frequency interference is too large, so that the signal of the previous stage is blocked, then the U5 comparator judges the signal amplitude, and when it is greater than 3.3V, it provides a falling edge to the single-chip CPU. Pulse signal, the CPU gradually reduces the gain of the front stage according to this signal, so that the total signal amplitude amplified by the front stage is less than 3.3V; In the pass filter, it will attenuate as much as possible, and the low-pass filter channel will attenuate -147dB (decibels) for frequencies above 50Hz; after that, the amplitude of the useful signal will be reduced, and then increased by the post-stage program-controlled gain. According to the result of A/D conversion, the MCU performs total automatic gain control. When the A/D conversion result is greater than 3.8V (Vref=4V), the potentiometer is linearly downshifted. When the A/D result is less than 3.0V, the potentiometer is Calculate linear upscaling. The signal output by program-controlled gain and low-pass filter is driven by direct blocking zero correction and precision operational amplifier A2, and then connected with electronic switch SWA and high-speed zero-crossing comparator A3. The sine wave signal measured by the phase excitation instrument passes through the After the zero comparison, output a high-level square wave corresponding to the sine wave 0---180°. The square wave is zero level when the sine wave is 180°---360°. This square wave is directly connected to the pulse signal of the CPU. The captured input interface is connected, and then the precise time of the rising edge and falling edge of the square wave pulse will be captured by the CPU; at the same time, the inverting level of the zero-crossing comparator outputting the square wave controls the SWA electronic switch, combined with the precision op amp with differential input A5, convert the absolute value of the AC sine wave output by A2 into a one-way DC signal, and then send it to the A/D input interface of the microcontroller.

Before the receiver can measure normally, the receiver must first capture the transmission synchronization of the AB power supply. When the receiver is working in capture and transmit synchronous mode, after the synchronous sine wave signal passes through the filter and the zero-crossing comparator into a symmetrical square wave signal, it is connected to the external interrupt interface of the CPU, and the CPU collects the rising and falling time of the pulse level , calculate the frequency and timing of the actual sine wave emission, and then the CPU maintains synchronization (frequency lock) with the sine wave clock emitted by AB by modifying the number of cycles of the on-chip timer, and the size of this cycle number is 32-bit binary , the number unit of the number of cycles is the instruction cycle of the single-chip microcomputer, which can generally reach tens of MHz of high frequency, so the resolution of the sine wave phase is very high. Since the microcontroller clock is a high-temperature-resistant quartz crystal oscillator, the stability and accuracy are very high. As long as the clock powered by AB does not change, as long as the phase shift ψ _AB of the AB current is stable, and as long as the microcontroller is running and does not shut down, then the microcontroller will The transmission signal of AB and AB is stably maintained in synchronous lock.

After the single-chip microcomputer captures and locks the synchronization, when the receiver is transferred to the general object detection measurement, the receiver is transferred to the normal measurement mode through the keyboard. In the measurement mode, the signal connected to the MN is filtered and high-speed zero-crossing comparator, on the one hand, it is connected to the external interrupt of the CPU in the form of a square wave, and the CPU captures the count value of the timer that is synchronously locked with the AB launch, and reads out the stimulus immediately. Electrical phase; at the same time, according to the captured phase time, delay ¼ emission cycle, wait until the sine wave signal changes from 0° to 90°, turn on the A/D sampling of the single-chip microcomputer, obtain the positive peak voltage of the ΔU _MN signal, according to the captured Phase time, delay ¾ transmission period, wait until the sine wave signal changes to 270°, then turn on the A/D sampling of the microcontroller, obtain the negative peak voltage of the ΔU _MN signal, and obtain the average value of the positive and negative peak values of the A/D sampling , multiplied by the coefficient of the geophysical detection device, and then divided by the AB emission power supply current, the apparent resistivity of the current measuring point can be obtained. Because the A/D acquisition is positioned at the peak of the sine wave, the signal amplitude is large, and the average filter after the absolute value conversion of the AC signal is not required, the resistivity acquisition has no delay, the signal-to-noise ratio is high, and the speed is fast. See Figure 10 and Figure 11.

Single-channel receiver signal filtering channel, the frequency attenuation curve of the circuit simulation is shown in Figure 12, the signal gain in the range of 1Hz-12.5Hz is -0.4dB--+2.4dB, and the attenuation of frequencies above 50Hz is greater than -147.4dB and less than 0.1Hz The attenuation of the low-frequency signal is greater than -79.4dB; due to the filter, the waveform of the measured signal will lag behind, and the simulated physical phase shift curve is shown in Figure 13, because the receiver circuit uses components that are resistant to temperature changes. After aging treatment, the filter circuit The parameters will not change with the change of the ambient temperature, so the physical phase shift of the fixed frequency is also fixed; while the signal of the sine wave phase excitation instrument is only a sine wave with a fixed frequency, and the measurement is synchronous and small The transmission synchronization signal obtained by cable synchronization and the same frequency signal measured at each measuring point have passed through a common filtering channel, and their physical phase shifts are the same, and are automatically compensated and offset on the single-chip microcomputer; therefore, this channel filtering does not It will affect the measurement result of the IP phase of the measuring point, which is the characteristic of the sine wave phase IP receiver.

B. Three-channel sine wave phase-induced electrical instrument receiver for receiving symmetrical square wave transmission signals:

The frequency of the symmetrical square wave emission is 1Hz-2.5Hz, such as 1.5Hz/2Hz. Its Fourier series is expanded, and there are fundamental frequency 1.5Hz/2Hz, triple frequency 4.5Hz/6Hz, fivefold frequency 7.5H/10Hz, Seven times frequency 10.5H/14Hz,..., and other harmonic sine waves, but except for the amplitude of the 135 times frequency signal, the amplitude of other higher harmonics accounts for the output power of the transmitter A small part can be ignored. The three-channel sine wave phase excitation instrument uses the 135 times frequency sine wave signal emitted by the transmitter to measure, and can simultaneously obtain the apparent resistivity ρs, apparent absolute phase ψs, and relative phase difference of different frequencies at three frequency points Δψs.

The three-channel sine wave phase excitation instrument collects signals at three frequency points, and passes through three dedicated tenth-order Butterworth narrow-band filter channels respectively. For example, when receiving and transmitting a 1.5Hz square wave, design the first channel filter passband ( - 3dB at 0.7Hz), stop band (-40dB at1.8Hz), the signal attenuation greater than 4.5Hz is greater than -75dB, the signal is greater than -95dB when less than 0.35Hz, and the signal gain in the range of 0.9Hz--2Hz is 1.7dB±1dB; the second Pass filter passband (-3dB at 0.7Hz), stopband (-45dBat 2.6Hz), center 4.5Hz signal gain 3V/V times, 4.5Hz±0.3Hz range gain +9.0dB--+9.6dB, for frequency The signal attenuation of less than 2.8Hz and greater than 7.2Hz is greater than -70dB; the third channel filter passband (-3dB at 1Hz), stopband (-40dB at 2.6Hz), center 7.5Hz gain 5V/V times, for frequencies less than The attenuation of 4.5Hz signal is greater than -73.38dB, the attenuation of 10Hz signal is greater than -44dB, and the attenuation of greater than 12Hz is greater than -68dB. The simulation curves of frequency attenuation and channel physical phase shift of the three filtering channels are shown in Figure 14, Figure 15, Figure 16, Figure 17, Figure 18, and Figure 19. See accompanying drawing 20 for the schematic diagram of the circuit.

The three-channel sine wave phase excitation instrument synchronizes the three independent signal channels separately, performs signal filtering separately, performs program-controlled automatic gain separately, performs high-speed zero-crossing comparison of sine wave signals separately, and performs phase inversion with electronic switches respectively. Complete the absolute value conversion of AC to DC, and perform A/D conversion at the respective sine wave angles of 90° and 270°, the data acquisition method of the excitation phase and amplitude of three channels and three frequency points, and single-channel sine wave The wave phase IP instrument is exactly the same.

(3) Signal synchronization of sine wave phase IP

There are four ways for the sine wave phase IP receiver to obtain the synchronization signal of the transmitting source, which are selected according to the preferred order. They are wireless synchronization of receiving wireless transmission signals, receiving GPS synchronization, accessing small cable synchronization, and measurement synchronization. The first two are The digital pulse signal is directly connected to the pulse interface of the single-chip microcomputer, and the latter two are analog signals, which are input through the MN port and the system signal filter channel. Among them, measurement synchronization is a special method for easy on-site disposal when other synchronization methods are inconvenient to use. Its operation is to set the receiver to the measurement synchronization mode, and the common geophysical background in the strong field source area is abnormal. point, emission synchronization obtained by MN electrode grounding measurements. Small cable synchronization is the basic synchronization method of the system, and its measurement method is also in the measurement synchronization mode, but the MN input is the small cable signal from the transmitter; the small cable signal is the transmitter current waveform signal sampled and isolated output , The magnitude of the signal is peak-to-peak 1V--2V, and there is a 100Ω matching resistor at the end of the small cable. Wireless transmission synchronization and GPS synchronization can ensure that the synchronization of the receiver is updated at any time. For example, the receiver automatically contacts and synchronizes during the process of measuring pole running and moving the base station, which does not affect the normal measurement time. However, these two synchronizations must be used before use. The small cable is used as a physical phase shift scale, and the scale value is saved by the single-chip microcomputer when it is powered off. During the phase-induced electrical measurement, the single-chip microcomputer adds the logical time received by wireless synchronization or GPS synchronization to the physical phase shift of the scale, and then differs from each measurement point. The frequency sine wave zero-crossing comparison signal is compared with the logic sequence to obtain the absolute bit phase at different frequencies of each measuring point.

During the phase IP measurement process, if the AB power supply electrode is well grounded and the phase shift ψ _AB is stable, then after the receiver is synchronized, as long as the transmitter and receiver are not shut down, then in the subsequent measurement, the transmitter Both the frequency lock and the synchronization are kept consistent through the quartz clock, and the receiver does not need to search for synchronization. The quartz clock has been adjusted at the factory, and its synchronization error is within the allowable range. If wireless synchronization or GPS synchronization is used, even if the signal transmission of wireless synchronization is partially affected by valley terrain, or the GPS reception is affected by dense forests, tunnels and other occlusion reasons, it will not affect the normal progress of IP measurement. During the measurement, if small cable synchronization or wireless transmission synchronization is performed at each measurement point, the sine wave phase excitation can work normally even when the grounding conditions of the AB electrodes are slightly poor and the _ψAB phase drift is unstable. If the phase drift of ψ _AB is unstable, and at the same time it is inconvenient to do wireless synchronization, GPS synchronization and small cable synchronization, then a certain receiver can be used to monitor and measure ψ _AB parameters in real time near the transmitter (ψs measurement of small cable signals) , according to the time axis records, the phase parameters collected by other receivers can be corrected indoors, so that the sine wave phase IP can still be carried out normally.

The requirements and operation of the small cable synchronization, wireless synchronization and GPS synchronization of the three-channel sine wave phase-induced excitation instrument are the same as those of the single-channel phase-induced excitation instrument. However, the wireless synchronization and GPS synchronization of symmetrical square wave transmission are the synchronization of the voltage V _AB signal of the transmitted pulse, while the wireless synchronization and GPS synchronization of the sine wave waveform transmission are the synchronization of the current I _AB signal, so the three-channel sine wave phase excitation instrument The calibration data of wireless synchronization and GPS synchronization include ψ _AB variables, and ψ _AB varies with the grounding of the AB power supply electrodes, so every time the grounding of the AB electrodes is changed, the three-channel phase excitation receiver needs to re-do the small cable calibration. Comprehensively correct the (ψ _AB + physical phase shift) of the three frequency points; or, under the condition that the existing calibration targets of each three-channel receiver are consistent, after the grounding of the new transmitting power supply electrode is changed, it is necessary to use a certain The receiver performs ψs measurement of 1/3/5 three frequency points on the new small cable signal, and measures the △ψ _AB variation of the three frequency points after the grounding of the AB electrode is changed. All receivers can use the existing calibration parameters normally. Carry out measurement, and finally correct the offset of the collected ψs parameters; if the number of receivers is sufficient, one receiver can be used to detect ψ _AB in real time, and other receivers can measure normally without being affected by the drift of ψ _AB influences.

5. Advantages of sine wave phase IP:

1. The sine wave phase IP has the characteristics of simple and quick principle, economical and practical equipment, portable instrument and fast data sampling speed. Due to the high emission frequency of the AB electrode, the geophysical single-point measurement can be completed within a few seconds. Compared with other IP instruments, the working efficiency is at least 10 times higher.

2. The sine wave phase is excited, and the transmission frequency is greater than 1Hz, which can effectively eliminate the interference of graphite and carbonaceous, and is sensitive to the phase response of metal sulfide ore bodies.

3. With sine wave phase excitation, the phase acquisition of the receiver is not affected by channel filtering, and the data acquisition is accurate and reliable.

4. Different from other spectrum IP and phase IP, the signal transmission of sine wave phase IP is transmitted in the form of a stabilized voltage source. There is no high-frequency signal in the sine wave emission, and the symmetrical square wave emission does not use the constant current source method used by other excitations. When the pulse direction changes, the voltage spike radiation caused by the sudden change of the current and the electromagnetic interference caused by the radiation Significantly reduced. Sine wave phase excitation, the frequency of the received signal is between 1Hz--12.5Hz, other signals are not concerned or affected, and can avoid the influence of any high-frequency spike radiation, so the sine wave phase excitation is not only It is green and environmentally friendly, and has strong anti-noise and adaptability to electromagnetic interference. It can work normally in areas with strong power frequency interference and strong stray DC interference, and is suitable for mine geophysical prospecting.

5. Sine wave phase excitation, the synchronization method of signal transmission and reception is more flexible than other spectrum excitation and phase excitation, and the wireless synchronization and GPS synchronization methods are less affected by changes in external conditions and are not affected by various The ability to adapt to the environment is strong.

6. The sine wave phase IP can also work normally when the grounding condition of the AB transmitting electrode is slightly poor, and the _ψAB phase drift is unstable; due to the use of full AC signals, the receiver automatically excludes DC and extremely low frequency instability factors The grounding condition of the MN receiving electrode is also lower than that of other IPs, and the field operation speed is fast and the quality is good. Therefore, compared with other IPs, the sine wave phase IP has a stronger ability to adapt to the geological conditions of the site.

7. The emission principle of symmetrical square wave IP is simple, the equipment cost is low, and the power is high, which is convenient for large-area and large-polar distance depth geophysical exploration.

Six, the prospect of the present invention

"Technical scheme of sine wave phase excitation", as a new method and new technology research of geophysical prospecting, is based on summarizing the existing spectrum excitation and phase excitation, in line with the needs of cheap operation, a successful invention New method, this solution solves the bottleneck problem of time domain IP, solves the shortcomings of high cost and low benefit of spectrum IP and existing phase IP, and the measurement speed is faster than spectrum IP, existing phase IP, and time domain The IP speed is fast, the grounding conditions are relatively minimum, and it is simple, fast, and cost-effective. It can be used as an important supplement to the application methods of spectrum IP and phase IP technology, and has become a fast and convenient means for the promotion of IP technology. Prospecting services for geological census and detailed survey.

The sine wave phase IP is especially suitable for geophysical prospecting in mines (regions). In terms of application, it surpasses the time domain IP and other frequency domain IP, and will become an important means used by mining companies such as non-ferrous metals in mine production and prospecting. Existing spectrum excitation and phase excitation can only carry out ground geophysical prospecting during the "lunch break" when industrial electricity is stopped in mines (districts), while sine wave phase excitation can be used in industrial power grids, rail transit, elevators, electromagnetic generators, etc. In a heavy environment, IP work can be carried out at any time, not only for ground geophysical prospecting, but also for underground phase excitation in deep tunnels where it is impossible to stop industrial power consumption, indicating the storage space on site and guiding tunnel production. Therefore, the future users of sine wave phase IP include not only geological colleges, geological and mining departments of land and resources exploration, gold troops, but also many state-owned mining enterprises, private enterprises and small mine owners, etc., and the economic benefits are expected to be considerable.

7. Description of drawings

Figure 1: The logical relationship diagram of the sine wave waveform corresponding to the absolute phase ψs and its main power supply V _AB and I _AB ;

Figure 2: Theoretical calculation spectrum curve of a certain sulfide mineral, excerpted from the master's thesis of Central South University of Technology "Xia Xunyin. Numerical simulation and physical simulation research of multi-frequency IP relative phase method";

Figure 3: Spectrum curve of theoretical calculation of graphite, excerpted from the master's thesis of Central South University of Technology "Xia Xunyin. Numerical simulation and physical simulation research of multi-frequency IP relative phase method";

Figure 4: The experimental spectrum curve of a pyrite sulfide mineral, excerpted from the master's thesis of Central South University of Technology "Xia Xunyin. Numerical simulation and physical simulation research of multi-frequency IP relative phase method";

Figure 5: Experimental spectrum curve of graphite, excerpted from the master's thesis of Central South University of Technology "Xia Xunyin. Research on numerical simulation and physical simulation of multi-frequency IP relative phase method";

Figure 6: Schematic diagram of the IP transmitter for sine wave waveform inverter transmission;

Figure 7: The change diagram of the duty ratio of the switching power supply in the subsequent stage of the sine wave waveform inverter emission;

Figure 8: Schematic diagram of the IP transmitter for symmetrical square wave emission;

Figure 9: Schematic diagram of the single-channel sine wave phase IP instrument receiver;

Figure 10: Schematic diagram of the acquisition of the absolute (delayed) phase and amplitude of the sine wave phase IP;

Figure 11: Schematic diagram of the acquisition of the absolute (leading) phase and amplitude of the sine wave phase IP;

Figure 12: Simulation frequency attenuation curve of single-channel sine wave phase IP instrument filter channel;

Figure 13: Single-channel sine wave phase IP instrument filter channel simulation frequency physical phase shift curve;

Figure 14: Three-channel sine wave phase IP instrument 1.5Hz narrow-band filter simulation frequency attenuation curve;

Figure 15: Three-channel sine wave phase IP instrument 1.5Hz narrow-band filter simulation frequency physical phase shift curve;

Figure 16: Three-channel sine wave phase IP instrument 4.5Hz narrow-band filter simulation frequency attenuation curve;

Figure 17: Three-channel sine wave phase IP instrument 4.5Hz narrow-band filter simulation frequency physical phase shift curve;

Figure 18: Three-channel sine wave phase IP instrument 7.5Hz narrow-band filter simulation frequency attenuation curve;

Figure 19: Three-channel sine wave phase IP instrument 7.5Hz narrow-band filter simulation frequency physical phase shift curve;

Figure 20: Schematic diagram of the three-channel sine wave phase IP instrument receiver.

Claims (3)

1. sine wave signal Frequency Locking (synchronous with Singlechip clock) and swash electric phase directly carve reading, A/D at sine wave wave crest Acquire amplitude.

2. in the narrow-band filtering of simple signal, the physics phase shift of sine wave signal can compensate for.

3. sine wave phase swashs ' sine wave emit with single channel sine wave phase induced polarization instrument receive ' subscheme of electricity and ' symmetrical Square-wave transmission is received with triple channel sine wave phase induced polarization instrument ' subscheme.