CN85103827A

CN85103827A - Geophysical electricity, magnetic variable are eliminated the device that power frequency is disturbed in measuring

Info

Publication number: CN85103827A
Application number: CN 85103827
Authority: CN
Inventors: 何朝明
Original assignee: Exploration Inst Of Geophysics & Geochemistry Ministry Of Geology And
Current assignee: Exploration Inst Of Geophysics & Geochemistry Ministry Of Geology And
Priority date: 1985-05-21
Filing date: 1985-05-21
Publication date: 1986-03-10
Also published as: CN85103827B

Abstract

The invention belongs to and be applied to electric variable measurement in the geophysical survey, magnetic variable measuring technique.The present invention disturbs with the power frequency of eliminating in the resistivity prospecting, improves accuracy of observation, enlarges application.Its major technique is characterised in that, the flip flop equipment that an auto-tracking power frequency disturbs is set in transmitter.Make the multiplying power of emission frequency tracking power frequency or power frequency, so that receiver utilization bipolar measurement principle of superposition is eliminated power frequency and harmonic interference.

Description

Geophysical electricity, magnetic variable are eliminated the device that power frequency is disturbed in measuring

The invention belongs to the electric variable, the magnetic variable measuring technique that are applied in the geophysical survey.

In the exploration of geophysics electrical method (following general designation physical prospecting), it is very general that power frequency is disturbed.(power frequency is a civil power week wave frequency.In China was 50 weeks, and some country was 60 weeks, the general designation power frequency.The related parameter that has in the literary composition all is as the criterion with 50 weeks.) this interference comes from power frequency electromagnetic field, the formed industrial travelling powder current of transformer grounding end of high-pressure delivery electrical network etc.Power frequency is disturbed except that first-harmonic, also with stronger multiple harmonic composition.Its cycle shakiness is the characteristics of giving prominence in China.Therefore, for the resistivity prospecting that belongs to faint electricity, magnetic signal measurement, it is very difficult overcoming the power frequency interference.Especially manufacturing district or city, power frequency is disturbed especially strong, so that becomes the forbidden zone of resistivity prospecting.

For a long time, the geophysical prospecting equipment worker disturbs a lot of work of having done for eliminating power frequency.Known to me, in the at present domestic and international electrical measuring instrument,, the known method that reduces the power frequency interference can reduce three kinds:

1. in receiver channel, being provided with various types of is the trapper of centre frequency with the power frequency, thus the power frequency composition in prevention or the attenuation measurement signal.As DJS-2 type, DJS-4 type (Chongqing Geological Instrument Factory), SJJ-1(Shanghai geological instrument factory), IPR-8(Canada SCINREX company), IPV-3(Canada PHOWIX company) wait induced polarization instrument and the Canadian CRON of PEM(company) the transient electromagnetic field instrument, all belong to this type of.

2. digital filter apparatus is set in receiver.In intelligent geophysical prospecting equipment, mostly adopt software digital filter in recent years, thus the power frequency composition in the filtered signal.As DWJ-1 type (Beijing geological instrument factory), IPR-11(Canada SCINTREX company), M-4(Canada HUNTEC company) wait induced polarization instrument and the Canadian GEGEONC of EM-37(company) the transient electromagnetic field instrument.

3. power frequency is disturbed and regarded as random disturbance, repeatedly duplicate measurements mode of Mining.After N measurement stack, make the power frequency interference reduction in the signal

\sqrt{N}

Doubly.With the way of sacrificing Measuring Time, partly eliminate power frequency and disturb.As SEROTEM transient electromagnetic field instrument (Australian CAR company).

(above all instruments overcome power frequency perturbation technique data, from instrument instructions) separately

The common feature of these three kinds of technology is that the measure that anti-power frequency is disturbed all is arranged in the receiver channel.For 1.2, the hardware and software filtering measures in the receiving cable, same decay is also suffered in the power frequency that not only decayed interference, and the power frequency composition of useful signal, causes the measurement distortion.Simultaneously, when cycle was unstable, the wave filter of its dead center frequency or filtering software do not possess and follow the tracks of the function that power frequency is disturbed, so filter effect weakened greatly.The 3rd kind of interference protection measure is to be cost with the sacrifice Measuring Time, inefficiency, and its effect also only is to reduce power frequency to disturb Doubly.Facts have proved, the strong jamming area, it is invalid to be still.

The invention reside in, interference protection measure is arranged in the transmitter, make emission frequency tracking power frequency or power frequency multiplying power.In view of receiver and transmitter synchronous, then with the power frequency interference signals and the useful signal Phase Tracking of harmonic wave.So receiver utilizes bipolar measurement principle of superposition, power frequency interference signals is balanced out to greatest extent, until offsetting fully, improved accuracy of observation.Because receiving cable does not add the measure of power frequency filtering hardware and software, therefore measure the power frequency composition that does not lose useful signal, improved the fidelity of measuring.

The present invention is the municipal engineering physical prospecting of carrying out present urgent need, and strong means are provided; Also, increase exploration concentration, created condition for improving the accuracy of observation of resistivity prospecting.

The present invention is provided with a flip flop equipment of following the tracks of power frequency in transmitter.Structured flowchart as shown in Figure 1.Fig. 1-1 is for the industrial frequency resonance coil or squeeze into the electrode (strong jamming area only use two leads also can) on the face of land, is used for the Mining collection to survey power frequency interference signals in the district.It is the narrow band filter (Fig. 1-2) of centre frequency that signal is sent into the power frequency, and bandwidth is ± 3HZ.Thereby obtain clean power frequency sine wave signal.This signal is sent into zero-cross comparator (Fig. 1-4) through gating switch (Fig. 1-3) after amplifying, and produces the power frequency trigger pulse.Trigger pulse is sent into the triggering delay circuit of being made up of monostable circuit (1), and trigger in (Fig. 1-5) forward position, and time-delay 10ms, forms approximate 1: 1 square wave of dutycycle.Through multistage frequency divider and selector switch (Fig. 1-7), can obtain respectively power frequency itself and a series of be 1: 1 square wave of multiplying power with the power frequency.As 50 weeks, 25 weeks, 12.5 weeks ... Deng.Through two-way differentiating circuit (Fig. 1-8), convert edge before and after the square wave to trigger pip.This pulse is seized distributor circuit through patrolling, and just can trigger the widely different road of bipolarity controllable silicon master, thereby launches powerful, as to follow the tracks of power frequency bipolar square wave.

The power frequency trigger pulse is sent into monostable (2) simultaneously and is triggered delay circuit.(Fig. 1-6) like this, in case after obtaining trigger pip, monostable (2) control gating switch immediately, and it is opened circuit.Behind the about 18ms of monostable (2) time-delay, control gating switch auto-closing is caught second zero cross signal so that pounce on.The effect of gating switch is to avoid the strong signal of transmitter emission, to zero-cross comparator generation false triggering.The sequential chart of this each functional block of flip flop equipment is seen Fig. 2-(a).

Receiver and transmitter are synchronous.Therefore, receiver observed bipolarity secondary field signal and power frequency interference signals are Phase Tracking.From Fig. 2-(b) as seen, the signal of receiver is the same superimposed of secondary field signal and undesired signal.The pure secondary field value of now ordering a certain sampling road is A; Interference value is B.Then measuring superposition value for secondary field positive polarity is C '=A-B; Measure superposition value C=A+B for the secondary field negative polarity, the twice measurement addition of the identical sampling of (see figure 3) positive-negative polarity road is removed by two then to be had

(C+C′)/2 ＝ (A-B+A+B)/2 ＝A

As seen, power frequency and harmonic interference value B all are cancelled.It is extremely easy finishing above-mentioned computing in receiver.

For macrocyclic measurement as shown in Figure 4, still can accomplish Phase Tracking.In like manner, after the bipolarity stack, power frequency is disturbed and can be cancelled equally.

Through observing, the amplitude and the waveform of power frequency interference field change.This variation is mainly from the load variations of electrical appliance.The cycle of this variation is longer, and comparatively speaking, the measurement of resistivity prospecting is fast.Therefore, in the measurement of twice positive-negative polarity, the probability that runs into interference variations is very little, even if run into occasionally, the difference that interference value wave-shape amplitude through superposeing under residual changes is through duplicate measurements several times, the overproof rejecting technology that utilization is commonly used or its residual difference distributed, its interference value is just very small.

In sum, compared with the prior art the present invention has following advantage:

1. this flip flop equipment is distinguished the collection in worksite power frequency interference signals from surveying, and converts the trigger pulse of transmitter to.Therefore, the function that has power frequency interference signals in motion tracking is surveyed the district.The national conditions that meet China's cycle shakiness.

2. tracking means is arranged in the transmitter, and receiver is not provided with the filter of power frequency and harmonic wave, has improved the fidelity of measuring greatly.

3. antijamming capability is strong, can not only overcome fundamental frequency and disturb, and the each harmonic of varying strength disturbs and is also eliminated to greatest extent, even all be eliminated.

4. have simple in structurely, technical difficulty is little, and is cheap, easily the advantage that realizes.

Optimum implementation as shown in Figure 5.This be tested successfully from motion tracking 50 all flip flop equipment circuit.What this circuit was used all is commonplace components and common circuit.Debugging technique also belongs to generally.Test point has been marked among Fig. 5, and its waveform as shown in Figure 2.

Frequency selective switch is divided into the 1-8 shelves.When disturbing first-harmonic to be 50 weeks, its transmitter frequency is listed as follows:

The 1-4 shelves are used for transient electromagnetic field method; 5-8 shelves induced polarization method.Can select and increase and decrease the frequency division shelves as required.

Input termination 50 all resonance coils or buried two electrodes of this flip flop equipment all can.The sensitivity of input end can be adjusted Amplifier Gain as required.Distributor circuit is seized in patrolling of the general transmitter of output termination, just can trigger bipolarity controllable silicon major loop.

This flip flop equipment will be realized in transient field instrument development project, will be tested and appraised in 87 years.

Description of drawings:

Fig. 1. auto-tracking power frequency flip flop equipment theory diagram.

1 industrial frequency resonance coil or squeeze into the pair of electrodes on the face of land;

2 power frequency narrow band filters;

3 gating switches;

4 zero-cross comparators;

5 monostable circuits (1);

6 monostable circuits (2);

7 frequency dividers and frequency division selector switch;

8 differentiating circuit;

9 patrol and seize distributor circuit and controllable silicon major loop.

Fig. 2. the sequential chart of auto-tracking power frequency flip flop equipment.

Corresponding test point is shown in Fig. 1 and Fig. 5.

Fig. 3. bipolarity is with superimposed principle of cancellation figure.

Fig. 4. long period is measured superposition principle figure.

Fig. 5. from motion tracking 50 all flip flop equipment circuit diagrams.

Claims

1, the invention belongs in the geophysical survey electric variable, magnetic variable measuring technique.The invention is characterized in, the utilization bipolar measurement principle of superposition, a flip flop equipment (Fig. 1) that power frequency is disturbed in motion tracking is surveyed the district is being set in the transmitter, and the bipolar square wave that transmitter is launched follow the tracks of power frequency or become multiplying power with power frequency is so that eliminate the power frequency interference.

2, in the flip flop equipment of claim requirement 1, there is one to be used for receiving the coil (Fig. 1-1) of surveying power frequency interference signals in the district or to imbed the pair of electrodes of surveying in distinguishing, the strong jamming area then only gets final product with lead.

3, in claim requires 1 flip flop equipment, before zero-cross comparator, a narrow band filter (Fig. 1-2) that is used for filtering and amplifying signal is arranged.Centre frequency is a work frequency, bandwidth ± 3HZ.

4, in the flip flop equipment of claim requirement 1, before zero-cross comparator, a gating switch (Fig. 1-3) is arranged.

5, in the flip flop equipment of claim requirement 1, a zero cross signal with power frequency interference signals is arranged, convert the zero-cross comparator of trigger pulse to.(Fig. 1-4)

6,, be to be subjected to a triggering delay circuit of forming by monostable circuit (Fig. 1-6) control at the gating switch of claim requirement 4.This circuit input end and zero-cross comparator output terminal join, in case after obtaining zero friendship trigger pulse, trigger delay circuit and control the gating switch open circuit immediately, time-delay 18ms makes gating switch connect 2ms.

7, claim requires in 1 the flip flop equipment, and by the delay circuit (Fig. 1-5) that a monostable circuit is formed, it forms the square wave that dutycycle is similar to 1: 1 with the trigger pulse 10ms that delays time.

8, in the flip flop equipment of claim requirement 1, a multistage frequency divider and a group selection switch (Fig. 1-7) are arranged so that according to measuring needs, select transmit frequency.

9, claim requires in 1 the flip flop equipment, has one square wave become the differentiating circuit of trigger pulse, is used for triggering the widely different road of controllable silicon master.(Fig. 1-8)