CN1928586B - RTK-GPS technique based high altitude measuring device and method thereof - Google Patents

Abstract

The related altitude measurement method based on RTK-GPS technology introduces gravity field, and can obtain altitude and altitude difference precisely. Wherein, the device comprises: a reference station, and a mobile station with a mini mobile station unit included a high-precise GPS OEM mainboard and anti-multipath specific antenna and HF radio and power. This invention has strong power and high precision, is easy to operation, and special fit to Chinese area measurement.

Description

Height above sea level measuring equipment and measuring method thereof based on the RTK-GPS technology

Technical field

The present invention relates to a kind of measuring method and equipment of height above sea level, is a kind of RTK-GPS of utilization accurately measures height above sea level in the application technology of fields of measurement method and apparatus specifically.Being suitable for earth surface, the particularly accurate height above sea level of CHINESE REGION surface target measures.

Background technology

GPS (GPS) is the cover satellite navigation and location system that the U.S. sets up.The GPS beacon that it provides has become global resources shared, has brought into play enormous function in fields such as navigation, measurements.Adopt two or many GPS receivers to carry out synchro measure, can accurately obtain the relative coordinate between two or many gps antennas, this method is called differential GPS and measures.If the GPS receiver utilizes carrier phase dynamic real-time difference (RTK) method, not only can provide parameter to be measured fast, and can reach centimetre-sized even millimeter rank measuring accuracy.Though above-mentioned employing RTK-GPS location technology can accurately be determined the three-dimensional position of spatial point, but regrettably, its elevation of determining is with respect to specific reference ellipsoid, be so-called geodetic height, rather than be widely adopted in actual applications with the closely-related height above sea level of the gravity potential of earth.

Summary of the invention

At existing RTK-GPS technology in the deficiency that exists aspect the measurement, integrated cost is high and to measuring normal high active demand, the invention provides a kind of height above sea level measuring method based on the RTK-GPS technology, it can not only provide longitude, latitude and the elevation of observation station accurately, but also can provide the height above sea level and the accurate height above sea level discrepancy in elevation.

The present invention also provides a kind of height above sea level measuring equipment based on the RTK-GPS technology.

For achieving the above object, the technical solution used in the present invention is:

A kind of height above sea level measuring equipment and measuring method thereof based on the RTK-GPS technology, its special character is:

Height above sea level measuring equipment based on the RTK-GPS technology comprises base station and movement station,

Base station is a GPS receiver, is utilizing under carrier phase dynamic real-time difference method (RTK) work pattern, and base station sends its observed reading and survey station coordinate information to movement station together by data chainning;

Movement station is a GPS receiver, and movement station comprises employing high-precision GPS OEM mainboard, the anti-multipath dedicated antenna, and high-frequency radio and power pack are synthesized a pocket mobile station unit; Movement station not only by the data of data chainning reception from base station, also will be gathered the GPS observation data, and forms the difference observed reading and handle in real time in system, provides centimetre-sized height above sea level positioning result simultaneously.

The measuring method of above-mentioned height above sea level measuring equipment based on the RTK-GPS technology, its step is as follows:

The first step: modelling

Utilize RTK-GPS to measure high-precision acquisition earlier and wait to ask a little three-dimensional space position, with three-dimensional geodetic position that records and high precision earth gravitation bit model, calculate the gravity position of this point, and then only adopt computing method to obtain the earth potential radix without measurement of the level, thereby determine to wait to ask normal height a little, determine that promptly normally height is realized in conjunction with the calculating of terrestrial gravitation bit model with the GPS measurement, need not with traditional geometric leveling, so be referred to as GPS gravity position level;

Second step: set up base station

When 5 of locking satellites are above, can enter setting, start base station;

The 3rd step: set up movement station

With the base station same satellite with after obtaining its error amount, calculate the accurate longitude of tested point, latitude and geodetic height in locking;

The 4th step: the calculating of tidal station gravity position

For arbitrary GPS/ leveling point i, can write out the potential difference equation

$\mathrm{\Δ}{W}_i={(W_T-W_0)}_i={\stackrel{\‾}{\mathrm{\γ}}}_i{H}_i+W_i-W_0$

W in the formula _TBe the position of the level surface of spending the T of tidal station water gauge zero point, W ₀Position (supposing known) for geoid surface; H is the normal height of an i, Be the corresponding mean normal gravity of an i, W is the gravity position of an i.Since n GPS/ leveling point arranged, n such ' observation ' potential difference arranged just; Suppose variances such as each potential difference has, then the probability value of gravity potential difference Δ W is the arithmetic mean of each potential difference, promptly

$\mathrm{\Δ}\hat{W}={\hat{W}}_T-W_0$

$=\frac{1}{n}\mathrm{\Σ\Δ}{W}_i$

$=\frac{1}{n}\mathrm{\Σ}({\stackrel{\‾}{\mathrm{\γ}}}_i{H}_i+W_i-W_0)$

Water Huaihe River face by tidal station is an elevation datum, W _TBe the position of elevation datum.The height tolerance of local in the world elevation datum and geoid surface is usually less than 1m; Work as W _TCan not accurately ask regularly, can replace the position W of geoid surface ₀, this moment, geoid surface was elevation datum; W _TCan utilize Chinese GPS leveling point data calculated in advance to come out;

The 5th step: the calculating of earth potential radix

The gravity position W of any is the potential of centrifugal force Φ sum due to the gravitation potential of earth V and the earth rotate, promptly

W＝V+Φ

$\mathrm{\Φ}=\frac{1}{2}{\mathrm{\ω}}^2(x^2+y^2)$

C＝W _T-W _P

The 6th step: the calculating of mean normal gravity

The reference ellipsoid face and like mean normal gravity between the shape face Calculate by formula:

$\stackrel{\‾}{\mathrm{\γ}}={\mathrm{\γ}}_0[1-\frac{1}{a}(1+f+m-2f{\sin }^{2}B)H_N+\frac{1}{a^2}{H}_N^2]$

Calculate mean normal gravity by following formula Use H _N, this by H and Loop iteration calculates;

The 7th step: demonstration, output data

By said process, draw the accurate longitude of tested point, latitude and height above sea level, be presented at it on output device and the sign storage, for further using.

The present invention is with respect to prior art, can not only provide longitude, latitude and the elevation of observation station accurately, and according to advanced algorithm and database software processing, can also provide the height above sea level and the accurate height above sea level discrepancy in elevation, it is powerful, and measuring accuracy height, speed are fast, easy simple to operate, degree of ripeness is higher, and risk is less.

Description of drawings

Fig. 1 is a theory diagram of the present invention;

Fig. 2 is the process flow diagram of measuring method of the present invention.

Embodiment

Conventional GPS measuring method, all need to resolve the precision that could obtain centimetre-sized as static state, rapid static, kinetic measurement afterwards, and RTK-GPS is the measuring method that can obtain the centimetre-sized bearing accuracy in the open air in real time, it has adopted carrier phase dynamic real-time difference (Real-time kinematic) method, it is the great milestone that GPS uses, it appear as engineering setting out, topographic mapping, various control surveys have brought Neoma Foam, have greatly improved the field operation operating efficiency.

The present invention has adopted carrier phase observation data, is made up of base station and movement station.The RTK location technology just is based on the real-time dynamic positioning technology of carrier phase observation data, and it can provide the three-dimensional localization result of survey station point in specified coordinate system in real time, and reaches the centimetre-sized precision.Under the RTK work pattern, base station sends its observed reading and survey station coordinate information to movement station together by data chainning.Movement station not only by the data of data chainning reception from base station, also will be gathered the GPS observation data, and forms the difference observed reading and handle in real time in system, provides the centimetre-sized positioning result simultaneously, lasts less than a second.Movement station can remain static, and also can be kept in motion; Can after carrying out initialization earlier on the point of fixity, enter dynamic operation again, also can under dynamic condition, directly start shooting, and under dynamic environment, finish the search finding of all blur leveles.The complete cycle end know number separate fixing after, can carry out the real-time processing of each epoch, as long as can keep the tracking and the necessary geometric figure of four above satellite phase observations values, then movement station can provide the centimetre-sized positioning result at any time.

The height above sea level measuring equipment that the present invention is based on the RTK-GPS technology comprises base station and movement station, base station is a GPS receiver, utilizing under carrier phase dynamic real-time difference method (RTK) work pattern, base station sends its observed reading and survey station coordinate information to movement station together by data chainning; Movement station is a GPS receiver, and movement station comprises employing high-precision GPS OEM mainboard, the anti-multipath dedicated antenna, and high-frequency radio and power pack are synthesized a pocket mobile station unit; Movement station not only by the data of data chainning reception from base station, also will be gathered the GPS observation data, and forms the difference observed reading and handle in real time in system, provides the centimetre-sized positioning result simultaneously.

Some important technological parameters of height above sea level measuring equipment of the present invention:

Passage: independent 24 passages

Tracking signal: L1/L2

Static plane precision: 5mm+1ppm

Static vertical accuracy: 1cm+1ppm

Static action distance: be better than 50 kilometers

Static memory: built-in 32M

RTK plane precision: 2cm+1ppm

RTK vertical accuracy: 3cm+1ppm

Communication modes: USB, serial ports

Data chainning: 25W/10W (emissive power)

RTK initialization time: typical case 12 seconds

Referring to Fig. 1, Fig. 1 is a theory diagram of the present invention;

In mapping operations, usually with geodetic height as topocentric third dimension coordinate.For the ease of more any difference in height, also need to determine starting at a little or reference field (China adopts Huang Hai mean sea level in 1985 as the unified elevation datum of China) of an elevation at 2.The always a certain relatively face of starting at of elevation is measured, geoid surface is a geometric surface, it is again a physical surface, the more important thing is that geoid surface is static seawater face, therefore, select geoid surface to start at face as elevation in mapping operations, this elevation gauging system is called the absolute elevation system; In geodetic surveying, claim orthometric elevation system again.At present, the legal elevation system of China is exactly an orthometric elevation system.

Strict absolute elevation (abbreviation height above sea level) is the distance of ground point along gravity vertical to geoid surface.When geoid surface below land, this segment distance is actually and can not directly measure.Suppose that from the sea level (can think geoid surface, its elevation is zero) rise and survey, measure land certain spot elevation undetermined, utilize potential difference to equal the principle of constant so with the method for measurement of the level:

Result's (potential difference) of the gravity value of the every segment discrepancy in elevation of leveling line * this discrepancy in elevation section=strict absolute elevation of tested point * its gravity mean value on along gravity vertical to geoid surface

Therefore, this gravity mean value of potential difference ÷ of Yan Ge height above sea level=record along leveling line.Though height above sea level can obtain by level and gravimetry, the operating cost of these methods is very high, and operating efficiency is relatively low.

Adopt the GPS space orientation technique, can determine three-dimensional position a little simultaneously, but regrettably, the elevation of being determined is with respect to specific reference ellipsoid, be so-called geodetic height, rather than extensively adopt in actual applications with the closely-related height above sea level of the gravity potential of earth.If but can reach out for geoidal rise or height anomaly on the respective point, and just can carry out the conversion of corresponding elevation system, geodetic height is converted to height above sea level.

It can not only provide longitude, latitude and the elevation of observation station accurately the present invention, introduces the gravity physical field, and in conjunction with measuring equipment of the present invention, can also provide the height above sea level and the accurate height above sea level discrepancy in elevation, and this is unexistent in other GPS measuring system.

The geoidal rise model is the mathematics face of a represents physical field shape, is made of the humorous polynomial expression of the ball of limited order, has following form:

$N=\frac{{\mathrm{GM}}^n}{R_{\mathrm{\γ}}}\underset{n=2}{\overset{\max }{\mathrm{\Σ}}}\underset{m=0}{\overset{n}{\mathrm{\Σ}}}{\left(\frac{a_e}{R}\right)}^n{P}_{\mathrm{nm}}\left(\sin \mathrm{\Φ}\right)[C_{\mathrm{nm}}^{*}\cos \mathrm{m\λ}+S_{\mathrm{nm}}\sin \mathrm{m\λ}]$

In the formula: φ, λ are the geocentric latitude and the longitude of calculation level; R is the earth's core radius of calculation level; γ is the normal gravity on the ellipsoid; a _eBe the terrestrial equator radius; G is a universal gravitational constant; M is an earth quality; P _NmThe Legendre function is followed on the m rank for n time; C _Nm ^*, S _NmN m rank spherical harmonic coefficient for the pairing reference ellipsoid gravity position of geoidal rise; N _MaxThe highest order for the spheric harmonic expansion formula.

The master data of geoidal rise model is the humorous gravity position coefficient of ball, resulting geoidal rise information is with respect to the earth's core ellipsoid, model accuracy depends on gravimetric observation value area coverage and the inferior factor of high-order of precision, satellite tracking data quality and quantity, geoid surface flatness and model that is used as boundary condition, and old system is lower than 1 meter at the absolute precision of general purpose geoidal rise model.And the physical field model that the present invention proposes, the regional level surface precision that combined ground gravimetric data, GPS measurement achievement and accurate level data are set up has reached 2-3 centimetre error precision.

Referring to Fig. 2, Fig. 2 is the process flow diagram of measuring method of the present invention;

The fashionable at present whole world of RTK measuring technique, main cause are that its measurement pattern of RTK measuring technique and measuring speed, ratio of precision metering system have in the past had very big change; Efficient significantly improves, and is the great milestone of measuring technique development, it appear as high-level efficiency engineering setting out, topographic mapping, various control surveys have brought Neoma Foam, have greatly improved the field work operating efficiency.For example in the past adopt the task in 1 year of traditional measurement method just can finish in one month by tens staff that adopt the RTK-GPS technology by hundreds of mapping workers.Therefore attract numerous enterprise's research and development and formed product.

The RTK measuring technique is ripe at present, and it develops main direction is to improve measuring speed and precision.Measuring speed is mainly determined by the initialization required time, the initialization required time is again by factor decisions such as RTK technology difference (various types have the different technology of resolving fast), the quality and quantity that receives satellite, RTK data chainning transmission qualities, it is advanced more to resolve technology fast, the number of satellite that receives under the certain height angle is many more, quality is good more, RTK data chainning transmission quality is high more, and the initialization required time is just short more.Under good environmental baseline, RTK initialization required time was generally tens seconds; (still satisfy the RTK basic operating conditions) under the unsuitable environmental condition, the RTK of advanced technology also needs a few minutes to tens minute, and other type RTK needs not even energy measurement of dozens of minutes.The Z-X double frequency RTK that produces as U.S. ASHTECH is under good environmental baseline, the initialization required time is 2-10 second, under unsuitable environmental condition, still can more successfully carry out RTK measures, mainly be that this type has that advanced Z-follows the tracks of patented technology, RTK (INSTANT-RTK) technology and multipath are subdued patented technology fast, test shows, even it is abominable to survey in the district some local environment, its observed reading mean square error of a point still ± below the 2.41cm.Product initialization time of homemade certain company is about 60 seconds, is generally 45 seconds, and being initialized as about 15 seconds of up-to-date clever sharp S80, so for adopting the RTK commercial measurement, the instrument difference of domestic and imported is not clearly.

In addition on the precision of RTK measurement products no more than total powerstation, this is because RTK is easier to the cause that influenced by satellite situation, weather conditions, data chainning status transmission.The RTK system of different quality, its precision difference is bigger.Solve this type of problem, at first will select all high-quality machines preferably of precision and stability for use, then, when the cloth reference mark, arrange " unnecessary " reference mark more, measure the check point of quality of achievement control as RTK.

Also have the RTK work pattern to require the conversion of elevation accurately necessary, but the existing height anomaly figure of China is in a lot of areas, especially mountain area, hills and area, basin, existence is than mistake, and China is owing to the physical geography condition reason, from south to north across thousands of kilometer, and many mountain areas, hills and basin; This just makes the work that GPS the earth elevation the is converted to absolute elevation quite difficulty that becomes, and precision is also inhomogeneous.

The GPS OEM mainboard that native system selects for use internationally recognizable Novatel company high-quality, that high precision has the RTK function to produce, the anti-multipath dedicated antenna, fast accurate algorithm, specialty is the high-power high-frequency data chainning efficiently, integrates the precision measurement system that forms.

Concrete steps are measured as follows:

A kind of height above sea level measuring method based on the RTK-GPS technology, realize by following steps:

The first step: principle explanation and model propose

By surveying high theoretical fundamental equation

dw＝-gdH

As can be known,, measured the gravity acceleration g on the point again, can obtain the gravity potential difference dW of point-to-point transmission if observed the discrepancy in elevation dH of contiguous point-to-point transmission.Along the leveling line integration of starting at the T to of tidal station ground point P a little as elevation, we have with (1) formula

$C=W_T-W_P=\underset{T}{\overset{P}{\∫}}\mathrm{gdH}$

W in the formula _TThe gravity position of representing the level surface of the T of tidal station, W _PThe gravity position of representing the level surface of ground point P.Gravity potential difference C=W _T-W _PBe called the earth potential radix.Know earth radix C, just can define various elevations.Normal height is defined as:

$H_N=\frac{C}{\stackrel{\‾}{\mathrm{\γ}}}$

In the formula

Expression normal ellipsoid face and like normal gravity mean value between the shape face.

Last three formulas are the basis of conventional geometric measurement of the level.The essence of geometric leveling be by on the observation leveling line between neighbor point the discrepancy in elevation and some acceleration of gravity obtain to wait to ask highly a radix.

The present invention proposes to utilize earlier RTK-GPS to measure high-precision acquisition and waits to ask a little three-dimensional space position, with three-dimensional geodetic position that records and high precision earth gravitation bit model, calculate the gravity position of this point, and then only adopt computing method to obtain the earth potential radix, thereby determine to wait to ask normal height a little without measurement of the level.Determine that promptly normally height is realized in conjunction with the calculating of terrestrial gravitation bit model with the GPS measurement, need not with traditional geometric leveling, so be referred to as GPS gravity position level.

Second step: set up base station

Intelligence, reliable base station can be annotated with the foolproof operation of hommization, and system operation is simple and convenient.The High Frequency Data Link of base station has the RTK data radio station technology of specialty, core, for the measurement operation of all-weather provides guarantee.

When 5 of locking satellites are above, can enter setting, start base station.

The 3rd step: set up movement station

Movement station is high-precision GPS OEM mainboard, the anti-multipath dedicated antenna, and high-frequency radio and power pack are synthesized a pocket mobile station unit.

With the base station same satellite with after obtaining its error amount, calculate the accurate longitude of tested point, latitude and geodetic height in locking.

The 4th step: the calculating of tidal station gravity position

For arbitrary GPS/ leveling point i, we can write out the potential difference equation

$\mathrm{\Δ}{W}_i={(W_T-W_0)}_i={\stackrel{\‾}{\mathrm{\γ}}}_i{H}_i+W_i-W_0$

W in the formula _TBe the position of the level surface of spending the T of tidal station water gauge zero point, W ₀Position (supposing known) for geoid surface; H is the normal height of an i, Be the corresponding mean normal gravity of an i, W is the gravity position of an i.Since we have n GPS/ leveling point, n such ' observation ' potential difference arranged just.Suppose variances such as each potential difference has, then the probability value of gravity potential difference Δ W is the arithmetic mean of each potential difference, promptly

$\mathrm{\Δ}\hat{W}={\hat{W}}_T-W_0$

$=\frac{1}{n}\mathrm{\Σ\Δ}{W}_i$

$=\frac{1}{n}\mathrm{\Σ}({\stackrel{\‾}{\mathrm{\γ}}}_i{H}_i+W_i-W_0)$

Water Huaihe River face by tidal station is our elevation datum, W _TBe the position of elevation datum.The height tolerance of local in the world elevation datum and geoid surface is usually less than 1m.Work as W _TCan not accurately ask regularly, can replace the position W of geoid surface ₀, this moment, geoid surface was our elevation datum.W _TCan utilize Chinese GPS leveling point data calculated in advance to come out.

The 5th step: the calculating of earth potential radix

The gravity position W of any is the potential of centrifugal force Φ sum due to the gravitation potential of earth V and the earth rotate, promptly

W＝V+Φ

$\mathrm{\Φ}=\frac{1}{2}{\mathrm{\ω}}^2(x^2+y^2)$

C＝W _T-W _P

The 6th step: the calculating of mean normal gravity

The reference ellipsoid face and like mean normal gravity between the shape face Calculate by formula:

$\stackrel{\‾}{\mathrm{\γ}}={\mathrm{\γ}}_0[1-\frac{1}{a}(1+f+m-2f{\sin }^{2}B)H_N+\frac{1}{a^2}{H}_N^2]$

Calculate mean normal gravity by following formula

Use H _N, this by H and

Loop iteration calculates.

The 7th step: demonstration, output data

By said process, draw the accurate longitude of tested point, latitude and height above sea level.Be presented at it on output device and the sign storage, for further using.

The present invention is of many uses, can be used for following field:

1, various control surveys: traditional geodesic survey, the triangulation network is adopted in engineering control survey, the traverse net method is come testing, not only time-consuming, require intervisibility between point, and precision skewness, and how do not know precision in field operation, adopt conventional GPS static measurement, rapid static, pseudo-dynamic approach, survey to establish in the process in field operation and can not know in real time positioning accuracy, after if survey is established and is finished, get back to and find that precision is nonconforming after interior industry is processed, also must return survey, and adopt the present invention to carry out control survey, can know in real time positioning accuracy and height above sea level, if positional accuracy requires to have satisfied, the user just can stop to have observed, and how knows observation quality, can greatly improve operating efficiency like this; Surveying a control point just can finish in several seconds even in a few minutes; In the past adopt the task in 1 year of traditional measurement method just can be finished in one month by tens staff that adopt the RTK-GPS technology by the hundreds mapping worker.

Therefore the present invention is used for Highway Control Surveying, Electronic Control measurement, hydraulic engineering control survey, geodesic survey, then not only can greatly reduces people's force intensity, cost saving, and greatly improved the operating efficiency of measuring.

2, topographic mapping: generally at first will set up figure root control point in the survey district when surveying topographic map in the past, total powerstation or theodolite cooperate the tablet mapping on then added at figure root control point, develop into now field operation and cooperate the atural object coding with total powerstation and data recorder, utilize large scale topographical map software to carry out mapping, develop into even nearest field operation electronic plane mapping etc., all require the detail points such as topography and geomorphology around survey station is surveyed, these detail points all with the survey station intervisibility, and at least 2-3 people's operation of General Requirements, in case need to when picture mosaic, the nonconforming field operation that also obtains of precision go to return survey, adopt now the present invention, only need a people to carry instrument one or two seconds kinds on the topography and geomorphology detail point that will survey is slow-witted, and input feature vector is encoded simultaneously, just can know in real time positional accuracy by hand-held set, indoor getting back to after regional the survey, software interface by specialty can be exported desired topographic map, like this with high accuracy RTK-GPS multidimensional real-time measurement system, only need one man operation, intervisibility between not requiring a little, greatly improved operating efficiency, adopt high accuracy RTK-GPS multidimensional real-time measurement system, cooperate the electronics hand-held set to survey and establish various topographic maps, such as common mapping, the survey of rail track belt topographic map is established, the survey of highway pipeline topographic map is established, cooperate sounding instrument can be used for surveying reservoir topographic map, navigation ocean mapping etc.

3, setting-out journey setting-out: be to measure one to use branch, it requires to adopt certain instrument by certain method is the people to come out to demarcation on the spot in the some position that designs, past adopts conventional setting out method a lot, such as theodolite intersection setting-out, corner setting-out of total powerstation etc., when generally wanting setting-out to go out a design point position, often need the target that moves around, and want 2-3 people to operate, intervisibility is all right between also requiring simultaneously to put in the setting-out process, efficient is not very high in production application, and the situation of sometimes meeting difficulty in the setting-out can be by means of the setting-out of a lot of methods ability, if when adopting the setting-out of high accuracy RTK-GPS multidimensional real-time measurement system technology, only need the position coordinate that designs is input in the data recorder, carry the GPS receiver, it can remind you to go to the position of wanting layout point, not only rapidly but also convenient, because GPS comes direct setting-out by coordinate, and precision is very high also very even, thereby efficient can improve greatly in the field operation setting-out, and only needs people's operation.

Claims (2)

1. height above sea level measuring equipment based on the RTK-GPS technology is characterized in that:

Height above sea level measuring equipment based on the RTK-GPS technology comprises base station and movement station,

Base station is a GPS receiver, is utilizing under carrier phase dynamic real-time difference method (RTK) work pattern, and base station sends its observed reading and survey station coordinate information to movement station together by data chainning;

Movement station is a GPS receiver, and movement station comprises employing high-precision GPS OEM mainboard, the anti-multipath dedicated antenna, and high-frequency radio and power pack are synthesized a pocket mobile station unit; Movement station not only by the data of data chainning reception from base station, also will be gathered the GPS observation data, and forms the difference observed reading and handle in real time in system, provides centimetre-sized height above sea level positioning result simultaneously.

2. the measuring method of the height above sea level measuring equipment based on the RTK-GPS technology according to claim 1, its step is as follows:

The first step: modelling

Utilize RTK-GPS to measure high-precision acquisition earlier and wait to ask a little three-dimensional space position, with three-dimensional geodetic position that records and high precision earth gravitation bit model, calculate the gravity position of this point, and then only adopt computing method to obtain the earth potential radix without measurement of the level, thereby determine to wait to ask normal height a little, determine that promptly normally height is realized in conjunction with the calculating of terrestrial gravitation bit model with the GPS measurement, need not with traditional geometric leveling, so be referred to as GPS gravity position level;

Second step: set up base station

When 5 of locking satellites are above, can enter setting, start base station;

The 3rd step: set up movement station

With the base station same satellite with after obtaining its error amount, calculate the accurate longitude of tested point, latitude and geodetic height in locking;

The 4th step: the calculating of tidal station gravity position

For arbitrary GPS/ leveling point i, can write out the potential difference equation

ΔW _i＝(W _T-W ₀) _i＝γ _iH _i+W _i-W ₀

W in the formula _TBe the position of the level surface of spending the T of tidal station water gauge zero point, W ₀Position for geoid surface; H is the normal height of some i, and γ is the gravity position of some i for the corresponding mean normal gravity of some i, W; Since n GPS/ leveling point arranged, n such ' observation ' potential difference arranged just; Suppose variances such as each potential difference has, then the probability value of gravity potential difference Δ W is the arithmetic mean of each potential difference, promptly

$\mathrm{\Δ}\hat{W}={\hat{W}}_T-W_0$

$=\frac{1}{n}\mathrm{\Σ\Δ}{W}_i$

$=\frac{1}{n}\mathrm{\Σ}({\stackrel{\‾}{\mathrm{\γ}}}_i{H}_i+W_i-W_0)$

Water Huaihe River face by tidal station is an elevation datum, W _TBe the position of elevation datum; The height tolerance of local in the world elevation datum and geoid surface is usually less than 1m; Work as W _TCan not accurately ask regularly, replace the position W of geoid surface ₀, this moment, geoid surface was elevation datum; W _TUtilize Chinese GPS leveling point data calculated in advance to come out;

The 5th step: the calculating of earth potential radix

The gravity position W of any is the potential of centrifugal force Φ sum due to the gravitation potential of earth V and the earth rotate, promptly

W＝V+Φ

$\mathrm{\Φ}=\frac{1}{2}{\mathrm{\ω}}^2(x^2+y^2)$

C＝W _T-W _P

The 6th step: the calculating of mean normal gravity

The reference ellipsoid face and like mean normal gravity γ between the shape face calculate by formula:

$\stackrel{\‾}{\mathrm{\γ}}={\mathrm{\γ}}_0[1-\frac{1}{a}(1+f+m-2f{\sin }^{2}B)H_N+\frac{1}{a^2}{H}_N^2]$

Calculate mean normal gravity γ by following formula and will use H _N, this calculates by H and γ loop iteration;

The 7th step: demonstration, output data

By said process, draw the accurate longitude of tested point, latitude and height above sea level, be presented at it on output device and the sign storage, for further using.

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