Some standard content:
GB12327:1998
In order to adapt to the needs of the development of hydrographic surveying in my country under the new situation, continuously apply new technologies and methods, and ensure the quality of hydrographic surveying results, this standard has revised GB12327-1990. When revising GB2327-1590, the operating methods and technical indicators in the previous GB12327-1990 that have been proven to be suitable for the current hydrographic surveying operations and are still effective are preserved. In accordance with the current status and trend of hydrographic surveying development, the mapping scale of the original 1:5000-1:500000 is changed to 1:2000-1:200000, the rules for large-scale mapping are supplemented, the positioning accuracy and sounding accuracy of water depth measurement are improved, the selection of instruments is classified and graded according to technical indicators, the specific content of instrument use is deleted, and the bottom classification mark and the map decoration format of water depth map and topographic map are redefined. This standard will replace GB12327-1990 from the date of implementation. Appendix A-Appendix U of this standard All of them are appendices of the standard. This standard is proposed by the Navy Headquarters.
This standard is under the jurisdiction of the Navigation Assurance Department of the Navy Headquarters. Drafting units of this standard: Naval Oceanographic Surveying and Mapping Institute. Navy 37205 Unit, Navy 37701 Unit, Guanjin Maritime Safety Supervision Bureau of the Ministry of Transport.
Main drafters of this standard: Zhai Guozai, Xie Xijun, Wang Rui, Li Jingfu, Xu Jiakun, Ma Bochang, Xu Guangyou. The first release date of this standard: April 19, 1990. This standard is entrusted to the Navigation Assurance Department of the Navy Headquarters for interpretation. irs:
1 Fan You
National Standard of the People's Republic of China
Specifications for hydrographic surveyGB12327-1998
I recite GR 1≥327—H0
This standard specifies the general principles, technical design, plane and elevation control measurement, water depth measurement, coastal topography measurement, technical summary, inspection and acceptance, and requirements and implementation methods for data submission of channel survey. This standard is applicable to various hydrographic survey operations with a scale of 1:20001:500000 in my country. 2 References
The texts contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the version shown is valid. All standards will be revised, so all parties to this standard should explore the possibility of using the latest version of the following standards. GB12319—1998 China Nautical Chart Diagram
GB/T7929-19951:500,1:1000,1:2000 Topographic Map DiagramCB 5791—19931:5 000.1 :10 000 Topographic map GE12898—1991 National third and fourth level leveling specifications National angle measurement and precision traverse measurement specifications 3 General provisions
3.1 The mission and mission of the hydrographic survey The main mission of the hydrographic survey is to conduct water depth measurement and sea topography measurement, obtain information such as seabed topography, bottom conditions and navigation obstacles, and its purpose is to provide data for the compilation of nautical charts to ensure the safety of ship navigation. 3.2 Basic contents of the hydrographic survey
a) Establish the basis for plane and elevation control measurement; b) Conduct water level observation, determine the average sea level, depth reference surface and calculate the water level correction during water depth measurement; c) Conduct water depth measurement, measurement of navigation aids, investigation and detection of navigation obstacles, hydrological and bottom quality determination, etc.; l) Conduct coastal topography measurement.
3.3 Datum used
3.3.1 Plane coordinates shall adopt the coordinate system uniformly stipulated by the state, and the relationship between them and the geocentric coordinate system shall adopt the conversion parameters uniformly used by the state or the regional conversion parameters that meet the accuracy requirements of this specification. 3.3.2 The elevation shall adopt the [985 national elevation datum. For islands and reefs far from the sea, the elevation datum may adopt the local sea surface. 3.3.3 The theoretical lowest tide level shall be used as the depth datum, and the height of the depth datum shall be calculated from the local average sea surface; in general, it shall be measured in conjunction with the national elevation datum. Once the depth datum is determined and has been used in regular water depth measurement, it shall not be changed. The height of the center of the light of lighthouses and light poles shall be calculated from the average high tide level. The coastline shall be surveyed and mapped based on the actual traces formed at the average high tide level. 3.4 Basic accuracy regulations for measurement and result drawings
Approved by the State Quality and Technical Supervision Commission on November 10, 19987:
Implementation on May 1, 1999
GB 123271998
3.4.1 The plane and elevation control basis of hydrographic surveying is developed on the basis of national geodetic network (points) and leveling network (points>). According to their surface excavation accuracy, hydrographic surveying control points are divided into first-class (indicated by H1) and second-class (indicated by I1.) points. The distribution of sea control points is based on the principle of meeting the requirements of water depth measurement and coastal topography measurement. For large-scale mapping at a scale of 1:5000 or less, the lowest plane control basis is the national fourth-class points; for small-scale mapping at a scale of 15,000 or less, the lowest plane control basis is the first-class sea control points. For mapping at a scale of less than (including>110,000), the lowest surface control basis is the second-class sea control points. The plane excavation points directly used for water depth measurement and coastal topography measurement are: for mapping at a scale of greater than 1:5000, the lowest plane control basis is the first-class sea control points. The sea control level-~ point is smaller than (including) 1:5000 and larger than F110000 scale for sea control level-2 point, smaller than (including) 1:[0000 scale for mapping is for mapping point (indicated by H.), which can be developed directly at control point 1. 3.4.2 The mean error of the positioning point in water depth measurement or in depth measurement: when mapping at a scale of 1:5000, it should not be greater than 1.5mml on the map, less than (including) 15000, when mapping at a scale of 1:100000, it should not be greater than 1.0mm on the map, and smaller than (including) 1:100000 scale for mapping should not be greater than 10㎡ on the ground.
3.4.3 Depth measurement generally uses an acoustic depth sounder. The provisions of the limit error of the depth measurement disk (confidence level 95%) are shown in Table 1 Table 1
Depth range Z
302≤50| |tt||50z100
23-100
3.4.4 The error limit of the drawing result relative to the calculated value; [The error of the length of the edge of the drawing shall not exceed 0.1mm on the drawing: the error of the diagonal length and the length of each line segment of the square grid shall not exceed 0.2mm on the drawing; the limit error 20
±×2%
The accuracy of the control point display is checked by the distance between the control points. The number of check edges for each control point shall not be less than two, and the intersection angle of the check edges shall be between 30150°. The error of the edge length shall not exceed 0.3mm on the drawing. The accuracy of the 1+ grid drawing shall be checked by the rectangular coordinates of the intersection point, and the coordinate displacement error shall not exceed 0.6mm on the drawing. For equiangular and equigrid grids, each copy shall have no less than five check points; for hyperbolic grids, each map should not Less than eight checkpoints. Checkpoints should be evenly distributed. 3.5 Mapping scale, projection, framing principles and standard map sheets 3.5. The basic mapping scale for bathymetric surveying must be determined according to actual needs and the complexity of the seabed landforms. Generally, it is stipulated as follows: a) Harbors, anchorages, narrow channels and sea areas with important use value should be surveyed at a scale of 1:2000~125000; b) Open bays, coastal areas with complex landforms and many islands should be surveyed at a scale of 1:25000; c) Coastal open sea areas with relatively flat landforms should be surveyed at a scale of 1:50000; d) Sea areas within 200 nautical miles from the coast should be surveyed at a scale of 1:100000 or 1:250000; e) Sea areas beyond 200 nautical miles from the coast should generally be surveyed at a scale of 1:500000. In order to show the seabed topography in detail, individual areas can be measured at a fire scale, but the control basis is still based on the original scale requirements. The mapping scale of coastal topography survey should be the same as the water depth mapping scale. 3.5.2 Mapping uses Gauss-Kruger projection. Mapping with a scale greater than 1:5000 uses 1.5° band projection, mapping with a scale greater than (including) 111000 uses 3 band projection, and mapping with a scale less than 1:10000 uses 6° band projection; mapping with a scale less than (including) 1:50000 can use Mercator projection, and the central latitude of the survey area is used as the base latitude. 3.5.3 The principle of surveying and retaining the map sheets should be to use the fewer map sheets that benefit the entire survey area. When dividing the map sheets, it is hoped that they will be consistent with the published map sheets of the nautical charts, and the integrity of the source area should be properly taken into account. 3.5.4 The standard map sheet size for water depth measurement is: a) 50cm×70cm b) 70cm×100cm c) 80 cmx1( cm. GE 12327-1998 3.5.5 The standard map sheet size for shore discharge measurement is 0cm50cm or consistent with the single map sheet size for water depth measurement: 3.6 The model number adopts the GR12319 4 technical design.1. City design
The main points of project design are,
a) Determine the scope of the survey area:
1) Divide the map sheets and determine the survey scale:c) Mark out the specific dividing lines (i.e., inflection points) between maps of different scales;d) Clarify the important technical guarantees for implementing the survey work;4.2 Professional design
First of all, the relevant data of the survey area should be collected and analyzed comprehensively, and a preliminary design should be carried out. Then, for some sea areas where the data is insufficient or the data availability is difficult to assess, field surveys and investigations should be carried out: on this basis, the preliminary design should be modified and enriched, and a technical design book should be prepared. 4.2.1 Data collection and analysis
Before technical design, the following data of the survey area should be collected: 1) The latest topographic map and sea map; 2) Control survey results data and their descriptions; 3) Water level control data; 4) Navigation points and navigation obstacles; 5) Other data related to the survey.
The collected data should be comprehensively analyzed for its reliability and accuracy, and a conclusion should be made on whether the data should be adopted or not. 4.2.2 Design procedures on the map
4.2.2.1 Excavation survey
a) Mark the known network (points), leveling routes and tide gauge stations on the topographic map or nautical chart of appropriate scale; b) When designing the network (point) to be measured, the old points should be fully utilized, and the navigation aids and significant objects in the survey area should be included in the plan. Estimate the accuracy of the newly designed network (point);
) According to the density requirements of the control network (point) for the height calculation point, design the water leakage joint measurement route of the control point; l) Under the premise of meeting the accuracy of the layout of the survey points, the height mark should be reduced as much as possible, the number of overlapping points should be reduced, and the graphics should be simple, the accuracy should be guaranteed, and the density should be appropriate:
4.2.2.2 Depth measurement
a 1) Determine the layout direction, interval and obstacles of various scaled survey and bathymetric lines, and the detection plan of bottom particles; 2) Determine the location and water level correction plan of shore stations, night stations, comparison points, tide gauges, and hydrological points, and estimate the error of the fixed image in the survey area; 3) Determine the inspection and measurement methods of positioning instruments and algae measuring instruments; 4) Propose the location and requirements for the shooting of the scenery. 4.2.2.3 Sea sheet topographic survey
\ According to the water depth measurement range and measurement scale, design the map according to the principle of free division and minimum division: 5) Determine the scope of revision and actual measurement according to the requirements of the industry and the existing data: 6) Propose the plan of adding survey points: 7) Determine the measurement method according to the size of the beach. 8) The design user on the map should be carefully checked and supplemented to ensure that all aspects of the design are complete and meet the requirements of this specification. 4.2.3 Field survey
GB 12327—1998
4.2.3.1 Field survey is an important part of revising and enriching the preliminary technical design. Therefore, before the field survey, the staff needs to conduct a thorough review of the preliminary technical design and then formulate a plan for the implementation of the survey. 4.2.3.2 Contents of the field survey
\) Survey the administrative divisions, social conditions, natural geography, hydrology and meteorology, communications, transportation, materials and equipment, medical care and ship shelter anchors.
h) Survey the location, type and preservation of the existing control network (points) and leveling points. Survey the visibility between the control points (including strategic and general physical markers) required for the field survey, determine their location, standard marker type and elevation: Survey the working conditions of the physical survey instruments on the line path. ") Check the preservation of existing tide gauges. For sea areas with insufficient data on tidal properties, stations should generally be set up for investigation. The stations set up in accordance with the provisions should be investigated for station locations and station conditions. d) Conduct field investigations on ports, estuaries and variable sections with insufficient resources to propose reasonable survey plans. e) Understand the changes in navigation obstacles in the survey area. [】 Investigate the location of shore stations, inspection stations, comparison points, test the interference of electromagnetic fields in the survey area on radio locators, and submit a written report on the results of the field investigation in a timely manner. The report should explain the contents of the investigation item by item and put forward suggestions for the improvement of the preliminary technical design.
4.2.4 Preparation and approval of technical design
4.2.4.1 The designer shall, based on the results of the field investigation, The preliminary design should be revised and supplemented, and a technical design document should be prepared. 4.2.4.2 The technical design document consists of a technical specification, a control survey, a depth survey and a coastal topography survey design diagram, and related drawings and schedules.
4.2.4.3 The contents of the technical specification are:
a) The source, nature and technical requirements of the task; the natural geographical characteristics of the survey area, the basis for the technical design and the background of the adoption of the original survey results.
h) The grade, type and number of landmarks and beacons of each survey control point; the depth survey map, depth measurement range, number of navigation obstacles, the map, area and length of the coastline of the coastal topography survey; C) The types and numbers of various major instruments, equipment and ships required for the operation. d) According to the geographical meteorological and technical equipment conditions of the survey area, the Establish the operation rate of different sea areas, and calculate the work orders and work numbers of various survey operations.
) According to the survey area and the technical level of the operation, put forward appropriate operation methods and precautions, and make specific technical instructions when necessary.
4.2.4.4 The design drawing of the bathymetric survey should mark the scope of the survey area, the number of the survey map, the scale, the tide gauge station, the hydrological point, the shore station, the danger inspection station, the comparison point, the survey area and the names of nearby important towns and roads. 4.2.4.5 The design drawing of the control survey should mark the names and grades of the known points and the points to be measured, the known sides and the sides to be measured, the known directions and the directions to be measured: the wire path, grade, line number, point number; the leveling route, grade, line number, number of points and the leveling points, triangulation points or other fixed points for route joint measurement 4.2.4.6 Coast Topographic survey design drawing: Cover the area according to the standard map sheet, mark the sub-map number, scale, and actual measurement and revision specifications. 4.2.4.7 The appendix includes the water level correction plan, positioning error calculation, obstacle detection statistics, and various statistical formats in the technical specifications, etc. 4.2.4.8 The technical design book needs to be bound into a book. It shall be submitted for approval after being signed by the designer and the person in charge of the business, and shall be implemented only after review and approval by the L-level business management department or the unit that issues the task. 5 Plane and elevation control measurement
5.1 General provisions
5.1.1 The "angle (traverse, GPS) points" measured at various times - those that meet the current national triangulation base and precision traverse measurement specifications\accuracy requirements can be used as the high control points of the seaway survey plate and the starting points for the development of sea control points. 5.1.2 The measurement of the same level points shall be carried out in accordance with the "National Triangulation and Precision Traverse Measurement Specifications". The method of distributing the first and second level points of sea control mainly adopts GPS measurement, traverse measurement and angle measurement. The mapping points can be measured by (PS fast measurement method traverse, branch line intersection method GB12327-1998
The graphic layout should be determined according to the terrain conditions and instrument equipment. 5.1.3 The basic accuracy indicators of sea control points and mapping points are shown in Table 2. Table 2
Limiting item E
Angle error\)
Point mean error of initial alignment starting point
Relative mean error of distance measurement
Intersection point
Maximum scale difference
1:10000 scale topographic map
Small-F 1:10 C00 scale topographic map
1/30 C00
1725 uoC:
1/2500
Note: When the mapping point is determined by the pregnant line method, the tolerance of the coordinate pull distance when the conductor line is calculated from one end to the other end is the same as the tolerance of the half-mark displacement when the mapping point is determined by the intersection method. bZxz.net
5.1.4 Old points in the survey area that meet the accuracy requirements specified in this specification can be regarded as points of the same level. 5.1.5 Navigation aids and significant objects such as lighthouses, light posts, beacons, wireless side beacons, high beams, poles, water towers, church spires, spire, etc. should be measured according to the requirements of mapping points.
a) For paired signs such as guide beacons and speed beacons, one of them must be set up for observation. It is best to set up a station for observation at the common point of the compass correction beacon, otherwise the other three points must be set up for observation. The true azimuth angle of the front and rear beacons must be calculated from the angle of direct observation; the distance between the front and rear beacons can be measured directly by steel tape measure or electromagnetic wave ranging, and the relative error of its length should be less than 1/2000; the horizontal angle is measured according to the requirements of the survey point, and then the coordinates are calculated by the polar integer method. b) For the measurement of natural day markers with value for depth measurement and navigation, such as independent rock peaks, magnets on the sea, independent rocks or trees on the top of the mountain, the measurement error and mutual error can be relaxed by times compared with the survey point, but the mutual error of the two sets of coordinates should not exceed 2m. 5.1.6 When laying out the attached conductor, its shape should be as straight as possible, and the ratio of adjacent side lengths should not exceed 1:3. The total length and number of sides of the sea control level conductor shall not exceed the provisions of Table 3. When the known high-level control point position and terrain restrictions exceed the provisions of Table 3, it can be solved by adding nodes: When it is difficult to lay out the attached conductor at the same time, the secondary conductor and the mapping conductor are allowed to lay closed conductors, but the total length and number of sides of the conductors shall not exceed the provisions of Table 3. When the branch conductor is used to measure the mapping point at the secondary conductor point, the instrument is limited to 100 sides. Table 3
Attached conductor
Extra length of conductor.km
Total length of conductor,km
Note: The length of the conductor between the node and the high-level point, and between the node and the node should not be greater than 0.7 times the specified length of the attached conductor. 5.1.7 The relative mean error of various electromagnetic wave distance measuring instruments shall be calculated according to the following formula: Relative mean error - mn = ± (a→b+) where: D is the actual measured distance, (1) the unit is m, (2) the unit is km; mn is the mean error of the distance measuring instrument itself, mm; - the proportional error coefficient related to the measured distance 10-.t
·(2)
5.1.8 When using different types of electromagnetic wave distance measuring instruments to measure the side length of a conductor, the range of the distance measurement shall be based on the nominal value at the time of leaving the factory (see Appendix 374
GB 12327—1998
Record (8) When the distance measuring instrument fails to reach the nominal accuracy at the time of leaving the factory, it can be tested and compared with the known baseline, and the accuracy level can be reduced according to the situation.
5.1.9 Requirements for wire selection
u) The irrigation line should be as high as possible above the ground or obstacles: more than 3m: 1) The measuring line should avoid the sky above large cities, rivers, lakes, reservoirs, etc. and smog areas as much as possible,) measuring line! When high-voltage transmission lines are parallel, they should pass 5 m away from both sides of the high-voltage lines. H should not cross the gap between the high-voltage lines and the ground.) The survey line base should try to avoid crossing the bottom-shaped valley, the solid flat land without alkali and other terrains that have strong electromagnetic reflection. e) The terrain through which the survey line passes must also be suitable for angle measurement and have no obvious side refraction effect. f) When the length of the survey line is less than 5 km, the height difference between the two ends of the survey line can be obtained by the "angle quotient method" of the opposite vertical angle. Otherwise, the height difference should be measured by leveling method. The height difference between the two ends of the survey line is m
, the height difference between the two ends of the survey line is m
, the height difference between the two ends of the survey line is m
, the length of the survey line is km
, and the main technical requirements for the side length observation should meet the requirements of Table 4. 5. 1. 10
Instrument type
Number of measurement loops
Interval of measurement loop readings
Interval of one-way measurement loop
Interval of round trip observation
5.1.11 The line name of the traverse is abbreviated as the line name based on the point names of the starting and ending points of the traverse. The traverse points are named from west to east or from north to south based on the point names at both ends, and the traverse point numbers are represented by 1, 2, 3*, etc. The point numbers are written after the line names. If there are natural place names, the place names should be added in brackets after the point numbers:
5.1.12 When using the angle measurement method to lay out sea control points and mapping points, the side length should generally be flexible within 1 to 7 km, and the internal angles or return angles of the triangle should not be less than 25°. When laying out shapes, the side angles should not be less than 25° , the angle of intersection in difficult areas should not be less than 20°; when laying out midpoint polygons or linear locks, the known side length should not be greater than 8km, the number of triangles should not be more than 6, and the linear lock must measure two orientation angles. 5.1.13 When laying out general intersection points, each intersection angle should not be less than 25\ or greater than 155, and each intersection angle in difficult areas should not be less than 20° or greater than 160\; the rear intersection point shall not be cocircular with the known points used for intersection, that is, the two intersection angles of the rear intersection and the corresponding fixed angles should not be between 160°--200°.
5.1.14 When it is necessary to use the coordinates to inversely calculate the side length azimuth as the basis for expanding the sea control point, the side length should not be less than 3km, and the starting point should be downgraded.
5. 1.15 The methods for measuring the elevation of sea control points and mapping points mainly include geometric leveling, distance measurement, trigonometric elevation measurement, PS elevation measurement, etc. Under the control of a certain density of leveling elevation points, trigonometric elevation measurement and GPS elevation measurement are the basic methods for determining the elevation of control points.
5.1.16 The sea control points, mapping points, tide gauge zero point, working leveling points and key leveling points used for trigonometric calculations shall all be determined by the method of joint leveling.
When joint leveling is performed, the measurement must start from the national level leveling point, and the measurement level shall be determined based on the required elevation accuracy and the latitude of the survey line. When leveling the level points, the corresponding national leveling specifications shall be followed. The joint leveling between the tide gauge point and the tide gauge of the tide gauge station shall be measured according to the requirements of the external leveling base. GB12327-1998
5.1.17 The high-speed nodes of sea control points should be arranged at both ends of the annual lock, the reverse edge of the net and the starting point of the wire. The interval between the small point on the net and the nearest sample starting point should not exceed the provisions of Table 5. 5
Average length.km
Sa,m
The maximum error of the point is 2.
5.1.18 The triangle side of the sea control points at all levels should be observable vertically with the side of the wire. The points measured by the intersection method should be at least one-way difference.
5.1.19 UsingThe angle of the intersection in difficult areas should not be less than 20°; when laying out the midpoint polygon or linear lock, the known side length should not be greater than 8km, the number of triangles should not be more than 6, and the linear lock must be measured with two orientation angles. 5.1.13 When laying out general intersection points, each intersection angle should not be less than 25\ or greater than 155, and each intersection angle in difficult areas should not be less than 20° or greater than 160\; the rear intersection point shall not be cocircular with the known points used for intersection, that is, the two intersection angles of the rear intersection and the corresponding fixed angles should not be between 160°--200°.
5.1.14 When it is necessary to use the coordinates to inversely calculate the side length azimuth as the basis for expanding the sea control point, the side length should not be less than 3km, and the starting point will be downgraded for use.
5.1.15 The methods for measuring the elevation of sea control points and mapping points mainly include geometric leveling, distance measurement, trigonometric elevation measurement, PS elevation measurement, etc. Under the control of a certain density of leveling elevation points, trigonometric elevation measurement and GPS elevation measurement are the basic methods for determining the elevation of control points.
5.1.16 The sea control points, mapping points, tide gauge zero point, working leveling points and key leveling points used for trigonometric calculations shall all be determined by the method of joint leveling.
When joint leveling is performed, the measurement must start from the national level leveling point, and the measurement level shall be determined based on the required elevation accuracy and the survey line length. When leveling the level points, the corresponding national leveling specifications shall be followed. The joint leveling between the tide gauge point and the tide gauge of the tide gauge station shall be measured according to the requirements of the external leveling base. GB12327-1998
5.1.17 The high-speed nodes of sea control points should be arranged at both ends of the annual lock, the reverse edge of the net and the starting point of the wire. The interval between the small point on the net and the nearest sample starting point should not exceed the provisions of Table 5. 5
Average length.km
Sa,m
The maximum error of the point is 2.
5.1.18 The triangle side of the sea control points at all levels should be perpendicular to the wire side. The points measured by the intersection method should be at least one-way difference.
5.1.19 UsingThe angle of the intersection in difficult areas should not be less than 20°; when laying out the midpoint polygon or linear lock, the known side length should not be greater than 8km, the number of triangles should not be more than 6, and the linear lock must be measured with two orientation angles. 5.1.13 When laying out general intersection points, each intersection angle should not be less than 25\ or greater than 155, and each intersection angle in difficult areas should not be less than 20° or greater than 160\; the rear intersection point shall not be cocircular with the known points used for intersection, that is, the two intersection angles of the rear intersection and the corresponding fixed angles should not be between 160°--200°.
5.1.14 When it is necessary to use the coordinates to inversely calculate the side length azimuth as the basis for expanding the sea control point, the side length should not be less than 3km, and the starting point will be downgraded for use.
5.1.15 The methods for measuring the elevation of sea control points and mapping points mainly include geometric leveling, distance measurement, trigonometric elevation measurement, PS elevation measurement, etc. Under the control of a certain density of leveling elevation points, trigonometric elevation measurement and GPS elevation measurement are the basic methods for determining the elevation of control points.
5.1.16 The sea control points, mapping points, tide gauge zero point, working leveling points and key leveling points used for trigonometric calculations shall all be determined by the method of joint leveling.
When joint leveling is performed, the measurement must start from the national level leveling point, and the measurement level shall be determined based on the required elevation accuracy and the survey line length. When leveling the level points, the corresponding national leveling specifications shall be followed. The joint leveling between the tide gauge point and the tide gauge of the tide gauge station shall be measured according to the requirements of the external leveling base. GB12327-1998
5.1.17 The high-speed nodes of sea control points should be arranged at both ends of the annual lock, the reverse edge of the net and the starting point of the wire. The interval between the small point on the net and the nearest sample starting point should not exceed the provisions of Table 5. 5
Average length.km
Sa,m
The maximum error of the point is 2.
5.1.18 The triangle side of the sea control points at all levels should be perpendicular to the wire side. The points measured by the intersection method should be at least one-way difference.
5.1.19 UsingAvoid implementation.
5.2.3.2.11 The determination of the central element shall be carried out in accordance with the provisions of the three and four equal points in the national triangulation and precision traverse specifications. 5. 2. 4 Distance measurement
5.2.4.1 Selection of instruments
Distance measuring instruments are classified according to the 1 km accuracy mz table 8 Table 8
Only the type of receiver
5. 2. 4. 2
Technical indicators of the receiver
Error in distance measurement
5-10
Examples of receivers
CMW20.DI3000.AGA112.AGA115
CA1000
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