APPENDIX

It is clear from the table that dual axis compensation has the most benefit when the elevation of the target is greater then 30° and the axis is tilted more than 10". The entries indicated in bold in the table show, in fact, that for many common surveying applications i.e. target elevation <30° and axis error <10", virtually no correction would be required. Dual axis compensation is especially suited then for applications where the sights are very steep.

Even though the compensators can correct horizontal angles for vertical axis errors, it is still important to use care in setting up the instrument.

Centering error, for instance, cannot be corrected by the compensators. If the vertical axis is tilted by 1’ with the instrument 1.4meters above the ground, a centering error of approx. 0.4mm will result. The maximum effect of this error at 10m is about 8" of horizontal angle error.

In order to maintain the increased accuracy possible through dual axis compensation, it is necessary to keep the compensators in proper adjustment.The compensators must agree with the actual level condition of the instrument. Through various environmental stresses, the agreement between the level condition sensed by the compensators and the true level condition of the instrument may be disturbed. In order to reestablish the correct relationship between the compensator and the true level condition of the instrument, it is necessary to carry out the vertical indexing procedure listed on Section 9.4“Adjustment of Compensation Systematic Error of Instrument” . This adjustment will both reset the vertical index (cause a direct + indirect zenith reading to the same elevation to equal 360°) and zero the level reference for the horizontal compensator. While correct vertical angles can be obtained by averaging direct and indirect reading even when the index is improperly adjusted, the same is not true for horizontal angles. Since the vertical axis error is fixed for a given setup, its effect cannot be removed by averaging two readings.

For this reason, it is extremely important to maintain the vertical indexing adjustment to insure proper correction of the horizontal angles.

APPENDIX-2

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Topcon GTS-821A, GTS-822A, GTS-823A, GTS-825A instruction manual APPENDIX-2
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GTS-822A, GTS-825A, GTS-821A, GTS-822A, GTS-823A, GTS-825A, GTS-823A specifications

Topcon's GTS series of total stations, including the GTS-821A, GTS-822A, GTS-823A, and GTS-825A, are known for their robust features and exceptional precision, catering to the needs of surveying and construction professionals. These instruments blend advanced technology with user-friendly interfaces to enhance productivity in the field.

The GTS-821A model is designed for reliability and accuracy. It offers a measurement range of up to 1,000 meters and delivers precision within ±2 millimeters, making it ideal for jobs requiring fine detail. Key features include a high-speed angle measurement system and a dual-axis compensator that ensures accuracy on uneven terrain.

In contrast, the GTS-822A model takes performance a step further by incorporating advanced optical technologies. It includes a high-performance EDM (Electronic Distance Measurement) that allows for faster measurements with a range extending up to 2,000 meters. This model also integrates a clear display and simple user interface, facilitating easier operation for users of all skill levels.

The GTS-823A represents a perfect blend of portability and advanced functionality. It is lightweight, making it easy to transport between job sites. This model incorporates GPS capabilities, allowing seamless integration with GNSS systems for enhanced positioning accuracy. Its onboard software supports various surveying methods, making it versatile for different applications.

The GTS-825A stands out for its advanced features tailored for high-precision tasks. This model supports wireless communication, enabling real-time data transfer to smartphones and tablets, which enhances collaboration in fieldworks. With an impressive measurement capability, it extends the measurement range and precision, meeting the demands of large-scale projects.

All models in this series share a durable design reputation, ensuring they withstand harsh environmental conditions. Their user-friendly interfaces are complemented by robust software support, providing surveying professionals with the tools they need to optimize their workflows.

In summary, Topcon’s GTS series, including the GTS-821A, GTS-822A, GTS-823A, and GTS-825A, represent the cutting edge of surveying technology, boasting features like extended measurement ranges, high precision, advanced EDM, and GPS integration. These instruments not only enhance productivity but also ensure that professionals can achieve their surveying goals efficiently and effectively. Whether for routine land surveys or complex construction projects, the Topcon GTS series delivers exceptional performance and reliability.
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