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Before any station setup, you will need to ensure the following:
- LPS_Setup program is installed on the instrument
- Units are set on the instrument
- A control file is loaded into LPS_Setup
- Now, go to Station Setup Wizard.
- The Setup method has three options in the dropdown box. This example will use Known station & BS pts.
- This uses two control points. The instrument will sit on one and a prism will occupy the second point. These must have a clear line of sight and be within the working range of the instrument.
- It is recommended to set a prism on a tripod over the backsight point during grading operations. This can be used as a quick check to ensure optimal accuracy of the setup.
- With the instrument setup over a control point, use a tape measure to measure the slant height from the control point to the vertical center of the instrument. This is the pivot point of the collumator. Most instruments will have a small mark on the side to measure to.
- This height is entered into the Instrument height field on the total station.
- Now, tap the Next button.
- The next screen is where you define what control point the instrument is on and what control point the backsight (prism) occupies.
- Tap the Station button to pick from a list of control points. For this example, the instrument will sit on Pole 1.
- Next, tap the Backsight button to choose which point the backsight is on. For this example, the instrument will sit on CP2.
- While not a common practice with LPS, it is possible to setup the backsight without using a prism. This is called reflectorless. If you wish to do this, enable the Measure reflectorless checkbox. For this example, a prism will be setup on the backsight.
- When using a prism, you need to establish the height of that prism from the control point. Again, this will be a slant height measurement from the center of the prism to the control point. Enter that measurement in the Target height field.
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When using a prism, you will need to define the type of prism used. The options are:
- Prism: A single-side prism commonly used for backsights
- Sheet: A flat target on a vertical surface such as a wall or support beam. Not commonly used in LPS.
- 360° Prism: A prism that can be viewed from any angle. Commonly used on machines and layout applications.
- Select the prism you are using. For this example, a Prism is used.
- Finally, you must define the Prism constant on the backsight prism. Prism constant is the offset from the center of the prism to the apex of the mirrors inside the prism. This number is usually shown as an offset or P.C. value in millimeters.
- Different prisms may have different P.C. numbers. It is important to enter the proper prism constant to avoid positioning and height errors.
- Once the P.C. has been entered, tap the Next button, sight the prism with the total station and hit the OK button to measure.
- Once the backsight is measured, you should see the results of the setup. Typically, setup numbers should be 0.01' (3mm) or better.
- Tap the OK button to save the setup. This should take you back to the main LPS_Setup screen.
- Tap the Start LPS Control button to launch External Link and begin tracking the machine prism.
- External Link must remain on for LPS machine control to work. Exiting the External Link screen will end LPS control.
