1) Align edge of compass between points A & B,
as shown in figure 2.
2) Orient compass dial to map North/True North, as shown in figure 3.
3) Record the bearing closest to the direction-of-travel line on the compass. This will be the bearing you will need to follow to reach your destination.
If you have multiple points to travel to, it is common practice to write down the bearing on your map so you can continue to navigate your points without having to find your bearing at every point. Figure 4 shows the compass on the map with the bearing towards the direction of travel.
4) Keeping the compass at a comfortable chest height (preferably away from any metal objects), turn your body until the red end of the needle is in the red arrow/box on the compass. This position is often referred to as getting "red in the shed."
5) Now facing the same direction, turn the dial to the same bearing you just found.
6) To reach your location, all you need to do is keep the red end of the needle in that red box and you will travel along that same line you drew from points A to B. Figure 3 shows a compass oriented to the map. Notice how the lines inside the dial are parallel to the grid lines on the map. This technique is helpful when trying to ensure the compass is oriented as accurately as possible to north on the map. Here is a video describing the process above.
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Figure 4 shows a compass oriented to true north on a topographical map. |
Friday, May 9, 2014
How to Find/Follow a Bearing: Using a Map and Compass for Navigation
TopCon Total Station
TopCon Total Station
1.Set up Survey grid/Study Area
Mark the boundaries of your study area. It is also very important to set flags where each of your occupied points are, as well as you back sight. **NOTE: your occupied points can be used as back-sights for successive occupied points if you find it necessary to move the total station to acquire a better vantage point to continue surveying.
2.Set up of the TSS
Tripod Setup
- Wipe off the head to ensure the surface is clean and free of dirt.
- Extend all three legs equally, prior to spreading the legs. Secure locking mechanisms for each leg.
- Spread the legs sufficiently to ensure a stable base for the tripod.
- Center tripod head over the point while maintaining a fairly level tripod head.
- Check centering by dropping pebble from the center of the tripod head. (within 2" of Pt)
- Step down firmly on the foot-pads to set the legs.
Instrument Setup
- Secure instrument to tripod and center over tripod head.
- Bring all leveling screws to a neutral position, just below the line on the leveling screw post.
- While looking through optical plummet (if needed adjust o.p. for parallax and focus on the ground) OR with the laser plummet on, position instrument directly over point by using leveling screws only.
- Observe what two legs need to be adjusted to bring bulls-eye bubble into the middle.
- Be careful not to move the third leg.
- Release horizontal tangent lock and rotate instrument until tubular level vial is parallel (in line) to two of the leveling screws. (this is POSITION 1).
- Rotate both leveling screws equal amounts in opposing directions until tubular level vial is centered.
- Rotate instrument until tubular level vial is perpendicular to POSITION 1.
- Rotate leveling screw equal until tubular level vial is centered.
- Re-observe the point with o.p. or laser plummet and adjust instrument over the point by loosening the center screw and shifting instrument over the point by loosening the center screw and shifting instrument over the point and re-tightening the screw.
- Re-check the fine (tubular) bubble vial in POSITION 1 and 2, and adjust as needed.
3.Set up Blue Tooth
- Turn on the total station
- Turn on the station Bluetooth. This is done within the menu area, and within the parameters portion.
- At this point, you will not see a Bluetooth symbol appear on the TSS. This will appear after you set up the TopSurv Job.
4.Set up TopSurv Job
- Open up TopSurv (if no short cut appears find the EXE in the Flash Disk by clicking on "My Device" from the home screen, then "flash disk, and then "TTS folder.")
- If TopSurv has icons instead of menus click the "TopCon" icon in the upper left corner and switch menus.
- Inside TTS - Make a new job.
- The "open job" menu will appear.
- To make a new job click "new."
- To type in a name, click on the space and a keypad will open up.
- Click "next," choose "My RT DGPS" for GPS + Config, and "My Reflectorless" for TS config.
- Set the projection accordingly.
- If you are planning to enter the coordinates in manually from a different GPS unit you need to choose the same projection as the coordinates that you have from the other unit.
- You may also need to change the datum (EX - if you are using UTM_N_15_NAD_83).
- Do NOT check "grid to ground."
- Set the Geoid to the first one that is in the list. Click "next."
- In the units menu set your distance units to meters and choose whatever else you want....temperature, etc.
- Coordinate type will be "grid," coordinate order should be "Easting, Northing, Ell Ht.," leave the rest.
- Turn on alarms if you wish.
- FINISH.
- The bluetooth manager will appear. Select the "GPT (TSS)," then choose "select." It should connect to the GPT. The bluetooth light on the GMS-2 should be blue, indicating that it is connected.
- You may need to go to the Job Menu, and go to "Observation mode." Select "Total Station." You could select GPS if you were using the GPS + a laser.
- If a window pops up asking you for codes.
- Type in the following codes for.
- The key value should read 2951612344
- TS: 142601006
- GIS: 142601214
5.Collect GPS points with the GMS-2 in TopSurv*
- From the job menu, go to "Obs mode."
- Check "GPS+"
- Then go to collect menu, and collect features.
- The point will auto label OCC1 - ***keep track of this, as you will need the name again.
- Place the GMS-2 over the laser point for the OCC. and click "start." The GMS-2 will begin logging points.
- If the GMS-2 will not log points, click on the settings button on the top and choose solution type DGPS, Auto. You can also set the number of positions to be averaged. This can also be set from the job configuration menu.
- Once you have collected enough points for a position for the OCC you can click accept.
- If you wish to also record the location of the BS (back sight) at this time you can follow the same procedure.
- ***Both the occupied point and the back sight are as accurate as the GPS unit you are using. If you wish to attain higher accuracy, it is recommended that you use a separate GPS unit that averages a high amount of points for the information you enter.
6.To Begin the OCC/BS setup...
Go back to the job menu, observation mode, and choose Total Station. Then proceed to step 8 "Set the OCC and BS," skip step 7.
7.If you have X,Y coordinates from a different GPS unit and wish to add the OCC/BS points in manually then...
- From the edit menu go to points.
- Click on "Add."
- Then click on "New."
- Name your point accordingly (EX - OCC1). Type in the coordinates you obtained from the GPS unit. These MUST be in the same coordinate system AND datum as the settings from the GPS unit.
- Click "finish."
- Repeat for the BS.
8.Set the OCC and BS.
- Go to the "Col menu," choose "OCC/BS setup."
- If OCC/BS does not appear in the menu check the File menu, Observation Mode and be sure it is set to "Total Station."
- If the BS setup tab, in OCC spot click on the drop down menu to the far right and choose from the list "point for the OCC" (either that you collected with the GMS-2 step 6, or added manually in step 7).
- Choose the point where the TSS is located - the OCC point you entered in the previous steps.
- Then set the height of the instrument by measuring from the ground to the horizontal line, the "mark," on the side of the TSS.
- Then set the height of the prism on the rod.
- If you wish to enter the BS point from the list....
- Then be sure the button nest to the pointing figure says "BS point," if it says "BS Azimuth" click the button and it will change to BS point.
- Use the pull down menu to find the BS GPS point (the same way you did with the OCC). Select that point.
- Then sight the TSS to the BS. You do not need the prism on the BS, you just need to have the TSS sighted in the exact direction of the BS.
- **NOTE: If you want to put the prism on the BS - no harm will come.
- **NOTE: if the "measure dist to BS" is check, then the prism must be at the BS and the TSS will shoot the BS.
- Once the TSS is sighted to the direction of the BS then click "HC set." The BS Azimuth will then be set to zero even though it is not north. This is OK because the software/TSS automatically does the calculations. This is so everything is relative to the angle between those two points.
- If you wish to use BS Azimuth.
- Orient the total station in the EXACT direction of the BS and enter in the angle from north for the BS. You can use a compass or laser finder to measure this angle. Follow step 10 above (once the TSS is sighted to the direction...).
- You are now ready to collect data.
9.Collect Data
- Go to the Col menu and choose observations.
- Then click measure once the TSS is sighted to the prism. Continue to do this and make sure the point's ID numbers are increasing.
- If you wish to verify the data, go to "edit" and "list" and look at the points you have been collecting. You can also view these points on the map tab.
- Continue collecting data.
***Be sure that if you change the height of the rod you must enter the new height of the rod into the collection screen fro each point.
Moving the TSS to a New Location
If you need to move the TSS then you will need to move it to the BS and go back to step 6 (setting the OCC and BS) and change the OCC to the BS and set a new BS.
10.Exporting Collected points to a shapefile from TopSurv
- Go to the job menu, export, to file.
- Choose points.
- If you export as Shapefile format (this will only be the points, not E (easting), N (northing), or Z (elevation)).
- If you wish to have a file with E, N, Z and any codes or comments choose "TopCon TXT file."
- You will need to open the text file and eliminate the header info and the extra breaks. Example....delete the highlighted info.
- Header>>Delimiter(,)FileFormat(Name,Lat(North),Lon(East),Ht(G),Codes)<<
- Transfer the file to your computer using Active Sync. Make sure you export this information to the appropriate storage location and it reflects the desired title for the the project.
To clear NVRAM if the GPS is not calculating a position on the GMS-2:
- Go to start settings, control panel.
- Scroll down to find GMS Tools.
- Go to the append Tab and click on NVRAM clear. To verify the receiver is working to to CE-CDU from the desktop.
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