Advanced Least Squares Adjustments for Post Processed GPS

Transcription

1 Advanced Least Squares Adjustments for Post Processed GPS 2018 Fall Conference October 18, 2018 College park, Maryland Instructor: Maser Consulting PA Independent Baselines The observations for GPS receivers collecting raw satellite data for stations at the same time are the ranges to the satellites for each receiver. Page 2 of 47 adragoo@maserconsulting.com 2018 Page 1 of 25

2 Independent Baselines When the ranges for each satellite at each station are differenced relative to one station, relative positions for the other points are derived that have survey quality positions relative to the station that they are compared to. Page 3 of 47 Independent Baselines When the position of stations are determined, errors can be introduced into station positions by positional errors. It is important to use high quality positions for data processing. Page 4 of 47 adragoo@maserconsulting.com 2018 Page 2 of 25

3 Independent Baselines These positions are reduced to the corresponding vector data (GPS Azimuth, Slope Distance and change in height) between the stations for the adjustment process. Page 5 of 47 Independent Baselines Since one GPS session is a no check solution and there is no redundancy or over determination. It is not valid to compute more vectors than one less than the number of stations in the session. Page 6 of 47 adragoo@maserconsulting.com 2018 Page 3 of 25

4 Independent Baselines 2 Receivers 1 Independent Baseline 5 Receivers 4 Independent Baselines 6 Trivial Baselines 3 Receivers 2 Independent Baselines 1 Trivial Baseline 4 Receivers 3 Independent Baselines 3 Trivial Baselines Page 7 of 47 Dependent Vs. Independent (B/L s) Base Lines Independent B/L s, data & setups divulge location of blunders. Processing independent B/L s makes it easier to detect blunders. Network design using independent B/L s makes it easier to assure sufficient redundancy. Even if you process all B/L s design your network to satisfy redundancy with independent B/L s Page 8 of 47 adragoo@maserconsulting.com 2018 Page 4 of 25

5 3 Receiver Session All Baselines Processed Page 9 of 47 3 Receivers: Only Independent Baselines Processed Page 10 of 47 adragoo@maserconsulting.com 2018 Page 5 of 25

6 4 Receiver Session All Baselines Processed Page 11 of 47 4 Receivers: Only Independent Baselines Processed Page 12 of 47 adragoo@maserconsulting.com 2018 Page 6 of 25

7 Real Life 4 Rec s Independent B/L Example VETERAN KORBACH City of Norfolk VA COWAN MONOLA NGS 150M FERREL 44 1 CRAB 3 NORFOLK WEST NORFOLK EAST 63 Page 13 of 47 Real Life 4 Rec s All Base Lines Processed Veteran 4 5 Cowan 73 Monola Korbach 138 NGS 150M City of Norfolk VA Ferrel 44 1 Crab 3 Norfolk West Norfolk East 63 Page 14 of 47 adragoo@maserconsulting.com 2018 Page 7 of 25

8 Real Life Example Saw Mill GPS Project 3 Receiver Sessions All Baselines Processed Page 15 of 47 Real Life Example Saw Mill GPS Project 3 Receiver Sessions Independent Baselines Processed 21 Trivial Baselines Removed Stations GLOS-1 and M-105 had problems with them and when a traverse was run between them it did not check Page 16 of 47 adragoo@maserconsulting.com 2018 Page 8 of 25

9 The Key to Post Processed GPS IF YOU DO IT RIGHT IT CAN T BE WRONG Good networks with sufficient redundancy give high confidence in results Weak networks makes you question what you have done. Page 17 of 47 If You Wonder If Your GPS Work Is Right, Your Work Probably Looks Like This Radial Surveys Have No Checks Page 18 of 47 adragoo@maserconsulting.com 2018 Page 9 of 25

10 Poor Network Geometry Page 19 of 47 Bad Network Geometry Page 20 of Page 10 of 25

11 When you stakeout a house would these be the only measurements you make? Page 21 of 47 Or would you include these? Does your GPS control deserve less? Page 22 of 47 adragoo@maserconsulting.com 2018 Page 11 of 25

12 Keep It Simple Network Planning Page 23 of Receivers: Independent Baseline Network Design Sta Horz 5 Sta Vert 23 Sta Total Page 24 of adragoo@maserconsulting.com 2018 Page 12 of 25

13 GPS Schedule Sheet Example: Station Receiver S/N Operator Remarks Tom Jerry Sam Session #1 Start Stop Session #2 Start Stop Jerry Tom Sam Session # Sam Start Tom Start Jerry 103 Session # Sam Start Jerry Stop Tom Session # Sam 115 Start Jerry Stop Tom Copy the session information from the sketch to the schedule sheet Page 25 of 47 Real Life 4 Rec s Independent B/L Network Design Example VETERAN 1 2 KORBACH 138 City of Norfolk VA 45 3 COWAN MONOLA 5 7 NGS 150M FERREL CRAB NORFOLK WEST NORFOLK EAST Page 26 of 47 adragoo@maserconsulting.com 2018 Page 13 of 25

14 GPS Log Sheet Data Station Name Calendar Date Julian Date Session Number Start Time End Time Use One Sheet of Paper For Each Station Occupation Receiver Serial Number Antenna Serial Number Antenna Model HI Meters HI Feet Measurement Method (Slope or Bottom Antenna Mount) Observer Comments Page 27 of 47 Example of Simple GPS Observation Log GPS OBSERVATION LOG Station Name: Calander Date: Julian Date: Session Number: Start Time: Observer: End Time: Receiver Serial Number: HI Meters: Antenna Serial Number: If Reg Trpod Feet: Antenna Model Type: Comments: Page 28 of Page 14 of 25

15 POST PROCESSING YOUR DATA IN TRIMBLE BUSINESS CENTER l29 Prepare TBC For Network Adjustment Load known horizontal and vertical control points and set to control quality Download GPS data files Check in GPS data files Make sure station names are correct and use the same name for each data set at that station. Make sure HI information is correct Page 30 of Page 15 of 25

16 When Bluebooking Project Use 4 Characher ID for TBC Point ID Use SPSN for TBC Feature Code Use Descriptor 1 and 2 as you wish Page 31 of 47 Click on View Menu and Choose New Time Based View Page 32 of 47 adragoo@maserconsulting.com 2018 Page 16 of 25

17 Time Based View is Shown Page 33 of 47 Right Click In This Area and Choose Zoom Session Page 34 of Page 17 of 25

18 Hold the Shift Key Down and Choose All Baselines In Session Page 35 of 47 Choose Plan View and Hold Down the Control Key and Left Click to Deselect the Dependent Baselines Page 36 of Page 18 of 25

19 Continue Deselecting The Dependent Baselines Page 37 of 47 Continue Deselecting the Dependent Baselines Page 38 of Page 19 of 25

20 When Only The Independent Baselines are Highlighted Click on the Survey Menu and Choose Process Baselines Page 39 of 47 Pick Time Based View and Right Click on a Baseline in the next Session Page 40 of 47 adragoo@maserconsulting.com 2018 Page 20 of 25

21 Hold Down the Shift Key and Choose All Baselines In Session Page 41 of 47 Hold Down The Control Key and Left Click to Deselect the Dependent Baselines Then Process Baselines Page 42 of Page 21 of 25

22 Click on View and Choose View Filter Manager and Under GNSS Data Type Choose Processed Baselines Only Page 43 of 47 TBC Tips And Tricks Be careful of spaces in station names. Computers think E26 and E 26 are different stations. Have data sets start and end at close to the same time. Do not allow data sets in one session to overlap data sets in another session. This is done by controlling the start and stop times for the field operations. Use the shift key to select more than one baseline for processing in one session. Page 44 of 47 adragoo@maserconsulting.com 2018 Page 22 of 25

23 TBC Adjustment Roadmap Process Independent Baselines Check RMS values Check Horizontal and Vertical precisions Check loop closures Hold 1 point fixed horizontal and vertical Assign H & V Setup Errors Perform minimally constrained adjustment Check for outlines Set station weighting until Chi Square Test passes Add one point at a time fixed horizontal Check for outlines Add one point at a time fixed vertical Check for outlines Page 45 of 47 Class Project Design Fast Static Network Page 46 of 47 adragoo@maserconsulting.com 2018 Page 23 of 25

24 GPS Schedule Sheet Session #0 Start Stop Session #1 Start Stop Session #2 Start Stop Session #3 Start Stop Session #4 Start Stop Station Receiver S/N Operator Remarks 0016 BILL 0071 ALAN 4893 KEN 1001 JAGUARS WADE STATE COLLEGE 1000 WADE PULLEN STATE COLLEGE JAGUARS PULLEN STATE COLLEGE BILL ALAN KEN BILL ALAN KEN BILL ALAN KEN BILL ALAN KEN Start all sessions on arrival. End all sessions on completion of last receiver. Page 47 of 47 Completed GPS Observation Logs Samples 3 of 15 Page 48 of 47 adragoo@maserconsulting.com 2018 Page 24 of 25

25 Thank You! Page 49 of Page 25 of 25