Allocating PPK Antenna Solutions

Assuming you have succesfully post processed kinematic antenna soultions, the next steps explain how these solutions are allocated to the multibeam soundings. The antenna solutions are translated according to the multibeam offsets and the motion data and then filtered to elliminate high frequency motion (e.g. heave).

1) Dump an ascii file with the antenna solutions. Be sure to dumpt the data with the following fomrat:
I used Tribmle Geomatics Office (TGO) voor the PPK processing and exported the data with the following custom export format
*** Note, it is important the data is exported in a time sequential manner, otherwise not all of the antenna solutions will be used.

2) Binarize the ascii data. I adopted the same philosophy as the binTide and MergeTide programs, but at the this time I don't understand why I created two seperate programs....I think I could have skipped this step in the first place....
Nayway, here we go: 3) Merge the antenna solutions with the multibeam soundings. You give it the binarized PPK file and the merged file(s). The program searches for matching times and writes out a PPK solution at each ping. A linear interpolation is made for pings in between GPS updates. The vessels roll, pitch, and offsets between antenna and transducer face, are used to translate the ellipsoidal height of the antenna to the transducer. The ellipsoidal height is writen to the "profile.RTK_at_RP" field. At this time the offset values are defined in the program, but these should become optional... 4) You may now view the ellipsoidal heights in the swathed time seires toolbox. If you compare the "RTK height at RP" with the heave, so will noticea correlation; the heave is overprinted on the RTK heights. So we need to filter out the high frequency motion --> low pass filter the ellipsoidal heights. DelayEditor runs a tampered cosine squared filter over the data. Decide on the width (depends on surface waves periods and update rate), I used 10 seconds mostly.
***Note, avpings is in seconds, not pings!

5) If you now compare the "RTK height at RP" with the "lpf RTK height at RP" you can examine the result. Each ping now has a (lpf) PPK ellipsoidal height attributed. If you want to grid your soundings w.r.t. the ellipsoid use the -blendRTK option in weigh_grid. Use the -rawRTK option is you don't want to use the lpf heights.

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Last modified: 2-9-08 Pim.