Thursday and Friday I had the pleasure of going to Arkansas to the Arkansas Society of Professional Surveyors Convention. The location for the conference was really nice, particularly for surveyors. It's in a remote area outside of Little Rock with a nice facility, well manicured landscaping, and a large pond.
Friday afternoon, I got together with Nate Dearyan and Steve Hankins, both surveyors who use the Triumph-LS. I thought that while I was there, we'd spend some time looking at some of the new features in the next release of J-Field.
We set up the base, a Triumph-2 with the HPT901BT spread spectrum radio on a retaining wall with a good view of the sky. We then walked around the pond and located three points, each with varying degrees of obstruction to the sky discussing some of the software changes as we went.
Point 1 was on a concrete slab with fairly open skies, the Point 2 was on a sidewalk passing under some deciduous trees, what I would consider light canopy, and Point 3 was under the drip line of a 40' tall cedar tree with some pine trees near by, what I would consider moderate canopy. We shot these points for about three minutes each along with a confidence of 20, minimum engines of 2, and validation with 2 engines at the end. So it resets the engines at the beginning of the shot about 20 times, waits until it has 2 engines fixed and records until the time is up (3 minutes) and resets one last time with validate until two engines are fixed, making sure that the last fixes match well with the first 20 fixes.
We walked back by the base and turned the radio off. The base is still running, but I have no communication. We walked through each point and collected them again. This time we used the Activate Post Processing After button that counts up to a required amount of time and notifies the user when the time has elapsed. So now we have no radio communication, but the base is recording raw data and the rover is recording raw data.
We collected raw data using Activate Post Processing to let us know when we collected enough data and we used the "Save Data for PP" which replaces "Accept" when there are no fixed epochs to use for a position. We did this for each of the three points and returned to the base. We used base rover setup to stop the base and download the data from the base to the rover. The base was logging at a rate of once per second. From my experience I estimate that the Bluetooth download of a file collected at the base at a rate of once per second requires about one minute for every hour recording. We recorded for about one hour fifteen minutes and Steve clocked us at a little under one minute for the download. Next we went inside and did our post processing.
It took a few seconds, literally, to connect to the WiFi hotspot for the convention center with the LS. I then went to DPOS on the LS and set it to only perform base processing, since I knew that CORS data was not yet available. Within about 3 minutes, the data had been uploaded to DPOS, the vectors processed and the results returned to the LS. This is how each compared:
Notice that point 3 has a valid RTK solution and Post Processed solution, but J-Field elected to use the post processed solution over RTK. This is because the RTK solution has 173 epochs vs. the PPK solution of 180 epochs. Also notice that the RMS is lower for the PPK solution than the RTK. The user is absolutely free to overrule this and select the other solution by selecting the radio button next to the solution type.
Notice that 4, 5, and 6 don't have RTK solutions (the radio was off), so the solution was Code Diff (using WAAS). The software automatically selected the PPK solution for these points. The radio button identifies the coordinates that are used in J-Field, such as for CoGo, as well as export.
How about the inverse between the first pass and second pass?
The base was about 500 feet from these points, give or take, but I believe these results could have been achieved with the same short data sets in the same unruly conditions just as easily within 3 miles (perhaps more).
Many surveyors are buying big 35 watt radios for the rare occasion that they need the extra operating distance. From what I understand, these guys mostly need to locate a point (like a section corner) and don't need the range for stake out. I believe this Hybrid RTK will significantly reduce the need for a big radio, allowing users more convenience and less expense.
Thanks to Nate for his endless enthusiasm while I was there and to Steve for his encouragement. We've got some really great people using this equipment out there.
Friday afternoon, I got together with Nate Dearyan and Steve Hankins, both surveyors who use the Triumph-LS. I thought that while I was there, we'd spend some time looking at some of the new features in the next release of J-Field.
We set up the base, a Triumph-2 with the HPT901BT spread spectrum radio on a retaining wall with a good view of the sky. We then walked around the pond and located three points, each with varying degrees of obstruction to the sky discussing some of the software changes as we went.
Point 1 was on a concrete slab with fairly open skies, the Point 2 was on a sidewalk passing under some deciduous trees, what I would consider light canopy, and Point 3 was under the drip line of a 40' tall cedar tree with some pine trees near by, what I would consider moderate canopy. We shot these points for about three minutes each along with a confidence of 20, minimum engines of 2, and validation with 2 engines at the end. So it resets the engines at the beginning of the shot about 20 times, waits until it has 2 engines fixed and records until the time is up (3 minutes) and resets one last time with validate until two engines are fixed, making sure that the last fixes match well with the first 20 fixes.
We walked back by the base and turned the radio off. The base is still running, but I have no communication. We walked through each point and collected them again. This time we used the Activate Post Processing After button that counts up to a required amount of time and notifies the user when the time has elapsed. So now we have no radio communication, but the base is recording raw data and the rover is recording raw data.
We collected raw data using Activate Post Processing to let us know when we collected enough data and we used the "Save Data for PP" which replaces "Accept" when there are no fixed epochs to use for a position. We did this for each of the three points and returned to the base. We used base rover setup to stop the base and download the data from the base to the rover. The base was logging at a rate of once per second. From my experience I estimate that the Bluetooth download of a file collected at the base at a rate of once per second requires about one minute for every hour recording. We recorded for about one hour fifteen minutes and Steve clocked us at a little under one minute for the download. Next we went inside and did our post processing.
It took a few seconds, literally, to connect to the WiFi hotspot for the convention center with the LS. I then went to DPOS on the LS and set it to only perform base processing, since I knew that CORS data was not yet available. Within about 3 minutes, the data had been uploaded to DPOS, the vectors processed and the results returned to the LS. This is how each compared:
Notice that point 3 has a valid RTK solution and Post Processed solution, but J-Field elected to use the post processed solution over RTK. This is because the RTK solution has 173 epochs vs. the PPK solution of 180 epochs. Also notice that the RMS is lower for the PPK solution than the RTK. The user is absolutely free to overrule this and select the other solution by selecting the radio button next to the solution type.
Notice that 4, 5, and 6 don't have RTK solutions (the radio was off), so the solution was Code Diff (using WAAS). The software automatically selected the PPK solution for these points. The radio button identifies the coordinates that are used in J-Field, such as for CoGo, as well as export.
How about the inverse between the first pass and second pass?
The base was about 500 feet from these points, give or take, but I believe these results could have been achieved with the same short data sets in the same unruly conditions just as easily within 3 miles (perhaps more).
Many surveyors are buying big 35 watt radios for the rare occasion that they need the extra operating distance. From what I understand, these guys mostly need to locate a point (like a section corner) and don't need the range for stake out. I believe this Hybrid RTK will significantly reduce the need for a big radio, allowing users more convenience and less expense.
Thanks to Nate for his endless enthusiasm while I was there and to Steve for his encouragement. We've got some really great people using this equipment out there.
