Borrow pit survey

[Robert Jordan]

The Triumph-LS amazed me again yesterday - it's a great piece of technology. I was solo on a construction site late in the day and needed to do a quick, rough survey of a 20-foot deep small (50'x100') borrow bit that was located in a low part of the site surrounded by trees. I didn't think the survey was doable with the LS, but I figured I'd give it a try. First I tried using my RTN network signal. I was able to get a few shots around the upper rim of the pit, but was having trouble maintaining fix even outside of the pit and was running out of daylight. I was about to give up and come back on Monday with a total station, costing my client a day of productive work, when I remembered I had my Triumph T2 and 1W radio in the truck. I quickly set up the base and radio and used the setup I'd configured the day before to do more "practice" using the 5Hz option.

Back at the pit, I was borderline shocked by the speed at which I obtained fixes at the top of the pit. And after climbing down 20 feet, I was in disbelief to see that I could get 5 or 6 engines fixed quickly when up against the side of a 20' vertical wall of dirt 20 feet tall and having only 30 degrees of sky (from zenith) visible in the other directions. I was able to topo the entire bottom of the pit in 5 minutes and then collect points around the upper rim in 5 more minutes and I was done. I've since confirmed that the data is good.

My question: Everywhere in the base/radio/rover settings that I could find, I had set a 0.2 second epoch time (5Hz). But on the rover data collection screen, I only see 1Hz in the green FIX box. Also, at least half of the time I'm collecting data, which is good according to the horizontal and vertical collection boxes, the upper left "fix" box is white and shows STN, not FIX. Even when the box shows STN, not FIX, the six-pack screen shows 5 or 6 engines fixed and the unit continues to log data (it's set to collect when fixed only). After I completed the pit survey I returned to the radio and the transmit light was flickering very quickly on and off (maybe 5 times per second - not sure - but definately greater then 1Hz).

Was I surveying at 5Hz and didn't know it? Because if that was 1Hz, I think the LS could survey in a coal mine at 5Hz.

 

[Matt Johnson]

Hi Robert, you need to disable packet repeating in Base/Rover Setup for correction rates greater than 1 Hz to work correctly with spread spectrum radios. You should then see the incoming correction rate displayed in the action screens displaying 5 Hz. I also saw that you did not appear to be using RTK Verification with Resets and Validation. In bad areas with multipath, it is imperative that you use these to prevent bad points from being accepted.

 

[Robert Jordan]

Thanks for the response. I'll disable packet repeating and give it a try.

 

[Adam]

I have had a few bad shots collected when set to without v6 reset and no validation. I was kinda testing it out both ways and no bad shots were collected with 2 min engines and resets on and validate with 2. This was in areas were I havent ever felt comfortable using gps to do the job. I feel a lot better about it using the LS. I caught the bad shots by having dist to last in my white box.