I had an incident happen for the first time in my 7 year career - someone moved my base station. About 20' from the control point. I was setup using the Carlson BRX7 on a tripod. Setup and left to go perform the survey. Came back 5 hours later, it had been moved sometime within that time frame. The data collector did not alert me that the base station position had been compromised. I'm not a huge fan of the BRX7 so far. I'm usually a Trimble person. Opinions, whatever, we all have them. I broke out the Trimble R12i, setup the base station on another occasion at a different location. Let it sit for a minute, then picked up the setup and moved it about 20'. No alert. Am I missing something here? I feel like this is a huge thing to not have some sort of alert that the base station has been disturbed in someway? Does no brand of GNSS receiver offer alerts to compromises made on the base station??ÿ
Within the past year we had our base picked up, moved over into an area of tall grass and gently laid horizontal.?ÿ A divorce is what made the survey necessary.?ÿ The ex-husbznd was still living in the house with a front lawn that made an excellent location for the base.?ÿ Suddenly, we couldn't get a fix.?ÿ As we approached we thought it had been stolen.
then picked up the setup and moved it about 20'. No alert. Am I missing something here?
I think the answer is Yes. You are missing the concept of how your Base works. When you set up a base, your controller sends a Lat/Lon/Ellip position to the unit. The software will check if the coordinates you send are relative to the current autonomous position of the base and warn you if they are not in harmony. The problem is, how good is the autonomous position? Most vendor software doesn't give a warning unless the difference exceeds 100 meters. They certainly are not going to warn you at just a 6m difference. This would be very annoying as your autonomous position could easily be 10m different. If your base has an IMU, then perhaps a software app could track movement during your session. The Base would then need to be programmed to send this message to your rover. This is likely another hurdle to achieve, as it would be vendor specific and not universal.
Does no brand of GNSS receiver offer alerts to compromises made on the base station?
Javad has several methods that do this. Tilt sensor in the base. (I DON'T work for Javad), and if it moves too much, it also alerts. I had to turn the sensitivity of the tilt sensor DOWN, due to wind buffeting the base, setting off the alert. I get a popup at the rover, telling me my base has shifted.
Nate
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Ditto with the Javad base.?ÿ It actually saved me once in very steep rugged terrain.?ÿ A big wind gust came up, knocked the UHF antenna into the base and knocked it just far enough out of level to cause a problem.?ÿ A window immediately popped up on my rover telling me the base had been moved ... feet.?ÿ I trekked back, reset everything and knew that all shots before that were still good and I had stopped as soon as I got the warning.?ÿ Otherwise, the whole day would have been worthless, not knowing when it had happened.
It only happened once but my Leica rover got a message something like: Position of base differs from that expected.?ÿ
It only happened once but my Leica rover got a message something like: Position of base differs from that expected.?ÿ
It only happened once but my Leica rover got a message something like: Position of base differs from that expected.
Trimble will send a similar "received base coordinates differ from job coordinates", but that is only if you are set up on a known point and the coordinates that the base is broadcasting are not the same as the coordinates for that known point in the rover's DC.
I don't think that any of the standard RTK correction broadcast formats include a section for "base integrity" or the like.
I'm not surprised that Javad has it, but that's a proprietary thing I think, and possible due to the IMU.
Without an IMU, it would be quite difficult to establish a positional cutoff to determine whether the base was moved - don't forget that 20 feet isn't very far in terms of an autonomous solution. And as Nate says, even with the IMU dialing in the sensitivity is crucial, or else you'll be chasing your tail and going back to the base constantly.
I think I have personally had my base moved while still broadcasting maybe 2-3 times in my ~20 years. Heard about another handful of cases. It's rare enough that I don't even consider it. But that could be because I try pretty hard to set the base well away from prying eyes and mischievous hands...
If you go into the webUI for a Trimble R10, R12, Alloy, R750, etc...there is a setting you can turn on...
The Alloy has RTX built in, no subscription, so that is a good way to monitor the base position.?ÿ
I have had wind blow down, had a unit when i was doing ppk. Get picked up set in the back of truck etc. When i am doing things like topo I always set a semi temp point. Maybe i take a ground shot but stuck a old golf tee in the ground flush. Sometimes as simple as a paint dot. This helps me ck initialization and Base being moved etc. ?ÿon control and boundary not as much. Because i am coming back anyway its those several hundred shots you don??t know when it moved etc. ?ÿjohn h i will be looking at that for sure. Always always when you cannot see the base set your self some easy checks. It could be the tip of a paint stripe etc. these are cks not for the accuracy of control but just to make sure nothing has moved periodically. ?ÿTop back of curb at a curb cut. Anything you know if you walk over you can see it??s in the same place type of thing. Topos are the worst. Like the old days when a data collector cold booted and you lost a half or full days worth of work. Ya just gotta start over. So when you are topoing that field. Just take a little extra time every so far . I use to have a small breast pocket field book I would write the number down. It was for me. And saved me a few times as I would only have to reshoot so many points versus all of them. Old golf tees were the best. Light weight and free lol. Even worked good in a pinch for a fly point traversing lol.?ÿ
Last topo I did was at a golf course, so the golf tee would be fitting. Lol. I did all of it with the robot though, after setting control.?ÿ
I have set up a base on a wrong point a few years back and didn't know until my check didn't check. If it had been a little bit further down the road it might have warned me about the position.?ÿ
I stand corrected...I haven't dealt with the WebUI in a long time. That's a handy setting.
We can barely get most of our staff to configure survey styles properly in Access, I'm hesitant to even show them the WebUI. Last time I did someone got into a unit and turned off half the constellations and set it to spit out one-hour static files. Fixable, but I'm not sure if it was worth the hassle...
definitely handy to be able to go into the webUI, but, as you say, can also be dangerous. You can set permissions for each user. I like being able to access it remotely.?ÿ
@350rocketmike I was processing data once for a static survey. Man i was having good results but i just had this one area I could not figure out. Someone had set on a azimuth mark and the next time on a reference mark. But the field notes said the actual monument. I sent the next crew out with a camera old school Poloroid. To figure it all out. ?ÿLol.
@rover83?ÿ
I went into the web UI the first day setting up my new r12i, just so I could see if the firmware needing updating. Unfortunately Trimble made it very hard to figure out what the latest firmware available was...but the web UI made it easy to figure out what I had at least.?ÿ
