Where are we headed? 100 hertz GPS!

Where is the benefit to 100 Hz? Isn't the bandwidth of the ionospheric path changes a lot less than that? I recall working with radio links having "fast" fading rates of perhaps 5 Hz.

And you certainly don't move your rover or grading machine very far in 1/100 second.

Higher hz rates, equates into more data. Kinda like a camera pic at 640x480 vs one taken at 1024x768. Then, if we go up to a 12 or 16 mb pic, now we are actually getting all the data. The point is that there was GOOD data, that was missed, at the 1 hz rate. The 5 hz rate allowed it to use the good data, that was not previously allowed. And, a faster processor is needed to handle that level of data throughput. I suspect that 2 radios would be needed to operate at 20 hz, RTK!

Nate The Surveyor, post: 342825, member: 291 wrote: What the??? Why would I want 100 hertz? It was an option, when I bought my Javad LS.
I can get 100 hertz, recording. (at a cost of 2 more k)
I can get 100 hertz, RTK, (at a cost of another 2 k)

I can run in BEAST mode, RTK @ 5HZ. RIGHT NOW (well, maybe on Friday, when it comes on the truck) The BASE model, (Like I got) comes rigged at 10 hz. Can I get my radio to function, at 10 hz? Maybe with 2 radios, on 2 separate channels?

Where are we going? What will tomorrow hold? What is this stuff for? What will tomorrow's GPS be capable of?

Danged. At those hertz rates, will it burn a hole for the rebar?

The unit I got has 2 cameras. One forward facing, and another down. Only some 3.xx Megapix. Looks like maybe the Good Doc borrowed some of yesterdays cell phone cameras, and stuck them in there. Motion sensors. One of them sends it's signal out the Screen side of the LS. In cold weather, with gloves, you WAVE at the LS, and it triggers a shot.

Will tomorrows units obey simple voice commands, and enter TEXT into the description, with voice?

Will tomorrows units have 32 Mega pic cameras, and Built in scanners, that ALSO derive distances, to all that's in the camera view, like a mini scanner?

Will tomorrows surveyor NOT NEED a total station?

The tilt sensors, and motion sensors, are likely borrowed from Cell phone Technology.

I am already planning to re rig one of my bipods, with a little extra weight in the feet.

Where will it end?

The Javad unit can NOW talk to you, to assist with stakeout. I am not sure what it will do yet. Left/right, then Go 150'. As you walk, it can then talk you to the point?

Hmmmmm This should amp up the game.

In a world where getting the truth out of your equipment, is paramount, I want all the truth I can get!

N

I recently accepted a new position that puts me in the field more. The last RTK system I used would give bad inits if you were near any source of multipath. The robot Bluetooth was hokey and cost 20 or 30 percent of productivity.
Last week I went out with an S6 and TSC3. 688 shots in 3 hours. The RTK system gave repeatable results matching record in marginal environments. The 2 of us did what I would have estimated minimum 3 days work in 2. That is where the equipment is taking us. There is however a dark side.
The mark of a good Surveyor is simple. Are the stakes you set and the points and lines you put on paper correct? Are we developing and teaching valid checks? Are we reinvesting some of our time savings in QA/QC?
For many the model is 'we will spent 30k to reduce our billable hours and undercut the other guy'. We have to do better. My apologies for the hijack, but you asked the question..
Thanks, Tom

Bill93, post: 343415, member: 87 wrote: Where is the benefit to 100 Hz? Isn't the bandwidth of the ionospheric path changes a lot less than that? I recall working with radio links having "fast" fading rates of perhaps 5 Hz.

And you certainly don't move your rover or grading machine very far in 1/100 second.

The real advantage of higher correction rates is that it reduces the time for the RTK engines to fix. In theory, the time required to acquire a fix is inversely proportional to the rate of the corrections. J-Field, Javad‰Ûªs field software for the TRIUMPH-LS and Victor-LS, has RTK Verification and Validation features that reset the RTK engines at the beginning and end of observations to ensure a bad fix never gets accepted in areas under tree canopy and areas with high multipath. By reducing the time for the RTK engines to fix, RTK Verification and Validation can be completed much quicker and surveyors can collect points in locations that previously very difficult and time consuming.

In a recent test I performed to quantify the improved performance with acquiring a fixed solution, a TRIUMPH-LS was setup to automatically collect 100 points in succession with correction rates of 1 Hz, 2 Hz and 5 Hz. RTK Verification was used to reset the RTK engines once and then collect 1 epoch after at least 4 of the 6 parallel RTK engines of the system have fixed, essentially measuring the time required for 4 of the RTK engines to fix. The test location was in an environment with some multipath and an approximately 75% open view of the sky. With 2 Hz corrections, the average time for 4 engines to fix was reduced by 46% to 6.7 seconds compared to 12.5 seconds with 1 Hz corrections. With 5 Hz corrections it was reduced by 72% to 3.5 seconds.

thebionicman, post: 343420, member: 8136 wrote: I recently accepted a new position that puts me in the field more. The last RTK system I used would give bad inits if you were near any source of multipath. The robot Bluetooth was hokey and cost 20 or 30 percent of productivity.
Last week I went out with an S6 and TSC3. 688 shots in 3 hours. The RTK system gave repeatable results matching record in marginal environments. The 2 of us did what I would have estimated minimum 3 days work in 2. That is where the equipment is taking us. There is however a dark side.
The mark of a good Surveyor is simple. Are the stakes you set and the points and lines you put on paper correct? Are we developing and teaching valid checks? Are we reinvesting some of our time savings in QA/QC?
For many the model is 'we will spent 30k to reduce our billable hours and undercut the other guy'. We have to do better. My apologies for the hijack, but you asked the question..
Thanks, Tom

Mr. Bionic, I am 'fraid you are right.

matt8200, post: 343421, member: 6878 wrote: time required to acquire a fix is inversely proportional to the rate of the corrections

There comes a point of diminishing returns, if the corrections aren't changing significantly from one to the next. It matches my radio experience to say that 5 Hz is beneficial, but not 100 Hz.

12.5 seconds, 6.7 , 3.5 sec ... you aren't going to save much by going faster still.

It's sort of like doing a topo on a 1-ft grid on a field where 25-ft grid would have captured the useful information.

Well, when it takes you 15 mins to go FIXED, but instead takes 1 minute... that is important!

I would agree that there is a point of diminishing returns and was not trying to suggest that correction rates of 100 Hz are needed, but rather just explaining the benefit of greater correction rates in general. Javad's current processing algorithms max out the hardware's capabilities just beyond 5 Hz but I'm told there is room for this to be improved with future software and firmware updates. With 12.5 kHz radio channel spacing a UHF radio comes close to maxing out the duty cycle at 5 Hz as well. If a FCC license for 25 kHz channel spacing was granted, a UHF radio should be able to transmit at 10 Hz.

Remember the 100Hz option is different from "Beast Mode". The 100Hz option is for solving an extrapolated position at the rover 100 times per second using the last available correction. This is good for mobile applications, machine control, aerial photogrammetry, mobile scanning etc. Resolving ambiguities requires more processing than solving a position from an already fixed solution. That's why 100 Hz is possible, it's a high rate position solution from an already fixed solution, which is less processing intensive.

It is important to carefully understand the distinction between high rate transmission (e.g. Beast Mode) and high rate positioning. Both have their uses, but are not nearly the same thing. Beast mode has demonstrated, both in Matt's testing and in many others' (including my own), the ability to reduce the TTF in a directly proportional way. What would take a minute to get a fix at 1Hz can be done in 12 seconds at 5Hz, because of the increased number of corrections the software can use for the instantaneous RTK solution. With the base transmitting 1Hz and a position rate of 100 Hz at the rover, the TTF will not be changed at all over 1Hz transmit and 1Hz positioning at the rover. The magic is in the transmission.

Currently, with Javad field software, 5Hz is about as fast as the processor can resolve ambiguities, just as Matt said above. I could be wrong, but I think that it's unlikely to see transmissions greater than 5Hz any time soon for land surveying purposes.

thebionicman, post: 343420, member: 8136 wrote: I recently accepted a new position that puts me in the field more. The last RTK system I used would give bad inits if you were near any source of multipath. The robot Bluetooth was hokey and cost 20 or 30 percent of productivity.
Last week I went out with an S6 and TSC3. 688 shots in 3 hours. The RTK system gave repeatable results matching record in marginal environments. The 2 of us did what I would have estimated minimum 3 days work in 2. That is where the equipment is taking us. There is however a dark side.
The mark of a good Surveyor is simple. Are the stakes you set and the points and lines you put on paper correct? Are we developing and teaching valid checks? Are we reinvesting some of our time savings in QA/QC?
For many the model is 'we will spent 30k to reduce our billable hours and undercut the other guy'. We have to do better. My apologies for the hijack, but you asked the question..
Thanks, Tom

Exactly right Tom. If you take the time savings and reinvest a fraction of them into improving QA/QC, you get the benefit of still being more efficient AND producing better, more reliable results. I think that is the most important aspect of faster technology and it is sadly overlooked way too often. What if you don't produce any faster results, but the results you get have much better quality and reliability with less effort.

5Hz is all that's needed for typical RTK surveying.

The faster rates, 10, 20, 100Hz are beneficial in vehicle based applications, such as airborne or mobile LiDAR. In other words, those systems work more on trajectories made up of individual positions, rather than the individuals points themselves. This solves the problem of the reference receiver and the vehicle receiver being out of sync.

I hope you get the jist of what I said above. I'm horrible at explaining things at times.