I’m looking into purchasing some equipment to help survey for some small civil engineering projects. I would like to use a local/temporary base along with a rover. I planned on purchasing an RTK Facet for the base. My question is is it worth purchasing a Torch to use as the rover instead of another RTK Facet? I really like the idea of having tilt compensation. Will the tri-band substantially increase the connectivity in more congested areas? I am not very familiar with GNSS hardware/specs and what it means practically. Any input would be appreciated.
Hey crashingspoon,
The RTK Torch has a few benefits over the Facet:
-
Corrections without base station (though from testing, a base station within 2-4 miles will likely give you better results than PointPerfect over IP)
-
Tilt Compensation (which we are quite proud of!)
-
Completely waterproof (with USB port closed)
-
Tri-band (has L5 support)
Both 1 and 4 come with some caveats. The PointPerfect corrections take longer to get you to a high precision RTK fix than just getting corrections from a Base station. I consider a properly setup Base to be the highest quality correction source, followed closely by PointPerfect over L-Band, then PointPerfect over IP (which is what the Torch can support), then Galileo E6 HAS (which the Torch also supports).
I think that the antenna in the Facet and Facet L-Band is simply more receptive than the one in the Torch. Case in point, I have one of each sitting on my desk powered on, completely surrounded by concrete and steel. The Facet is seeing 8 satellites, the Torch is seeing 3. Having to access to L5 generally means it works better with skyview obscurations, but it is hard to beat the sheer size of the antenna in the Facet type receivers.
Additionally, the Facet / L-Band has radio ports, while the Torch does not. To send corrections to the Torch, you’ll need to broadcast your Base station corrections using an NTRIP service, then subscribe to that service with the Torch. For the Facet’s, you’d just need to add radios to each one.
So, to sum this up, there are pros and cons to each device. I’d say the Torch is generally a more robust and feature complete system on its own, without needing a Base station, while the Facet is a good choice if you know you want to do a Base/Rover setup.
I’m looking into purchasing some equipment to help survey for some small civil engineering projects.
On many of my Civil projects, we are generally just shooting site features and performing very basic Topo’s.
Point Perfect (Facet L-Band or IP corrections w/ Torch) can save a lot of time and hassle verses setting up a temp base and accurately establishing it’s position.
We will reference a few permanent structures/points as TBM’s on our plans.
However, if you intend on performing tasks such as stake out (w/ Vertical), then a base would be extremely helpful.
But just to muddy the water : I’ve had great results on testing the repeatability of specific points using the Facet L-Band for almost a year now 
With PointPerfect, It’s nice to be able to step out of the truck and shoot a Hwy Crossing in the time it takes to walk across the Right of Way.
Thanks for the input. What kind of accuracy do you get with the L-Band? You’re right, we’ll mostly be shooting general site topography, ditch flow lines, etc.
swells:
Hey crashingspoon,The RTK Torch has a few benefits over the Facet:
Corrections without base station (though from testing, a base station within 2-4 miles will likely give you better results than PointPerfect over IP)
Tilt Compensation (which we are quite proud of!)
Completely waterproof (with USB port closed)
Tri-band (has L5 support)
Both 1 and 4 come with some caveats. The PointPerfect corrections take longer to get you to a high precision RTK fix than just getting corrections from a Base station. I consider a properly setup Base to be the highest quality correction source, followed closely by PointPerfect over L-Band, then PointPerfect over IP (which is what the Torch can support), then Galileo E6 HAS (which the Torch also supports).
I think that the antenna in the Facet and Facet L-Band is simply more receptive than the one in the Torch. Case in point, I have one of each sitting on my desk powered on, completely surrounded by concrete and steel. The Facet is seeing 8 satellites, the Torch is seeing 3. Having to access to L5 generally means it works better with skyview obscurations, but it is hard to beat the sheer size of the antenna in the Facet type receivers.
Additionally, the Facet / L-Band has radio ports, while the Torch does not. To send corrections to the Torch, you’ll need to broadcast your Base station corrections using an NTRIP service, then subscribe to that service with the Torch. For the Facet’s, you’d just need to add radios to each one.
So, to sum this up, there are pros and cons to each device. I’d say the Torch is generally a more robust and feature complete system on its own, without needing a Base station, while the Facet is a good choice if you know you want to do a Base/Rover setup.
I wasn’t even aware that the RTK Facet didn’t have an internal radio. What is your recommendation for achieving range >1 mile via radio? What product?
In this context, I prefer to speak in terms of precision and repeatability.crashingspoon:
Thanks for the input. What kind of accuracy do you get with the L-Band? You’re right, we’ll mostly be shooting general site topography, ditch flow lines, etc.
For a quick mission that occurs in a couple of hours, I have no problem repeating positions to <0.1’ with L-Band corrections.
For “important” assets, we will shoot them at the beginning of the mission and also a check shot towards the end of the mission for comparison.
The key is to consider the elevations as “relative”.
For instance : We establish the elevation at a fire hydrant as a TBM. The Delta Z for the TBM to a Manhole Lid is x.xx feet. If you come back 1 week later, you might get different Z values for both points, but the Delta Z will still be in agreement.
I wouldn’t consider L-Band (or any PPP-RTK) a replacement to traditional surveying tools for Control Work.
But the Facet-LB (and the Torch I assume) can still connect to any available CORS Network or private Base over NTRIP, or log for Post-Processed Control Work. PPP-RTK really shines in the GIS world.
FWIW: I don’t have any experience with the Torch, yet. I’m waiting for the FW to mature a little bit more before I start testing it. I do love it’s formfactor. The Helical Antenna is a disadvantage over the Facet’s, but the helical is what allows the clean look of the Torch. I’m interested in finding out if the Tri-Band (L5) makes up for it in the Wild. If I had to guess today… I’d probably guess Yes, but that’s just a guess right now.
I’ve contemplated the same question and think the Torch/Facet combo is the way to go. The Torch can be used solo as a rover with or without corrections subscription. It can be used in tandem with the Facet as a Base/Rover (with the addition of a telemetry radio for the Facet - the Torch has a built-in LoRa radio). The overall cost is about $2500 which is remarkable for this tech.
A post was split to a new topic: Connecting a Facet to a Torch using LoRa
A kit with a Facet and an Torch is indeed amazing tech for the price. Lots of options (network, L-band, local base, etc.) for RTK with the Torch as a rover. The Torch + a network correction service can get you tri-band (L1, L2, L5) RTK with tilt at a very reasonable cost.
I will add that when using the Facet as a base and the Torch as a rover, the L5 signal won’t be used in the RTK positioning, because the Facet doesn’t receive the L5 signals and has no L5 observations to send to the rover.
RTK with two Facets with only L1&L2 does work amazingly well unless the tree canopy is dense. My usual RTK kit is two Facets, and if the tree canopy is dense I wait for the leaves to drop, or I get out my total station.
L5 makes a huge difference in the woods and other challenging situations, in my experience with commercial survey receivers. But you need L5 receivers on both ends of the RTK to get the benefit. Many/most network CORS stations in the US are L5 now or will be upgraded soon.
I hope to see a Tri-Band Facet released someday 
.
1 Like