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The Kinematic Difference

How LS Drone perfects accuracy

The LS Drone difference:

Where accuracy matters, we have perfected our craft.

 

Leveraging the power of Kinematic technologies, LS Drone increases the positional accuracy of drones. Without some type of positional correction, the data a drone collects can be near useless. LS Drone uses years of experience to implement advanced positional correction. We also stay in front of emerging technology and techniques to ensure that the data we present our clients is unparalleled in accuracy and detail.

 

Others use RTK / PPK, we just do it best.

What is RTK / PPK

Real Time Kinematic and Post-Processed Kinematic is the correction of GPS data based on known points.

GPS data is tremendously inaccurate. It is off by about 3 feet at any moment, and can be off by as much as 30 feet if there is a heavy cloud cover or high winds. Why is this? Well, not to get too mired down in the detail, a simple way to visualize it is this: if you have ever looked across a hot parking lot, you see thermal waves. The reason you are seeing the waves is because they are bending light. Light is energy. If the energy of light can be bent and manipulated by the thermal differences in air, it can certainly skew the radio waves that have to travel from the GPS satellites in orbit. 

RTK and PPK technology is a simple concept: introduce another known point into the equation. This time, however, instead of the distance between known points being over 12,000 miles or 19,300 km as with GPS satellites to us, it is a few miles or less to a RTK base station. That means that the radio waves have far less of a chance to be disrupted by air pressure differences, thermal variances, or simple wind. It also means that you can collect any of those errors, log them, and apply them to a positional data-set later for post processing correction (PPK).

The science behind GPS and location acquisition is far more complicated, but for the sake of brevity, that puts us on the right path to understanding why it is so vitally important to drone operations. 

Knowledge is everything

Technique and applied knowledge make all the difference with RTK and PPK. Technology is making the process faster, but even with how advanced positional systems have gotten, knowing how to implement each is essential. 

More than anything, that is the LS Drone difference. Our survey and mapping experts have the operational knowledge that others simply do not. From certified photogrammetrists to licensed surveyors, we carry an incredible knowledge base with us when we arrive at your site.  

Let LS Drone show you what we are capable of by scheduling a free demonstration. 

RTK:
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RTK stands for Real-time Kinematic because the positional correction happens AS you are in the field. 

The positional system begins the same way with RTK and PPK, with the GNSS (Global Navigation Satellite System). The GNS satellites provide the baseline position for all the equipment in the field. As a stand-alone system, this will get your equipment within about a 3 meter circle with ideal weather and sky clearance. 

The next step begins the positional correction process. A base station will be established to a fixed point. This point can be achieved by several means. 

Method 1: Use a previously established survey marker, monument, or benchmark. 

Method 2: Use a CORS point. Continuously Operating Reference Stations are placed across the world. As the name implies, they continuously broadcast the position for kinematic purposes. The information is provided through NTRIP (Networked Transport of RTCM via Internet Protocol), which is a fancy way of saying over the internet. 

There are other means of establishing the base station, but for now, we will focus on those. 

Once the base station has been established, the fun begins. The RTK base station will broadcast its position to the other pieces of equipment in the field. This can include RTK Rovers, local RTK base stations, the Drone, and anything else equipped with a RTK system. 

Because all the data is collected in real-time, the data for the mapping has already been adjusted when it is pulled off the drone. This can dramatically speed up the process of post processing work for map, orthomosaic, and LiDAR data. With all that going for it, there can't possibly be any drawbacks, right? Not so fast. Because the data is collected in real-time, there are several factors that can bring the desired accuracy from 1mm to say, 4-7mm. The biggest factors will be the CORS station and the communication between all the equipment. Moreover, as mapping often takes place far outside the reliable internet of an urban area, RTK can be somewhat unreliable for the precision that professionals need to hand over deliverables with tack sharp accuracy to clients. 

PPK:

PPK isn't just the name for a beautiful sidearm for martini drinking spies. Post-Processed Kinematic, as the name implies, makes the corrections after the fact. 

A base location still needs to be established, as with RTK. However, the base station can be established long after the fact. Positional logs are saved that can be used during post-processing. 

All the equipment in the field log their own independent positional data. Base station, Rover, Drone, etc. 

After the mission, the logs are all inputted into a computer where the kinematic magic happens and the data the drone collected are applied. 

The advantage to PPK is a lack of dependence on the internet since no communication is needed between the equipment. The drawback is that experience and preparation are far more important with PPK. Many argue that PPK is the superior form of location correction because the lack of variables in the field. 

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RTK vs PPK:

Within the fields that use RTK and PPK on a regular basis, the debate over the superior method can get intense. On one side, those that prefer RTK enjoy the simpler post processing, lack of having to download log files for all the equipment, and built-in solutions for their drones. In the other corner, PPK advocates will tout the lack of error-inducing variables, simplified equipment setup, and the confidence in their own post-processing workflow. 

 

There are merits to both sides. Anyone who has run a drone mission that takes place over 3,000' knows that radio signals can get pretty sketchy when trees are even partially blocking the line-of-sight between the drone and the controller. This same thing can happen when you are having to maintain a link between the RTK base station and the drone or rover. PPK systems can operate, theoretically, over much further distances and in extremely varied conditions. 

 

The Answer:

 

LS Drone uses both methods.  Each system comes with distinct advantages. They are both simply tools in a large map and survey making tool bag. RTK represents the quick and dirty method when precision isn't as important as getting in and out faster.  It can certainly be just as accurate as PPK, but it takes slightly more ideal conditions to achieve those results. PPK is the benchmark method for positional correction. However, its very nature prevents it from being used by a crew-based activity like survey work. When the technicians on the ground need the data in real-time, PPK simply cannot perform. 

If you are interested in how LS Drone applies years of experience in RTK and PPK, let us demonstrate. Click below for a free demo of our skills.

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