Only a few years ago RTK GNSS equipment used for surveying was a lot more expensive. Back then, mostly professional-grade surveyors and those with educational backgrounds were the ones using it. But with the development of the market and the equipment itself, we now have much cheaper and affordable GPS receivers that various types of surveyors are using in for their tasks.
Today’s GNSS receives and surveying equipment has become much more user-friendly, so nearly anyone can use it. Not only that, but the price has gone down. Making it much more accessible to even those who are not doing surveys that often.
However, with so many RTK GNSS receivers available on the market, you may not be able to know how to get the exact one you need unless you do some digging around. In fact, you are going to do a lot of research and consider various factors and parameters to come up with decent results. To help you save time, we thought it would be a great idea to explain to you which are the most important things that you need to keep an eye out for, which will ultimately help you get the exact RTK GPS receiver that you will be using for a long time.
Understanding Different GNSS Setups
The first thing that you are going to have to understand is that there are different setups. There are GNSS surveying sets that consist of multiple parts, and it mostly depends on those components which type of setup you will need to choose. There are two types of setups:
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GNSS Rover Set: A standard set used for terrain mapping, collecting points, and staking out.
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GNSS Rover and Base Set: Has a secondary GPS receiver that acts as a base station that helps with correction data.
Therefore, the biggest difference between these two is that the Rover and Base Set provides you with two receivers that help with correction data. GNSS receivers on their own are never centimeter-accurate, a secondary set will help to correct the received data and pinpoint everything much more accurately. Here are a few examples showing you the exact accuracy of used equipment.
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SBAS corrected GNSS - 0.5 to 1-meter accuracy
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Stand-alone GNSS - 1 to 5 meter accuracy
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Mobile phone GPS - 15 to 20 meter accuracy
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L-Band corrected GNSS - 5 to 10 centimeters
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RTK corrected GNSS - 1 to 2 centimeters
Stand-alone GNSS receivers are not centimeter-accurate because the satellite signals have to go through the atmosphere, leaving room for errors. The correct these errors, you will need an RTK correction service or set up your own base station.
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GNSS Base Rover Set |
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GNSS Rover Sets |
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RTK GNSS Receivers
What an RTK GNSS receiver does is to take care of all the positioning data, and does so by using the signals received from all the available satellites. GNSS receivers take care of the positioning part, but you will still need something for correction data to improve the accuracy. This is where suitable software comes into play as it processes the collected data. Just positioning won’t do you any good.
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GNSS Receivers |
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What to look for when buying an RTK GNSS receiver?
Picking the right kind of GNSS receiver will help you get more accurate results, and in most cases, you won’t even need to go for the most expensive one. Simply think about getting the one that satisfies your needs.
The main parts you will be looking to consider are the following:
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Internet and mobile data
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Tilt sensor and IMU
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Constellations, channels, and frequencies
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Batteries
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Radio
Internet and Mobile Data
Internet connectivity becomes a vital part when doing GPS surveys. RTK correction is offered via the internet, and without it, you are not going to be able to do much. You can still setup your own base, but that will incur you more costs and make the entire process a lot more difficult.
Make sure to check for the mobile data band that is available. The higher the better, of course. Nowadays, you can pick from 2G, 3G, 4G, and even 5G. However, we would also recommend that you pick at least 4G or higher. If they plan to stop using 2G and 3G like the rumors say, you won’t need to upgrade your equipment and you will also be able to work for longer.
Tilt sensor and IMU
A tilt sensor has to be the best possible additional created to help GPS surveying. Back in the day, with the older models, we had to make sure to keep the surveying pole level at all times. Now, the tilt function allows us to keep an angle while still being able to measure the point.
However, the angle plays a massive role in how far you can actually tilt the sensor. There are cheaper models with a sensor that goes up to 30 degrees. But the newer models come with an IMU (Inertial Measurement Unit) sensor. The technology basically allows you to measure at an angle of up to 60 degrees.
Constellations, Channels, and Frequencies
GNNS receivers with access to multiple satellite constellation systems have the capacity to perform much better compared to the ones that only have GPS. Be sure to pick a device that covers them all, and has access to GPS Glonass Galileo BeiDou QZSS SBAS IRNSS, and more.
Also, a GNSS receiver with at least 250 to 400 channels is more than okay. You don’t really need a device that gives access to 500, but be sure to avoid those with less than 200. As far as the frequency of the GNSS antenna goes, be sure to
Batteries
GNSS RTK receivers have different setups, but some include battery setups as a key component. You will be picking the battery setup based on what kind of worker you are, and it mainly depends on how much time you regularly spend in the field. You really have a choice between devices with internal and external batteries.
Receivers with internal batteries will ensure that you never lose your battery pack while in the field. They can be charged easily with the help of a USB cable. Unfortunately, the more you use the device the more likely it is for the battery to degrade. In this case, you can’t just swap out the battery, you will need to replace the entire thing.
As far as external batteries go, it is what most surveyors use. Those that have a hot-swappable system are the ones to look for, especially if they have 2 battery slots. The receiver runs on one battery during a survey. So once it runs out, it will immediately switch to the other, allowing you to continue the work without any interruptions. Also, you can easily replace a battery if it degrades or gets damaged.
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Surveying Batteries |
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Leica GEB222 Li-ion Battery Pack for TS02/06/09/1200 Series Total Station, 1200 Series GPS |
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Leica GEB221 Li-ion Battery Pack for TS02/06/09/1200 Series Total Station, 1200 Series GPS |
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Leica GEB242 Li-ion Battery Pack for TS Series, TM30/50/60 Series Total Station |
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Leica GEB211 Li-ion Battery Pack for TS02/06/09/1200 Series Total Station, 1200 Series GPS |
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FAQ
Consider a few FAQs for the end.
What kind of GNSS do surveyors use?
Most survey-grade receivers use two types of GPS frequencies, L1 and L2.
How to use RTK in land surveying?
One unit is positioned at a fixed location with specific coordinates and is referred to as the base station. It employs a high-frequency radio to send its raw data to the second unit, called the rover. The rover then utilizes both sets of observations to calculate its position in relation to the base station in real time.
Which is the most accurate RTK GNSS?
It is Point One Polaris RTK Network, which uses signals from GPS, Galileo, GLONASS, and BeiDou satellite constellations, helping to enhance by over 100x for a precise centimeter-level positioning with a 5-second correction time.
What is RTK GNSS surveying?
Real-time kinematic positioning (RTK) is a surveying technique used to rectify typical errors found in modern satellite navigation systems (GNSS).
