GNSS accessories and land surveying equipment positioned in a green field with buildings shown in the background.

Choosing the Right GNSS Accessories for Optimal Surveying Performance

Like most technology that we have today,  Global Navigation Satellite Systems (GNSS) technology is advancing at a rapid pace. Today it is more essential than any time before to determine and know the exact location of an object, a person, or a building. GNSS technology is being used in such fields as asset tracking, fitness, fraud prevention, but more importantly, in land surveying.

GNSS accessories have become an essential asset in a surveyor’s tool kit. Sometimes you can’t get around a work site without proper equipment, and with so many brands out there, it becomes difficult to pick the appropriate GNSS receiver for the job you need to do. Today we want to emphasize the importance of having the right GNSS tools for the job and what you need to concentrate on to pick a proper one.

How to Choose a GNSS Receiver?

When assembling your surveying field kit, you can’t just go for any old GNSS GPS accessories. You have to know what to look for first so as to get proper results. Sometimes going for a top brand or the most expensive GNSS tracking antenna is not the proper choice, you have to go into detail and specifications to get a fitting one.

Look for Details in the Specifications

You have to go a bit technical at first. Check the GNSS receiver specification to determine how the product works and so it can provide you with the necessary results, There are seven main points to look at:

  1. Signal tracking (Channels, GPS, BDS, GLONASS, Galileo, OZSS, Navic, SBAS)
  2. Electrical (Power, battery, power consumption)
  3. Accuracy (RTK reliability, RTK initialization, hot start, cold start, re-acquisition time, static post-processing, RTK, RTD, SBAS, tilt surveying)
  4. Environmental (Working temperature, storage temperature, waterproof & dustproof, shock & vibration, humidity)
  5. Physical (Size, weight, memory, display, button, indicator, housing, speaker, NFC)
  6. Data format (Data recording formats, correction data formats, data output formats, data output rate, supported protocols)
  7. Communication (BT, Wi-Fi, 4G, UHF modem, interface)

What Functions Do You Need?

You can’t only concern yourself with the basic parameters. You never know if a certain type of function may come in handy at some point. Also, if you already know exactly what you are going to need it for, you will be getting a device with a specified function.

  • 4G & Radio: A way to establish communication between Rover and Base.
  • IMU for Tilt: Helps to improve the efficiency of surveying projects, especially on rigorous terrain.
  • NFC Connection: Necessary to simplify the connections that go between GNSS receivers to data collection.
  • WiFi & Web UI: Helpful when downloading static data to the WiFi of the receiver.
  • Front Panel: The base ones come with status indicators and a power button. But if you are in need of advanced products, there are ones with configuration buttons as well.

Reasonable Pricing

As we already mentioned, the most expensive GNSS antenna may not be able to get you the results you need. Sometimes a cheaper one will do the trick. However, you still have to look at the specs and compare them to other products. If you are doing a more demanding type of survey, you may not be able to avoid spending a little bit more money on the tool you require.

Warranty & After-Sales

While most people will tell you to always buy from an original manufacturer or a local distributor, what you have to look for is getting a proper warranty on the GNSS equipment you purchase. Brand aftermarket capabilities and having a decent warranty on your equipment should be something that you carefully need to consider no matter where you buy it from.

Choosing a GNSS Antenna

Picking a proper GNSS antenna is much more crucial than you think. It can make or break your entire setup. Even a minute lack of functionality can cause problems for a tracking device where reliable and constant reports on a precise location are key.

Today, you have many different GPS accessories for surveying made out of different materials, each coming with its own advantages and disadvantages. In order to pick a proper one, here are the elements that you need to consider.

Transmission Frequency

In order to work, your antenna has to operate in an appropriate frequency range for GNSS signals. Almost every country has its own satellite system and every one of them operates at a different frequency. What you have to determine is the satellite system and the associated frequency bands your GNSS tracking device will be using.

Antenna Size

There are many antenna sizes with each of them having their own footprint on a circuit board. In the case of land surveying, you are going to want your antenna to be as small as possible. You can check the specifications first to determine what the final design of your device will look like before inserting the antenna.

Material and Form

Old school antennas that we had on our TVs or radios were made out of silver metal materials. Today, the materials used are much more extensive ranging from ceramic to flexible, allowing for added pliability of GNSS trackers. One of the main ways to pick an antenna is based on the surroundings you will be working in as the environment will affect the function of the antenna.

For instance, if you need your device to be wearable, you are going to need a more flexible antenna. On the other hand, for rugged devices, you are going to need a sturdier or a metal one that can be securely placed on a GNSS antenna mount.

Ground Plane Requirements

Taking notice of ground planes is crucial if an antenna is going to be able to reliably send and receive transmissions. But they require added space on a tracking device. Be sure to determine how much space your antenna needs for a far more effective ground plane. 

There are some antennas that can utilize other components as part of their ground planes, but most require clear space on a circuit board. A wise choice would be to consult a wireless engineer to ensure a proper antenna choice.

Minimizing Interference

It is more than likely that your tracking device is going to be exposed to a range of environmental interference. Glass, metallic objects, wireless devices, tall buildings, and even some components of the device itself might potentially disrupt the antenna.

You need to pick an antenna GNSS antenna design that can isolate interference or at least minimize the disruption to its signal. Ceramic antennas are actually the best when isolating interference. Also, the positioning of the antenna is key when avoiding unwanted interference.

Omni-Directionality

Your portable tracking devices need to be able to send out a signal no matter the position. Whether it is vertical, horizontal, or resting diagonally, they have to be able to give off their position. For that reason, an omnidirectional antenna opposed to a dipole one works much better.

But, you are going to have to think about component selection and positioning as well. It is essential to pick an antenna that will work no matter the components you decide to fit on your tracking device.

GPS Accessories for Surveying

For surveyors to fully utilize the benefits that comes from using GPS technology, there are a various GNSS GPS surveying equipment accessories that they will be able to use during their daily routines.

GPS Receivers

A GPS receiver is probably the most important part of the entire GPS system. It is responsible for receiving signals from a GPS satellite, but there are a lot of them that may come with additional features like having an internet modem or IMU tilt sensors

Data Collector

To put it in simple wording, a data collector is a portable device where all the GPS data is collected and stored. It basically does the function of being an interface between a surveyor and a GPS receiver. Most data collectors come with a built-in GPS while others will need an added external GPS receiver. Things that you must consider when picking out a data collector are its durability, battery life, and software compatibility.

Surveying Pole

You are going to need a surveying pole in order to elevate a GPS antenna so it is at least two meters above the ground. This is to ensure that the GPS receiver sticks enough so there are no interferences. A surveying pole should come with a bubble level to ensure accuracy if you are working with a receiver without an IMU tilt sensor. It is also good for it to have a mounting bracket to be able to attach the antenna and carry it with ease.

Controller Bracket

To make things immensely easier for you, you can attach your data collector to a controller bracket and mount it to a surveying pole. However, be sure to pick the size of a bracket that fits the size of a controller you are using.

Software

GPS software is needed to process and analyze the collected GPS data. What you need to make sure is to install the software which is compatible with both the data collector and the receiver. Some types of software already have a variety of built-in features such as geocoding, mapping, and contouring. 

Tripod

If you are planning on using a rover and a base set, you need to position your GPS receiver in a fixed position for improved accuracy. For that reason, a tripod is the best possible choice as it allows for stable positioning of the GPS antenna. The tripod needs to be adjustable and come with a quick-release mechanism to allow for easy setup. Also, be sure to use those that are made out of lightweight but sturdy materials like fiberglass tripods, as they are both lightweight and sturdy enough.

Radio Modem

A radio modem also works when working on a rover and a base set. With it, your base receiver can transmit corrected GPS data to a receiver and ensure pinpoint accuracy. Most GPS receivers have a built-in radio modem, but some will require an external one.

GNSS Surveying Methods

With the help of various GNSS accessories, surveyors are not able to complete extensive surveys much more easily, faster, and with more accuracy. But there is more GNSS surveying techniques with each one having its own set of specific usages.

Single Point Positioning (SPP)

Single point positioning is the most basic form of GNSS surveying. Here a single receiver collects satellite signals and determines the position. Unfortunately, it is not so accurate and can only pinpoint objects within meters due to factors involving atmospheric interference and satellite geometry.

Differential Positioning (DGPS)

Differential positioning has improved accuracy compared to single point positioning. It uses a reference station within known coordinates. By comparing the position of the reference station with the measurements taken by the receiver it eliminates errors that may be caused by atmospheric disruptions, satellite errors, or clock inaccuracies.

Real-Time Kinematic (RTK)

Real time kinematics is not only useful for delivering real time data, but it is also very accurate. It uses a base station and rovers to receive signals. The base station gets the signal from the satellites and transmits the data to the rovers, which then in turn create precise coordinates. With RTK, surveyors can achieve centimeter-level accuracy.

Post-Processing Kinematic (PPK)

With the post processing kinematic method, raw GNSS data is collected and processed. Using a base station or a virtual reference station, the method will calculate precise coordinates of the survey point. PPK is as accurate as RTK. However, it requires some added post processing time.

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