How to select GPS/GNSS antennas for time synchronization

  • For Timing

When using a product embedded with GPS/GNSS receiver for timing, the GPS/GNSS antenna and peripheral parts must be properly selected and installed.This section explains how to select and install GPS/GNSS antennas for long-term timing solutions without malfunction or troubles.

How to select GPS/GNSS antenna

Select the right GNSS antenna for your GNSS receiver

There are many frequencies broadcasted from satellites depending on the type of constellations and signals. For example, the L1 signal of the GPS constellation is 1.57542 GHz and the L1 signal of the GLONASS constellation is 1.602 GHz. Please check the satellite systems and signal types supported by the GNSS receiver and select a GNSS antenna accordingly.

Select the right antenna according to the environment

Satellite signals are very weak. When installing a GNSS antenna close to other antennas ex. radio system, a noise filter built-in antenna is recommended.
Regarding the shape of the antenna, if the antenna is to be installed in an area with heavy snowfall, special shape to prevent snow from accumulating is recommended.
In addition, GNSS antennas are recommended to be installed in an open sky environment, which is often on rooftops. If lightning surge protection is required, please consider installing a lightning arrester as part of the set.

Notes for GPS/GNSS antenna installation

Cable (coaxial cable) length and distribution

When the distance between the antenna and receiver is long, such as when the GNSS antenna is installed on the roof of a building and the GNSS receiver is installed indoors, signal attenuation must be considered. Please consider adding an amplifier.
Also, when using the signal from one GNSS antenna with multiple GNSS receivers, please use a dedicated splitter.

Antenna setting and waterproofing

It is highly recommended to install the GNSS antenna outdoors with open sky, in order to ensure good reception of signals from GNSS satellite. The antenna should be fixed with a pole or similar structure using a dedicated mounting tool.
Even if the antenna itself is waterproof, the coaxial connector is not, so please use self-bonding tape or other waterproofing treatment.

Reference materials

GNSS Antenna Installation

Using Furuno GNSS antennas as an example, this document explains the mounting bracket required for installation and the installation procedure with photographs.
Downloads (Documentation, Software)

Three essential points when installing a GNSS antenna

When installing a GNSS antenna, components such as the coaxial cables and amplifiers should be selected to satisfy the antenna specifications of the GNSS receiver. It is also necessary to consider the propagation delay between the antenna and the receiver.
In this document, we explain how to calculate the required specification values with concrete examples from the viewpoint of a GNSS receiver manufacturers.
・Total gain
・Total NF
・Propagation delay in coaxial cables

It is especially useful for those who are new to GNSS receivers.
We have prepared an Excel tool for calculating "Total Gain" and "Total NF" due to their complex formulas.
Please fill in the form to download the document and calculation tool.
GNSS Antenna Installation Guide Download Form

How to install a "surge protective device" to enhance lightning surge resistance? (with examples and test results)

There are two types of surge protective devices (SPDs) for GNSS receivers
・Against direct lightning strikes, that is against surges caused by direct ligthning strikes on the antenna.
・Against induced lightning, that is against surges caused by the magnetic field generated by near-by lightning strikes.
By combining the above two types of SPDs, lightning surge resistance is enhanced.

Due to recent abnormal weather conditions, countermeasures against lightning surges are becoming more important. Using our SPD model TVA-03C for direct lightning and model TVA-03V for induced lightning as examples, we will introduce their installation methods and the results of lightning impulse tests.

You can download this document by filling out the form below.
Surge Protective Device Document Download Form

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Column by Mr. Mitsunari Kita  (Science and technology writer)