What is a GPS / GNSS Repeater?

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- everything RF

Jun 16, 2023

A GPS/GNSS Repeater is a device that receives, amplifies, and retransmits GNSS signals to extend their coverage area or overcome signal blockages caused by natural or man-made obstacles. These obstacles can include dense urban environments, tunnels, indoor spaces, and remote areas with limited satellite visibility. GNSS repeaters are designed to support multiple constellations to provide compatibility with various global navigation satellite systems like GPS, GLONASS, Galileo, BeiDou, NavIC (IRNSS) and QZSS.

GNSS has revolutionized the way we navigate and position ourselves in the world. From personal devices to commercial applications, GNSS technology has become an integral part of our daily lives. However, there are instances where the signals from GNSS satellites may be weak or blocked, leading to reduced accuracy and reliability. To overcome these challenges, GNSS repeaters have emerged as a valuable solution, enhancing the performance and reach of GNSS signals in various environments. By installing a GNSS repeater, users can ensure seamless connectivity, improved accuracy, and uninterrupted GNSS services in challenging environments where the signal from the satellite would typically not be accessible.

GPS or GNSS repeaters consist of three main components: an active outdoor GPS antenna, typically mounted on the roof of a building to pick up signals, a repeater unit with a built-in passive antenna used to re-transmit the GPS signal indoors, and a coaxial cable that connects the two. All the repeaters in a single network transmit the coordinates of the outdoor antenna and not the position of the repeater unit itself. In case the same signal needs to be transmitted to multiple floors of a building, this can be done by using a signal splitter and then connecting each split signal to a repeater located on a different floor.

GPS/GNS repeaters in a building operate by receiving satellite signals with an antenna located outside of a building, and then re-transmit the signals indoors, resulting in consistent and uninterrupted access to signals underground or in other hard-to-reach areas. The use of re-transmitted signals means that the GNSS receiver is tracking the current GNSS status so that when the receiver moves outdoors, it picks up the same signals directly from the satellites avoiding any downtime.

Wide or long-range GNSS coverage through a GNSS repeater kit allows numerous GNSS devices, whether inside or outside of a building, to access and lock on to the same signal at all times. This is a benefit that proves to be critically important for emergency service workers, first responders, and military personnel who need instant location accuracy. The environmental conditions are very important for deploying a GNSS repeater system in a building. As this RF system works with a very low power level, it is very important to install the receiving antenna and the repeater unit at planned locations to avoid unnecessary interference.

With the help of GPS/GNSS repeaters, rescue vehicles no longer have to wait to acquire signals upon exiting a building, allowing a constant state of readiness. Repeaters are also useful in computer and electronic testing facilities, aircraft servicing hangars where on-board satellite navigation equipment is tested indoors and in all areas or locations where signal strength may be an issue.

Benefits of GNSS Repeaters

Extended Coverage Area: GNSS repeaters amplify and retransmit satellite signals, effectively extending the coverage area beyond the limitations of direct satellite visibility. This is particularly beneficial in areas with obstructed views, such as urban canyons or densely forested regions.

Increased Signal Strength: Weak GNSS signals can lead to reduced accuracy and reliability in positioning applications. GNSS repeaters amplify the signals, increasing their strength and improving the quality of positioning information. This is crucial for applications that demand high precision, such as surveying, construction, and autonomous vehicle navigation.

Enhanced Indoor Navigation: Indoor environments pose a significant challenge for GNSS signals due to signal attenuation caused by building structures. GNSS repeaters can bridge this gap by bringing satellite signals indoors, enabling accurate indoor navigation and positioning in facilities like airports, shopping malls, and warehouses.

Improved Reliability: GNSS repeaters mitigate the impact of signal obstructions, reducing the risk of signal loss or degradation. By ensuring a reliable and consistent GNSS signal, these repeaters enhance the dependability of critical applications, including emergency response systems, maritime navigation, and precision agriculture.

Applications of GNSS Repeaters

Transportation and Logistics: In the transportation and logistics industry, GNSS repeaters play a vital role in enabling accurate tracking and navigation of vehicles, vessels, and aircraft. They enhance signal reception in tunnels, underground parking lots, and remote areas, improving route optimization, asset management, and overall operational efficiency.

Construction and Surveying: Construction sites often involve dense urban areas or obstructed landscapes where direct GNSS signals may be weak or unavailable. By deploying GNSS repeaters, construction and surveying professionals can achieve precise positioning and ensure accurate machine guidance, leading to improved productivity, reduced errors, and enhanced safety.

Public Safety and Emergency Services: GNSS repeaters are crucial for public safety applications, such as emergency response systems and search and rescue operations. They ensure uninterrupted GNSS signals in challenging environments, enabling accurate location tracking and efficient coordination during critical situations.

Indoor Navigation and IoT: With the proliferation of indoor positioning systems and the Internet of Things (IoT), GNSS repeaters are essential for seamless indoor navigation and connectivity. They enable real-time tracking of assets, personnel, and equipment in large facilities, improving workflow efficiency, safety protocols, and inventory management.