What is GNSS And Why Do Some Teltonika Routers Support GPS?

What is GNSS?

GNSS stands for Global Navigation Satellite System. It is the umbrella term for all satellite-based positioning and timing systems, of which GPS (Global Positioning System) is the most widely known example. GPS is one GNSS constellation operated by the United States. Three other major global constellations – GLONASS (Russia), Galileo (European Union), and BeiDou (China) – also operate independently and cover the entire Earth. Most modern receivers, including those built into Teltonika routers, use multiple constellations simultaneously.

The distinction between GPS and GNSS matters in practice. A receiver that only uses GPS has access to approximately 31 satellites. A multi-constellation receiver has access to more than 100 satellites from all four systems. More visible satellites means faster position fixes, better accuracy in difficult environments such as urban canyons or dense tree cover, and redundancy if one system has reduced availability.

The Four Major GNSS Constellations

Teltonika routers label the GNSS function as “GPS” in the RutOS WebUI, which is the familiar term most users recognise. In practice, the GNSS receiver inside the cellular modem supports multiple constellations depending on the modem module fitted. Supported constellations vary by model – check the datasheet for each device to confirm which systems are enabled.

How GNSS Works

Each GNSS satellite continuously broadcasts two pieces of information: its precise position in orbit and the exact time that broadcast was transmitted, kept accurate by onboard atomic clocks. A receiver on the ground picks up signals from multiple satellites simultaneously. Because the signal travels at the speed of light, the receiver can calculate the distance to each satellite by measuring how long the signal took to arrive.

With three satellites, a receiver can calculate a two-dimensional position (latitude and longitude). A fourth satellite is required for a full three-dimensional fix that includes altitude and allows the receiver to correct its own clock error. In practice, modern receivers typically have six or more satellites in view, which improves accuracy and reduces the dilution of precision.

Typical unassisted GNSS accuracy under open sky is 3-5 metres with GPS alone. Using multiple constellations simultaneously improves this further and maintains accuracy when some satellites are obscured. Differential techniques such as SBAS (Satellite-Based Augmentation Systems like EGNOS in Europe) can push civilian accuracy below 1 metre for static applications.

Beyond position, GNSS is one of the world’s primary time distribution networks. Financial exchanges, power grids, mobile networks, and industrial control systems all rely on GNSS-derived timing to synchronise their operations to nanosecond precision. This timing function is independent of whether the receiver is moving – a fixed site can use GNSS purely for clock synchronisation with no position output required.

Why Would a Router Need GNSS?

The question is reasonable. A router sitting in a fixed cabinet does not obviously need to know where it is. However, GNSS in a cellular router serves several distinct purposes, and not all of them require the router to move.

Fleet and Vehicle Tracking

The most direct use case. A router installed in a vehicle, vessel, or mobile asset publishes its GPS coordinates continuously via the cellular connection. Fleet operators see every vehicle on a map in real time. The Teltonika ATRM50, built around M12 connectors for vibration-resistant vehicle installation, is a purpose-built example. Position data can be sent via MQTT to a fleet management platform or forwarded as NMEA sentences to an onboard vehicle system.

Location Tagging of Sensor Data

When a router collects Modbus readings, I/O states, or environmental sensor data and forwards it via MQTT or HTTP, attaching a GPS coordinate and timestamp to each packet adds significant value. A water quality monitor published with its exact location at each reading becomes a geospatial dataset. A pressure alarm from a pipeline includes the precise segment coordinates. RutOS supports including GPS data in Data to Server payloads alongside any other data source.

Geofencing and Event Triggers

RutOS includes a geofencing function that monitors the router’s position relative to a defined boundary. When the device enters or leaves that boundary, it can trigger an action – sending an SMS alert, switching network profile, activating an output, or publishing an MQTT event. This is used in asset theft detection, vehicle compliance monitoring, and logistics boundary alerts.

Precise Time Synchronisation (NTP)

For fixed infrastructure, GNSS provides a Stratum-1 time source independent of internet connectivity. The Teltonika NTP001 is a dedicated Stratum-1 NTP server that derives its timing directly from GNSS satellites. Industrial control systems, telecommunications infrastructure, and energy management systems require time synchronisation accurate to within microseconds. GNSS delivers this without depending on upstream NTP servers that introduce variable latency. Even standard Teltonika routers with GNSS can serve as accurate local NTP sources for devices on their LAN.

Remote Site Identification and Network Monitoring

In a large distributed deployment – water utility sites, telecoms infrastructure, renewable energy installations – knowing the precise location of each router helps operations teams correlate network events with physical geography. A router reporting poor signal quality can be cross-referenced against its GPS position to identify obstructions, coverage gaps, or the need for a different antenna orientation.

How Teltonika Implements GNSS in RutOS

GNSS on Teltonika routers is controlled through the Services section of the RutOS WebUI. The primary settings page covers enabling the GNSS service, selecting which satellite constellations to use, and configuring how the position data is handled. Changing constellation settings requires a modem reboot to take effect.

Once the GNSS service is enabled and a fix is obtained, the router’s current position is visible on a map within the WebUI. Position data is also readable via Modbus TCP registers, making it accessible to SCADA systems and data collection pipelines without any custom integration.

NMEA Data Forwarding

NMEA (National Marine Electronics Association) is the standard sentence format used by all GNSS receivers to output position, velocity, heading, and time data. Teltonika routers can forward NMEA sentences over a serial port (RS232 or RS485 on models with those interfaces) or over TCP/UDP to a network endpoint. This allows a router to feed position data directly into third-party fleet management systems, SCADA displays, or onboard vehicle navigation systems that accept NMEA input.

NMEA Collecting

The NMEA collecting function stores GNSS sentences locally on the router. The router can be configured to select which specific sentence types are forwarded or collected and at what update frequency. Supported sentence types depend on the modem module fitted; details are available on the Teltonika wiki for each model.

GPS Data in Data to Server

RutOS allows GPS coordinates to be included as a data source in the Data to Server pipeline. This means position data can be published via MQTT, HTTP, or other protocols to any cloud platform alongside Modbus readings, I/O states, and router system metrics. Every outbound payload can carry a timestamp and coordinates, creating location-aware telemetry with no additional hardware.

RMS Location Visibility

Devices with GNSS enabled and connected to the Teltonika Remote Management System (RMS) report their GPS position to the RMS dashboard. Fleet operators and network managers can see all devices on a map in RMS, track movement history, and set location-based alerts.

GNSS Antennas – Selection and Placement

GNSS signals are transmitted at low power from satellites approximately 20,000 km above the Earth. By the time they reach a ground-level receiver, the signal is extremely weak. Antenna selection and placement have a direct impact on the quality of the position fix, the time to first fix, and whether a fix is achievable at all in difficult environments.

The Dedicated GNSS Antenna Port

Every Teltonika router with GNSS capability has a dedicated SMA female connector labelled GPS or GNSS, separate from the cellular antenna ports. This port must have a GNSS antenna connected for the service to function. The cellular antennas on the adjacent ports cannot receive GNSS signals – the two systems operate on entirely different frequencies and use different receiver hardware inside the modem.

Antenna Types for Teltonika GNSS Applications

Placement Principles

The key requirement is an unobstructed view of the sky across as wide an arc as possible. GNSS satellites are distributed around the sky, and blocking low-elevation satellites reduces the number of visible satellites, which degrades accuracy and fix reliability.

• Vehicles: The roof is the ideal mounting point. A magnetic patch antenna on the vehicle roof has sky coverage in all directions and the metal roof acts as a ground plane. Avoid mounting near roof-mounted equipment that creates obstructions above 30 degrees elevation.
• Fixed enclosures outdoors: Mount the antenna on top of the enclosure or on a short mast above it. Do not mount on the side of a building or pole where half the sky is blocked.
• Fixed enclosures indoors: Run a cable to an external antenna mounted on the building exterior or on a window with good southern sky exposure in the northern hemisphere. GNSS signals do not penetrate concrete, brick, or metal roofs.
• Avoid interference sources: Keep the GNSS antenna physically separated from cellular antennas where possible. Cellular transmit power can desensitise GNSS receivers if the antennas are mounted directly adjacent. A separation of at least 20-30 cm is advisable on multi-antenna installations.
• Cable length: GNSS signal is weak, and long coaxial runs introduce loss. Most standard GNSS patch antennas include an integrated low-noise amplifier (LNA) to compensate for cable loss. Confirm the antenna spec supports the cable run length planned.

GNSS Use Cases on Teltonika Routers

Commercial Fleet Management

HGVs, vans, and light commercial vehicles carry a Teltonika router as the primary cellular gateway for the cab. The router publishes GPS position, speed, and heading via MQTT to a fleet management platform at configurable intervals. Geofences around depots, customer sites, and restricted zones trigger SMS or email alerts when crossed. All vehicle telemetry – including diagnostics from onboard equipment – is geo-tagged at source.

Construction Plant and Equipment Tracking

High-value plant – excavators, generators, pumps – moves between sites and is vulnerable to theft. A ruggedised router such as the RUTM55 or RUTM56, with its RS232 and RS485 interfaces, reads engine hours and operating data via Modbus while simultaneously publishing GPS position. A geofence alert fires if the machine leaves its permitted operating area outside working hours. The GNSS position is included in every Modbus data payload sent to the cloud platform.

Marine and Inland Waterway Vessels

Commercial vessels require AIS position reporting and onboard connectivity. A Teltonika router with GNSS provides the position data and forwards NMEA sentences to onboard navigation and AIS equipment. The cellular connection provides crew internet access and vessel monitoring. Multi-constellation support is particularly valuable at high latitudes where GLONASS adds satellite visibility.

Precision Agriculture

Autonomous and semi-autonomous agricultural machinery requires accurate position data for controlled application of inputs. RutOS 7.03 added NTRIP protocol support, allowing Teltonika routers with GNSS to stream correction data for Real Time Kinematic (RTK) positioning. RTK uses differential corrections from a ground reference station to achieve centimetre-level accuracy, which is the precision required for row-by-row autonomous seeding, spraying, and harvesting operations.

Utility Infrastructure Monitoring

Fixed water, gas, and electricity monitoring points use GNSS for two purposes: site identification in large distributed networks, and time synchronisation. Each sensor reading is time-stamped with GNSS-derived time, creating an accurate audit trail that is independent of network connectivity. The NTP001’s Stratum-1 GNSS time source provides microsecond-accurate synchronisation for protection relay systems in electrical substations where event timing is critical for fault analysis.

Cold Chain and Logistics Tracking

Refrigerated trailers and temperature-controlled vehicles need continuous location and environmental monitoring. A Teltonika router with GNSS publishes GPS coordinates alongside temperature sensor readings at every reporting interval. Geofences around loading docks and delivery points automate arrival and departure logging. If a trailer departs unexpectedly or diverts from a planned route, an alert is triggered immediately.

Emergency Services and Critical Response Vehicles

Command and control systems for emergency fleets require real-time vehicle positions with high update rates and resilient connectivity. A Teltonika router with dual SIM failover and GNSS provides continuous position reporting even when one network is congested. NMEA forwarding allows position data to feed directly into CAD (Computer Aided Dispatch) systems alongside the cellular data connection.

Teltonika Devices That Support GNSS

The table below lists all current Teltonika devices with GNSS capability, all of which are available from routerstore.com. All support GPS at minimum. Multi-constellation support (GLONASS, Galileo, BeiDou) depends on the specific modem module fitted – refer to the individual product datasheet or wiki page for confirmed constellation support on each model.

All models require a dedicated GNSS antenna connected to the GPS/GNSS SMA port. The antenna must have a clear view of the sky to obtain a fix.

Related Products and Further Reading

For vehicle and mobile deployments requiring GNSS with ruggedised M12 connectors, the ATRM50 is the purpose-built choice. For 5G fleet deployments with GNSS, the Teltonika 5G router range includes RUTM and RUTX series options with full GNSS support. For RS485 Modbus devices requiring location-tagged data, the TRB series gateways combine serial interfaces with GNSS in a compact DIN rail package. For sending GNSS data to cloud platforms, see our MQTT explainer. For remote management of GNSS-enabled devices, see the Teltonika RMS guide. For SIM connectivity suited to mobile deployments, see the IoT SIM connectivity hub.