Spherefix SP20 RTK GNSS Rover Base Set with Controller

A Complete Local RTK Rover and Base Solution

The Spherefix SP20 Rover and Base Set gives surveyors and construction teams the equipment needed to create their own local RTK correction link. One SP20 receiver is positioned over a known or calculated base coordinate and transmits correction data to the second SP20, which is carried around the site as the rover.

This arrangement is particularly useful on projects where a mobile RTK network is unavailable, coverage is inconsistent or the team prefers to operate an independent base station. It is suitable for construction stakeout, topographic and cadastral surveying, site control, utility mapping, earthworks, as-built measurement, GIS data collection and drone ground-control surveys.

Two Identical SP20 GNSS Receivers

The system uses two multifunctional Spherefix SP20 receivers rather than a restricted base-only unit. Each receiver can be configured for rover, base or static operation, giving the equipment more flexibility between projects.

Crews can use the two receivers as a conventional base-and-rover pair, operate either unit as a network rover or use one receiver for static observations. This interchangeable design also simplifies equipment management because both receivers use the same controls, batteries, communication options and configuration interface.

1,408-Channel Multi-Constellation Tracking

Each SP20 has a 1,408-channel GNSS board that tracks signals from GPS, GLONASS, BeiDou, Galileo, QZSS, SBAS and NavIC. Multi-frequency and multi-constellation tracking gives the receiver access to a larger number of satellites when calculating its position.

In real fieldwork, this can improve satellite geometry and help the system maintain a usable RTK solution when part of the sky is blocked by buildings, site machinery or vegetation. As with every GNSS system, the best performance is achieved with a clear view of the sky and a stable correction connection.

Centimetre-Level RTK Positioning

With suitable correction data and field conditions, the SP20 has a stated RTK accuracy of ±(8 mm + 1 ppm) horizontally and ±(15 mm + 1 ppm) vertically. This level of positioning supports detailed survey and construction tasks where ordinary standalone GPS is not sufficiently accurate.

Construction workers can use the system to set out foundations, drainage, utilities, roads and structural points from digital coordinates. Surveyors can collect topographic detail, establish local site control, check finished work and perform cadastral measurements. GIS crews can record accurate asset locations, while drone operators can measure ground control points and independent checkpoints for aerial mapping.

IMU Tilt Measurement for Difficult Points

The SP20 includes calibration-free IMU tilt compensation through an inclination of up to 60°. Instead of holding the survey pole perfectly vertical, the operator can lean the pole while the receiver calculates the position at the pole tip.

This is useful when measuring beside walls, beneath overhangs, at building corners, close to fences or around open excavations. It can also reduce the time spent centring the bubble at every point, helping both experienced surveyors and construction crews work more efficiently.

The specified tilt-positioning accuracy is within 2 cm across the supported tilt range under suitable conditions. Satellite geometry, movement, magnetic interference and the quality of the RTK solution can still affect field results.

Built-In UHF Base-to-Rover Communication

Each SP20 contains a 410–470 MHz UHF radio. When one receiver is configured as the base, it can transmit correction messages directly to the rover using a compatible radio protocol and channel.

The internal radio supports selectable transmission power of 0.5 W or 1.5 W. Actual working range depends on antenna height, terrain, buildings, vegetation, radio interference and local regulations. Raising the base station on a tripod and maintaining a clear path between the base and rover generally improves radio performance.

Supported radio settings and protocols allow the system to be configured for different field requirements and compatible equipment. Users must select frequencies and transmission power that comply with the radio regulations in the country where the equipment is operated.

Network RTK and Mobile Data Support

The receivers also include an internal 4G modem. This allows an SP20 to receive internet-based corrections from an NTRIP or CORS service when a suitable subscription and mobile connection are available.

Teams can therefore switch between a local radio base and network RTK according to the project. A local base is useful in remote areas or on long-running sites, while network RTK can reduce setup time when reliable coverage and a suitable correction service are available.

C100T Android Survey Controller

The included Spherefix C100T controller is designed for outdoor survey data collection. It runs Android 11 on an eight-core 2.0 GHz processor and provides 4 GB of RAM with 64 GB of internal storage.

Its 5.45-inch touchscreen is designed to remain readable in bright sunlight. Physical navigation, number and function keys provide an alternative to touchscreen-only operation, which is practical when entering point numbers, codes and heights repeatedly or when working with gloves.

The controller supports 4G, Bluetooth, dual-band Wi-Fi and NFC. Bluetooth is normally used to connect the controller to the rover, while mobile connectivity can support NTRIP corrections, cloud data transfer and communication with the office. A 13-megapixel rear camera can be used to document measured assets and site conditions.

Base Station Setup in the Field

For local RTK work, the base receiver is normally mounted securely on a tripod over a known control point or started using a suitable calculated coordinate. The antenna height and base coordinates must be entered correctly because any error in the base position is transferred to every rover measurement.

Once the base has started transmitting corrections, the rover receives the data through its internal UHF radio. The operator can then use the C100T controller to measure points, perform tilt surveys, stake out coordinates, localise the project and export completed field data.

The base must remain stationary throughout the survey. Moving the base, changing its antenna height or entering an incorrect coordinate can shift the complete dataset.

Flexible Surveying and Stakeout Workflows

The SP20 system supports point surveying, tilt surveying, point stakeout, localisation, control-point calibration and static data recording. These workflows allow the same set to serve multiple teams and project stages.

During stakeout, the controller guides the operator towards the required design coordinate. For topographic work, measured points can be stored with codes and descriptions for later use in CAD, GIS or survey-processing software. Localisation tools allow site coordinates to be related to the required project grid when suitable control points are available.

Long Battery Endurance

Each SP20 contains a 9,600 mAh internal battery. The stated endurance is more than 16 hours during typical GSM rover use, while static collection can run for up to 24 hours under the stated conditions.

The C100T controller uses a 9,000 mAh battery and offers up to 18 hours of operation. Actual battery life will depend on radio transmission power, mobile data, screen brightness, temperature, satellite conditions and the way the equipment is configured.

Lightweight and Protected for Outdoor Work

The SP20 weighs approximately 740 g and uses a magnesium-alloy main body. Its low receiver weight reduces strain during long periods of pole-mounted surveying and makes the complete set easier to transport between sites.

The receiver is IP68 rated for resistance to dust and water ingress and is designed to withstand a 1.5 m pole drop at room temperature. Its specified operating range extends from -20°C to +60°C. Protective covers and ports must remain correctly closed to maintain environmental protection.

The C100T controller also carries an IP68 rating, helping it withstand normal construction, surveying and mapping conditions. As with all precision equipment, both the receivers and controller should still be transported in their protective cases and inspected after significant impacts.

Suitable for Independent and Remote Survey Work

A rover-and-base system is a practical choice for teams that frequently work outside established RTK network coverage. It gives the operator direct control over the correction source and removes the need for a continuous internet connection between the base and rover when UHF radio is used.

The same system can also be used on urban projects where a site-specific base is preferred for consistent local control. Because both receivers support 4G and radio workflows, crews are not limited to one correction method.

Configuration and Support from Global GPS Systems

Global GPS Systems supplies the Spherefix SP20 Rover and Base Set for surveyors, construction companies, engineering teams, GIS professionals and drone operators who need an independent RTK solution.

Our team can help match the system to the required field software, coordinate workflow, survey pole, tripod, tribrach and radio configuration. Support is also available when deciding between a local base station, an NTRIP correction service or a workflow that uses both methods.

Correct base coordinates, antenna heights, radio settings and project coordinate systems are essential for dependable results. Choosing a properly configured set helps crews integrate measured data into existing CAD, construction, GIS and mapping workflows.