Spherefix SP35Pro RTK GNSS Rover and Base Set

Independent centimetre-level RTK surveying

The Spherefix SP35Pro Rover and Base Set gives field crews the equipment needed to create a local RTK correction link. One SP35Pro receiver is installed over a known or newly established point and configured as the base, while the second receiver is used on the survey pole as the rover. The included C100T Android controller is used to configure the system, collect points, stake out designs and manage field data.

This workflow is useful on sites where a commercial RTK network is unavailable, mobile coverage is unreliable or the project requires direct control over the base position. It is well suited to land surveying, construction layout, earthworks, road projects, infrastructure measurement and GIS data collection.

Two matching SP35Pro GNSS receivers

The set uses two identical SP35Pro receivers rather than a restricted base unit and a separate rover model. This gives crews more flexibility when planning their work. Either receiver can be assigned to the base or rover role, and the equipment can also be used in network RTK or static data-collection workflows when required.

Each receiver weighs approximately 770 g, making the rover comfortable to carry during long survey sessions. The compact design also makes the base equipment easier to transport between projects.

Local corrections through the integrated radio

Each SP35Pro contains a 410–470 MHz transceiver with selectable 0.5 W and 1.5 W power. In a typical base-and-rover setup, the base receiver calculates correction data and transmits it directly to the rover through the integrated radio.

This removes the need for a separate external radio in many standard surveying situations. It also allows the system to continue working in areas without dependable mobile internet, provided that the base and rover have a suitable radio link and the selected frequencies are permitted in the country of use.

Actual radio range depends on the terrain, antenna height, interference, local regulations and obstacles between the receivers. Positioning the base in a clear and elevated location generally provides a more stable connection than placing it close to buildings, machinery or dense vegetation.

Network RTK when a local base is not required

The SP35Pro also includes 4G connectivity for receiving corrections from compatible NTRIP and CORS services. This means the rover can be used independently with a correction network when coverage is available, while the second receiver remains available for another task or project.

Wi-Fi supports receiver configuration and visual data transfer, while Bluetooth provides a practical connection to the C100T controller. NFC is available for compatible identification and connection workflows.

Photogrammetry for inaccessible features

The SP35Pro incorporates a wide-angle photogrammetry camera that works with the receiver’s GNSS positioning and inertial sensors. This allows the operator to collect visual information for points that are difficult, unsafe or inconvenient to occupy directly with the pole.

Examples include building corners, façades, trench edges, features behind fences, roadside objects and utility assets surrounded by obstructions. In these situations, photogrammetry can reduce the need to physically place the pole tip on every required feature.

The visual measurement workflow is intended to complement conventional RTK observations. Measurement quality still depends on correct field procedure, suitable image capture, the surrounding environment and the software used to process the observation.

AR real-scene stakeout

A dedicated camera supports augmented-reality stakeout by displaying navigation information over a live view of the site. Instead of relying only on arrows and numerical distances, the operator can see the direction of the design point in relation to the actual surroundings.

This can make construction layout and utility marking easier to understand, particularly when moving between many stakeout points or working on large open sites. The visual guidance helps the user approach the target efficiently before making the final precise adjustment.

Survey with the pole tilted

The integrated IMU provides tilt compensation through an angle of up to 60°, with a stated positioning error of less than 2 cm within that range. The survey pole therefore does not need to remain perfectly vertical for every point.

This is useful beside walls, under vegetation, near site machinery and around other obstacles that prevent the pole from being positioned vertically over the feature. Tilt compensation can also speed up routine topographic collection by reducing the time spent levelling the pole before each observation.

Full-constellation GNSS tracking

Each receiver uses 1408 channels to track signals from GPS, GLONASS, BeiDou, Galileo, QZSS, SBAS and NavIC across multiple frequencies. Access to several satellite constellations improves the number of signals available to the receiver, which can support better positioning availability when part of the sky is obstructed.

The stated RTK accuracy is ±(8 mm + 1 ppm) horizontally and ±(15 mm + 1 ppm) vertically under suitable operating conditions. The receivers support RTCM 3.x correction data and an update rate of up to 20 Hz.

Real-world accuracy depends on the quality of the base coordinates, satellite geometry, baseline length, radio or internet connection, multipath and the surrounding environment. A carefully established base position is important because any error in its coordinates will also affect the rover results.

C100T Android survey controller

The C100T controller provides a 5.45-inch sunlight-readable touchscreen together with a physical keyboard. This combination lets operators use touch controls for mapping and menus while retaining hardware keys for data entry and operation in wet or cold conditions.

Its eight-core processor, Android 11 operating system, 4 GB of RAM and 64 GB of storage provide a suitable platform for compatible GNSS field software. The controller also includes a 13 MP rear camera, Wi-Fi, Bluetooth and mobile-network connectivity.

A 9000 mAh battery provides up to 18 hours of stated operating time. The IP68-rated housing is designed for regular outdoor use on construction sites, roads and survey projects.

Designed for demanding field environments

The SP35Pro receiver combines a magnesium-alloy body with a protective plastic top cover. It is IP68 rated, has a specified operating-temperature range from −30°C to +65°C and is designed to withstand a 2 m pole drop at room temperature.

Each receiver contains a 6500 mAh battery that provides more than 16 hours of typical rover operation using GSM. USB Power Delivery charging allows the equipment to be charged with compatible mains, vehicle and portable power solutions.

Practical applications

The Spherefix SP35Pro Rover and Base Set is suitable for projects that require repeatable RTK positioning over a local working area. Common applications include:

• Topographic and cadastral surveying
• Construction layout and as-built measurement
• Earthworks, grading and volume surveys
• Road, rail and infrastructure projects
• Utility mapping and GIS asset collection
• Surveying in areas without reliable network RTK coverage

Choosing between network RTK and a rover-base set

A single network rover is often sufficient when a dependable correction service and mobile connection are consistently available. A rover-and-base set is more appropriate when crews work in remote areas, require an independent correction source or need to establish project-specific site control.

Because both SP35Pro receivers can fulfil several roles, the set can also support mixed workflows. A crew may use local radio corrections on one project and operate one or both receivers through an RTK network on another.

Configuration and support from Global GPS Systems

Global GPS Systems can help configure the Spherefix SP35Pro Rover and Base Set for the intended survey software, coordinate system, radio protocol and country of use. Radio frequencies and permitted transmitter power differ by region, so these settings should be confirmed before field deployment.

The correct accessories and working method also depend on whether the base will be positioned over known control, established through an averaged position or coordinated through a separate survey process. Matching the equipment and setup procedure to the required accuracy helps ensure dependable results in daily fieldwork.