GCS Base Station

What is the purpose of a base station?

A GCS base station makes highly accurate GPS data possible by measuring and correcting errors in positional information from satellites. A base station on a job receives the same satellite data as a rover (a machine with GPS equipment). If the GPS data indicates that the base station is moving, it uses that apparent movement to broadcast a correction (since the base station cannot move) to the rovers in the field. This correction is what makes possible tolerances suitable for construction with GPS data.

Just how accurate is GPS data with GCS software?

Actual accuracy on site is dependent upon the type of GPS equipment used, reception conditions and satellite coverage. The greater number of satellites in the sky that are available, the greater the percentage of time accurate data possible. The number of satellites receivable overhead varies, since satellites fly in asymmetrical orbits around the earth and the surface of the earth is uneven, interfering with line of sight. Contact with five or more satellites is adequate to get quality data most of the time. With only four in contact with the base station or rover (any machine/ATV using GPS), survey quality data may not always be available.

Some of our customers report an average of +/- .005 ft (0.015m) accuracy, but others have reported accuracy up to +/- .001 ft (.003m). By contrast, uncorrected GPS data is only accurate to +/- 9.8 ft (3.0m).

How will my fleet of equipment save money with a base station?

Error correction is broadcast one way, via radio, to the rovers (machines/ATVs using GPS). One base station can support as many rovers as are in range of the base station. This reduces the cost of driving several machines with GPS equipment.

Why is a GPS system with a base station better than my current positioning equipment?

A GPS-equipped base station does not need to be relocated as often as optical positioning equipment, such as a robotic transit or rotating laser. The fact that the base station communicates via radio makes it much less vulnerable to line of sight interruptions. Depending on the radio used, some base stations communicate effectively in a five mile radius. GPS technology is solid-state, and has no delicate exposed components. As such, GPS better withstands operation in dirty and harsh conditions than optical positioning equipment.

The rugged, water-resistant design of the base station protects the equipment from harsh conditions. Since the GCS base station is powered by GPS technology, it can operate fully in many kinds of poor weather that would cause a delicate optical system to fail. Our customers have used GPS in rain, snow, dust, high winds and fog. With GCS positioning control and GPS, job operation is not at the mercy of the weather.

How can I achieve even more accurate data?

If the job requires greater accuracy than what GPS can provide, GPS equipment can be coupled with a rotating laser and mast. The GeoSite Manager System module GCS: Base integrates laser data with GPS to provide even greater vertical accuracy. However, the level of improvement depends upon the accuracy of the laser and laser receiver a customer decides to use.

GCS: Base uses the plane created by a rotating laser as a vertical reference, supplementing the accuracy of GPS. Curved and banked surfaces are easy for the software to create, even with a laser (which is one-dimensional) because incorporating GPS makes the data 3-D. No longer will vertical or horizontal curves be made of flat sections.

Are there any downsides to using a GPS with a rotating laser?

Incorporating a rotating laser makes your system vulnerable to a host of laser shortcomings. Lasers require line of sight with any machine they communicate with. Any obstructions, such as a person, a vehicle, the landscape or particulates in the air can interrupt communication. Rotating lasers must be moved and reset if line of sight is obstructed. Additionally, laser masts on construction equipment have a fixed length. If the machine moves out of the vertical range of the mast and laser, the laser will have to be moved to continue working. One can get around this problem by setting up more than one laser in a stack.

Will my operation require the added accuracy of a rotating laser?

Many customers use GPS exclusively for their work. For example, pipelaying, landfill compacting, bulldozing and grading are unlikely to need a laser. Certain tasks utilizing machine control may require a laser, such as operating a trimmer.

What if satellite reception is poor or unavailable on the job?

If your job involves tunnel work, work under a bridge, work in an "urban canyon" (where surrounding tall buildings reflect satellite signals) or work in a large building, GPS will not work. Although GCS sells majority of its systems to work with GPS equipment, GCS software does support robotic transits and lasers, which are not dependent upon contact with satellites. For a comparison of the advantages and disadvantages of using various positioning equipment with GCS software, click here.

GeoSite Manager System module GCS: Base

Positional Equipment Comparisons

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