GNSS Services

Following is a description of the structure of our GPS Network and some benefits to subscribers of our RTK and/or CORS data.

The Network when complete will be comprised of 14 reference stations spaced out at between 20 and 60 km intervals over the geographical area shown on our coverage map.

GPS antennas that we mount on buildings have a clear view of the sky, are minimally obtrusive (only about 8" diameter) and are mounted on stainless steel GPS/CORS Tribrachs especially made for this purpose. The tribrachs are then attached to a 1.5"- 3" vertical steel pipe that typically does not rise more than 4 ft above the parapet. The antennas are connected via coaxial cable (with lightning arrestor) to the GPS receiver mounted on a wall inside the building. The GPS receiver has a dedicated electrical outlet and a UPS to provide uninterrupted power. The receiver is connected to a dedicated network connection for access to the internet. All abovementioned GPS receiver components (except GPS antenna and cable) are securely enclosed in a steel electrical box that is locked to prevent tampering and to provide clean and functional housing.

The RTK corrections, for real-time solutions, collected by each reference station are streamed, via the internet, to a central server in Salisbury, MD. Once a subscriber dials into this server via cell phone modem, using either IP or NTRIP protocols, the TopNET RTK software checks the position of the user and chooses the closest reference station to them, as to provide the most accurate results. The subscriber can also choose from several ports to select the preferred correction format such as RTCM 2.3, CMR, etc... (see current list on Services Page).

In addition, raw data (CORS) from each reference station is streamed to a server in Southern Delaware, every hour on the hour, where it is stored for a minimum of 6 months and backed up each day. This data is available for post processing of static GPS data by subscribers.

TOPCON Network GPS benefits:

  • Real-time survey grade GPS corrections via internet for users dialing into network with their own RTK GPS receivers.
  • Expanded use of RTK equipment beyond current radio communication limits with the use of cell-phone technology.
  • Ability to output GIS corrections to hand-held GPS units improving real time accuracy.
  • Improved efficiency by eliminating base GPS setup. No stationary GPS receiver needed for RTK survey anymore.
  • Lowers expenses for GPS survey by only requiring one GPS receiver with a cell phone modem (approximately 50% reduction in equipment expenses).
  • Shortens preparation and setup time; makes GPS surveying less cumbersome to operate in the field.
  • Raw files in TPS (Topcon Positioning System) format for post-processing, a free RINEX converter is provided.
  • Continuous tracking of both GPS and GLONASS constellations
  • Ability to utilize signal for machine-controlled construction and agricultural equipment.