Is my spot covered?
Type an address, city or ZIP code, or use your location. We'll show your state, the closest NOAANational Oceanic and Atmospheric Administration. The US agency that includes NGS and runs the CORS network.Full definition Base stationA GNSS receiver sitting still on a known spot. It figures out how wrong the satellite signals are right now and shares that as corrections.Full definition, and every correction service listed for that state.
Try "Harrisburg PA", "80202" or a full street address.
How far is too far?
RTKReal-time kinematic. A way to make GPS accurate to about an inch by getting live corrections from a nearby base station.Full definition works by comparing your receiver with a base station that knows exactly where it is. Both see the same satellites through the same air. The closer you are to the base, the more alike their views are, so errors cancel out. Farther away, the air and signals differ more, and error creeps in.
- Rule of thumb from NOAA's National Geodetic Survey: with a single base, keep your distance (the BaselineThe distance between the base station and your rover. Shorter is better for accuracy.Full definition) to 20 km (about 12 miles) or less. (NGS Single Base Real Time Guidelines v2.1)
- Spec sheets often say something like "8 mm + 1 ppmParts per million. In GPS specs, 1 ppm means 1 mm of extra error for every kilometer you are from the base.Full definition". The ppm part means about 1 mm of extra error for every km away. See baseline length and accuracy.
- Network RTK, like VRSVirtual reference station. The network blends nearby stations to create a pretend base right next to you, which keeps the baseline short.Full definition, uses many stations to model errors near you, so the nearest single station matters less.
- NOAA CORSContinuously Operating Reference Station. A permanent GPS receiver that records satellite data all day, every day.Full definition stations are free data stations. Many feed state networks, but most don't stream live RTK to the public. You can always use their files for PPK after the job.
Address lookup: US Census Geocoder, then OpenStreetMap Nominatim as a backup (© OpenStreetMap contributors). State detection: US Census. Your address goes only to those lookup services and isn't stored by FixFinder. Coverage lists come from operator pages; a state on a list doesn't promise coverage at your exact spot.