To avoid collecting data during a geomagnetic storm, see NOAAs Space Weather Prediction Center, which issues geomagnetic storm alerts.
Convert Opus Files Software Which ComputesOPUS uses software which computes coordinates using the NOAA CORS Network (NCN).![]() Correctly selecting your antenna will help OPUS apply the appropriate antenna calibration model to counter the unique measurement biases inherent in each antennas design. Choosing an incorrect antenna may result in a height error as large as 80 cm and a horizontal error up to 1 cm. Enter the vertical height (in meters) of your Antenna Reference Point ( ARP ) above the mark. See antenna calibration for a drawing of the ARP for your antenna (usually the center of the base or tripod mount). Your OPUS solution will be sent to this address when processing is complete. Your coordinates are the average of three independent, single-baseline solutions, each computed by double-differenced carrier-phase measurements from one of three nearby CORSs. Rapid-static processing has stricter requirements for data continuity and geometry; in some remote areas of the country OPUS-RS may not work. To check if OPUS-RS is available in your location, see the OPUS-RS precision and availability map. However, estimating the accuracy for a specific solution is difficult because formal error propagation is notoriously optimistic for GPS reductions. User errors (such as misidentification of antenna or ARP height) cannot be detected. Local multipath or adverse atmospheric conditions may also negatively impact your solution. One advantage of peak-to-peak errors is that they include any error from the CORS (base station) coordinates. Our experiments indicate that the actual error is less than these estimated accuracies more than 95 percent of the time. For estimates of precision in your area, see the OPUS-RS Map. The figure below shows the correlation between session duration and accuracy. Please note: this figure is a result of a published regional study, and the performance of OPUS may be slightly better or worse in your geographic location. For details on this regional study, see Gillins, D.T., Kerr, D., and Weaver, B. Evaluation of the Online Positioning User Service for Processing Static GPS Surveys: OPUS-Projects, OPUS-S, OPUS-Net, and OPUS-RS, ASCE Journal of Surveying Engineering, 145(3): 05019002. ![]() Rapid orbits, available at 17:00 UTC the next day, may offer a slight improvement in your accuracy. ![]()
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