1 / 11

By Paul Bolstad, et al. Northern Journal of Applied Forestry. 2005. 22(1):5-11

Some notes from: “ A Comparison of Autonomous, WAAS, Real-Time, and Post-Processed Global Positioning Systems (GPS) Accuracies in Northern Forests ”. By Paul Bolstad, et al. Northern Journal of Applied Forestry. 2005. 22(1):5-11 . Receiver types by accuracy.

mike_john
Download Presentation

By Paul Bolstad, et al. Northern Journal of Applied Forestry. 2005. 22(1):5-11

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Some notes from: “A Comparison of Autonomous, WAAS, Real-Time, and Post-Processed Global Positioning Systems (GPS) Accuracies in Northern Forests” By Paul Bolstad, et al. Northern Journal of Applied Forestry. 2005. 22(1):5-11 GPS Accuracy in Northern Forests

  2. Receiver types by accuracy • Survey grade – cm or less. (carrier based signals) • “Course acquisition” or C/A code receivers. Smaller, lighter, less expensive, don’t require open sky conditions. • C/A receivers range from a few feet (sub-meter) to several tens of feet (5 to 10 meters). • Manufacturer reported accuracy may be optimistic or might be the expected accuracy. GPS Accuracy in Northern Forests

  3. Improving GPS accuracy • Improvements in hardware and software • Differential correction • Altering data collection methods GPS Accuracy in Northern Forests

  4. Differential correction types • Post-processed. • Real-time. Coast Guard or other beacons. • WAAS GPS Accuracy in Northern Forests

  5. What they tested • Accuracy evaluation of two inexpensive, WAAS capable receivers and three differential-capable receivers. • Quantify the realized accuracy to establish average accuracy of WAAS receivers relative to non-WAAS receivers in open and forest conditions. GPS Accuracy in Northern Forests

  6. Testing, continued • Establish the frequency distribution of errors for a single fix. • Quantify the relationship between the number of fixes averaged for a point and positional accuracy. • To measure how often WAAS corrections are available under a forest canopy. GPS Accuracy in Northern Forests

  7. Methods • Collecting positions at three known open positions and three known forest locations. • Comparing GPS-measured positions to “true” positions. • Very detailed and specific conditions used to standardize measurement. GPS Accuracy in Northern Forests

  8. Measuring Sites • Open positions in agricultural fields or along roadways. • Forest points had more than 70% sky obstruction. GPS Accuracy in Northern Forests

  9. Measuring Process • Very detailed set of measuring procedures. • Detailed set of repetitions. • Detailed set of statistical tests applied. GPS Accuracy in Northern Forests

  10. Some Results • No statistically significant differences under open locations. • Significant differences in the mean positional error due to receiver type under forest canopies. • Recreational accuracies much less consistent than GIS receivers with higher frequencies of large errors. GPS Accuracy in Northern Forests

  11. Results continued • In subcanopy conditions WAAS signals available between 8 (moving) and 23 (stationary) % of the time for the recreational receivers. • And for GIS receivers 22 (moving) and 33 (stationary) % of the time. • Hand-held GPS did have the fewest interruptions in forest canopy conditions. GPS Accuracy in Northern Forests

More Related