Performance of Stand-Alone GPS - Understanding GPS: Principles and Applications - page 371

June 8, 2000

3.5

3

2.5

2

1.5

1

0.5

0

− 90 − 80 − 70 − 60 − 50 − 40 − 30 − 20 − 10 0 10203040 50607080 90

Latitude (degrees south to north)

Ratio of single-frequency
vertical/horizontal RMS error statistics
Ratio of dual-frequency
vertical/horizontal RMS error statistics

ANALYSIS NOTES
- All-in-view position solution
- 5-degree mask angle
- Sampled every minute over 24-hour sample interval
- Global grid of 1,666 points equidistantly spaced
- Single-frequency error modeled using AFWA PRISM
database and IS-GPS-200 single-frequency algorithm

Vertical/horizontal error statistic ratio summary
Single frequency

Dual frequency

Global average 2.1 1.6

Worst site 6.4 2.4

Figure 7.33 Comparison of vertical/horizontal error ratios for single- and dual-frequency receivers.

A 2-year trend of dual-frequency PPS three-dimensional position error across
the globe is presented in Figure 7.34. 2 The demonstrated performance is consistent,
with global median 95% position errors trending to well below 5m over a 24-hour

2. Derived from GPS performance data posted daily on the DoD GPS Support Center's Web site (http://www.

schriever.af.mil/GPSSupportCenter).