Product specifications

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We make a DOS-based RINEX translator available, however, RINEX has no facility to
store station information. Our translator is available by contacting technical support
at Hemisphere GPS.
Note: To assist you in your integration of the Crescent, we can equip you with
some code snippets to help you incorporate support for the Bin 95 and 96
messages within your software. If this is a need for your application, please
contact your representative at Hemisphere and we will assist you further.
E VALUATING C RESCENT V ECTOR P ERFORMANCE
As mentioned earlier, Hemisphere GPS evaluates performance of the Crescent Vector
module with the objective of determining best-case performance in a real-world
environment. Our static testing has shown that the Crescent achieves DGPS
positioning performance better than one meter 95% of the time.
The qualifier of 95% is a statistical probability. Often you may see manufacturers
using a probability of ‘rms’ or standard deviation. Performance measures with these
probabilities are not directly comparable to a 95% measure since they are a lower
probability (less than 70% probability).
The following table summarizes the common horizontal statistical probabilities.
Table 2-1. Horizontal Accuracy Probability Statistics.
Accuracy Measure Probability (%)
Rms (root mean square) 63 to 68
CEP (circular error probability) 50
2drms (twice the distance root mean square) 95 to 98
R95 (95% radius) 95
It’s possible to convert from one statistic to another using the following table. Using
the value where the ‘From’ row meets the ‘To’ column, multiply the accuracy by this
conversion value.
Table 2-2. Horizontal Accuracy Statistic Conversions.
To
CEP rms R95 2drms
CEP 1 1.2 2.1 2.4
rms 0.83 1 1.7 2.0
R95 0.48 0.59 1 1.2
From
2drms 0.42 0.5 0.83 1
For example, if Product A after test results in an accuracy of 90 cm 95% (R95) and
you want to compare this to Product B that has a sub-meter horizontal rms
specification, select the value from where the ‘R95’ row and the ‘rms’ column
intersect (to convert to rms).
You will see that this conversion value is 0.59. Multiply the 90 cm accuracy by this
conversion factor and the result will be 53 cm rms. If you now compare this to