PolyQuick Description

PolyQuick is a purely geometric (e.g. no orbit determination) rapid performance analysis tool used in both co-location and benchmarking data reduction algorithms (e.g. normal point generation, new data processing techniques). In co-location, PolyQuick intercompares quasi-simultaneous ranges from two systems to the one millimeter level with the following assumptions:

  • The co-locating systems must be within 600 meters of each other.
  • There is an accurate (one millimeter in all components) relative survey tie between the systems.
  • The elevation and azimuth angle accuracy of the "standard" system is better than 1 millidegree. Note: This can be achieved by using computed angles.

The required input data set for co-location analysis is quasi-simultaneous fullrate data (ranges and angles) sorted by satellite and time plus the relative coordinates between the two systems. Using this information, PolyQuick analyzing the co-location data a pass at a time. First, the "standard" system ranges from each pass are geometrically translated to the "test" system. These translated ranges will be smoothed (i.e. outliers identified and removed) using a least squared polynomial. The accepted residuals will be binned and then averaged. Next, using the same least squared polynomial, range residuals will be formed and smoothed for the "test" system. The "test" system accepted residuals will also be binned and then averaged. Next, the mean binned residuals from both systems will be differenced. A mean offset will be computed for each collocated pass. These binned differences and mean pass offsets will be stored and aggregated for the entire co-location data set.

Next, these binned differences and pass mean offsets will be analyzed for trends (e.g. short term bias stability, long term bias stability, azimuth, elevation, range, range-rate, system delay correlation). The possible root cause of any systematic errors using trend analysis can usually be quickly identified through process of elimination coupled with a detailed knowledge and understanding of the system(s) capabilities.

PolyQuick can also be used to benchmark new normal point or data processing techniques by using the data from the new processing software system and comparing it to the old processing software system. In this specialized co-location, the two systems are at exactly the same location and may be truly simultaneous, the only difference is the data processing. The only pre-requisite needed here to perform the analysis is the data from the two different processing systems are uniquely identified.