This file defines the columns of data in the navsol.log files produced by the
GRID software receiver. Each navsol.log file contains time-stamped navigation
solutions that represent the receiver's best estimate of position, velocity,
receiver clock error, and receiver clock error rate as calculated from data
provided by all participating receiver banks.  Offset receiver time (ORT) time
stamps indicate the time at which the navigation solution applies, according to
receiver time.  Note that GRID automatically adjusts ORT periodically to bring
it within a few ms of true GPS time.

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Column        Quantity

1 ----------- ORT week number. 

2 ----------- ORT whole seconds of week.

3 ----------- ORT fractional second. 

4,5,6 ------- X,Y,Z receiver antenna position expressed in meters the ECEF
              reference frame.

7 ----------- deltR, the receiver clock error expressed in equivalent meters.
              True GPS time (TGT) is related to deltR by TGT = ORT - deltR/c.

8,9,10 ------ Xdot,Ydot,Zdot receiver antenna velocity relative to the ECEF
              reference frame expressed in meters per second in the ECEF frame.
              These velocities are the time derivatives of X, Y, and Z with
              respect to deltR.

11 ---------- deltRdot, the receiver clock error rate expressed in equivalent
              meters per second.

12 ---------- Flag returned from the navigation solver:
              0   SOL_NO_FIX
              1   SOL_PRELIMINARY_FIX
              2   SOL_STANDARD_FIX
              3   SOL_PRECISE_FIX

13 ---------- NISratio: ratio of normalized innovation squared statistic to
              the total number of measurements. If the estimator is tuned
              properly, this ratio should be near unity.  If it's low (high),
              then the assumed measurement and/or process noise is too
              conservative (optimistic).

14 ---------- Signal Group associated with navigation solution: 0 for the
              primary antenna, 1 for the ALT1 antenna, etc.  A value of -1
              indicates an invalid identifier.

15-22 ------- Diagonal elements of the error covariance matrix corresponding to
              the state vector [rG; deltRMeters; deltRDotMps; vG], where rG is
              the receiver position in ECEF meters, deltRMeters is the receiver
              clock error expressed in equivalent meters, deltRDotMps is the
              receiver clock error rate expressed in equivalent meters per
              second, and vG is the receiver antenna velocity relative to ECEF
              and expressed in meters per second in ECEF.
              
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