This file defines the columns of data in the iqtaps.mat files produced by the
GRID software receiver.  The iqtaps.log files contain symaccumulation-length
in-phase and quadrature symaccumulation data. A symaccumulation is a coherent
accumulation that is time-aligned with data modulation (if any) and of length
equal to the minimum of the symbol interval and the standard accumulation
interval. See channel.txt for a definition of RRT.  Time stamps in RRT
correspond to the end of the interval over which each in-phase and quadrature
symaccumulation was computed.

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Column            Quantity

1 --------------- RRT week number.

2 --------------- RRT seconds of week.

3 --------------- Signal GenericType. See signaltype.h for GenericType values.

4 --------------- Transmitter identification number (TXID).

5 --------------- Signal Group.

i=6,...,N+5 ----- In-phase symaccumulation corresponding to the ith tap of N
                  total taps over the interval ending at the specified RRT, in
                  receiver front-end units. If the signal is data-bit
                  modulated, then the data bit modulation has been wiped off
                  assuming the corresponding data bit value given in iq.log.

i=N+6,...,2*N+5 - Quadrature symaccumulation corresponding to the ith tap of N
                  total taps over the interval ending at the specified RRT, in
                  receiver front-end units.  If the signal is data-bit
                  modulated, then the data bit modulation has been wiped off
                  assuming the corresponding data bit value given in iq.log.

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