=============================== iqdef.txt ===================================
This file defines the columns of data in the iq.log files produced by the GRID
software receiver.  The iq.log files contain high-rate in-phase and quadrature
symaccumulation and beat carrier phase 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 channeldef.txt for definitions of RRT and ORT.  Time stamps in
RRT and ORT correspond to the end of the interval over which each in-phase and
quadrature accumulation was computed.
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Column        Quantity

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

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

3 ----------- ORT week number. 

4 ----------- ORT whole seconds of week.

5 ----------- ORT fractional second. 

6 ----------- Beat carrier phase in cycles at the specified RRT and ORT;
              changes in the opposite sense as pseudorange but is consistent
              with the IQ data so that the instantaneous high-rate beat
              carrier phase is this quantity plus atan2(Q,I)/2/pi.

7 ----------- In-phase symaccumulation over the interval ending at the
              specified RRT and ORT, in receiver front-end units.  If the
              signal is data modulated, then the data bit modulation has been
              wiped off assuming the data bit value below.

8 ----------- Quadrature symaccumulation over the interval ending at the
              specified RRT and ORT, in receiver front-end units. If the
              signal is data modulated, then the data bit modulation has been
              wiped off assuming the data bit value below.

9 ----------- Data symbol (0 or 1) assumed by the phase tracking algorithm to
              be in effect over the symaccumulation interval ending at the
              specified RRT and ORT.  For data-free signals (e.g., pilot
              signals) this value is set to 1.

10 ---------- Signal type (see channeldef.txt for list of possible types).

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

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