Wavecom PXGF streaming format (GEW) V1.24 - Manual (Page 14)

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GSY-0D8-SE RESTRICTED Interface Requirement Specification for PXGF Streaming and File Format
Element Type Description
lTimestamp int64 The timestamp of the first sample in microsecond
resolution, this is the number of microseconds since
beginning of the epoch
awIQData int16[(length of the
group IQ data
array] IQ pairs of signed int16 short numbers. Note that
regardless of the number of valid bits, the most
significant bits in each short should be used. This
allows us to specify the full-scale level without needing
to
specify the number of bits.
The packing used is described by the GIQP chunk.
Table 3.12: The GSIQ chunk
3.4.12 Group IQ Packing - GIQP chunk
Since the GSIQ chunk supports many variations in contents, the content specific information is
supplied by the GIQP chunk, and is required to parse the chunk correctly.
Element Type Description
iNumChannels int32 The number of channels in the group
iIsIQPacked int32 Value 1 for IQ ordering and value 0 for QI ordering. The
first int 16 in the awIQData array mentioned above is
an “I” sample if the value is 1.
iIncrement int32 The number of samples to increment to read the next
sample for a particular channel. The value of
iIncrement will be 1 or iNumChannels.
aiChannelOffset int32[iNumChannels] The channel offset to the start of each channel given in
samples where a sample is an IQ pair.
Table 3.13: The GIQP chunk
Examples:
Take a stream which contains 4 channels of IQ data A,B,C and D. If the data were packed as follows
(where N = number of samples per channel):
• A[0] A[1] A[2] ... A[N-1] B[0] B[1] B[2] ... B[N-1] C[0] C[1] C[2] ... C[N-1] D[0] D[1] D[2] ... D[N-1]
For this packing scheme: iIncrement = 1 and aiChannelOffset = [0 N 2N 3N]
• A[0] A[1] A[2] ... A[N-1] B[0] B[1] B[2] ... B[N-1] D[0] D[1] D[2] ... D[N-1] C[0] C[1] C[2] ... C[N-1]
For this packing scheme: iIncrement = 1 and aiChannelOffset = [0 N 3N 2N]
• A[0] B[0] C[0] D[0] A[1] B[1] C[1] D[1] A[2] B[2] C[2] D[2] ... A[N-1] B[N-1] C[N-1] D[N-1]
For this packing scheme: iIncrement = 4 and aiChannelOffset = [0 1 2 3]
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2009-01-13 RESTRICTED Page 13
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