Wavecom PXGF streaming format (GEW) V1.24 - Manual (Page 13)

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GSY-0D8-SE RESTRICTED Interface Requirement Specification for PXGF Streaming and File Format
3.4.8 dBTotal Gain – dBTG chunk
Element Type Description
fGain_dB float32 The total analogue gain from the input of the receiver
(usually an antenna) to the input of the ADC.
Table 3.9: The dBTG chunk
3.4.9 IQ DisContinuity – IQDC chunk
This chunk should be sent as indicator to the reading application to reset it's history. Discontinuities
may be caused by samples being dropped, changes in sample rate, changes in bandwidth, changes in
centre frequency or changes in receiver gain. In systems where continuous data is expected from a
stream an IQDC chunk should not be expected unless a parameter change has forced a discontinuity.
In some applications it may be necessary to send an IQDC chunk if the writing application doesn't
support the necessary chunk to identify an obvious discontinuity, for instance if CF__ chunks were not
supported but it was known that the centre frequency had changed an IQDC chunk could be send.
This chunk has zero size.
Element Type Description
N/A N/A N/A
Table 3.10: The IQDC chunk
3.4.10 Single channel Short Real data - SSR_ chunk
Data is assumed to be continuous when using this data format, if the data is blocky, an IQDC chunk
should be sent after every block of continuous data. This chunk can be used to send audio data.
Element Type Description
lTimestamp int64 The timestamp is stored as a 64 bit signed number,
representative of the time of capture of the first sample in the
chunk block, in microsecond resolution. It is stored as the
number of microseconds since beginning of the epoch (i.e. 1st
January 1970 midnight).
awRealData int16[length of
real data array].
The length of the
array must be a
multiple of 2. Real 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 number of
real int16 shorts in the array must be a multiple of 2.
Table 3.11: The SSR_ chunk
3.4.11 Group Short IQ time data – GSIQ chunk
The Group IQ chunk came out of the need to send multiple channels worth of time data sampled from
several adjacent channels in the frequency domain. These channels are often slightly overlapped in
the frequency domain and can be used to create FFT information of a wider bandwidth than what is
contained in a single channel.
Data is assumed to be continuous when using this data format, if the data is blocky, an IQDC chunk
should be sent after every block of continuous data.
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2009-01-13 RESTRICTED Page 12
Issue 1.24