Wavecom W61PC V7.5.0 - Manual (Page 309)

WAVECOM Decoder W61PC/LAN Manual V7.5 WAVECOM Data Formats  299
WAVECOM Data Formats
IP-CONF TCP/IP Data Format
The decoder is able to receive signal data over a TCP/IP stream.
The data format is as follows:
 Sampling rates from 8 kHz to 192 kHz
 IQ data (I) respective “Left Channel”
 IQ data (Q) respective “Right Channel”
... Left 16 Bits Right 16 Bits Left 16 Bits Right 16 Bits ...
It is not allowed to change the sampling rate during decoding.
IP-PXGF TCP/IP Data Format
OVERVIEW
The PXGF streaming and file format provides a framework for the streaming and storage of sampled data
along with the meta data required to process the sampled data. It is a streaming format in that synchroni-
zation can be regained if lost.
A file using the PXGF format contains a PXGF stream with a prepended header. The header was designed
to allow an application to identify a file without processing the file. The capability to identify files becomes
more important as file sizes get bigger. The PXGF file format supports large file sizes.
PXGF DESCRIPTION
The PXGF format was designed to represent sampled data with additional information pertaining to the
way in which the data was sampled.
BACKGROUND
The PXGF format is loosely based on the Microsoft RIFF file format. The RIFF format is based on the con-
cept of a chunk. Chunks are blocks that contain specific application defined data. In the RIFF format the
complete file is a single RIFF chunk. RIFF chunks and LIST chunks are currently the only two types of
chunks that may contain sub-chunks. All the remaining chunks in the file are children of the global RIFF
chunk.
The RIFF format is unsuitable for our purposes for two primary reasons:
 The global RIFF chunk is limited in size to 4GB, thereby effectively restricting the file size to 4GB.
 The RIFF format is unsuitable for streaming applications as one need to read the whole file se-
quentially to be able to parse it. There is no synchronization mechanism available.
For these reasons a new file and streaming format was proposed and developed, namely the PXGF format.
THE PXGF CHUNK STRUCTURE
The PXGF format puts data into chunks. Different types of chunks are defined to store different infor-
mation. The type of a chunk is specified by an int32 field in the chunk as shown in table 3.1. An applica-
tion that requires data from a particular chunk will register to receive data from that type of chunk.
Chunks that are not recognized are simply skipped over. The size field in the chunk allows unrecognized
chunks to be skipped over. Each chunk starts with the sync number 0xa1b2c3d4.