The TRAC:IQ:DATA? query returns a modified version of the SCPI standard (IEEE 488.2) block data format. The header contains three fields with a newline delimiter separating the header from the I/Q binary data:
#AXL\n
A is a single ASCII digit specifying the number of digits in X.
X is one or more ASCII digits specifying the number of bytes of binary I/Q data and ASCII GPS location coordinates.
L is the ASCII string containing the GPS location in the form 'latitude, longitude' in decimal degrees. The coordinates record where the I/Q capture was triggered.
\nis a single byte newline delimiter marking the end of the GPS location component and start of the I/Q data. The I/Q data is in binary format and is described below.
I/Q Frame Structure
I/Q data is organized into two levels: frame and extended frame. The lowest level is a 64 bit frame. which may contain one to four I/Q sample pairs depending on the selected I/Q bit resolution. The second level is an extended frame which can be used for the stamp information. The first column of the IQ vector contains Q and the second column contains I.
The 64 bit frame contains one to four I/Q sample pairs depending on the selected I/Q bit resolution.
I/Q Bit Resolution
IQ Sample Pairs per 64 Bit Frame
24
1
16
2
10
3
8
4
24 Bit Resolution
16 Bit Resolution
10 Bit Resolution
8 Bit Resolution
Note
The frame structure will be modified slightly when there is a time stamp. This will be described in a later section.
I/Q Extended Frame
An extended frame consists of 64 frames. When time stamp information is used, each frame contains one bit of a 64 bit time stamp data. An extended frame is 64 frames that contain a time stamp.
