Technical data

9-3
Understanding the CITIfile Data Format
The CITIfile Data Format
A CITIfile Package
A typical package is divided into two parts: The first part, the header, is made up of keywords and setup
information. The second part, the data, usually consists of one or more arrays of data. Example 1 shows the
basic structure of a CITIfile package:
Example 1, A CITIfile Package
The “header” part CITIFILE A.01.00
NAME MEMORY
VAR FREQ MAG 3
DATA S RI
The “data” part BEGIN
-3.54545E-2, -1.38601E-3
0.23491E-3, -1.39883QE-3
2.00382E-3, -1.40022E-3
END
When stored in a disk file there may be more than one CITIfile package. With the 8510 network analyzer,
for example, storing a "memory all" will save all eight of the memories held in the instrument. This results
in a single file which contains eight CITIfile packages.
The CITIfile Header
The header section contains information about the data that will follow. It may also include information
about the setup of the instrument that measured the data. For example, the header may include
information such as:
• CITIfile version number
• Analyzer model number
• Firmware revision currently installed in the analyzer
•Type of Data
• Data Format
• Measurement parameters
• Start and stop frequencies
• Number of sample points
The CITIfile header shown in Example 1 has just the bare minimum of information necessary; no
instrument setup information was included.
An Array of Data
An array is numeric data that is arranged with one data element per line. In the Smith chart and polar
formats, the data is in real and imaginary pairs. In all other formats, the data is still in pairs, but the second
term of the pair is 0E0. All information is true formatted data in the same format as on the analyzer display
(dB, SWR, etc.). A CITIfile package may contain more than one array of data. Arrays of data start after the
BEGIN keyword, and the END keyword will follow the last data element in an array. A CITIfile package
does not necessarily need to include data arrays; for instance, CITIfile could be used to store the current
state of an instrument. In that case the keywords VAR, DATA, BEGIN, and END would not be required.
CITIfile Keyword
Keywords are always the first word on a new line. They are always one continuous word without embedded
spaces. A listing of all the keywords used in the latest A.01.01 version of CITIfile is shown in "CITIfile