Specifications
8-5
Understanding the CITIfile Data Format
The CITIfile Data Format
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 Keywords." When reading a CITIfile, unrecognized
keywords should be ignored. This allows new keywords to be added, without affecting an
older program or instrument that might not use the new keywords. The older instrument
or program can still use the rest of the data in the CITIfile as it did before. Ignoring
unknown keywords allows backwards compatibility to be maintained.
CITIfile Examples
Example 2, An 8510 Display Memory File
Example 2 shows a simple file that contains no frequency information. Some instruments
do not keep frequency information for display memory data, so this information is not
included in the CITIfile package. Note that instrument-specific information (#NA=
Network Analyzer information) is also stored in this file. This convention allows the
designer to define keywords that are particular to his or her particular implementation.
Example:
CITIFILE A.01.00
#NA VERSION HP8510B.05.00
NAME MEMORY
#NA REGISTER 1
VAR FREQ MAG 5
DATA S RI
BEGIN
-1.31189E-3,-1.47980E-3
-3.67867E-3,-0.67782E-3
-3.43990E-3,0.58746E-3
-2.70664E-4,-9.76175E-4
0.65892E-4,-9.61571E-4
END