If data is not be displayed correctly or if you want to convert the data file, resample the output, perform another IQ Capture, or listen to an AM/FM demodulated signal, you may set new data file parameters in the panels - Input File Type, Input File Description, Output File Type, or Output File Description.
Set the Input File Type
The following types of files that can be loaded into the IQ File Converter are Anritsu Capture files, an Anritsu VSG files, a text files, or binary files. If loading a text file, you may need to specify the delimiter used in the file in the Input File Type window.
1. Click Text.
2. Click the List arrow button.
3. Click the type of delimiter used in the input file: Comma, Tab, or Semicolon.
This is the character that separates the I and Q data values. IQ pairs are assumed to comprise a single record in the file, separated by a carriage return or line feed character (or both). The values in a single record may be separated by a comma, semicolon, tab, or space character. If Auto is selected, IQ File Converter will try and determine the correct delimiter to use. This is usually accurate and you will not normally be required to specify this.
For binary file types, there are several parameters that describe how the data is stored in the file. The number of bits in each sample point and the byte order of the data in the file.
Byte order, endian, refers to the sequence of bytes stored in computer memory. Big-endian is the order in which the most significant value is stored first at the lowest storage address. Little-endian is the other in which the least significant value in the sequence stored first storage address.
If you have the bit-resolution correct, then selecting the wrong bit order setting will produce random noise. It is usually easiest to just try the different settings for binary files until you see an IQ diagram that makes sense for the data you are looking at.
1. Click Binary.
2. Click the list and enter the number of bits.
3. Click 8 bit, 16 bit or 24 bit.
4. Click the arrow to click either Big Endian or Little Endian.
Set the Input File Description
In order to resample, the original sample bandwidth must be known. For most file types, when you load an input file, the number of points, maximum value and RMS value fields are calculated and displayed. The Bandwidth field cannot be determined from the raw data, and must be input by the user. Enter the known bandwidth into the Bandwidth parameter or the Input File Description.
After entering the known bandwidth, a resampling of bandwidth may be necessary. “Resampling” means to change the bandwidth, as though a different bandwidth had been used to do the original capture. The AM/FM demodulation option also enables the user to remotely capture AM/FM signals and listen to the signals via their PC/laptop. The AM/FM signals can also be saved as WAV files to be played at a later date.
Set the Output File Type
Three output file types are available.
VSG
Anritsu’s VSG file format has a header containing useful information that is displayed in the VSG application. The fields for Description and Name are pre-filled for you, but may be edited. Both fields have a character limit and the input boxes match that limit.
Text
If saving as a text file, you can chose the delimiter to use.
Binary
There are no options for saving to a binary file. It is always 16 bit little-endian.
Select the output file format in the Output File Type settings box: VSG, Text, or Binary. The file type selected will determine the output file type extension .vsg, .txt, or .bin that will be added to the output file.
Set the Output File Description
You may set the same output format as the input format. This is useful when all you want to do is change the sample bandwidth.