This topic describes how to create a waveform marker file, but first, an overview of the VXG signal generator waveform file structure is useful.
To play back a waveform, the VXG signal generator uses data from the following sources:
|
Source |
File Extension |
Description |
|---|---|---|
|
IQ File |
*.wiq, *.bin, *.csv |
Also known as the waveform file. Contains the interleaved I and Q data points (signed 16–bit integers for each I and Q data point). Each I/Q point equals one waveform point. |
|
Marker Data |
*.wmk |
Uses one byte per I/Q waveform point to set the state of the four markers either on (1) or off (0) for each I/Q point. |
If you do not provide marker data as part of the download, the VXG signal generator sets all markers to zero (off).
Both the waveform file and marker file must use the same name (except for the extension).
Waveforms must contain a minimum of 512 points and be a multiple of 8 points.
The marker file uses one byte per I/Q waveform point to set the state of the four markers, either on (1) or off (0), for each I/Q point. When a marker is active (on), an output trigger signal is sent to a corresponding connector. Because markers are set at each waveform point, the marker file contains the same number of bytes as there are waveform points. For example, for 512 waveform points, the marker file contains 512 bytes. Although a marker point is one byte, the signal generator uses only bits 0–3 to configure the markers; bits 4–7 are reserved and set to zero. (Figure 1.) The binary marker file must also represent each byte in hexadecimal format. (Figure 2.)
Figure 1. Bit Assignments in an Example Marker Byte
Figure 2. Example Marker Byte in Binary and Hexadecimal Formats
Figure 3 shows a binary marker file (all values in hex) for a waveform with 512 points. Notice the first marker point (0f) shows all four markers on for only the first waveform point.
Figure 3. Example Waveform Marker File
Use the MMEMory:DATA command to transfer the contents of the waveform marker file into the signal generator:
|
A |
my_file.wmk |
Enter the file name of the marker data. It must have the same name as the waveform file, but with a .wmk extension. |
|
B |
# |
Indicates the start of the data block |
|
C |
3 |
D has three decimal digits |
|
D |
240 |
240 bytes of data to follow in E |
|
E |
12%S!4&07#8g*Y9@7... |
Representation of some of the binary data downloaded to the signal generator |
Then use the following command to select the waveform file. The associated marker data is automatically applied to the waveform.
SOURce:SIGNal:WAVeform:SELect "my_file.wiq"
The above example is for channel 1, if your instrument supports multi-channel apply the appropriate channel designators.
A waveform marker file must meet the following requirements:
Minimum of 512 bytes
Multiple of eight bytes
Equal number of bytes as the waveform data points
Matches the IQ file name, but uses a .wmk extension
Binary file using hexadecimal values to represent each byte