Advanced Arbitrary Waveform Creation
The ARBs (WF2 and WF3) have a number of predefined waveforms available, including: Sine, Square, Quadrature Sine, Edge ACPR (patch p21c.408), OFDM (patch p21c.615), Ramp and Modulation among others. It is also possible to construct and run custom waveforms with system option 029A (ARB hardware, 74202A and newer) and patch level p21c.357.
Data File format (.wav)
A simple two column CSV (comma separated) ASCII text file that defines the voltage levels for Wf2 and Wf3 is needed to program the custom waveform. (See the table below )
When constructed, the file should be saved with the suffix ".wav". The file must reside in the default Test Plan directory to be selected. Once selected in a Test Panel, it must be available to the Test Plan to load at compile time, therefore it must reside in the same directory as the Test Plan to be run. The file must not contain more than 4090 (approximately 212) records due to the hardware limitations of the ARB. The amplitude of the waveform should be normalized (defined) from +1 to -1. To normalize the MAX/MIN to +/-1 for the ARB you need to divide the largest (+ or -) value of the data.
The actual Voltage output will be set in the program as waveform value*WF amplitude + WF offset.Also, the waveform "phase" button is not supported for custom arbitrary waveforms.
Here is an example waveform File for a dual ramped waveform:
Example Test Plan
The following Test Plan uses the custom 31 point waveform created above and stored in file "300ramp.wav". The timing of the waveform is set by the waveform sample rate button. This ranges from 100uSec, 10uSec, 1 uSec, 100nSec, and on the 74210 Arbs, 25 nSec. The ARB will emit the next sequential value in the CSV at the time interval specified (here we chose 10usec for a total of 310usec) . The ARB will then repeat the waveform. For single shot or non repetitive functions see the document : Synchronizing Arbitrary Waveforms WF2 WF3: Run, Stop, PMStart, PM Stop and Trigger.
Example Test Plan Output
This is the waveform created and output from the Arbs at WF2 and WF3.
1) The delta voltage of ramp waveform 2 is 400 mV
2) There are 31 points in the waveform and the volatges will move to the next setting in the CSV file every 10usec, therefore we see that the ramp takes approx. 310usec to complete.