Waveforms -
The AWG module has several pre-stored waveform styles that you can configure with specific parameters. From the Waveform panel, there are two ways to recall a pre-stored waveform: either select one from the pop-up menu or enter a waveform code.
Pop-up menu:
Select the waveform named "Sample (Demo.wfa)" to choose a Sine wave at 1/16ths of the clock frequency. Optionally, you may adjust the parameters for this waveform. The computer calculates the newly parameterized data, although data on the AWG does not yet change.
Press the Download button (at the lower right corner of the waveform panel). The computer then downloads the parameterized data to the AWG memory so that the firmware generates the actual waveforms. You must press the Download button each time you finish changing the parameters.
Waveform code:
Entering Waveform Codes
» Enter a whole number from the table below to designate a waveform style. Each code corresponds to one style. Frequency units are Hertz (Hz).
| Waveform Code | Waveform Style | Waveform Specific Parameters |
| 1 | Sine | Frequency (Hz) |
| 2 | Sine A/B |
A=dividend, B=quotient, (unsigned integers) A/B is a fraction of the clock frequency |
| 4 | N Tones | Frequency, Amplitude (dBc) relative to full scale, Phase (degrees) |
| 31 | Ramp | A=dividend, B=quotient, (unsigned integers) |
Waveform Code
is the index that the operating system uses to identify the waveform style.Waveform Style
will headline the waveform-specific parameters and will help you identify the waveform. It appears to the right of the waveform code.Waveform Specific Parameters
» After you have entered a valid waveform code, style-specific parameters will appear below the common parameters section. There, you may change the specific parameters to your desired settings.
Sine
Enter a numeric frequency. The units are Hertz (Hz). For example, to output a 1 MHz sine wave, enter 1000000. Note that this is an absolute frequency based on your input clock. If you set this frequency but then change the input clock then the output sine wave will no longer be at the same frequency as the one you entered.
Sine A/B
This sine wave frequency is the input clock frequency scaled by the ratio A/B.
The dividend, A, and the quotient, B, must be unsigned integers.
N Tones
The multi-tone waveform style can be configured to have a different amplitude and phase for each frequency tone.
Each row in the table corresponds to one tone. For each desired tone, enter in one row:
- the frequency in Hertz (Hz)
- the power amplitude in dB, relative to full scale
- the phase in degrees
Please be aware that when the amplitudes of each waveform (each tone) add constructively, the instantaneous amplitude of the envelope waveform (the n tones) may exceed the full scale amplitude. When this occurs, the overflow data will be truncated.
To illustrate, consider the case of two tones, each set to -3 dB amplitude.
Their peak voltages
would be 1/sqrt(2), or about 0.7 of the full scale. When added constructively, the
peak voltage is 1.4 times the full scale. When the instantaneous
voltage exceeds the full scale, the data wraps around back to 0. Other ways to think
of it are that the overflow data is ignored or that the data is modulo
full scale.
The remedy in this case is to set the amplitudes of each tone lower than -6 dB,
relative to full scale.
The example My 2 Tones has two tones at 567 and 568 MHz with equal amplitude and different phase.
The example My N Tones has 6 tones between 1 MHz and 100 MHz, with various amplitudes and phases, and uses raised cosine (Hanning) windowing.
Ramp
The AWG produces a ramp by multiplying the data point index by the A/B slope factor and the resolution of the DAC which is 4096. If you wanted a ramp with a high slope then you would have A/B more than 1. If you wanted a ramp with a low slope then you would have A/B less than 1.
Download the waveform
Finally, click the Download button to download the waveform to the board.
» You may save the waveform with all of the current parameters by clicking the Save As button. A new dialog box will appear, where you can edit the names and parameters before you save the waveform.
