Free Run Mode -
In Free Run mode, the DSM board will output a continuous waveform without pause. All that is needed to be connected to the board is the input clock at DDSCK and the outputs DDSOP and DDSON. You can hook up the outputs to an oscilloscope and spectrum analyzer to view the output waveforms.
Free Run Mode Operation Example:
» Power up the DSM board by turning on the power supplies. Remember that you should turn them on in the right order as specified in the Hardware Setup page. When the board powers up, you should see the demo waveform displayed in the oscilloscope with the corresponding spectrum in the analyzer.
» Open the DSM application. Upon loading, the board will stop producing the demo waveform.
» Adjust the clock in the "Module Parameters" window. For our example, we have set the clock to 1.8 Ghz since our clock
input is at 1.8 GHz.
» Click on the "Configuration & Status" tab to go to that window. Make sure that the configuration is
Endless Loop.
» Click on the "Waveform" tab to go to that window. Click on the drop-down box and click on the "User Defined 1" waveform.
» The "User Defined 1" waveform should load and you should already be able to see the output in the oscilloscope and the
analyzer.
» We are going to change the waveform. We want to chirp from 5 Mhz to 505 Mhz in 10 KHz steps. There are 50,000 steps in
this chirp so we will set Data Length to "C350" which is equal to decimal 50,000.
Also we will set the Memory Depth to "65,536/10000" so that it is above the Data Length.
For Frequency we enter 5,000,000, 505,000,000, and 10,000 for Start frequency,
Stop frequency, and Step frequency respectively.
The program will change the values slightly to the real frequencies that it will output.
» Now click on Download Waveform.
» The outputs on the oscilloscope and analyzer will change.
You probably will not see much in the oscilloscope but you can verify that there is a frequency plateau from from 5 Mhz
to 505 Mhz in the spectrum analyzer.
» If you go to the "Configuration & Status" window and click on Update Status, the application will
show that it is in the "In Loop" state. This is correct since the board only produces output waveforms in the "In Loop" state
as discussed on the Internal States page.
