User Manual LW120
Now that we have both frequency values for the carrier and the
shifted sample clock, we can go directly to front panel
programming. Refer to Figure 3-23 for this example
1. Press the FREQUENCY button. Modify Sclk display
10.00000MS.
2. Press the UTILITY button
3. Select and press the Modulations option
4. Select and press the FSK option
5. Select the FSK State option
6. Rotate the dial clockwise to turn the FSK function ON
7. Select and press the Sclk2 parameter
8. Rotate the dial to adjust the Sclk2 parameter to 25 MS
9. Apply your FSK control signal to the trigger input
If you did not make any programming errors, the front panel outputs
will generate FSK modulated waveforms having carrier frequency of
10 KHz and shifted frequency of 25 KHz.
We’ll now check the results at the rear-panel sine output connector
and compare what we get there to what we see on the front panel.
Remove the cable from the main output connector and connect to
the rear-panel SINE OUT connector. Here is what you should
expect to see when you check this output:
1. Carrier is sine waveform with fixed amplitude level of 1V
into 50
Ω
.
2. Carrier frequency is 10 MHz
3. Shifted frequency is 25 MHz
Ramped FSK
Ramped FSK is very similar to the FSK function except, when the
hop command is received, the output frequency ramps to the
shifted frequency at a rate set by the ramp time generator. The
ramp time is programmable from 10
µ
s to 1 second.
The procedure how to set up the carrier and shifted frequencies for
the ramped FSK function is exactly as shown above for the Hopped
FSK except an additional parameter has to be specified – ramp
time.
Do the following to access and modify the ramp time parameter:
1. Press the UTILITY button
2. Select and press the Modulations option
3. Select and press the FSK option
4. Select the press the FSK Type option
5. Rotate the dial clockwise to modify the FSK type to RAMP
6. Press again the FSK Type button
Using The Instrument 3-32