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Pulse Generation and Acquisition with Timeline

This tutorial introduces the working principles of the Timeline module in the LabOne user interface when the AWG option of the instrument is installed. In this tutorial, the main aspects of the Timeline module, i.e. pulse generation and pulse acquisition are explained. It is intended for users who want to create and inspect pulse sequences in the Timeline module and capture the generated signals with the instrument's oscilloscope and demodulators.

Note

This tutorial is applicable to all VHFLI instruments with the VHFLI-AWG Arbitrary Waveform Generator option installed.

Preparation

Make sure the instrument is powered on and connected by Ethernet to your local area network (LAN), or by USB to your host computer. Start the LabOne User Interface as explained in Connecting to the Instrument. The LabOne Data Server and Web Server are automatically started and run in the background.

This tutorial uses the Signal Output 1 +V port to generate the pulses, and the Signal Input 1 +V port to measure them. Therefore, these two ports must be connected by a BNC cable in loop back.

Create a Pulse Sequence in the Timeline Editor

In the Setup space, bring the blocks for Signal Output 1 and Voltage Input 1 to the canvas using the "+" menu on top of the screen. Adjust their signal settings like Range and Coupling according to Figure 1. Then, open the Timeline window from the bottom of the screen. The Timeline window includes 3 main areas: Editor, Viewer, and Settings. The Timeline editor allows you to build pulse sequences by placing waveform events on the timeline. Each event defines the channel, amplitude, duration, and timing of the generated waveform. The parameters of each event can be adjusted from the Settings area on the right.

Figure 1 shows a simple pulse sequence in the Timeline editor. The sequence consists of two pulse events with some delays in between and around that produce the output signal. The entire section is performed in a Single iteration.

Figure 1: Setup space of LabOne user interface where the signal processing blocks and the Timeline area including editor, viewer, and settings are displayed.

To build the sequence:

  1. Add Signal Output 1 under the Section in the Timeline editor.
  2. Add pulse and delay events using the editor controls.
  3. Adjust the pulse and delay parameters from the Settings area.
  4. Use the Timeline viewer to verify the event timing.

Once the sequence is configured, press the "Run Timeline" button to generate the corresponding signal on Signal Output 1.

Capture the Generated Pulses with the Scope

The Scope tool displays the received waveform on the Signal Input 1 port. It is useful for verifying the pulse shape, amplitude, and timing. Add the Scope to the Timeline editor as a measurement line with time-adjusted delay and measurement boxes. By opening the Scope tool in the Measurement space, and running the Timeline, the captured pulses can be displayed as a trace or an image as seen in Figure 2. The signal trace corresponds to the waveform defined in the Timeline editor which includes a Gaussian pulse followed by a Drag pulse.

Figure 2: Scope displaying the captured waveform which includes a Gaussian pulse and a Drag pulse separated by a delay of 96 ns.

If the waveform does not appear as expected, check the event parameters in the Timeline editor as well as the Scope settings. Note that the same Timeline module can be accessed from the Setup and Measurement spaces.

Apply Amplitude Modulation

The Timeline module can also apply amplitude modulation to the generated waveform. This feature enables the envelope modulation using a sine generator linked to one of the instrument's numeric oscillators. To apply the modulation, enable the corresponding feature in the Timeline settings as seen in Figure 3. The selection of oscillator, phase, and harmonic can be done in the Generator block attached to the Signal Output block.

Figure 3: Timeline with amplitude modulation enabled where the modulation carrier is controlled by a Sine Generator.

When modulation is enabled, the generated signal follows the defined envelope shape but oscillating according to the modulation frequency of the Sine Generator. Figure 4 shows the modulated waveform captured by the Scope tool.

Figure 4: Scope displaying the amplitude modulation of the Gaussian and Drag pulses.

By modifying the numeric oscillator's frequency, the modulation carrier can be set anywhere within the instrument's frequency range.

Demodulate the Received Signal

To obtain the envelope of the modulated pulses, add a demodulator to the Signal Input block as seen in Figure 5. The demodulator uses the same oscillator as the modulation carrier created by the Sine Generator. Moreover, the acquisition window is set by adding a Measurement line to the Timeline editor which is assigned to the corresponding Demodulator with properly adjusted Delay and Measurement boxes.

Figure 5: Timeline editor showing the Demodulator and Timeline settings for measuring and acquiring the demodulated signal.

Use the Timeline viewer to verify that the sequence of events are aligned with the expected timing of pulse generation and acquisition.

Inspect the Waveform in the Timeline DAQ

The Timeline DAQ tool in the Measurement space provides time-domain and frequency-domain monitoring of the acquired signal after demodulation. It is useful for checking the temporal and spectral content of the played pulse sequence, and confirming that the output matches the intended waveform.

Figure 6 shows the temporal (left) and spectral (right) content of the demodulated pulses captured by the Timeline DAQ tool. The time-domain traces are the quadrature components of the demodulated signal; while the frequency-domain trace displays its two-sided spectrum.

Figure 6: Timeline DAQ displaying the time-domain and frequency-domain signals after demodulation.

Note that different signal components like amplitude, phase, and their spectrum can be added to the list of signals captured by the Timeline DAQ tool.