Generate and Acquire a Test Signal

This tutorial is applicable to all UHFQA Instruments.

Goals and Requirements

This tutorial explains how to generate and measure a simple pulsed signal with the AWG and the Monitoring Scope in the Quantum Analyzer Input tab.

The measurements in this tutorial can be performed using simple loop back connections.

Preparation

Connect the cables as illustrated below. Make sure that the UHF unit is powered on and connected by USB to your host computer or by Ethernet to your local area network (LAN) where the host computer resides. After starting LabOne the default web browser opens with the LabOne graphical user interface.

fig tutorial monitor setup
Figure 1. UHF connections for the Input Monitor tutorial

The tutorial can be started with the default instrument configuration (e.g. after a power cycle) and the default user interface settings (e.g. as is after pressing F5 in the browser).

Test Signal Generation

First, we enable both outputs of the UHF instrument.

Table 1. Settings: enable the Signal Outputs
Tab Sub-tab Section # Label Setting / Value / State

In / Out

Signal Outputs

1

On

ON

In / Out

Signal Outputs

2

On

ON

Copy the following code into the Sequence Editor in the AWG tab.

const length = 4096;
wave w = gauss(length, length/2, length/8);
var loop_cnt = getUserReg(0);
var wait_time = 0;

setTrigger(0);
repeat (loop_cnt) {
  playWave(w, -w);
  wait(50);
  setTrigger(AWG_MONITOR_TRIGGER);
  setTrigger(0);
  wait(1000);
  waitWave();
}

Upload this sequence program to the UHF-AWG by clicking on "Save" or "To Device". This program will generate a series of dual-channel Gaussian pulses. The repetition number is defined by the integer variable loop_cnt. To make it possible to control the repetition number through the user interface, we use one of the User Registers rather than to write this number into the program.

Apply the settings in the following table in order to configure the AWG output as well as the User Register.

Table 2. Settings: configure the AWG output
Tab Sub-tab Section # Label Setting / Value / State

AWG

Control

Rerun

OFF

AWG

Control

Output 1

Amplitude (FS)

1.0

AWG

Control

Output 1

Mode

Plain

AWG

Control

Output 2

Amplitude (FS)

1.0

AWG

Control

Output 2

Mode

Plain

AWG

Control

User Registers

Register 1

64

Configure the Input Monitor

In the Quantum Analyzer Input tab, apply the settings in the table below.

Table 3. Settings: configure the Input Monitor
Tab Sub-tab Section # Label Setting / Value / State

QA Input

Control

Input Monitor

Length

4096

QA Input

Control

Input Monitor

Averages

64

QA Input

Control

Run / Stop

ON

In the AWG tab, click on "Start/Stop" in order to run the AWG. The lines setTrigger(AWG_MONITOR_TRIGGER); and setTrigger(0); in the AWG sequence program generate a rising and falling edge of an internal trigger line reserved for the Input Monitor. See Architecture and Signalling for an overview of the different functional blocks and internal trigger lines. The Input Monitor acquisition started at the rising edge. 64 consecutive dual-channel pulses are acquired, averaged, and displayed. The figure below shows the signal as displayed in the QA Input tab. We denote the raw input signals (without averaging) as V1(t) and V2(t).

The Input Monitor Averages setting must agree with the number of Input Monitor triggers generated by the AWG in one measurement burst (here this is determined by the User Register 1 equal to the sequencer variable loop_cnt. If the AWG generates more triggers than that, which is e.g. the case when AWG Rerun would be enabled, the Input Monitor may not be able to process and transmit all data in time, and may deliver corrupted data to the computer.

fig tutorial monitor signal
Figure 2. Test signal as measured in the Quantum Analyzer Input tab