Generate and Acquire a Test Signal¶

Note

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.

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;

repeat (loop_cnt) {
  playWave(w, -w);
  startQA(QA_INT_NONE, true);
  playZero(LENGTH);
}

Upload this sequence program to the AWG of the UHFQA 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 QA setup tab¶

In the Quantum Analyzer Setup tab, apply the setting in the table below.

Table 3: Settings: configure the integration delay in the QA Setup tab
Tab	Sub-tab	Section	#	Label	Setting / Value / State
QA Setup		Deskew		Delay (sample)	200

This setting configures the trigger delay of the monitor, so that the generated signal is correctly aligned with the acquisition window.

Configure the Input Monitor¶

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

Table 4: 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 line startQA(QA_INT_NONE, true); triggers the Input Monitor acquisition. See Architecture and Signalling for an overview of the different functional blocks and internal trigger lines. 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).

Note

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.