Knowledge Base

Set Up NTP Client on the Participant PCs

Aim: To set up the NTP Client on the Participant PCs to achieve synchronization of time between them.

Before You Begin

To achieve 1ms accuracy on the Participant PC, the following conditions should be met:

• The participant PC must have better than 0.1ms of network latency between its time source (NoldusHub server).
• The participant PC must be no further than stratum 5 from a highly accurate time source (NoldusHub server).
• The participant PC must be within 4 or fewer network hops from the highly accurate time source (NoldusHub server).
• The one-day average CPU utilization across each stratum must not exceed 80%.

For an explanation on how to verify these conditions, see Procedure below.

Note

The NTP Server is configured when you run SetupNoldusHub-Server-Docker.bat, which should have been done during the previous step Install NoldusHub on the server.

In case the Windows Date & Time settings are changed, rerun Setup-NoldusHub-Participant-NTPClient.bat on the participant PCs and rerun SetupNoldusHub-Server-Docker.bat on the server PC.

It is essential to achieve an exact common timebase for all Participant stations and the NoldusHub server. Therefore, all participant stations need to be synced with the NoldusHub server. However, there is no such requirement for the Test leader station. Test leader stations only require a Chrome Browser to operate NoldusHub and are typically synced with a Microsoft time server or a time server in the company network. If NoldusHub time and Company network/Microsoft time are not in sync, the liveview data may be only partially visible, or not visible at all since the Liveview time axis is not aligned with the timeline of the live data sent by the NoldusHub server. Therefore, it is important to verify that the NoldusHub time server is synced with a reliable external time server, while also the Company network time server needs to be synced with a reliable external time server.

Small deviations (less than 3 seconds) do merely cause small deviations in the liveview but recorded data will still be in sync.

Procedure

To configure NTP Client on Participant PC:

1. Locate the Scripts folder in the installation folder of NoldusHub, under the N-Linx Agent folder. This folder contains two files: Setup-NoldusHub-Participant-NTPClient.bat and Setup-NoldusHub-Participant-NTPClient.ps1.
2. Copy the folder Scripts to C:\ProgramData\Noldus.
3. Open Setup-NoldusHub-Participant-NTPClient.bat in the text editor and replace the server IP address (127.0.0.1) with the hostname of the NoldusHub server.
4. Right-click on PowerShell and click Run as administrator.
5. Execute the command Set-ExecutionPolicy RemoteSigned.
6. Run Setup-NoldusHub-Participant-NTPClient.bat.
7. Restart the Participant PC.

To verify the 1ms accuracy conditions on the Participant PC, as mentioned in the Before You Begin section:

Measure Network Latency Between NTP Server and NTP Client

1. Run the following command in Windows PowerShell:
   w32tm /stripchart /computer:IPAddressOfNtpServer /rdtsc /samples:450 > c:\temp\Target_TsB.csv
2. Calculate the RoundTripDelay average value from the CSV file; it should be less than 0.1ms.

Find the Number of Stratums Between NTP Server and NTP Client

1. Run the command in Windows PowerShell: w32tm /resync
   Note: This command should be run after the server and client are already configured in the registry.
2. Run the command in Windows PowerShell: w32tm /query /status.
3. Check the value after Stratum; it should be 5 or less.

Find the Number of Network Hops Between NTP Server and NTP Client

1. Run the command in Windows PowerShell: tracert IPAddressOfNtpServer
   Note: If you receive a timeout error, temporarily disable the firewall on both the client and server PC, then try to run the command again.
2. Each line starting with a number in the result represents a hop. The last hop number is the number of total hops.
3. The total hops should be 4 or less.

Find the One-Day Average CPU Utilization Across Each Stratum

1. Run the following command in Windows PowerShell and let it run for 24 hours:
   Get-Counter -Counter "\Processor(_Total)\% Processor Time" -SampleInterval 10 -MaxSamples 8640 | Select-Object -ExpandProperty countersamples | Select-Object -ExpandProperty CookedValue | Measure-Object -Average > D:\CPUUsage.txt
2. After 24 hours, results can be found in D:\CPUUsage.txt.
   Note: The script can be adjusted; for example, the output can be directed to a location other than D:\CPUUsage.txt. The sample interval can be more frequent than 10 seconds, but then MaxSamples should be increased so that SampleInterval x MaxSamples is always 86400 (the number of seconds in 24 hours).

Set Up Participant PCs

Aim: To display the screen and camera of your participant PCs in NoldusHub. Please follow this procedure for the initial setup of every participant PC.

Before You Begin

• The latest version of Google Chrome should be installed.
• The participant PC must be connected to the server PC through a 1 Gb Ethernet network.
• The IP addresses of both computers fall in the same IP range.
• The Firewall allows inbound and outbound traffic through TCP port 5671. See also Firewall settings.

Procedure

1. Connect a USB camera to the test participant PC. It is also possible to use an internal webcam on a laptop.
2. If you have a previous version of NoldusHub, first uninstall N-Linx Agent and delete all content in the folder C:\ProgramData\Noldus\N-Linx Agent\Plugins. If this is the first time NoldusHub is being installed on this computer, skip this step.
3. Copy the N-Linx Agent subfolder from the NoldusHub installation folder to the desktop of the participant PC.
4. Open the folder, double-click the file N-Linx Agent Setup and follow the instructions on your screen. Accept the terms in the End-User License Agreement.
5. N-Linx Agent now opens automatically. If not, open the system tray and double-click the N-Linx Agent icon to open N-Linx Agent.
6. Enter the hostname of the server in the N-Linx Server Address field and click Connect. At the bottom of the N-Linx Agent window, you will see the text Connected.
7. Click Add plugin and browse to the Media plugin in the N-Linx Agent > Plugins folder on the desktop. Select it and click Open.
8. Check that the status of the plugin is Online.

Prepare Participant PCs for Eye Tracking

Aim: To set up the participant PCs with your specific eye trackers. Follow this procedure once on every participant PC that will use eye tracking.

Before You Begin

• The latest version of Google Chrome is installed.
• The participant PC is connected to the server PC through a 1 Gb Ethernet network.
• The IP addresses of both computers fall in the same IP range.
• The Firewall allows inbound and outbound traffic through TCP port 5671. See also Firewall settings.
• The eye tracker is supported, and its firmware is updated to the most recent version. See also Supported eye trackers from the reference manual.

Source: NoldusHub 1.7 Installation Documentation, Noldus Information Technology