Knowledge Base

The On-Off Signal

The On-Off signal coincides with the start and stop of an observation. The Observer XT sends a 'one' at the start and a 'zero' at the stop of an observation. When you use the On-Off signal you need to start the DAQ system before you start an observation and switch it off after the end of your observation.

The Time Code (TCAP) Synchronization Signal

Use the TCAP signal in the following situations:

• When the DAQ system uses scheduled sampling, i.e., when sampling is carried out at set intervals (for example, 5 minutes every hour).
• When the sample rate of the DAQ system is higher than 10 Hz.

With the Time Code signal, The Observer XT continuously sends encoded pulses of zeros and ones to the DAQ system during an observation. Each pulse (consisting of 60 bits) contains time and date information in the initial bits. Pulses and the empty spaces between pulses are evenly divided over time. When you use the Time Code signal during an observation, you can start acquisition of physiological data any time during that observation, because the DAQ system can 'catch up' with The Observer XT based on the time and date information in each pulse.

The external data are saved in the computer dedicated to the DAQ device, not in the PC with The Observer XT. The Observer XT PC only records the manually coded data (events). During the observations, you do not see the external data on your Observer screen.

It is possible to import data sets from more than one DAQ system, each with its own TCAP signal.

Import External Data

What do you want to do?

• Import External Data as Text Files
• Import European Data Format Files
• Manual Synchronization

Import External Data as Text Files

Aim

To import external data that were exported from your DAQ system as text files.

Prerequisites

• Your license for The Observer XT includes the External Data Module.
• You acquired the data with your DAQ system.
• You exported the data from your DAQ system as a text file.

Procedure

1. Choose File > Import > External Data, or in the observation, click the Import Data button on the toolbar and choose Import External Data.
2. The Import External Data window opens. The Observer XT contains import profiles for text files from several DAQ systems. Select your system from the Files of type list. Next, select the external data file. If your type of file is not in the list of predefined files of type, you can create an import profile, or contact Noldus Support to make one for you.
3. Next to Import to, select an existing observation from the list or choose New observation.
4. To import the complete file including all data sets, click Open. To import specific data sets from the external data file, continue with the steps below.

To Import a Specific Data Set

If your external data file contains more data sets than you want to import:

1. Follow the instructions above until step 3, then click the Manual import button. A new Import External Data window opens showing the data sets. The Independent Variable List also appears.
2. Select one or more data sets and drag-and-drop them to the observation in the Independent Variable List window. If The Observer XT sent a synchronization signal to the DAQ system, make sure you import this data set as well. The row containing this signal has a clock icon on the left side. If not, right-click the first cell in this row and select Sync Data Set.
3. Click Import.
4. If you used the DAQ system stand-alone, and therefore did not let The Observer XT send a synchronization signal, continue with Manual Synchronization.

Import European Data Format Files

Aim

To import European Data Format (EDF) and BioSemi Data Format (BDF) files.

Background

European Data Format (EDF) and BioSemi Data Format (BDF) are standard binary formats to store and exchange physiological data. BDF is the 24-bit version of EDF, which is 16-bit. Many systems to collect physiological data can export to EDF or BDF.

Prerequisites

• Your license for The Observer XT includes the External Data Module.
• You exported your external data as EDF or BDF files.

Procedure

1. Open the observation that you want to import the data into.
2. Click the Import data button on the toolbar and select Import European Data Format Files. Alternatively, choose File > Import > European Data Format Files.
3. Locate the file and click Open.

You can now:

• If necessary, synchronize the imported data with the event log. See Manual Synchronization.
• Select data based on the value of the imported data. See Select Intervals by External Data in Select Data for Analysis.
• Visualize the imported data. See Visualize External Data in Visualize Data.
• Analyze the imported data with Numerical Analysis. See Calculate Statistics.

Notes

• Importing European Data Format files with a synchronization signal from The Observer XT was not tested. Therefore, we recommend exporting text files instead and importing these if you want to synchronize with a synchronization signal. See Import External Data as Text Files.
• If you do not have an observation open, a new observation will be created.
• Importing EDF+ or BDF+ files that contain annotations is not supported.