Knowledge Base

The SyncBox

Introduction

When you use The Observer XT as part of a complex lab setup, it is necessary that the observational data from The Observer XT and external data from other applications/devices play back as synchronized as possible. Such a complex setup might consist of (depending on your type of research):

• The Observer XT — to record a participant's behavior.
• One or more cameras and the MediaRecorder software — to create one or more digital video files.
• An eye tracking system — to monitor the point of gaze of a test subject when testing a website or software.
• One or more data acquisition systems — to measure, for example, heart rate or galvanic skin response.

Synchronize the Data Sets

One way to achieve simultaneous playback of observational and external data is to start external applications from within The Observer XT as External Programs at the start of an observation. However, most applications take some time to start which results in a delay between the start of the observation in The Observer XT and the start of the external application.

Use the SyncBox to Determine the Delay

The SyncBox is a device that has been developed to determine this delay. Once you know the delay for a specific external application, you can set this in The Observer XT, so the start of the observation and the start of the external application are synchronous.

In general, you can determine the difference in offset between The Observer XT and external applications/devices by using one of the following methods:

• At the start of an observation in The Observer XT, record one signal in all applications/devices and a synchronous time stamped trigger comment in The Observer XT — for example, record a visual and/or auditory cue for video or a pulse in the physiological data signal. Afterwards, the difference in offset between The Observer XT and other applications/devices can be determined and set in The Observer XT.
• Record a series of signals in all applications/devices at fixed intervals during an observation and a synchronous time stamped trigger comment in The Observer XT — this might be necessary for long observations when you expect the different computer clocks to start running asynchronously. Afterwards, you can determine the difference in offset between The Observer XT and the other applications/devices at the start and end of the observation and correspondingly stretch the external data. You can only stretch external ASCII data, not video data.

Note: If you have MediaRecorder 2.5 or higher, and start video recording together with a live observation in The Observer XT, you do not need to measure the delay between The Observer XT and MediaRecorder video. In this case The Observer XT takes care of correcting for this delay when importing the video files. For more information, see The Observer XT Help and the MediaRecorder Help.

How the SyncBox Works

The SyncBox is triggered by The Observer XT to send out different types of signals at exactly the same time to one or more external applications, based on the clock of The Observer XT computer. Simultaneously, a time stamped trigger comment is recorded in The Observer XT. After import of the different data streams into The Observer XT, you can use the trigger comment and the recorded signals to manually synchronize the observational and external data. By doing this, you can determine the difference in offset and set this in The Observer XT as a delay. Subsequently, an observation and external applications will start synchronously. Furthermore, when you trigger the SyncBox to send out a series of signals during a longer period of time, you can use these multiple trigger events to correct for your (long) observation and the external applications/devices running out of sync.

Note: Use the SyncBox before you actually start acquiring data. Create a SyncBox project in The Observer XT, carry out a test observation while The Observer XT triggers the SyncBox to send out its signals and determine the difference in offset between the trigger comment(s) in the observation and the external applications/devices. These differences in offset can then be used in the real observation to correct these offset differences.

Components of the SyncBox

The SyncBox system consists of the following components:

• SyncBox — Contains a Power in, a COM in, X-keys out (2x), LED out (4x), Sound out (4x), TTL direct out (6x), TTL opto-isolated out (2x), a Trigger button, an Auto off/on switch, and a Speaker off/on switch.
• Power supply (2x) — You can either use the 5V VDC medical power supply or the USB-to-5V supply cable to get power from a PC.
• COM cable — To connect the COM port of the SyncBox to the COM port of the The Observer XT PC (or the USB-to-COM converter).
• LED box — A box with a red and infrared light connected to a cable (length: 5 m) with a white RCA plug at the end.
• Sound box — A box with a small speaker connected to a cable (length: 5 m) with a red RCA plug at the end.
• Line-in cable — A cable with an RCA plug on one end and a stereo 3.5 mm phone plug on the other end. This cable connects a Sound output of the SyncBox with the line-in of a PC or amplifier.
• TTL cable — A cable (length: 5 m) with a 3.5 mm phone plug on one end. The white minus wire and brown plus wire can be connected to a plug suitable for your data acquisition system (for example, a phone plug or RJ-11 jack).
• X-keys USB cable — A USB-A-B cable that connects the X-keys outputs to a USB port on a test PC.

How to Install the SyncBox

The SyncBox gets its power (5 VDC) from the provided power supply or from the USB port of a computer via the supplied USB-to-5V cable. All signals are functional once you plug in the power supply.

Using the SyncBox Signals

The SyncBox can send out the signals described below. Which signal you use depends on the application or device you send the signal to.

The LED Signal

A LED signal is a light signal. There are 4 LED signal outputs and one LED light on the SyncBox itself. The LED signal is sent via an RCA connector to a LED box with a red and infrared LED light.

Connect the RCA connector of the LED box to one of the LED signal outputs.

Use the LED signal when you use a camera; record the LED signal as a visual cue in a video recording.

The Sound Signal

The Sound signal is an audio signal (audio frequency: 2.3 KHz). There are 4 Sound signal outputs. The Sound signal is sent via an RCA connector to a Sound box with a speaker. Alternatively, the sound signal can be sent to the Line-in of a PC or other equipment.

You can also hear the Sound signal through the internal loudspeaker on the SyncBox when the Speaker switch is set to On.

Connect the RCA connector of the Sound box to one of the Sound signal outputs, or connect the RCA connector of the Line-in cable to one of the Sound outputs.

Use the Sound signal when you use audio equipment; record the Sound signal as an auditory signal in an audio file.

Note: When you use a microphone to record the Sound signal, make sure you place the Sound box as close to the microphone as possible so the sound travels the shortest distance possible.

The TTL Direct Pulse

The TTL direct pulse is an electrical signal (Max. DC levels: less than +1 Volt and greater than +3 Volts). There are 6 TTL direct pulse outputs. The TTL direct pulse is sent via a TRS connector (or phone plug/jack plug) to a DC input on a data acquisition system.

Connect the 3.5 mm phone plug of the TTL cable to one of the TTL direct pulse outputs. The type of connector that you need to attach to the other end of the cable depends on the type of input on your data acquisition system.

Use the TTL direct pulse signal when you use a data acquisition system; record the signal as a marker in the data file.

Note: We recommend using the synchronization signal when acquiring physiological data, rather than the TTL pulse. The synchronization signal enables you to automatically synchronize your observational and physiological data. See The Observer XT Help for information on how to use this signal. Use the TTL direct pulse in case the sensors on your subject are wirelessly connected to the data acquisition system.

The TTL Opto-Isolated Pulse

The TTL opto-isolated pulse is an electrical signal. There are 2 TTL opto-isolated outputs. This TTL pulse signal is optically isolated from the SyncBox electronics and all connected devices.

Connect the 3.5 mm phone plug of the TTL cable to one of the TTL opto-isolated pulse outputs. The type of connector that you need to attach to the other end of the cable depends on the type of input on your data acquisition system.

Use the TTL opto-isolated pulse signal when you use a DAQ system; record the signal as a marker in the physiological data file.

Note: We recommend using the synchronization signal when acquiring physiological data, rather than the TTL pulse. The synchronization signal enables you to automatically synchronize your observational and physiological data. See The Observer XT Help for information on how to use this signal. Use the TTL opto-isolated pulse in case the sensors on your subject are connected through wires to the DAQ system. The opto-isolated pulse prevents a high voltage from being applied to a subject attached to the data acquisition system, in the unlikely case that the SyncBox might malfunction.

The Keycode Signal

The keycode signal sends out a pre-programmed keyboard key. There are 2 keycode signal outputs (via the X-keys device).

The X-keys device is a keyboard simulator that can send out any keystroke. The X-keys device in the SyncBox sends out a "t". Please contact [email protected] when you want the SyncBox to send out a character other than "t".

Connect the X-keys USB cable between one of the X-keys outputs and a USB port on the PC you want to send the signal to. A green light above the output indicates that the port is active.

Use the Keycode signal when you use an application that records keystrokes or captures the screen of the test computer:

• Screen capture software — Use the Keycode signal to record a "t" in Notepad. While the software captures the screen, simply open Notepad and the character "t" appears in the screen capture when the SyncBox sends the Keycode signal.
• Eye tracking system — Use the Keycode signal to record a "t" in Notepad. While the eye tracking system captures the screen, simply open Notepad and the character "t" appears in the screen capture when the SyncBox sends the Keycode signal.