D1: Tools for Usability and Accessibility Analysis: Hardware

Overview of the "Hardware" Component of the Mobile Usability Lab (MU-Lab):

• Mobile, modular system that depends heavily on wireless products
• Integrates commercial products:
  • laptop with data interface board
  • wireless digital cameras (up to 4) with various tripods, and wireless/environmental microphones
  • digital video codecs, time-stamped voice overlays
  • advanced video editing hardware and software that builds on Adobe Premiere
• Specialized software for video and audio data collection and analysis
  • Ergonomics software - SVDA for real-time data collection and MVTA for event-based data analysis (both developed by Dr. Robert Radwin and colleagues at the Univ of Wisconsin - Madison, commertially available through NexGen Inc)
  • Video editing using Adobe Premiere-based packages (Cannopus, Matrox)

Summary of Hardware Components and Assembly (for more details see MU-Lab Manual, RERC-AMI Tech Report TR-001):

Suitcase and Components.

All of the MU-Lab hardware components (see table below) fit within a standard carry-on suitcase (approximately 9"x14"x22"). The suitcase is protected with hard plastic shielding and contains a customized foam insert to permit safe and secure travel with the MU-Lab. A laminated copy of the Quick Start guide, System Diagram and Pocket Inventory are included with the suitcase.

• Quad Processor
• Vanguard Pan/Zoom/Tilt Camera
• X10 XCam2 Camera
• X10 XCam2 WideEye Camera
• X10 Wireless Video Receivers
• Wireless Microphone Transmitters
• Wireless Microphone Receiver
• Manfrotto Micro Tripod 714SHB
• Manfrotto Mini Tripod 714B
• XCam2 Tabletop Tripod
• Super Clamp and Articulated Arm

Color Quad Processor

Because SVDA currently supports only one video input for data collection, the Grand Magic Guard II color quad processor is used to capture several video streams and compile them into one output. The unit supports input from up to four separate video cameras (with standard RCA video cables) and outputs one real-time composite video that is inputted into SVDA (with an RCA to USB adapter cable). There are several display options with the quad processor: display of any single video feed, any two video feeds via Picture in Picture (PIP), or up to four video feeds with a quadrant display. Either the remote control or the buttons located on the front of the quad display can be used to program and switch between available options, as well as display time, date and/or separate channel names.

Vanguard Pan/Tilt/Zoom Camera

The Vanguard Pan/Tilt/Zoom camera can be used either wirelessly (with the video receiver plugged into the quad processor) or tethered with a standard RCA video cable (plugged directly from the camera into the quad processor). A remote control is used to adjust the camera settings and to pan, tilt and zoom, which has clearly labeled buttons. There are also buttons to Zoom In and Zoom Out as well as an Iris button to adjust the amount of light that enters the lens. There is also an Autofocus button and Manual Focus buttons to allow you to adjust the focus of any particular area of interest within the camera’s field of view. This camera is equipped with the standard tripod mounting screw threading, so it can be easily attached to any tripod.

XCam2 and WideEye Wireless Video Cameras

The low-cost XCam2 and WideEye cameras have the same basic components but different lenses. These are "back-up" cameras used in tight situations, or where details are not necessary.

Wireless Video Receivers

To transmit the video signals wirelessly a separate video receiver must be used for each camera. Each video receiver requires an ACDC adapter and power supply for operation. The appropriate number of receivers should be plugged into one of the four available input channels of the quad processor using a standard RCA video cable. It is also necessary to tune each camera and corresponding receiver to the same channel, which is different from all the other camera channels being used. The Vanguard Pan/Tilt/Zoom camera has a channel selection switch on the bottom of the unit and both models of the XCam2 cameras have switches on the top of the unit, underneath the black rubber insert. The receivers can detect a signal from a camera that is located up to 100 feet away, even through walls since the signal is radio frequency (RF).

Wireless Microphone Transmitters and Receiver

A discrete two-channel receiver and two wireless microphone transmitters are included to facilitate audio collection. The normal protocol is to use the two wireless transmitters to capture and record the audio of the researcher and subject during experimentation. The microphone receiver should be plugged into the microphone port of the computer, prior to starting SVDA. The microphone system operates in the 169-172 MHz bandwidth, where interference is minimal.

Camera Stands

There are several camera stands that can be included within the MU-Lab. All of the cameras and stands are equipped with the fittings necessary to secure the cameras to the stands. At least 3 camera stands can be stored within the carrying case. The height range for each camera stand is listed below.