Wireless Network & Video Transmission
Background - Developing Wireless Ship to Shore Networks
 Fig 1: Parabolic antenna on Pilgrim Monument receiving wireless video from R/V Connecticut at sea. |
For the past three years, NURC has collaborated with the University of Connecticut's Information Technology Services to conduct research and development activities to develop wireless transmission capabilities from the research vessels (such as the R/V Connecticut) to shore using evolving and very cost-effective 802.11b protocols. These systems, while effective nearshore, lacked the ability to send a signal further than 9-10 miles from ship to shore. The requirements for such a wireless network depend upon the quality of the video signal desired. Earlier research sent video signals from the underwater camera on the ROV or from a camera in the laboratory on the ship to a laptop computer with QuickTime Broadcaster software used to encode the video into the MPEG4 streaming format. The laptop sent the streaming file back to shore via the wireless network using the 802.11b antennas, routed to a land-based network, then sent to the Internet where it could be viewed by the free Quicktime viewer software in the classrooms. Communications from the schools to the ship was implemented using AOL Instant Messenger that provided an interactive element to the Webcasts to engage students at the other schools in an active question/answer session with the teachers and experts on the ship.
Improving Video Transmission over Wireless Networks
|
|
The 802.11b networks are limited in range (< 10 mi) and bandwidth (1-2 Mbps). In 2004, NURC experimented with and then purchased a broader bandwidth and greater distance wireless network solution developed by Orthogon Systems. This system relies upon a higher frequency (5.8 GHz vs 2.4 GHz) than 802.11b and also relies upon multiple antennas in a polarized (horizontal and vertical) configuration on the shipboard side (Figure 2). The receive antennas are parabolic dishes of 2 or 3 feet in diameter (Figure 1). The signal is received by the parabolic dish, then sent via an Ethernet cable to the shore-based network at Pilgrim Monument. This system provides increased distance (>25 mi) and greater bandwidth (>25Mbps; Fig 3).
Fig 3: Illustration
of the range of data & video transmission
in the S.W. Gulf of Maine through NURC's wireless network
In addition to improving the bandwidth of the wireless network, NURC has invested in a hardware based video encoding system developed by VBrick Systems Inc. These "appliances" have the ability to encode an MPEG-4 signal for web streaming and to encode an MPEG-2 signal that provides DVD quality video. The video signal is sent over the wireless network to a "set-top box" that provides a simple composite video out that can be plugged into a TV or video projector. When the signal arrives at the receive dish on Pilgrim Monument it will be sent to a router or switch and a CAT 5E cable is hardwired into the Pilgrim Monument Museum exhibit center. In addition to providing a MPEG-4 stream over the web, Pilgrim Monument will receive a high quality video signal for a special presentation on Sat. July 10, 2005.
Last Updated: April 28, 2006