Wireless Projection

Several clients are asking about wireless projection and if it should be included in the design of their facility. Wireless projection can be done in different ways. The first and most common method is where the laptop and projector communicate only wirelessly. The other method uses a combination wired and wireless Ethernet network where the laptop is operating wirelessly to upload the presentation to the projector or send keyboard/video/mouse (KVM) updates to the projector but the projector is connected to a wired Ethernet network.

Issues that should be considered include how the data is sent (compression method) and the data transfer rate, which affects the amount of time lag before the image on screen is updated.

Compression Method: Currently all wireless projection which use a wireless card within the laptop and the projector use some type of proprietary compression method to send the screen information to the projector. Because of the proprietary compression, the software that does the compression must be loaded on each computer before it can talk to the projector. Most manufacturers provide the software driver for free from their website. NEC, Sanyo, Epson and Infocus all have this type of solution. The alternative is to use a stand-a-lone box at each end that performs the compression. This avoids proprietary software, but these boxes must be connected to the monitor connector at the computer and projector and therefore don’t provide the best portable solution.

Data Transfer Rate: The bad news is that most of the wireless projection systems currently suffer from slower image updates on the projected image than does a wired solution. For example, most wireless systems today take a second or two for a PowerPoint slide to “appear”. Some of the original systems just a few years ago took several seconds each time a slide changed, so things are getting better. But since these systems are all essentially “screen scrapers” that send the video information to the projector, they don’t work well for rapidly changing video images such as moving graphics or video windows on a computer. The exception is the new Video Streamer from *Avocent, which was designed with auto setup and self-adjusting hardware. The result is a smooth motion video with a stable image. The content is transmitted immediately and securely in the 5 GHz band. See this blog post for more information.

*Avocent merged with Emerson Network Power in 2009