These days almost everything is wireless and cheap. We're surrounded by an absolutely packed electromagnetic spectrum, stuffed with everything from Bluetooth to HDTV. Recently, even power can be transmitted wirelessly. So why is wireless video so expensive and difficult?
Most of the times I have needed to use wireless transmission of video in a theatrical setting, it was in the form of either a camera or a screen that needs to travel on a free-moving unit or be carried by an actor onstage. Low-end solutions intended for the surveillance and security industries are not robust enough: their analog signals disrupt either partially or entirely as either the transmitter or receiver moves around the stage. Interference is a perennial problem as well. In general, video signal transmission is difficult to execute cleanly. The only solutions that seem to work consistently are intended for the broadcast industry and cost more than the average theatrical production can afford.
In many cases, the best answer is to piggyback video on an 802.11n (wireless Ethernet) signal. These systems are generally stable and reliable but require having an expensive and usually bulky computer at either end (at least until we all get Apple iPads), but recently, a range of devices have started to become available at approachable price points that can eliminate the PCs in the system. Most of these products are intended for applications in digital signage, but their affordability, relatively small size, and low power draws make them adaptable enough for use onstage.
An example of these types of products, Avocent's MPX1550 transmitter unit has an impressively high data rate of 110Mbps in wireless mode. You can link eight receivers to each transmitter (an optional extender unit expands this to 16). It handles 1080i resolution splendidly, and I have a hard time imagining too many stage applications that would require greater resolutions from a wireless video setup. Unfortunately, the signal's stability in motion, while far greater than the analog surveillance systems, still leaves something to be desired. Wiring up to high-impact modern dancers is not recommended.
In the long run, wireless video is going to be one of those lucky theatrical applications that benefits from the home and wireless entertainment industries – the very American desire to watch TV whenever and wherever we go virtually guarantees it. In the meantime, products like Avocent's may help fill a gap.
A tip of the hat to Michael Matthews for the hands-on review.