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New System for In-House HDTV Distribution Announced

WHDI LLC this week announced the completion and availability of the WHDI (Wireless Home Digital Interface) specification.

A key feature of the WHDI 1.0 spec is that it allows wireless transmission of uncompressed HDTV content up to 1080p at 60 Hz at a range up to 100 feet through walls. Latency is less than 1 millisecond and power consumption is low enough to allow it to be used in battery operated devices.

WHDI achieves this performance by using a video modem that breaks down the HDTV stream into elements of visual importance. More important elements are transmitted with more robust modulation than less important elements. This allows less important elements to be transmitted with higher level modulation with more errors, increasing bandwidth but making errors less noticeable. Other forms of wireless data transmission, such as WiFi, treat all data the same and thus can't achieve the same data rate.

The standard uses the same 5 GHz frequencies as 802.11a, but the WHDI FAQ notes that the specification employs spectrum management capabilities to avoid interference. In the event of interference, WHDI will automatically switch to an unused channel. The FAQ also mentions that there is approximately 600 MHz available in the 5 GHz band, but WHDI will work in a bandwidth of either 20 or 40 MHz, allowing for multiple routers and WHDI devices in the same environment.

While this specification was designed for consumer electronics, I can see it being used in short range wireless HD camera locations. In this application, it could compete with other systems that use frequencies in the 60 GHz band.

Doug Lung is one of America's foremost authorities on broadcast RF technology. He has been with NBC since 1985 and is currently vice president of broadcast technology for NBC/Telemundo stations.