As wireless technology starts to appear in more and more consumer electronic devices, manufacturers have to find newer, better ways of incorporating the technology – particularly now that HD is in play.

Wireless technology is increasingly coming to the fore in home entertainment equipment. And, there are two different ways that it is being used: one for traditional computing-type network functions involving consumer electronics and the other to move actual video and sound signals around from device to device.

As we shall see, these are very different functions.

Doing it the computer way, wireless communication relies entirely upon the usual computer-style WiFi signal and is primarily for shifting either non-time critical data around (eg. Electronic Program Guides downloaded from the Internet) or lowish bitrate data (eg. audio files). Remember: WiFi is just like a wired network, only slower.

The reason for this is because computer networks are not really designed for serial data, but for ‘packets’. Everything that goes across the Internet – including Voice over Internet Protocol (VoIP) and streaming video from YouTube – has to cope with the fact that it will be broken up into bite-size chunks. Each chunk (packet) is sent independently from the source to the destination via whatever route may be most convenient at the time. That route can vary widely from second to second, so the first packet from, say, Melbourne to Los Angeles may go via Taiwan, while the next packet goes via Dubai. They won’t necessarily arrive at the destination in the correct order, but each packet contains enough information for them all to be put back together in the right order once all the packets have arrived.

This, of course, doesn’t suit the transmission of uncompressed high definition video in the consumer context, but we’ll get to that soon.

The PlayStation3 and some digital TV receivers feature this type of wireless technology, primarily for EPGs and shuffling files off to computers. The next generation of Blu-ray players are also likely to incorporate it in order to support the BD Live functionality by allowing Internet access without the need for network wiring to your home entertainment system.

All these make relatively low demands on bandwidth, and so work very nicely with WiFi.

But the main function of consumer electronics is all about a steady, unbroken signal, much of it very dense in data. It has very different requirements to most computer networking communications.

Most of us have experienced the latter with something like YouTube. You click on a video clip, and then wait while the player loads some of the video into its buffer. This is designed to carry the video unbroken over any brief delays in communication. But you are sure to have endured a slow connection one day, and had the clip stop, wait for a few seconds, resume, and repeat this process until you have gotten sick of it and closed that window.

That simply cannot happen with consumer electronics. If it did, the equipment would be returned to the maker, or at least be lodged with a service agent for warranty repairs.

So even to the extent that they use packets for the purposes of error correction, any wireless systems for replacing the usual connections in a consumer electronics context must ensure that the signal gets through with 100% reliability, and without any delays.

With some applications this is relatively easy, such as with wireless speaker systems. These need to be able to transmit sound – usually two channels – to a CD quality standard. That means about 1.4Mbps, plus some management overhead.

The new breed of wireless TVs are another matter. For them, the wireless system is supposed to replace an HDMI cable. But even under the oldest HDMI standard, it is supposed to support up to nearly four gigabits of video per second – some 25,000 times the amount of data required for two channels of high quality sound.

For Blu-ray players, much of the output is at 1080p60, which requires just under 3Gbps. The typical throughput of the latest WiFi standard – 802.11n – is just 144Mbps, or less than 5% of the required data rate.

So it isn’t surprising that there are limitations on what can be achieved.

So far I’ve seen two implementations of wireless high definition digital video: one by Sony and one by Panasonic.

Neither is the perfect solution, but both suggest that things are getting close.

The Sony system is a proprietary system and has the major advantage of being available on products that you can purchase right now in the Sony ZX and EX TVs. The former presently consists of one model: Sony’s ultra-thin Bravia KDL-40ZX1 LCD TV. The EX range is more conventional, with models reaching from 101cm to 132cm in size.

Their main limitation is that Sony’s wireless system only supports 1080i50 and 1080i60 signals. That introduces a number of problems.

The first is due to Sony’s TVs being quite poor at deinterlacing 1080i50 signals. They usually degrade the picture quality by assuming that it is always sourced from some kind of video camera, when in fact it often carries film-based images.

The second is the loss of the smooth motion delivered from film-based Blu-ray discs using the 1080p24 signal standard. The Sony wireless TVs’ external ‘Media Receiver’ boxes can accept this signal, but undo its essential goodness by turning it into 1080i60.

Which is odd, since 1080p24 actually requires less bandwidth than 1080i60. I expect Sony will correct that oversight at least in the next version.

Panasonic, in turn, is promising to release its first wireless high definition TV in September this year. The Panasonic Viera TH-P54Z1A is a 137cm unit, so Panasonic is starting at the premium end of the market, and it measures a mere 25mm thick. It is a plasma display rather than the LCD/LED technology used by Sony.

Panasonic says that it uses ‘WirelessHD’ technology.

We are likely to see that name – WirelessHD – fairly frequently over coming years, because that is the fruit of the broad based WirelessHD consortium. This employs available space in the 60GHz frequency spectrum (most WiFi uses 2.4GHz) to provide up to as much as 25Gbps of bandwidth!

Sony is also a member of the consortium, but its system – called ‘BRAVIA 1080 Wireless’ – works in the 5GHz band. Perhaps they were impatient in waiting for WirelessHD.

WirelessHD is designed to support full high definition up to 1080p, and may in the future even support resolutions beyond the capabilities of Blu-ray. For example, ‘Deep Color’ (which uses more than eight bits per colour to allows more precise colours) should be supported. But that’s for the future.

For now – or at least for September – Panasonic’s WirelessHD relies upon visible transmitters and receivers which poke out from the other equipment (Sony’s system keeps its antennae completely hidden). At a demonstration I went to in April, Panasonic were keen to point out that you could walk between the transmitter and receiver without interrupting the signal. Thankfully.

The range is likely to be in measures of several metres, rather than tens of metres, and the communication signal is highly directional, rather than ‘broadcast’, so some set-up will likely be required.

At the demonstration, it certainly looked like it was doing its job, and with the wide range of companies involved, it seems likely that WirelessHD will be here to stay.

At least for those applications where it is required. In most cases, a HDMI cable can do the job at least as well, for a far lower cost.