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Why Infrared is a Must for Data Transfer in Many Applications

Fri, 04/06/2001 - 7:06am

Secure Data Transfer, Faster Speeds, Lower Cost

By Dr. Werner Schairer, Vishay Intertechnology

A wireless communication link is indispensable in most mobile digital devices — it is more convenient, more reliable, smaller, and cheaper than cables. If point-to-point communication is the main target, infrared will be the solution of choice for a long time to come. Unlike Bluetooth and other RF solutions, "point-and-shoot" infrared communication is inherently secure — an important feature when executing file transfers from notebook to notebook, business card exchanges from PDA to PDA, e-mail transfers from a notebook to a mobile phone, synchronization of agendas between a PDA and a phone or notebook, and, most importantly, sending money or credit card information in a point-of-sale transaction. Additionally, the high data rate offered by infrared — up to 4 Mbit/s and soon up to 16 Mbit/s — is a must for file transfer and printing. Small size and low cost make IR the top choice in miniaturized devices like wristwatches, but also in mobile phones and toys. Communication between all these different devices and platforms is standardized by the IrDA and supported by software from Microsoft, among others.

Characteristics of IR
Because infrared is used in hundreds of millions of remote control devices, nearly all consumers are already familiar with some of its most important features. IR radiation forms a straight beam with a design-dependent opening angle. Walls and most objects reflect and/or absorb the beam. These properties enable the point-and-shoot usage model developed and supported by the IrDA (Infrared Data Association), the organization concerned with the standardization of IR-related hardware and software.

Existing and New Applications
The characteristics of IR make it the best choice for the majority of today's applications. The first question when considering infrared components must always be: is a wireless external communication link really necessary? In most mobile applications, the answer is yes — in mobile equipment, it's a nuisance to use cables and the associated multitude of poorly standardized connectors. Moreover, a wireless link is usually smaller and much cheaper than cables and connectors.

The choice between IR or RF (Bluetooth) is always application dependent, however, and therefore cannot be decided upon without a specific analysis of the intended application. Still, in all existing and most future applications, infrared will provide the most convenient and low-cost link for point-to-point, short-range data transfer, whether at low or high data rates.

One of the biggest, although not obvious, advantages of IR is the easily controlled confidentiality due to the short-range point-to-point connection. This model is sometimes called point-and-shoot. Confidentiality can be controlled directly by the hardware and the people involved. No software coding or recipient identification and discrimination are needed. In a simple file transfer between notebook PCs (NB), the IR beams are merely pointed at each other. In instances where additional control is needed, the software displays the respective recipient prior to file transfer. Nobody has to worry that the IR beam will penetrate the walls of the room, and due to the short range — 80 cm in the miniaturized Vishay TFDU4201 IR transceiver, for example — potential wrong recipients inside the room are also easily excluded.

Another application that takes advantage of these IR features is the exchange of business cards from PDA (Personal Digital Assistant) to PDA. Synchronizing agendas or address lists between a PDA and notebook is another example of an application that benefits from the key characteristics of infrared wireless communication. It's simply more convenient to use infrared to transform a mobile phone into a modem that can send emails or facsimiles from a notebook computer. Because infrared data rates will increase to 16 Mbit/s in the very near future, file transfers between notebooks and from a notebook to a printer will become much faster, and the percentage of standard printers equipped with IR is rapidly increasing.

New applications jumping on the IR bandwagon include wristwatches and cameras, where compact size and cost-efficiency are important considerations, but so also are high data rates — as needed in today's cameras. Just recently, the Special Interest Group for the Promotion of Financial Short Distance Transactions opted for IR instead of RF as a financial transaction medium, simply for the advantage of easily achieving confidentiality. The IrDA has already created the IrFM Prototype Transaction Specification, which will use all kinds of IR-supporting hardware like phones or PDAs as an electronic purse that can pay at the point of sale in avenues such as supermarkets or ticket counters.

Ease of Use
It's true that infrared data connections have not always been easy to use, but nowadays software is available that makes the installation, configuration, and application of the components relatively straightforward. Microsoft Windows versions now support IR (WIN 95, 98, 2000) and facilitate all IR applications. The IrDA has recognized the potential improvement and has created an IrReady label that certifies that a specific product equipped with IR will work properly "out of the box."

Market Development
The IrDA recently developed a market overview, which predicts a total volume for the year 2001 of close to 250 million IR units and a growth rate of around 40% — decreasing to 30% and 25% in 2002 and 2003. Vishay's infrared data communications business unit estimates that both the absolute volumes and the growth rates are too optimistic and should be decreased by roughly one third, but confirms the strong growth trend from a high absolute volume.

It is clear that mobile or cellular phones form the largest market segment for IR implementations. In the cellular phone segment, RF has some merits in all hands-free applications. However, existing and future phones have already or will soon implement new features like games, business cards, synchronizing functions, and financial transactions — to name just a few — and in all these applications the point-and-shoot feature of IR is the optimal choice.

Growth of the IR market is also supported by other applications where IR is the ideal solution — like notebooks and PDAs. In addition, there is an increasing IR trend in applications where size and low cost are the essential features, such as in PDAs, wristwatches, toys, and yes, mobile phones, too. The price for a complete RF solution today is still in the range of $10 to $20, whereas prices for IR transceivers start at $0.90 for serial infrared and $1.80 for fast infrared. Such a huge price difference makes RF implementation in low-cost equipment unlikely.

On the other hand, there are high-end applications like mobile phones for hands-free operation or very high-end notebooks for local ad hoc networking that will use RF as the wireless data transfer medium of choice. The average user, however, will not accept that his new high-end phone or notebook refuses to communicate with his PDA or with another, less-sophisticated notebook. As a consequence, most manufacturers will continue to implement IR alongside RF in high-end equipment, especially in mobile phones.

Future Trends
The roadmap to the future clearly follows the trends of the past. Package sizes will continue to shrink, with transceivers like Vishay's MicroFace measuring just 7.3 mm × 4.55 mm × 2.8 mm. New techniques are being developed to make IR solutions even more power efficient than before. Vishay's TFDU4202, for example, uses a split power supply connection that reduces the drain on the battery serving the stabilized voltage, since only the receiver circuit is connected to a regulated power supply, while the high IR current is generated by a less controlled power line or directly from the battery. Other devices, like Vishay's TFDU4204, fit into power-conserving designs by offering compatibility with 1.8 V logic.

The price of IR components will decline even further, although the rate of decrease will likely slow down, especially with serial infrared (115 kbit/s) devices. Simultaneously, data rates will go up. The first 16 Mbit/s devices will hit the market in 2001, while the IrDA discusses the next step — which may lead to 32 Mbit/s for uncompressed video transmission. Existing and new applications will be better supported by more user-friendly software. Indeed, making the enormous installed base of infrared data communications components easier to use is now a key agenda item for the IrDA.

Dr. Werner Schairer is vice president of the Infrared Data Communications Division for Vishay Intertechnology, located in Heilbronn, Germany.

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