Wireless communication is gradually becoming in our lives and in our computers and mobile devices. More recently, infrared arouse admiration - should be the same! through the air, without wires - mysticism, but now it is commonplace, but still outdated - many nose gate! We now have a new fad - the wireless network when the wall is not a hindrance, and the wires under your feet (or hands) do not interfere. In the mass is still, however, is still making slow progress - the wires are still cheaper to go out, but on the horizon rapidly materialized ghost bright future when all devices within a single office or apartment, including telephones, computers, televisions and microwave ovens will be linked in a network of invisible threads. That's what most of these filaments, we are now and we'll talk.
IRDA
In fact, IrDA - is an international organization that develops and implements wireless standards. IrDA provides wireless connectivity to devices that otherwise would have used for similar purposes of the cable. To connect via IrDA device must be in direct line of sight of each other (an infrared beam emitted by a 30 ° cone) and away from full contact to one meter. Transmission speed ranges from 9600 bps to 16 Mbps. The popularity of the communication standard is explainable - the cheapness and ease of use. No need for any wires - brought the device to each other and in the bag, and implementation of such a port in the unit cost producer in the $ 1 ... Advantages and disadvantages of this method of communication are clear. Of the shortcomings of most, perhaps all, you can call one for communication devices must be in direct line of sight. Plus, some types of lighting (eg solar) may interfere with communication, as used, though invisible to the eye but luminous flux ... The next limitation - it's communication range, and a meter is not always enough. The main advantage of the same - the price, until now, as you know, continues to play a major role in the calculations of producers and serve the promotion of the format. LOS, may also be a plus - in the first place, this condition provides a simple physical security of information transmitted - to catch her because of all the limitations of infrared connection is problematic. (Except that try to "fit in" with the receiver anywhere within the 30 ° cone :-) And with the third party, often require communication between two specific devices, which provides a brilliant infrared connection. And the price, and a small power consumption, and compactness, and versatility make the IR port is ideal for our brothers pocket. On large computers, he already looks unforgivable remnant of the old - and slow and, in general, not very convenient, considering the condition of line of sight ...
 |
Bluetooth - another communication standard, which predict a bright future. If we believe the promises, predictions, and already a fact, shortly Bluetooth wireless modules will appear on all devices, including refrigerators and microwaves. Unfortunately, this standard is somehow hard to go out of its infancy. More than a year talking about him, but many more of his eyes and something not seen before. Thus, a high-speed microwave standard that allows data transfer at up to 10 meters. Bluetooth operates at a frequency of 2,56 Ghz and is able to simultaneously connect up to 8 devices. This standard does not require any skills from the user - as the only Bluetooth-enabled devices converge at a certain distance, they immediately share information and establish a small network. Bluetooth module is small and consumes about 1 mW of energy, which is not very much, even for mobile devices. Time to talk about the advantages and disadvantages of Bluetooth. The biggest advantage of this standard is that for communication devices is not required line of sight - the device begin to "see" each other as similar to each other at a certain distance.This standard transcend even the walls and it can be used to create small networks in the apartment, and for example, the compound of a handheld computer with a mobile phone can be done at all without removing the last say, out of pocket. Unfortunately, in practice it is much more complicated and lack of properly written programs and drivers for Bluetooth-enabled devices is creating a situation where the advertised ease of using it grows into a big problem ... Well, for example, if one device "sees" another, and then it - no . Here and go, smash his head, where the dog is buried - setting a minimum. On the other hand it is omnivorous Bluetooth could become one of its drawbacks. Suppose, in a room sitting at the negotiations for a number of people with Bluetooth-enabled devices. Provided that all the devices "see" each other, but you need to pass information to, say, a business card to a specific person, you may have problems in finding this man. In this case, infrared communication may be more convenient. At the same time, Bluetooth is still much more expensive than the IR port, although the promise that the situation should be in the near future to correct a little bit. Theoretically, nothing prevents the manufacturer to include both device communication standard, because, in fact, they are designed for different things. So yes, it is, in practice, and is, in any case, the first devices equipped with Bluetooth, such as PDAs or mobile phones. But unfortunately while Bluetooth is not so developed to gain popularity. For our country, its development, in particular, hampered by the fact that it has not yet received the state license though, I note, nowhere in the world licensed to such frequencies are not required. But, I think, to have little time ...
IEEE 802.11b
 |
Another wireless protocol on the market, call names very much tongue-and at the same nezvuchnoy acronym for IEEE 802.11b. His friend, the advertising name sounds like an abbreviation Wi-Fi Wireless Fidelity or wireless impeccable and the people it is called Radio Ethernet. Commercially available, and along with popular, this format was in 1999 with the release of AirPort - the device lets you connect your computer to the Internet or local area network without wires. Standard that allows data transfer speeds of up to 11 megabits per second at distances up to 300 meters. Operates on IEEE 802.11b frequency of 2.4 gigahertz, which is close enough to the Bluetooth. Simply put, Wi-Fi transforms Ethernet into a wireless network status and is ideal for creating small local networks in those places where it is impossible to lay cables, for example, if a company has two offices located across the street ... Each of the radio outlets may, depending on the software installed serve as the end point of reception of information and hub. For handheld devices and laptops are available adapters, that's just not all necessary. For example, computers, Palm, for which there are also adapters for IEEE 802.11b is not "incarcerated" for work in the networks of Ethernet, but for the Pocket PC such an accessory in the form of Compact Flash can be a very useful thing, and greatly facilitate the work. IEEE 802.11b is not a competitor to Bluetooth, after all, in fact, they are designed for completely different tasks and, more importantly, for entirely different devices. Direct competitor of IEEE 802.11b is another interesting standard called Home RF.
 |
In fact, Home RF is the same as IEEE 802.11b, only in a more advanced version. If Radio Ethernet is designed specifically for data transmission in computer networks, the HomeRF can connect together, and computers and phones, streaming video and audio.In essence, Home RF is a symbiosis of the previously described technologies Wireless LAN and rapidly growing wireless technology, DECT. Home RF group developed Home Radio Frequency Working Group (WG), which includes more than 50 companies.
 |
| HomeRF USB Adapter and PC Card Adapter |
Apparently, this standard can be called a home and suitable for a particular small digital microcosm within their own apartment. By the way, it works everything is at a frequency of 2,4 Hz - nothing like? The only restriction until the Home RF is that the information is transmitted at a speed of 1.6 megabits per second, so obviously no match does not go from 11 megabits to the case of IEEE 802.11b. On the other hand for the house-it can be more and do not need - where and how you drive the data with a similar rate, the more so as long as Home RF is more favorable price. Developers, of course, also do not sit on the ground and is on the way Home RF 2.0, which will provide speeds up to 10 megabits per second, but then when there will be! Remember the story with USB 2.0 - which still spoke of him, and now look at your computer - what standard it used for? Surely even 1.0. Therefore, a good spoon for dinner and talk about the updates can last for years!
Problem
Despite the reasonableness of each of the formats, divorcee use technology and differentiation in the use of the frequency of a used one and the same, and therefore may be even very serious problems associated with the intersection of information flows. All three methods operate on the principle of separation of the frequency channels. In this case, Bluetooth and Home RF «jump" from one channel to a certain pattern in the spectrum of 83.5 MHz .. IEEE802.11b divides the spectrum into crossing the 22 megahertz channels and already-nm transmit information. Understand what is happening in the room during simultaneous operation of all three standards, we can imagine 84-hour lane freeway at rush hour. On it goes a lot of small cars, which occupy less than one band, but nonetheless famously rebuilt from one to another (Bluetooth), there is heavy tracks with enormous vans that take up several pages, but rarely moving from their seats - are currently in their Right at cruising speed and everything (IEEE802.11b), but there are also all kinds of vans, small trucks, "Gazelle" and "Bulls", which, despite the fact that cars are much more, behave less rude, trying to cut and also jump from band to band (Home RF). Presented? Now tell me, whether in this case, to avoid accidents? This is now a major, but if she decides to Bluetooth, the creators of the Home RF and Wi-Fi in no hurry to agree - it was too dense, they are competitors, and the attention of computer companies, more and more pulled in toward the latter.
Outcome ...
When it's bright future and we will completely abandon the wiring is not clear, but now there is a choice and, if correctly formulated problem and a certain level of funding, the solution could be found, although the universalization not yet in sight. Nevertheless, from the infrared port does not want anyone to refuse - it was too much desire to save money, and the use of Bluetooth and Wi-Fi is limited nedorabotannostyu technology and high price. What would be good - brought the printer to the computer, and it is already connected ... Hey, would be enough patience .... The authors, translation:
Alexander Eremeev