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What is it - GPRS?
For all its contemporary theoretical and practical bases of GSM have been developed for a long time and largely behind the users' requirements. The current data rate in these networks - 9.6 kilobits per second (1,2 KB / s). Even under the most modest needs such speed can not provide a complete work. In addition, with this method of connection fee is to wait. In the present situation, when many people need to be always on-line is absolutely unprofitable. To remedy the situation, at one time, a new data transfer protocol in mobile networks, which received a resounding title GPRS (General Packet Radio Service - the packet data service over the air). As seen from the explanation of the abbreviations, the transfer is "packets", ie not used all the radio, on which there is also a voice, but pauses that occur during the transmission of voice information. The phone can handle multiple channels simultaneously - both the reception and data transfer. The new protocol will dramatically increase the speed - ideally - to 171.2 Kbps. In reality, the speed is limited capabilities of terminals, ie handsets. Modern tube can use up to 2 channels for the transfer - about 13 kbit / s and up to 4 to receive data - about 40 kbps (5 KB / s). In many ways, the connection speed is determined and the overall workload of the network. It is important that the GPRS-connection fee is charged based on the number of incoming and outgoing information, rather than time. That is, users of GPRS if you want can always be connected to the internet, because he pays only for traffic. This kind of access is much easier, and cheaper than traditional GSM-speed data transfer.
Mobile Internet: PDA or handset?
Manufacturers of mobile phones today are building into their products a lot of additional tools: an organizer, phone book, to-do list, games. And often, of course, GPRS. With the tube becomes possible to learn the schedule of the aircraft, weather forecast, currency rates and much more. Your mobile phone can be connected to global networks, and this opens up broad prospects. But this raises the issue of quality user experience with the Internet. Screens of mobile phones today are extremely low, so a full-fledged surfing the net is almost impossible. Of course, there are sites that are adapted for viewing on small screens, but it's mostly dry information sources that provide background information or at best a summary of the latest news. And what about chat rooms, forums, ISQ? A good idea to get access to data and remote home or office computer, and use the full email client, which can, for example, display, save, and send email attachments. But would still need to work with Web pages without going through all the links one by one the phone button, but simply pointing to the right as on the desktop ... Ah! .. All this mobile phones, unfortunately, are not able. There are not going to use something else other than a mobile phone. Options are not too many: laptop, desktop, or PDA (personal computer). The most powerful tool will, of course, laptop. He is mobile and the most versatile. But the laptop - it's more than 800 dollars a kilogram minimum weight, it is a decent size, it's about 2-3 hours (the more expensive models have worked for longer). Besides all the above, the laptop does not use on the go. It necessarily have to open and wait until the system boots or come out of hibernation. The second option - it's handhelds. All the advantages and disadvantages here to mirror the situation with laptops. Pocket PC today is inexpensive - from $ 200, but the average price of a typewriter for a good price / quality ratio - $ 300 PDA weighs only 150-200 grams, it is flat and quietly fit in your pocket, it is very convenient to carry in a belt or cheholchike purse. Battery life varies widely, averaging 5 to 12 hours (net time!). PDA enabled instantly: got, clicked the button work. Practice shows that the PDA is quite resistant to accidental drops, vibration, rain.The touch screen and control buttons make the work enjoyable, with many actions you can do with just one hand. When you visit Internet resources ligament PDA + phone provides a lot more than just a mobile phone that supports GPRS. A relatively large screen, ample opportunities for input, the ability to install additional software, support for today's Internet technology - all this speaks in favor of the CCP. In many cases, the network can use services with the same ease as on the desktop. For PDAs, there are versions of popular programs such as ICQ, Windows Messenger, etc. But, nevertheless, the possibility of handhelds are not limitless. When working with network resources frequently encountered problem with displaying national symbols, and many handheld browsers will not be able to automatically detect the page encoding to spend a lot of time on the repartitioning of pages for viewing on a small screen, can not work with animated images. Nevertheless, for mobile surfing on the go, anywhere - the best solution to date is not there. Although, in fairness, it is worth mentioning another class of devices - smartphones - a sort of hybrid mobile phone and a full-fledged handheld computer. But we tell about them below.
Several ways to combine a PDA with a mobile phone
Link PDA with a mobile phone in several ways. Typical estimates of each method can be easy connectivity, reliability, convenience and, of course, price. Let us consider all possible types of connection. Firstly, it is a direct cable connection. Special devices are connected to cable via serial ports. This connection could be considered the most reliable and cheap, but given the variety of PDAs and cell phones on the market, such a method will be most difficult. The developers did not seek to unify the devices, and virtually every new model has its own interface and connector. Of course, you can try to find a suitable model of PDA and phone, search for shops or solder a very appropriate cable, but it's too expensive. Cable connection is not convenient (imagine that your PDA and phone all the time, connect the wires) and virtually a thing of the day before yesterday afternoon. Therefore, in this review, the cable connection is not considered. A more common way to make friends PDA and cell phone - it's an infrared port (IrDA). Device "wink" to each other rays bottom of the spectrum, not visible to the human eye. Such a combination is used for a long time and was very widespread. Almost all PDA models have this port, and you just have to pick up the appropriate receiver. The process itself will be discussed in detail hereinafter. Looking ahead we can say that this method is the most inexpensive of the above. However, there will have to live with some restrictions mobility ligament - a device constantly need to be in direct line of sight to each other at a distance of no more than 2 meters. To use such a bunch on the run, will require considerable skill. In addition, in very bright light and sunshine connection on the IR port will be difficult.
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And the third possible way to combine - it's communication at radio frequencies, when using Bluetooth. Bluetooth - a high-speed microwave standard that allows data transfer at up to 10 meters (in practice more). Clocked at 2,56 Ghz and is able to simultaneously connect up to 8 devices in one group. The main charm of Bluetooth - a sufficiently high exchange rate and the time that the devices need not be in the line of sight. No need to worry that someone can connect to your phone via Bluetooth and will "sit" on the internet your money. User-level protection against unauthorized access to your device is organized with multiple levels of trust that can be set independently.The highest level - Trusted. In this mode, the owners of Bluetooth devices once spend on their typewriters special authorization procedure, after which the devices can exchange data without asking for additional evidence. Lower level - Discoverable. In this mode, your Bluetooth device is visible to all others who are in range. However, all manipulations with data transfer require you to confirm. And finally, there is almost completely hidden mode when your PDA can not be found. In this mode, it will only communicate with the Trusted devices, if any. At the moment the technology is becoming more widespread, and these modules are integrated into an increasing number of devices - from watches to refrigerators. Minus - pretty high price for the device with built-in Bluetooth-modules, because basically these modules are equipped with top models of equipment. However, the situation is gradually getting better, and the standard, finally, may well become nationwide. For example, the latter belonging to the class cost model iPAQ h1945 Pocket PC equipped with such a module.
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If the PDA does not have full-time wireless data transmission capabilities, it is quite simply "cured" through an optional module in the slot the PDA. The procedure to install the Bluetooth connection in some cases even easier than IrDA, and will also be discussed in detail hereinafter. In terms of ease of use, "Blue tooth" of course, be the first place. To access the Internet, you will not even get the phone from his pocket. In transport, on the street, at work, at home and study you will always be on-line. With the help of special software can work with text messages and make calls directly from the PDA. Chances are, of course, very broad, but, as mentioned above, it is worth the money.
Test Equipment
