Kamis, 22 Mei 2008

What Is a DECT Phone


Properties and Features

A DECT phone, commonly known as DECT 6.0 in the US, requires a base station to charge the handset and receive the phone's signal. It usually comes with one handset, but additional ones can be added on some models. This makes them useful in homes with multiple floors or large layouts, and for offices that want several cubicles to access the same phone system. Each handset is set up to communicate with the same base station, and usually comes with its own charging dock or "cradle."

The range of use for a handset depends on the phone itself, though it typically can reach over 300 feet (up to 100 meters). Digital technology allows a DECT phone to have much greater range than was previously possible, though this can be affected by various environment factors. Objects between the handset and base, for example, can potentially disrupt the signal and reduce the range of these phones. 

Some DECT phones can be used with general wireless technology, allowing different handsets connected to the same base station to be used as walkie talkies. Other standards, such as Wi-Fi®, have been more popular in some markets, however, so DECT technology has not expanded to many other devices in places like the US. A DECT phone can often be used with Voiceover Internet Protocol (VoIP) technology, allowing it to remain functional with the new communication platform.

Risks and Concerns

One of the biggest issues with DECT 6.0 technology in the US is that it does not include a single technology profile for use by all manufacturers. This means that a handset produced by one company does not typically function with a base or accessory made by another. Someone using a DECT 6.0 phone should look for accessories and parts made by the same manufacturer to ensure all of the components are compatible.

There is some question of how secure the signal is from this type of phone. DECT technology uses encryption to protect the signal, but the encryption has been broken and someone could potentially listen in on a phone call. It is also possible for someone to intercept the signal from a handset to the base. This allows a different device to act as the base, sending a call through it to another location, rather than through the actual base and phone line.

There is concern among some people about the radiation released by DECT phones. In general, they emit only a low level of radiation during use and while charging; even using the phone frequently should not cause any health issues. Many devices used on a daily basis do emit some radiation, however, and while individually these items are harmless, there is some concern about the possibility that long-term use of multiple devices could result in sufficient cumulative exposure for health concerns. Research into this exposure is ongoing.

History and Terminology

The DECT phone was initially introduced in Europe, and was first referred to as a "Digital European Cordless Telephone." It has since become an industry standard in many parts of the world. The term "DECT" by itself is typically used in Europe and other regions, such as Australia and different Asian countries. 

In the US, the term "DECT 6.0" is used, but this does not indicate any particular technological designation. The "6.0" was chosen simply to indicate that it was a new technology for American consumers. A DECT phone in the US operates at 1.9 GHz, and often replaced phones that used the 5.8 GHz frequency. It was decided that "1.9" might seem inferior to "5.8," despite this not being technically accurate, and so "6.0" was chosen for US marketing.

Selasa, 20 Mei 2008

What are Some Common Abbreviations Used in Text Messaging



Many of the common abbreviations used in text messaging are shortened versions of expressions, such as AAMOF (as a matter of fact), IMHO (in my humble opinion), or PLMK (please let me know). Other common abbreviations that replace expressions include:
    BBS: Be back soon
  1. BBT: Be back tomorrow
  2. BIB: Boss is back
  3. CM: Call me
  4. CYE: Check your email
  5. DIKU: Do I know you?
  6. F2F: Face to face
  7. HB: Hurry back
  8. JFF: Just for fun
  9. KOTC: Kiss on the cheek
  10. OMG: Oh my God!
  11. OOTO: Out of the office
  12. PSOS: Parents standing over shoulder
  13. PU: That stinks!
  14. SLAP: Sounds like a plan
  15. TMB: Text me back
  16. UGTBK: You’ve got to be kidding
Other abbreviations used in text messaging represent people or relationships, like BIL (brother in law), SO (significant other), or DWF (divorced white female). Some additional text message abbreviations that indicate people:

  1. B/F: Boyfriend
  2. BFAW: Best friend at work
  3. DD: Dear daughter
  4. DH: Dear husband
  5. DS: Dear son
  6. DW: Dear wife
  7. G/F: Girlfriend
  8. GRL: Girl
Even other abbreviations used in text messaging represent shortened versions of commonly used words, such as B4 (before), NE (any), or W? (why). Other abbreviations used in text messaging for frequently used words include:
  1. AIGHT: Alright
  2. GB: Goodbye
  3. GL: Good luck
  4. HV: Have
  5. K: Okay
  6. M8: Mate
  7. ONL: Online
  8. OVA: Over
  9. PEEPS or PPL: People
  10. PLS: Please
  11. PZ: Peace
  12. TTLY: Totally
  13. W? Why
  14. X: Kiss
  15. Z: Zero
Some abbreviations used in text messaging incorporate symbols to represent words or phrases, like 411 (need information), 121 (private chat), and ?4U (question for you). Not as many common abbreviations start with symbols, but some others are <3 (represents a sideways heart), 4COL (for crying out loud), and 2G2BT (too good to be true).

Selasa, 13 Mei 2008

What are the Disadvantages of Solar Power



One disadvantage of solar power is consistency and reliability. Solar-powered devices rely on the steady delivery of special particles called photons to keep the electricity generating process going. As soon as the sun falls below the horizon at night, photons stop striking the solar panels and the power drops instantly. This means that storage technology, such as batteries, or an alternative source of energy is always required to ensure uninterrupted power flow. Otherwise, if there is no sun, there is simply no power.

Some of the major disadvantages of solar power are economic in nature. Solar panels designed to generate electricity are still fairly expensive to produce. Since single solar panels can only generate a relatively small amount of electricity, an large arrays of solar panels are needed to provide a sufficient level of electricity to power a number of homes. These solar panels also have to be adjusted throughout the day in order to maintain a direct angle with the sun, so a mechanical orientation system also needs to be implemented to turn all of the solar panels. 

Other disadvantages of solar power are technical. The materials used to create a solar panel are constantly exposed to other things besides photons. The constant bombardment of ultraviolet (UV) rays and other solar radiation often causes the panels themselves to deteriorate, much like any other material left exposed to the sun for extended periods of time. Other environmental factors like rain and dirt also take their toll.

Technology changes rapidly, and the number of disadvantages of solar power that seemed virtually insurmountable only a few years ago are now relatively minor inconveniences. With continuing advances in photovoltaics and other solar power technology, the cost of adding solar panels to houses, for example, has dropped significantly. The growing "green movement" has also spurred further development of alternative fuels, and created a greater interest in overcoming those disadvantages of solar power that remain.

Senin, 21 April 2008

What Is a Firewire® to USB Adapter



Even if you don't have a Firewire® to USB adapter cable, it doesn't mean that your Firewire® devices are useless if you have a USB port, or vice versa. Several companies do provide dual hubs. This type of device has two ports in a single hub, which may be either external or internal; one port is used Firewire® and one for USB, allowing either type of device to function. The combination hub is actually two separate ports combined into a single form factor for convenience; there is no conversion between Firewire® and USB taking place when you use one of these hubs.

Another alternative is simply to add two separate cards, assuming your computer has enough available slots. Firewire® and USB cards are both coming down in price, and adding whichever one is missing should not represent a major expense.

Both Firewire® and USB are efficient, high-speed bus standards. A Firewire® hub can support a data transfer rate of up to either 400Mbps or 800Mbps, depending on the standard, and a single Firewire® port can connect up to 63 devices and deliver a guaranteed rate of speed to each one. Firewire® is often used for devices that require real-time operation such as audio and video systems because of this guarantee, and it is also used frequently in storage area networks.

USB can connect more devices (up to 127), but supports data transfer rates of only up to 12Mbps. It is more often used for standard peripherals, such as mice, modems, and keyboards. The USB 2.0 standard supports speeds of up to 480Mbps, which makes it more competitive with Firewire®. On 17 November 2008, USB 3.0 specifications were released, with a transfer rate 10 times that of USB 2.0; consumer devices that use this standard were expected to be available by 2010.

If you cannot purchase a Firewire® to USB adapter, using a hub allows you to use devices that are compatible with either technology. Both technologies support Plug-and-Play and hot-plugging (hot-swappable).

Selasa, 15 April 2008

What is the Difference Between GSM and CDMA



The GSM Association is an international organization founded in 1987, dedicated to providing, developing, and overseeing the worldwide wireless standard of GSM. CDMA, a proprietary standard designed by Qualcomm in the United States, has been the dominant network standard for North America and parts of Asia. However, GSM networks continue to make inroads in the United States, as CDMA networks make progress in other parts of the world. There are camps on both sides that firmly believe either GSM or CDMA architecture is superior to the other. That said, to the non-invested consumer who simply wants bottom line information to make a choice, the following considerations may be helpful.

Coverage: The most important factor is getting service in the areas you will be using your phone. Upon viewing competitors' coverage maps you may discover that only GSM or CDMA carriers offer cellular service in your area. If so, there is no decision to be made, but most people will find that they do have a choice.

Data Transfer Speed: With the advent of cellular phones doing double and triple duty as streaming video devices, podcast receivers and email devices, speed is important to those who use the phone for more than making calls. CDMA has been traditionally faster than GSM, though both technologies continue to rapidly leapfrog along this path. Both boast "3G" standards, or 3rd generation technologies.

EVDO, also known as CDMA2000, is CDMA's answer to the need for speed with a downstream rate of about 2 megabits per second, though some reports suggest real world speeds are closer to 300-700 kilobits per second (kbps). This is comparable to basic DSL. As of fall 2005, EVDO is in the process of being deployed. It is not available everywhere and requires a phone that is CDMA2000 ready. 

GSM's answer is EDGE (Enhanced Data Rates for GSM Evolution), which boasts data rates of up to 384 kbps with real world speeds reported closer to 70-140 kbps. With added technologies still in the works that include UMTS (Universal Mobile Telephone Standard) and HSDPA (High Speed Downlink Packet Access), speeds reportedly increase to about 275—380 kbps. This technology is also known as W-CDMA, but is incompatible with CDMA networks. An EDGE-ready phone is required. 

In the case of EVDO, theoretical high traffic can degrade speed and performance, while the EDGE network is more susceptible to interference. Both require being within close range of a cell to get the best speeds, while performance decreases with distance. 

Subscriber Identity Module (SIM) cards: In the United States only GSM phones use SIM cards. The removable SIM card allows phones to be instantly activated, interchanged, swapped out and upgraded, all without carrier intervention. The SIM itself is tied to the network, rather than the actual phone. Phones that are card-enabled can be used with any GSM carrier. 

The CDMA equivalent, a R-UIM card, is only available in parts of Asia but remains on the horizon for the U.S. market. CDMA carriers in the U.S. require proprietary handsets that are linked to one carrier only and are not card-enabled. To upgrade a CDMA phone, the carrier must deactivate the old phone then activate the new one. The old phone becomes useless.

Roaming: For the most part, both networks have fairly concentrated coverage in major cities and along major highways. GSM carriers, however, have roaming contracts with other GSM carriers, allowing wider coverage of more rural areas, generally speaking, often without roaming charges to the customer. CDMA networks may not cover rural areas as well as GSM carriers, and though they may contract with GSM cells for roaming in more rural areas, the charge to the customer will generally be significantly higher. 

International Roaming: If you need to make calls to other countries, a GSM carrier can offer international roaming, as GSM networks dominate the world market. If you travel to other countries you can even use your GSM cell phone abroad, providing it is a quad-band phone (850/900/1800/1900 MHz). By purchasing a SIM card with minutes and a local number in the country you are visiting, you can make calls against the card to save yourself international roaming charges from your carrier back home. CDMA phones that are not card-enabled do not have this capability, however there are several countries that use CDMA networks. Check with your CDMA provider for your specific requirements.

According CDG.org, CDMA networks support over 270 million subscribers worldwide, while GSM.org tallies up their score at over 1 billion. As CDMA phones become R-UIM enabled and roaming contracts between networks improve, integration of the standards might eventually make differences all but transparent to the consumer. 

The chief GSM carriers in the United States are Cingular Wireless, recently merged with AT&T Wireless, and T-Mobile USA. Major CDMA carriers are Sprint PCS, Verizon and Virgin Mobile. There are also several smaller cellular companies on both networks.

Senin, 07 April 2008

What Are Unlocked Cell Phones


Potential Advantages

One advantage to buying an unlocked cell phone is the ability to buy almost any GSM (Global System for Mobile Communications) phone, rather than being restricted to a limited selection offered by a specific carrier. This can include phones only distributed in certain countries, or with features that are not available on all carriers. People also don't need to wait for a contract to expire to buy a new phone; they can remove the SIM (Subscriber Identification Module) card from an existing phone and insert it into a new one when they are ready for a replacement. This allows them to keep their number while upgrading the phone, without having to go through the carrier.

Additionally, the ability to use an unlocked cell phone with a variety of SIM cards can be convenient for travelers. Most carriers only supply service to a particular country or area; when traveling outside the coverage zone, the mobile phone user will have to "roam" on another carrier's network, which often comes with a high fee. To avoid roaming fees, a person can buy a SIM card from a local carrier at his destination and insert it, preserving all his existing phone settings but getting a new number and a local calling plan. In addition to less expensive calling rates, this provides the added benefit of having a local number while in the area.

Potential Disadvantages

Not all unlocked phones have all the same features as their locked counterparts even when the provider is the same. Carriers may include such features only on locked phones, which use their proprietary software and settings. Some carriers offer free calling to a number of contacts or one-button access to certain features that can only be used on locked phones. Consumers concerned about specific features may want to check with a carrier to see if they are available on unlocked cell phones. 

In addition, such phones tend to be more expensive. Locked phones are often costly because they usually come with phone service contracts that commit the consumer to that service provider for a certain period of time (like two years). Unlocked phones typically sell at or close to retail price because the buyer can use the phone with a number of different carriers.

Another issue with unlocked cell phones is that they may not work on all GSM bands; as of 2012, a quadband phone could operate anywhere in the world with a GSM network, but other phones could not. This may be a concern for international travelers especially, since not all bands are used in all countries. For example, in South America, the 850 MHz band is in common use, but others may not be available. It is advisable to check on which bands the phone uses, and which bands are available in given travel destinations.

Getting an Unlocked Phone

One way to get a phone without proprietary settings is to buy it new from a third party vendor in its original, unlocked state. Third party services are also available to unlock a person's cell phone for a fee, usually by attaching it to a special piece of hardware specially designed for this purpose. This doesn't guarantee the phone will always work correctly, as carrier settings might remain in the software. 

There are also instructions online to unlock most models. In many cases, unlocking a phone is just a matter of activating the phone and entering a specific code; some phones, however, require a series of steps before the code can be entered. Not all codes work, and trying to enter codes that are incorrect can cause the phone to "hardlock" and prevent it from being unlocked. Certain models of cell phones can only be unlocked using the hardware method, which may also worked for hardlocked phones.

Some cell carriers sell unlocked phones at full price, usually allowing consumers to pick a flexible plan such as month-to-month or pay-as-you-go billing. This can provide access to carrier-specific features with the flexibility of an unlocked phone. If a customer has been with a carrier for some time — sometimes for as little as 90 days — the carrier may even be willing to supply an unlock code for a locked phone, although they may charge a fee.

Cell Phone Carriers

The majority of the world — 99% — uses the GSM network, and numerous carriers use it for their services. The competing network is CDMA, or code division multiple access. Most carriers on the CDMA network do not, as of 2012, use card-enabled phones; instead, subscriber information is stored in the cell phone's memory, which means it cannot be transferred to another phone. The CDMA equivalent of the SIM card — the R-UIM — is likely to be used by these carriers in the future, and is already in use in some parts of Asia. This card contains software that allows it to be used in GSM phones as well.

Jailbroken Phones

A jailbroken phone is not exactly the same as an unlocked phone. Most often used in reference to Apple's iPhone®, when a phone is jailbroken, it has been modified to allow it to download applications (apps) not approved or sold by the carrier, such as the Apple App Store. A phone that has been jailbroken is not unlocked, although it may be necessary to jailbreak a phone before unlocking it is possible. Jailbreaking a phone is considered legal in the US, although it may violate the warranty.

Senin, 17 Maret 2008

Why Can't You Use Your Cell Phone on an Airplane



The FCC regulates the use of all electronic devices, including cell phones, on airplanes under the assumption that they may affect the communication systems on board. The Federal Aviation Administration (FAA) agrees with the FCC that cell phones may cause substantial interference with aircraft systems and supports the ban for all commercially operated airplanes. The use of cell phones on private or charter planes is not regulated, however, and many private flights permit passengers to use cell phones while in flight. 

Lots of debate has surrounded the use of cell phones on airplanes. The primary concern is that cell phones may interfere with the navigation and communication systems of the plane, potentially resulting in devastating failure. Numerous airlines have reported disruptions in cabin pressure, compass function, and wireless navigation systems associated with the use of cell phones on board. The FCC, it seems, erred on the side of caution when it enforced an outright ban on the use of radio frequency emitting devices which could potentially cause an aircraft to crash. 

There have also been some reports that the use of cell phones on planes may cause disruptions in ground communications because of interference. Others claim that the airlines and the FCC would simply prefer that consumers use the telecommunications systems mounted on most seat backs in commercial airplanes, because these phones are said to be highly profitable. Newer cell phones are capable of operating on very low power settings, which may not interfere with the aircraft as much. The FCC is attempting to establish an acceptable threshold of radio frequency emissions, so that cell phones could be used on airplanes without any fear of the navigation system failing or service on the ground being disrupted.












 

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