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These days, people seem to find every possible outlet of self expression. Common items are being personalized to proclaim the owners individuality. Sometimes personalization is purely for the owners enjoyment, so that just looking at the item reminds them of their favorite past time. A cell phone is a prime candidate for this personalizing, since it's pulled out regularly for use. Most cell phone covers come only in boring black, gray, or white. However, there is a more exciting world of customized cellphone covers out there. Men, women and children can find customized cellphone covers, suited to styles and age groups.

What exactly is it that you are looking for in a phone cover? Do you want to be able to change them regularly? Do you want to have a picture of your favorite musician, like Elvis, on it? Is it meant to be feminine or masculine? Whatever you are looking for, you can find cell phone covers made just for you. Rhinestones can be applied, as can pictures of favorite musicians and bands. Kids phone covers can have cute, kooky creatures printed on them. Couples can even have their pictures printed on a cell phone cover sticker!

Your cell phone covers can change as quickly as your mood or the occasion. Clip on phone covers are made of hard plastic that comes in a variety of colors. You can find patterned ones as well. The clip on style of cover must be specifically for your make and model otherwise it will not fit. These are great because, if your mood changes, you just pop off the cover and replace it with another! You can even build a collection of cell phone covers, and use them interchangeably. Paste on or stick on covers are both admired and desired among younger cell phone users. Lets say you have a favorite photo, perhaps of you and your sweetie, printed with a sticker-back. Simply trim the sticker to the shape of your phone, and apply.

What about gender related cell phone covers? Women have a larger selection from which to choose, while men have more detailed covers to browse. Female oriented covers, like rhinestones, can be custom built at cellphone supply outlets. Rhinestones sparkle magnificently. Then there are the classics, like puppy and kitten covers. Cell phone covers for men tend to gravitate towards beautiful women and sports themes. Dragon designs are popular, while basketball textured cell phone covers have a realistic touch. With the attractive women theme, no offensive material should be used, as many men have experienced legal woes over this issue.

Spice up your cell phone! When you get a call from grandma, you can have an extra nice conversation with a sparkly rhinestone cover, or that manly dragon design.

Ralph Jarvis runs his own mail order business as well as running several shopping based websites. His particular speciality is electronics and computers. Visit his website which is full of Discount Consumer Electronics resources or one about Cell Phones accessories.
http://www.fantasyelectronics.com

# posted by ujx @ 4:36 PM 0 comments

:: What are fiber optic transmitters?

Optical transmitters generate the light signals carried by a fiber optic communication system. a transmitter includes a light source but also includes signal generation circuit and components such as an electro-optic modulator.

The transmitter contains electronics that modulate the light source. At low speeds, the transmitter directly modulates light emission by varying the drive current to the light source. But the transmitter needs a high performance external modulator such as a electro-optic modulator for high speed applications. It maintains a constant drive current to the light source, producing a steady output beam, which passes through the external modulator that produces the 1 and 0 signals.

Transmitters can have more than one light source. Each light source operates at different wavelengths and are modulated separately with their corresponding signals. These light sources are then coupled to a single fiber with WDM (wavelength division multiplexing) technology. DWDM (dense wavelength division multiplexing) technology essentially expand a single fiber's information carrying capability by hundreds of times.

:: What are fiber optic light sources?

A fiber optic light source emits continuous light without any modulation or signal processing. It is one component of a fiber optic transmitter.

In fiber optic communication, the standard light sources are LEDs(light-emitting diodes) and semiconductor lasers. Other types of lasers such as gas lasers may be used in some special cases.

Lasers emit much higher powers than LEDs and can transmit much faster signals. But lasers are also much more expensive than LEDs.

:: LED light sources

All plastic fibers transmit visible light better than infrared light, although they can only carry low speed signals at short distances. So visible red LEDs are widely used in all-plastic fiber data links. One sample application is a data link on same floor of an office building.

Light sources emitting at 750nm to 900nm (central wavelength is 850nm) are used for higher speed and longer distance applications which utilize glass optical fibers. This type of light sources include 850nm LEDs and 850nm semiconductor lasers which are made from gallium arsenide (GaAs) and gallium-aluminum arsenide (GaAlAs).

A typical application for this type of light source is between buildings on a campus. LEDs do not offer any cost advantage over inexpensive GaAs lasers so they are less common.

:: Semiconductor laser sources

Semiconductor lasers emitting at 1310nm, 1550nm and up to 1610nm are used in much longer distance glass optical fiber networks. The applications range from inter-building links to transcontinental cables.

These lasers are made from indium gallium arsenide phosphate (InGaAsP). They produce much higher power and speed. Their major applications are in telecommunication systems.

:: Considerations for light source

Many factors determine the choice of light sources for fiber optic systems. Here are a few listed.

1. The wavelength must fall within a transmission window of the optical fiber being used

2. The power must be high enough to span the distance between optical amplifiers

3. The power must not be too high so that it causes nonlinear effects in the fiber or overloads the receiver

4. The range of wavelengths emitted by the source should not be so broad that dispersion limits transmission speed

5. The light source must be able to couple light effectively into the optical fiber

Colin Yao is the sales manager at Fiber Optics For Sale Co. and an expert on fiber optic technologies and products. Learn even more about fiber optic light source, multimode light source and 850nm source on Fiber Optics For Sale Co. web site.

# posted by ujx @ 2:25 PM 0 comments