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Electronics

Electronics are a branch of technology and science that deals with the control of the flow of electrons.

3,725 Questions

What is difference between OFDM - orthogonal frequency division multiplexing and GMSK - gaussian minimum shift keying?

Orthogonal FDM is a method of passing digital data that uses multiple carriers. The basic idea is, you take a high-rate data stream, convert it into a number of low-rate data streams, put each of these streams on a slightly different frequency and dissemble all of it back into the high-rate stream at the distant end. A low-rate stream doesn't require as much bandwidth as a high-rate one does, so you can afford to use multiple frequencies without knocking everyone else off the air. Error correction schema are used to prevent losing data, and monitoring the atmosphere allows the radio to move channels around as necessary to ensure reliability. The reason you want to go through all this trouble is to be able to communicate when atmospherics turn bad. A similar technique is used in tropospheric-scatter radios, which bounce radio waves off part of the upper atmosphere; because the troposphere changes all the time, the only way to reliably communicate via it is to transmit the same data over several different frequencies at once. But in troposcatter, it's called diversity operation.

Minimum-shift keying is a form of frequency-shift keying, in which one frequency stands for a 1 - or 'mark' in teleprinter terms - and a different frequency for a 0, or space. This is a technique that's over a century old, and a century ago the way you did it was to wire a small capacitor in series with the contacts on an electromechanical relay, wire that assembly in parallel with the frequency-determining capacitor in your transmitter, and wire the relay's coil to your teleprinter. When the system needed to send a mark, the teleprinter closed the relay which changed the total capacitance of the LC tank which caused the radio's transmitting frequency to change. And they did it this way for at least seventy years! The problem with it (besides needing all those mechanical parts to get the thing to work, and the slow transmitting speeds it required; you certainly wouldn't be able to watch YouTube videos on your phone by keying an oscillator with a relay) is the technique created huge, bandwidth-eating sidebands that didn't matter when the only people sending FSK data were police departments and newspapers, but these days the only people NOT sending FSK data are babies too young to use phones, your grandma who refuses to buy a cell phone, and people in prison who aren't allowed to own cell phones. Today you couldn't get away with eating this much bandwidth, so "minimum-shift keying" - an FSK technique that creates very small sidebands - is the way to go, and feeding the signal through a gaussian filter to create gaussian MSK gives you a very reliable way to transmit data.

A good answer to put on your paper might be "OFDM uses multiple carriers and GMSK uses a single carrier."

Does Four 1000 Ohm resistors placed in parallel have a resistance of 250 Ohms?

Yes. The equivalent resistance of resistors in parallel is written as 1/Req=1/R1+1/R2+1/R3+... which, in this case, would be 1/Req=1/1000+1/1000+1/1000+1/1000=0.004. This means that Req=1/0.004=250Ohms.

How do you calculation uncertainty of an electronic balance?

the least count of the device must be noted first. the uncertainty of this will be the least count divided by 2. so if its is 0.1 then it will be 0.05

When I log on it just shows my background and nothing else this isn't my PC task manager doesnt say you have any programs and restarting doesn't help?

open your task manager => click file, then new task and type "explorer" without the "

or press windows key + "R" and type "explorer" without the " there

if this won't work, reinstall windows. Don't format, just insert the windows CD and Choose "install" all ur files will be in "windows.old folder

buying a mac, as the old answer stated won't help you, you won't be able to run 99% of the programs you use now.

How do you remove a TV turntable from a cabinet?

Turntable RepairHow to remove your turntable from your console:

If there are no obvious screws attaching the turntable unit to the furniture or cabinet you may need to remove the back piece of the cabinet which is usually a thinner price of ply-board. Upon removing the ply-board their should be some screws attaching the turn table from the inside that can be disconnected using an average philips head screw driver.

Change speed governor on international have computer need password to change?

The password is set by whoever owns the vehicle. They put those passwords in because they don't want drivers changing those parameters.
If it is your truck to do this with, then try "0000" - when used trucks are sold, that's typically what the ECM passwords are changed to in order to allow the next buyer to set them up how they want to.

Is phone harassment a law?

No. It is illegal to harass people over the phone or any other media.

What are the best site for Technology?

Go to technologystudent.com its quite good its 4 kids but secondary school and up

it looks really weird at first but have a click around and u should find some useful stuff!

hope this is helpful!!

How can you reuse the LCD from a broken portable DVD player?

You can take the LCD out and sell it on eBay or craigslist. Also the board is recyclable.

What is a group of computers connected together and share resources called?

Several computers connected together to share resources and data compose a computer network.

A group of linked computers, working together closely thus in many respects forming a single computer composes a computer cluster.

How you can prove the Peak voltage?

Use an oscilloscope. That shows the voltage waveform and you can read the peak value.

How many photos does a TB hold?

It depends on the file size of your pix.

My camera uses about 0.8 megabytes per picture, so I would get about:

1,000/0.8 approx 1250, 0.8 megabyte pictures to one terabyte (which is 1,000 megabytes).

You'll need to know roughly how many megabytes your pix are, on average.

What is IPC 610?

IPC-A-610 is the most widely used electronics assembly standard (a document) in the world. A must for all quality assurance and assembly departments, IPC-A-610 E is the latest revision. It illustrates industry-accepted workmanship criteria for electronics assemblies through full-color photographs and illustrations.

What is an Electronic catch phrase?

"Electronic Catch Phrase" is a word game based on an older guessing game simply known as "Catchphrase". The game is manufactured by Hasbro and is available from several stores nationwide.

What is a voltage rectifier?

A rectifier is a device that is used to "change" (rectify) some kind of alternating current (AC) into direct current (DC). There is more to the story, but basically the rectifier is a "one-way" device that will permit current to flow though it in only one direction. That way one or more of these devices can be used in different curcuit configurations to change an AC input into a DC output.

What is the ascii code for a division symbol?

The ASCII code for the division symbol is 247.

What are the working principles of operational amplifiers?

They work by making the sound louder. You can take a little sound that only a few people can hear and plug it in to make it available to a large group.

Can you text or email on your e reader?

Depending on the eReader device, you may or may not be able to send and receive short text messages (SMS) or email.

Alternative devices with a similar form factor, such as 7" tablet computers, often include these services and provide an application for email. These devices are thus more versatile in principle, but lack the long battery life and excellent reading quality provided by the e-ink display technology commonly used by "pure" e-Reader devices.