what is the purpose of transmition media?
365811
to reduce the time only
949199
Television signals are broadcast using the FM (Frequency Modulation) method; only radio signals are broadcast in AM (Amplitude Modulation).\n\nThe earliest signals were broadcast as AM signals.  They are still used when long distance is required, since these signals can be bounced off the Ionosphere and therefore travel beyond the horizon, but this method of broadcasting doesn’t create as clear a signal so it is normally only used for voice.\n\nFM signals are used for stereo radio and televisions signals because they broadcast a clearer signal.  They can also support signals of a higher bandwidth, packing more of a data stream into one channel.\n\nSo what is FM and AM?  A radio or television signal is sent out on a sine wave pattern.  Imagine looking at a series of ocean waves from the side.  You will see the water go up and down in the same regular pattern.  A sine wave is very similar it starts at zero and goes up to a certain height, then it drops to zero, and goes down to that same height, then it goes back up to zero, then up to the same height and it continues.  The height of the wave is called the amplitude, the length of one cycle is called the frequency, and the spot on the electromagnetic spectrum where it is broadcast at is determined by the channel or the spot on the radio dial where you have tuned in the signal (this is the broadcast band and sometimes it is called the frequency; a left over from the days of on AM signals).  This is commonly called the radio or television band.  The signals are considered a band because you need two signals for stereo sound, and more for all the picture data.\n\nSo an AM signal has higher wave heights and lower wave depths on the signal.  The signal is encoded on the wave frequency between each wave high and low point.  Send it fast enough and you can carry audio signals, like voice and mono music.  If you tried to broadcast two signals on the same AM band then you don’t get the sine wave again; you end up with each signal interfering with itself creating just noise.  The AM signals simply add together making stronger signals, but they cancel out the information encoded into that signal.  When you use a shortwave, CB (Citizens Band) or police radio you are broadcasting with an AM signal.  If two people try to talk then they either interfere and cancel each other out, or the more powerful (or closest) signal “walks” over the other signal so you only hear on voice.  This is why when talking on a short wave radio you need to say “over” so the other person knows that they can talk now.  The advantage with this type of system is that you can use the idiosyncrasies of our atmosphere to bounce a signal off the Ionosphere.  Since there is a clear difference between each atmospheric layer it is possible to bounce the signal around (http://en.wikipedia.org/wiki/Ionospheric_reflection).\n\nLook at this picture:  http://upload.wikimedia.org/wikipedia/en/f/f1/Voice_waveform_and_spectrum.png\nOn the chart with the green lines the difference between the base line and the height of each green wave is the amplitude. \n\nFM signals work in a different fashion.  The signal is encoded in the height and depth of each wave so you can broadcast several signals on the same band without having them interfere with each other.  This lets you broadcast a stereo signal to a FM radio.\n\nTelevision signals are broadcast this way as well so that stereo sound can be sent (in the early days of TV stereo wasn’t used).  This broadcast method also allows the more complex data of the television signal to be sent along with the audio signals. But, this still isn’t enough so TV signals are broadband; several signals are sent at the same time across a series of bands, close together on the spectrum, so all the information gets through.  When you tune your TV you are actually selecting several bands grouped together which carry all the signals required.  If you tried this with an AM band then you would ha
275463
What purpose would it serve good or bad to do so???
269855
Its a good medium to grow bacteria and allows them to clearly be seen. Also,its relatively inexpensive to make agar.
112156
The purpose of the internet is the free exchange of ideas.\n\nSpread the Gospel of God's Salvation for all!
396079
It is an effective medium of advertisement called as 'Outdoor Media.' To make it effective use the following tips:\n1. Images should be catchy (grasp attention), clutter breaking\n2. Copy should be very brief, so that people read what u want to communicate while passing-by quickly.\n3. Use the location relevent to your target market segment.
999919
It's there to keep the environment in the display case humid. It helps when you're displaying gems and especially pearls, which need humidity to retain its lustre.
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Progressive scan allows for a better quality picture when viewing media from a source that support it as well.\n\nfor example, if you DVD player support progressive scan, your TV must also support it inorder to use the function.
36159
As mechanical engineer this is out of my normal field but felt you deserved an answer of some sort.\n\n"Because of diffraction effects caused by slits or apertures in optical measurement systems, the radiation energy which is directed towards a particular region on a sample will be spread over a larger area than desirable. By employing an apodizing filter in the radiation path in such system, diffraction tails of the system will be reduced. The apodizing filter preferably has a pattern of alternating high transmittance areas and substantially opaque areas where the locally averaged transmittance function is an apodizing function. In the preferred embodiment, the locally averaged transmittance function varies smoothly and monotonically from the periphery to the center of the filter"\n\nI see the theory here, also found on on using an apodizing mirror to stabalise images in a telescope\n\n"I built and used an apodizing screen for my 6" f/8 scope many years \nago. I made it by layering several layers of window screen, each one \nwith a circular cutout of different diameter. The result was an aperture \nmask with a step-wise approximation to a smooth apodizing function. It \nwas claimed to improve contrast for planetary viewing. Anyway, my \nexperience was that it seemed to make the image more stable but if it \nimproved contrast, I couldn't see it. If you do this on-axis, the \ndownside is that your diagonal mirror will now become more of a factor \nin the contrast equation. The bottom line is I wouldn't recommend it."\n\nAlso "An excellent reference for all sorts of technical techniques is\n>"Procedures in Experimental Physics" (also printed under the title\n>"Physical Laboratory Practice") by John Strong.  I don't recall the\n>publisher, but it came out in the 30's.  The bad news it that it's been\n>out of print for decades (and some SOB stole the copy I got from my\n>father!); the good news is that an outfit called Lindsay is reprinting it\n>in paperback.  (Don't have their name/address here in the office; I'll try\n>to remember to look it up tonight.)\n>\n>                            Dr. Kurt Hillig\n\nEvery ATM should have a copy of this great book. Lots of stuff on\nmirror making, figuring, special laps,making flats, prism ,etc.\nThere is nice modifed Draper machine ( upper disk also powered)\nand a homemade diamond cutting wheel to cut small glass blocks.\n( I would like to build this one someday ) A great section on\nkinematical mechanical construction. Yeah this a mid 30,s book but the \ninfo\nstill can be used. No I don't work for Lindsay Publications,<G>\n\nBob Pfaff\n\n\n This book, in paperback form, can be ordered from\n      http://www.amazon.com, on the Web. It can also be ordered\n      through your local bookstore. Amazon prices it at $23.95, and\n      provides the following information:\n\n      Published by Lindsey Publications\n      Publication date: June 1986\n      ISBN: 0917914562"\n\nSorry couldn't find any really decent expplanations, but at least you've got a starting point.
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TV and Radio\n\nBoth use transmitter networks and satellite to transmit the media to the public so have a look at them and see if that helps
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A modulator is used to impress the information from a single source upon a radio wave or other system carrier, such as the process that happens when you play a VCR through channel three of your TV. The audio and video program are modulated onto a high frequency radio wave which can be received by your TV (demodulated). A radio wave can easily pass through space unlike the baseband video and audio signals.\n\n   A multiplexer may be thought of as a time sharing system in which several program sources are alternately routed to an output. An example of this would be in security systems where the pictures from several cameras are combined to be seen on one monitor screen.\n\n   Modulation has a 'one to one' relationship, as well as does its inverse, 'demodulation'. Multiplexing has a 'many to one' relationship. Its inverse, demultiplexing, has a 'one to many' relationship useful for extracting the various original signals.\n\nWK
47709
Copying data byte by byte without looking at the bigger picture like the file or application you are actually trying to replicate to another site. This ensures system indifference, some level of security and sometimes it is the only way to copy across different storage networks. Fairly useful technology.
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It's to make your email stand out and easier to find. It's like a reminder or a point of interest. Thats the only purpose I can think of.
159332
Ever watch football (USA) and see the first down line and the line of scrimmage? Same technology. I used to know the technical term for all of this but it's just technology being able to project an image on a screen, much like a blue screen I think. close enough for now I guess.
490702
That's because its supposed to be secret! Something like the frequency and much more. We aren't permitted to braodcast anything above permitted frequency, as a part of general public. (Frequency emission includes, usage of home-RF devices) Please make sure to get information from the military if you are making a geniune effort, other than, putting the stake at risk!
797999
NOTHING....JUST MEDIA
252949
It's basically one way to encapsulate data.  If you send a 1 MB transmission it is chopped into smaller bits so that it can be sent efficiently.  One way to do this is frame relay, another way is ATM.