how does mibile being a digital device recieve  fm signals which r analog in nature?
826878
All radio transmissions can be considered analog even the digital ones like FSK, PSk,QAM, since the carrier is sinsoidal which is analog, however the data are digital so they change the carrier characteristic in discrete way. in mobile systems such as GSM the type of modulation is GMSK (gausian minimum shift keying), which is a special type of FSK (frequency shift keying), in FSK the frequency of the carrier is alternating between two values, each frequency represents a logic state (digital), which can be processed by the mobile circuitry. again the FSK is an FM signal whith the message being digital (binary)
151211
The voice / music is modulated (FM: Frequency or AM: Amplitude), once the signal is modulated it is amplified and trasmitted to an Antenna that amplifies the signal again in order to reach your radio device.\nYour radio take that signal from the air (it has been atenuated while travling in the air), de-modulate the signal and extract the voice/music to be amplified so you can listen what is being played at radio station...\nThis is the basics, but there are many things involved in a broadcast process...
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An amazing circuit board containing the brains of the phone \nAn antenna \nA liquid crystal display  \nA keyboard \nA microphone \nA speaker \nA battery \n\nSignificance when we study it?\n\n\nThe analog-to-digital and digital-to-analog conversion chips translate the outgoing audio signal from analog to digital and the incoming signal from digital back to analog. You can learn more about A-to-D and D-to-A conversion and its importance to digital audio in How Compact Discs Work. The digital signal processor (DSP) is a highly customized processor designed to perform signal-manipulation calculations at high speed. \n\nThe microprocessor handles all of the housekeeping chores for the keyboard and display, deals with command and control signaling with the base station and also coordinates the rest of the functions on the board.   \n\n\nThe ROM and Flash memory chips provide storage for the phone's operating system and customizable features, such as the phone directory. The radio frequency (RF) and power section handles power management and recharging, and also deals with the hundreds of FM channels. Finally, the RF amplifiers handle signals traveling to and from the antenna. \n\nThe display has grown considerably in size as the number of features in cell phones have increased. Most current phones offer built-in phone directories, calculators and games. And many of the phones incorporate some type of PDA or Web browser.     \n\nSome phones store certain information, such as the SID and MIN codes, in internal Flash memory, while others use external cards that are similar to SmartMedia cards. \n  \nCell phones have such tiny speakers and microphones that it is incredible how well most of them reproduce sound. The speaker is about the size of a dime and the microphone is no larger than the watch battery beside it. Speaking of the watch battery, this is used by the cell phone's internal clock chip
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When two modems are communicating over a phone line, they use audio signals at specific frequencies as the "0" and "1" of binary code.  That noise you hear is the rapid alternation of audio signals between those two frequencies.  They do this since phone lines were designed to transmit audio frequencies, so the modems use audio frequencies to communicate in binary form.\nIt's that simple.
10500
I think the previous answer is geared towards channel allocation and not bit rate vs bandwidth.  I will try to clarify the issue.\n\nFirst, you must understand how FM works and how a digital signal converts to FSK (frequency shift keying).  Therefore I will use a simple example.\n\nEach bit takes up some frequency.  For example, the bit '1' could take up 5 Hz carrier frequency on the bandwidth spectrum and '0' could take up 6 Hz on the bandwidth spectrum.  Therfore, there is a seperation of 1 Hz between bits.  \n\nIf I send a '1' followed by a '0' then on a meter I should see 5 Hz freqency and then a 6 Hz frequency back to back.  We could speed this up to infinity and therefore have these 2 frequencies transmitting all data at infinite speeds.\n\nIn the real world however, a '1' may fall around the 5 Hz frequency but not exactly on it.  It may be about 5 Hz.  Why around 5 Hz and not exactly on it everytime?  Because in the real world we have noise in transmission lines.  Noise can distort the frequency causing it to be a little less than 5 Hz or a little more than 5 Hz.  Imagine if the '1' bit is transmitted but on the receiving end it ends up receieved as 5.5 Hz.  What happens now?  It's not quite 5 Hz and it's not quite 6 Hz.  Noise caused it to move 0.5 Hz away from 5 Hz.  It is in the middle of 5 Hz and 6 Hz.\n\nNow the receiving end has to decide if this is '1' or '0'.  What are the odds the receiving end gets it right?  By slowing down the speed the 1s and 0s that are transmitted , you can hold steady the 5Hz or 6 Hz for that bit.  The faster you go, the less accurate the bit will fall exactly where it should on the frequency.\n\nSo, what are some possible solutions?  Well, you can slow the frequency down or make the frequency seperation larger.  For example, make a '1' be 5 Hz and make '0' be 10 Hz.  Now you have 5 Hz seperation between bits instead of 1 Hz seperation.  Now if the frequency of 5.5 Hz is received, the receiving end can determine that this should have been 5 Hz.  It's highly unlikely it was originally transmitted at 10 Hz.  Therefore, the receiving end detects a '1'.  \n\nBut what have you lost by doing this increase in frequency seperation?  You have taken up more bandwidth.  Every cable has only so much bandwidth and if you have several channels on a cable all transmitting at the same time, you need to limit the amount of bandwidth each channel takes up or you will run out.\n\nSo, therefore, since most companies don't want to backdown on speed to the consumer (you), then they upgrade their technology (i.e. cables) to higher bandwidth cables such as fiber optic cables.\n\nI hope this helped.  Others, please feel free to expand on this topic.  I've only discussed FSK modulation.  Other techniques such as PSK, ASK, QPSK, bit stuffing, NRZI, CRC, and FEC codes can improve bit rate over channels.\n\nYou can read more about bandwidth limits.  Shannon and Hartley came up with a theorem which still holds today and is used quite extensively.  I even know someone who worked with Shannon at Bell Labs back in the day.  Shannon's theorem is C = BW*log2(1+S/N) where C is the channel capacity in bits per second,  BW is bandwidth, S is the signal power and N is the noise power.\n\nWF\nTelecom Engineer
964371
This is a loaded question....\n\nThere are many encoding schemes, some complex some not....\n\nBut basically, you have to know how the voice data is recorded first.  If it is simply a series of data in time scale encoded in amplitude only (for example, first data in the file representing the amplitude of the first instance, and the second representing the amplitude of the second), then you just have to sequentially read the bytes (or whatever the bit length) of the file and feed it into the D/A converter.  (Digital to Analog converter)\n\nBUT, I don't think the application would be that simple.  With today's audio boards and compression schemes, it could be far different.  \n\nYou have to study what digital data you are working with, and figure out what is required to reproduce the original data (voice)
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microwave are the same as radio waves \nsatellite are when you transmit to a satalite \nradio waves are basicly any sound. \nlaser is energy in the form of light, \noptical fiber is used for telephones which transport light instead of radio waves, which is much faster\ninfared it think is just a laser used to transfer data
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In certain low volume and high speed circuits, transistors will always have their places. ALthough their are now many more radio chips.\nMIKE
622008
analog portable covers longwave (141-290 kHz), medium wave (525-1620 kHz), FM and nine shortwave bands: 4.75-5.06, 5.9-6.2, 7.1-7.35, 9.4-9.99, 11.6-12.1, 13.57-13.87, 15.1-15.8, 17.48-17.9 and 21.45-21.75 MHz. FM stereo is featured to the earphone jack. Features: 2¼ inch speaker, wrist strap LED tune indicator, flip stand, 3 VDC input jack and stereo earphone jack.
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YOU SURE DON'T WANT MUCH DO YOU!\n\nFIRST ANALOG DATA IS THE TALK DATA, THERE IS A CARBON MICROPHONE IN THE PHONE HANDSET WHEN YOU TALK IT CHANGES RESISTANCE AS THE SOUND WAVES HIT IT.  NOW THERE IS A DIRECT CURRENT 20 MILIAMP FLOWING THRU THIS IT ALSO FLOWS THRU A NETWORK WHICH IS IN THE BASE OF THE PHONE.  YOUR EARPHONE IS MAGNETIC AND IT CONVERTS THE CHANGING IN THE CURRENT BACK INTO SOUND. ANYWAY THE TALK PART OF PHONE, THE ORIGINAL THING PHONES DID IS CARRIED OUT BY DIRECT CURRENT, (BATTERY POWER). THE PHONE RINGS WITH A ALTERNATING VOLTAGE OF 90 VOLTS AT 20 CYCLES PER SECOND.  THE BELL IS CONNECTED TO THE LINE THRU  AN CAPACITOR WHICH PASSED THE AC BUT DOES NOT PASS THE TALKING DC VOLTAGE. THUS THE BELL DOES NOT MESS UP YOUR TALK!\n\nDIGITAL DATA IS SUPERIMPOSED ON TOP OF THE DIRECT CURRENT AND IT IS A VERY HIGH FREQUENCY! SO THAT IT CAN BE SEPARATED FROM YOUR VOICE FREQUENCY, THUS THERE IS A FILTER WHICH IS INSTALLED AHEAD OF THE PHONE WHICH SEPARATES THE HIGH FREQUENCY DIGITAL FROM THE LOWER FREQUENCY VOICE.  THIS HIGH FREQUENCY DIGITAL SIGNAL IS FED INTO THE MODEM AND CONVERTED TO PURE DIGITAL SIGNAL FOR THE COMPUTER.\n\nSO WE HAVE 2 LITTLE WIRES CARRING MANY SIGNALS\n\n1. RINGING SIGNAL AC 20 CYCLES 90 VOLTS\n2. TALK SIGNAL DC VOICE FREQUENCY 3-6 VOLTS\n3. DIGITAL SIGNAL AC HIGH FREQUENCY \n\nTHATS IT.\n\nHOPE I HELPED YOU!\n\n\nAPS
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Frequency modulation, called FM, is a more sophisticated modulation scheme than AM modulation. It is well-suited to the inherent properties of optical fiber since proper recovery of the encoded signals only requires measurement of timing information, one of fiber’s strengths. FM is also immune to amplitude variations caused by optical loss, one of fiber’s weaknesses. The heart of the FM modulator revolves around a high-frequency carrier. Now, instead of changing the amplitude of the carrier, the frequency of the carrier is changed according to differences in the signal amplitude. Part of the advantage of FM systems is buried in mathematical analyses that show that the signal-to-noise ratio at the receiver can be improved by increasing the deviation of the carrier. \n\nFM also has the advantage of eliminating the need for highly linear optical components that are required for AM systems. Often optical systems employing FM encoding refer to the technique as pulse-frequency modulation (PFM). This simply means that the FM signal is limited (converted to digital 0’s and 1’s) before it is transmitted over the fiber. The result is the same. In multiple channel FM systems, each video signal is modulated on a separate carrier. These carriers are then combined to modulate one light source. Each FM video modulator is adjusted to balance distortion products, achieve best signal-to-noise/bandwidth plus compensate for the non-linearity of the light source. As more video channels are added, the overall modulation index of the combined signal increases, which degrades the per channel signal-to-noise ratio (i.e., there is less optical power available per channel.) \n\nFrequency modulation uses the information signal, Vm(t) to vary the carrier frequency within some small range about its original value. Here are the three signals in mathematical form: \n\nInformation: Vm(t) \nCarrier: Vc(t) = Vco sin ( 2 p fc t + f ) \nFM: VFM (t) = Vco sin (2 p [fc + (Df/Vmo) Vm (t) ] t + f) \n\n\nand if u get the below article whole funda be resolved
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HD Radio uses a digital signal – like HDTV – for pure, clear sound.
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well,\n\nif you meant what technology should you be using, then i recommend using FM or Bluetooth; each have some pros and cons!\n\nFM is cheaper to implemet, but harder to implemet, bluetooth (lets say 2 serial bluetooth adapters) are more expensive but much much easier to implement... specially with digital signals!\n\nif you ccan edit or give more information about what you want maybe i can help you more!
45066
Analog communication uses continuously varying signals.  In digital communications, only discrete values are used.  Think of analog being like real numbers and digital being like integers.  When using digital, the real signal is "quantized", that is, represented by the closest digital value.  With enough quantization levels, the digital signal cannot be distinquished from the original analog.
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Well... that's kind of a broad question, but here's the basics both signals. \n\nDigital Signal\n----------------------------\nA digital signal is like an electronic representation of bianary.  it has 2 states, high and low.  It depends on the logic being used (CMOS, TTL, or ECL), but the lows can run anywhere from -5.2 VDC in ECL Logic, and the highs up to +5.2VDC in TTL Logic.  in the o'scope, all you will see looks a little like:\n_-_--____--_--__--_--_____-__-----_       <==== where you can see definate highs and lows.\n\n__--__--__--__--__--__--__--__--__--__ <== A typical digital clocking signal, like in your computer\n\nAnalog Signal\n------------------------\nAn analog signal is like what you see in your windows media player when you turn on the o'scope visualisation (do it, it's a good example of an analog signal).  The pure definition of an analog signal is a variable signal that is continuous in both time and amplitude.  It could be a perfect Sine, triangle, square, or sawtooth Wave ( http://en.wikipedia.org/wiki/Image:Waveforms.png ), a straight DC level, or what you see in the Media Player Example.
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Frequency-division multiplexing (FDM) is a form of signal multiplexing where multiple baseband signals are modulated on different frequency carrier waves and added together to create a composite signal.\n\nHistorically, telephone networks used FDM to carry several voice channels on a single physical circuit. In this, 12 voice channels would be modulated onto carriers spaced 4 kHz apart. The composite signal, occupying the frequency range 60 – 108 kHz, was known as a group. In turn, five groups could themselves be multiplexed by a similar method into a supergroup, containing 60 voice channels. There were even higher levels of multiplexing, and it became possible to send thousands of voice channels down a single circuit.\n\nModern telephone systems employ digital transmission, in which time-division multiplexing (TDM) is used instead of FDM.\n\nFDM can also be used to combine multiple signals before final modulation onto a carrier wave. In this case the carrier signals are referred to as subcarriers: an example is stereo FM transmission, where a 38 kHz subcarrier is used to separate the left-right difference signal from the central left-right sum channel, prior to the frequency modulation of the composite signal.\n\nWhere frequency division multiplexing is used as to allow multiple users to share a physical communications channel, it is called frequency-division multiple access (FDMA).\n\nFDMA is the traditional way of separating radio signals from different transmitters.\n\nThe analog of frequency division multiplexing in the optical domain is known as wavelength division multiplexing.\n\nContents [hide]\n1 Level 1 Diagram \n2 Level 2 Diagram \n3 Level 3 Diagram \n4 See also
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Like color TV was added to B&W TV in the mid '60s, stereo was added to FM radio several years after FM broadcasting first began.\n\nIn recent years, stereo has likewise been added to AM broadcasting, at least by the FCC. There's no technical reason why stereo can't be added to an AM signal. However, AM lately has been relegated to mostly 'talk radio', instead of music, and very few stations/radio manufactureres have adopted it.\n\nIt's kinda like adding Dolby 5.1 to 8-track tapes...who cares?