what is the application of amplitude shift keying(ASK) and frequency shift keying(FSK)?
150565
They are two ways of modulating a carrier wave to carry digital, i.e. binary, information.  In ASK the amplitude of the signal is varied between two levels to indicate a one or zero (on/off keying is a special case of ASK where one of the amplitudes is chosen to be 0).  In FSK the frequency is varied to indicate ones and zeros.  Both are applied in broadcast radio communications and wired data transmissions.  FSK is less suceptible to interference, like FM signals in general.
429859
Take a look at...\nhttp://www.ampercom.com/download/RScript%20User%20Guide%201.0.pdf
373020
They are both ways of putting information on a bigger pipe.\n\nFor modulation, you modulate a carrier frequency with a signal.\n\nMultiplexing involves taking multiple signals and placing them on the same baseband to carry them.\n\nThat isn't much of a similarity, though.  I guess the other one would be that you can have either digital or analog modulation and you can have either digital or analog (FDM) multiplexing.
713379
I know a lot about HF communications, but I don't know what the abbreviation, "Ofdm" means.  You'll have to be more clear...\n\nAddition: "orthogonal frequency division multiplexing"  no wonder I didn't get it.  That's done at UHF/microwave frequencies.  My experience is in the broadcsting (AM/FM/TV) field, and I'm a ham.  HF is 3-30 MHz.
911903
Well, you could build a *relatively* simple circuit that simply cut the frequency in half, but then again, what kind of sensor are you dealing with?\n\nWhy do you want to tune it to a lower frequency? It is not simple to just shift a frequency, there are many things to take into account; input impedance, output impedance (both may be frequency dependent), signal amplitude, and required voltage swing.\nI would only attempt this if it was not a vital sensor I was messing with.
314002
You can set the band of your radio to SW or short wave. Start tuning. You will get many international channels. The clarity will be poor though. Satellite radio is the best.
1061929
i guess A, U and mu law are used for pulse code modulation. i have no idea that these are different for different countries or country specific. u can try google.
849482
Have you thought about using FFT (Fast Fourier Transform)? That should be easy to implement.
800644
You mean like a radio station? You can't really, Radio Station's  run their signals  on different frequencies then a wireless router.\n\nYou don't have the hardware to broadcast that high of a frequency not to mention modulate it. Like FM or AM..\n\nYou can do Internet raido..
1108108
Remote keyless entry systems use a 300 to 900 MHz frequency RF signal. They also have a 125 kHz freq if you have remote engine start. The signal will go thru walls (except metal) and is usually limited by distance and line of sight to the receiver.
682558
It is impossible to give the simple answer for which you seem to be searching.\n\nThere are many frequencies which could be used to cover that distance.\n\nI recommend you read about radio communication in general and about h.f., v.h.f. and u.h.f. communications in particular.
952318
there will stretching to the string, and the amplitude and frequency will be tranmitted....but the cycles wont be at light speed...so they wont allow for instantaneous communication.  Now if the cable was fiberoptic...and pulses were transmitted...hmm
450183
this might prove to be useful:\nhttp://islab.oregonstate.edu/koc/ece575/02Project/Mor/
387983
A digital signal is composed only of electrical pulses representing either zero or one. Because digital signals are made up only of binary streams, less information is needed to transmit a message. Digital encoding therefore increases the capacity of a given radio frequency. Furthermore, only digitized information can be transported through a noisy channel without degradation\n\nSignals that are recorded in analogue format are modulated, ie their information is contained in amplitude or amount of signal. Digital, conversely, is either on or off, and amplitude is identified in a different way
224327
You can but u have to know some electronics for it...you can add abeat freq oscillator to receive ssb signals or attach a signal preamp at the antenna input to boost the reception and receive weaker stations or modify the mixer sections to change the receiving freq bandwidth.......possibilities are countless.
1004957
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
101135
Single sideband transmission can afford, "efficient spectrum use, bettter signal-to-noise ratios at low signal levels and better transmitter efficiency" per "Conclusion" on P. 7 of link.  Good luck.