(please give me example in such modulation scheme)Who says that it does? There are modulation schemes that have a completely suppressed signal at the carrier frequency. So you need to be much more specific about what you are looking for.
SSBSC(please give me example in such modulation scheme)
How as ASK and FSK examples of "generally rect functions"? I think, but am not sure, that by "generally rect functions" you are talking about the spectrum of the information signal being modulated onto the carrier and not the modulation schemed used. Is that correct?for example in ASK or FSK or i should say generally rect functions .. they have the greatest value at center frequency !?
You want an intuitive explanation without math of a process that is best and most easily understood by understanding the mathematical details of the process involved? Why?also in FM modulation .. why values of frequency components are decreasing as we move from the center frequency ?
Yes , but do not understand what is the difference ?How as ASK and FSK examples of "generally rect functions"? I think, but am not sure, that by "generally rect functions" you are talking about the spectrum of the information signal being modulated onto the carrier and not the modulation schemed used. Is that correct?
Otherwise, I ask again who says that they have the greatest value at the center frequency? Why wouldn't the shape depend on the details of the signal being modulated onto the carrier.
yes exactly that is my question , I could not think of a reason other than math ( Fourier ) !!You want an intuitive explanation without math of a process that is best and most easily understood by understanding the mathematical details of the process involved? Why?
Perhaps you should come at it from the other side. We have baseband signal, say audio, that has a certain bandwidth. We want to modulate that into a certain part of the radio spectrum, say 900 MHz. There will be a peak somewhere, right? There will be upper and lower limits, at least in practice, to the frequency content of the signal, right? What intuitive reason would there be for the maximum to occur somewhere in the middle of those limits?
Look at the diagram you posted. For ASK, the notion of "bits as square pulses" makes some sense, but look at FSK and PSK. What are the "square pulses" there? In FSK I see some time periods for which there is one frequency and other time periods for which there is a different frequency. Notice that there are never any time periods in which the signal is at the carrier frequency. So how much energy is going to be sitting at the carrier frequency in this case? In PSK I don't see any changes in frequency or amplitude at all, just shifts in phase at the boundaries, so what are the "rectangular pulses" here?SSBSC
Yes , but do not understand what is the difference ?
I mean in digital we send 1 , 0 .. so Regardless of type of modulation used we represent the bits as square pulses , Right ?
as in this pic..
thank youFor the AM case,have a look at this:-
http://www.pa2old.nl/files/am_fundamentals.pdf
Read it the whole way through.
It has some Mathematics,but it isn't really tough stuff!
Well, acknowledging the foregoing, I may offer the following: many years ago I worked as a production engineer in a radio factory. Near the end of the production line we had to "tune" the AM and FM parts of each radio.hello
My question is why the magnitude of a signal at the center frequency or carrier frequency is the greatest ? and falls down as we move away right or left ?(sinc)
I need an intuitive explanation without math.
Very "un-math",& quite misleading!Well, acknowledging the foregoing, I may offer the following: many years ago I worked as a production engineer in a radio factory. Near the end of the production line we had to "tune" the AM and FM parts of each radio.
AM by definition can operate optimally at a single carrier frequency, where the AMPLITUDE varies according to the modulation. So on either side of that carrier frequency we would want to suppress other frequencies. We used a sweep generator and 'scope to give a display like attachment AM.jpg.
FM by definition varies the FREQUENCY according to the modulation. This requires that the RF response curve allows for the varying carrier frequency. So the width of the response curve is wider like in attachment FM.gif. We used a thing called a "wobbulator" and 'scope to display the image.
So the reason the "magnitude of a signal at the center frequency" is greatest is because of the tuned circuits being used - rejecting (as much as possible or required) frequencies on either side of center.
I hope this is "un-math" enough to get the picture (pun intended!).
Sorry,no idea,I just found the site by Googling.thank you
could you tell me the name of this book?
by Jake Hertz
by Jake Hertz
by Duane Benson
by Jake Hertz