i have question

[mam2008]

Hi
i would like to thank you about this great explaining in (all about modulation part 1) ebook.
i have one thing I does not understand it.
in (page 33) you said map each symbol to I and Q using the amplitudes in table 4.
my question is:
how you got (I data) and (Q data) from the signals (s8 s6....)?
What is the mathematical equation that you have made?
i hope you can replay as soon as Possible
thank you
my regard

[faisal]

can anyone explain me how an encryption system works in most simplified way(in layman's language)?
Please help

[el007cat]

mam2008, in a two dimensional space, components I and Q are the components of the vector. For example from figure 37:

s0={1.414,0} => I0=1.414 , Q0=0

s1={1,1} => I1 =1, Q1=1

etc

then you make the signal by:

s(t)= I(n) cos(...) - Q(n) sin(...)

and the baseband signal is bs(t)= I(n) + jQ(n)

[charan langton]

Not sure what topic you are talking about.

[charan langton]

Going from baseband to a modulated signal in IQ space

I and Q is same as saying what is the x and the y projection of a point in 2-D space. The x-axis is called I and y-axis is called Q. NOw if we want to send a 8-PSK signal, then we have 0, 1, 3, ...7. symbols. Each symbol is binary group of three bits, 000, 001, 010, .. 111. Assign each one of these to a digit from 0 to 7. Now look at the constellation diagram, which has all 8 points arranged out in the I-Q 2D space. Each point has a unique set of IQ projections.

If you want to send 000 -> 1, for example, go to the constellation diagram and get its I and Q values. Then the I signal (which is a cosine) will be sent with the amplitude that is the I-axis value and Q signal (which is sine wave) will be sent with the Q-axis value. You add these two together and you get a real signal ready to be transmitted via the antenna.

Charan Langton