I/Q Modulation Questions

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mossman

Joined Aug 26, 2010
131
I'm studying up on I/Q modulation (4-QAM in particular) and am having difficulty finding references pertaining to the baseband I and Q signals. I understand that the I and Q signals are mixed with a 0 degree carrier and a 90 degree carrier, but what happens to the digital baseband signal prior to this stage? In other words, if I have a 4-QAM system, how are the 0's and 1's converted? Is a DSP used to group the data bits in two's (for QAM) then output an analog voltage on the I and Q data lines, which then modulate the carriers?
 
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