I have one confusion in QAM about in-phase I and quadrature Q part, i.e. do they transmit identical data or not? For e.g. if i have 11001001 as a byte to be transferred, so will 4-QAM separate it like?

I 01 00

Q 10 11

or both I and Q are similar at any instant of time?

Thanks for answers


No, both the I and Q parts carry only one bit at any time, and a total of two bits are carried by the 4-QAM signal during each signaling interval. The data bits in the two parts (during a signaling interval) might happen to have the same value (both $0$ or both $1$) or they might happen to have different values (one of the bits is $0$ and the other is $1$.

For a lot of detail about how all this happens, read this answer that I wrote some time ago..

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  • $\begingroup$ Thanks Dilip, so Q and I are two different information bits but not the same information bit. Also, the post shared is very very helpful, cleared lots of other doubts on QAM. :) $\endgroup$ – Ashutosh Sep 22 '14 at 7:54

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