Quardrature Amplitude Modulation. I know the basic techniques, like when you have 1 point and only two signals are to be multiplexed. But the constellations got me a bit confused. My text-book doesn't explain it thoroughly, and there isn't much deep information about it on the internet. "The number of "dots" in the constellation is given as a number before the QAM, and is always an integer power of two -- from 2^1 (2QAM) to 2^12 (4096QAM)." This is from wikipedia site. I'm just wondering, each point adds two signals? or multiply the number of signals mulitplexed by two?? This is an example exercise: An analog passband channel can pass a maximum of 20 KHz. If the channel is used for transmission of digital data, what is the minimum number of points in a QAM constellation if 5 ADPCM signals are to be multiplexed in an the analog channel? In both cases of my interpretation, the answer would be 3 points, no??