Final answer:
In a baseband PAM system with K=3 and an alphabet of four symbols, there are 64 different transmit signals possible.
Step-by-step explanation:
When considering baseband Pulse Amplitude Modulation (PAM) with K=3 and a symbol alphabet A={−3,−1,1,3}, we are dealing with a scenario in digital communication where each symbol can represent a certain number of bits. Since there are 4 different symbols in the alphabet, this means each symbol can represent 2 bits (since 2^2 = 4). Therefore, with K=3 symbols per transmission, we find the total number of different transmit signals by calculating 4^3, because each of the 3 symbols can be one of 4 values.
Thus, the total number of different transmit signals is 4^K = 4^3 = 64. That means there are 64 unique combinations of the symbol values from the set A that can be transmitted.