This will maximise efficiency and proficiency of the technician who must maintain these networks. Still, baseband digital transmission would require between 3 and 12 MHz to transport these signals. The excessive bandwidth problem of digital video services is solved through the use of higher order digital modulation techniques. This is the most efficient and economical way to send digital information on an analogue plant. Each phase shift is 90 degrees.
Every cycle represents a symbol.
In QPSK, there are 2 bits per symbol. This would give a theoretical throughput of 2 bits per Hz. Other modulation schemes like QAM utilise amplitude and phase manipulation to achieve more bits for every cycle. This can be confusing to people because baud is symbols per second, which is different than bits per second bps. In the case of QPSK modulation of an analogue carrier, we may use 6 MHz for the whole haystack, which may actually be 5 MHz of payload because of filter skirts.