Re: Simple Question
Considering it's about baseband transmission - no modulation, it depends on the coding. More exaclty, it depends on the period of the shortest signal element. The data being random, it's a bandwith, not a single frequency.
If NRZ coding is employed, for a bitrate of X bps, the signal spectrum will have a peak at X/2 Hz. The spectral energy will ocupy an theoretical unlimited - but in practice limited bandwidth, since the data is random.
For Manchester/Biphase coding, bitrate X bps, the signal spectrum will have a peak at X Hz.
For multilevel coding (rarely used, egg. fast Ethernet), the significant spectrum portion can be less than X/2 Hz, as the number of levels is increased from 2 up.