A system is required to transmit the baseband analogue signals from 40 users over an available bandwidth of 4.4MHz (from 10MHz to 14.4MHz). The system design parameters require that the transmission of each users modulated signal must be isolated by a guard-band frequency of at most 10% of the users useful signal bandwidth (3dB bandwidth.)

a) What bandwidth would each user have available for its baseband signals useful bandwidth if the guard bands are required to be implemented at the 3dB points (useful bandwidth of the baseband signals.)

b) Sketch a frequency spectrum diagram of the system showing where the first 3 users baseband signals are placed into their own portion of the 4.4 MHz bandwidth.