Four signals, each having W = 3 kHz, are to be frequency-division multiplexed with 1-kHz guard bands between channels. The subcarrier modulation (modulation to accomplish the FDM) is AM, with one signal left at baseband. The composite FDM signal is then input to another AM modulator for transmission. Sketch the spectrum of the baseband FDM signal (use arbitrary shapes for the spectra of the 4 FDM'd signals) and the transmitted signal, and calculate the transmission bandwidth.