A narrow band FM signal has a carrier frequency of 110 kHz and a deviation ratio of 0.05. The modulation bandwidth is 10 kHz. This signal is used to generate a wide band FM signal with a deviation ratio of 20 and a carrier frequency of 100 MHz. The scheme utilized to accomplish this is illustrated in Figure 4.12. Give the required value of frequency multiplication, n. Also, fully define the mixer by giving two permissible frequencies for the local oscillator, and define the required band pass filter (center frequency and bandwidth).

Figure 4.12

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Narrowband FM signal: Carrier frequency = fc1 Peak frequency deviation = f1 Deviation ratio = D, Wideband FM signal: Carrier frequency = f2= nfe1 Peak frequency deviation = f2= nfal Deviation ratio = D2= nD1 Narrowband хn frequency modulator system Bandpass filter Frequency multiplier -X(t) of Figure 3.22 Local oscillator Mixer