Consider the following two cases: Let\'s assume that FCC has changed the AM rang
ID: 1715981 • Letter: C
Question
Consider the following two cases: Let's assume that FCC has changed the AM range to 1500 kHz - 3300 kHz with the IF frequency of f_IF = 300 kHz. If you have the option of choosing the local oscillator's frequency as either f_o=f_c+f_IF or f_o=f_c-f_IF, which one do you choose and why? For this case, let's assume that FCC has changed the AM range to 510 kHz - 2010 kHz with the IF frequency if f_IF = 490 kHz. If you have the option of choosing the local oscillator's frequency as either f_o=f_c+f_IF or f_o=f_c-f_IF, which one do you choose and why?Explanation / Answer
Given,
a) The FCC has changed the AM range to 1500KHz to 3300KHz
Iif = 300KHz
Local oscillator frequency FLO =
In this case we always have two choices,
1) Flo1 = Frf - Fif
A. 1500 -300 = 1200KHz
B. 1700 - 300 = 1400KHz
2) Flo2 = Frf + Fif
A. 1500 + 300 = 1700KHz
B. 1700 + 300 = 2000Khz
b) In this case the same methods goes,
AM range is 510Khz to 2010 KHz
IF Frequency = 490KHz
Now again we have two cases
1) Flo1= 510-490= 30KHz / 2010 - 490 = 1520KHz
2) Flo2 = 510+490 = 1000KHz / 2010 + 490 = 2500KHz