practice problem 1
Start by determining the beat and carrier frquencies from the information given in the description.
|fbeat =||3.5||/||0.03283 s||= 107 Hz|
|fcarrier =||29.75||/||0.03283 s||= 906 Hz|
Then work backward to determine the two source frequencies. The beat is the difference in two frequencies and the carrier is their mean.
|fbeat =||f1 − f2||= 107 Hz|
|fcarrier =||f1 + f2||= 906 Hz|
A little bit of algebra on the carrier equation gives us two equations that can be added. Watch one of the unknowns vanish.
|f1 − f2||= 0107 Hz|
|f1 + f2||= 1812 Hz|
|2f1||= 1919 Hz|
And we're done.
f1 = 960 Hz
f2 = 853 Hz
These are indeed the values specified by US federal law.
practice problem 2
practice problem 3
practice problem 4