The input reference to the quadrature detector is

The inputs to the two DBMs within the quadrature detector become

since one of the DBMs has a 90^{o} phase shifter before it.

According to the trigonometric identities introduced in Chapter 2, the outputs from the two DBMs in the quadratre detector are

Sin(2π ν t) Cos(2π ν_{o} t) = 1/2 Sin(2π ν t + 2π ν_{o} t) + 1/2 Sin(2π ν t - 2π ν_{o} t)

The filters remove the high frequency components, leaving

IM = 1/2 Sin(2π ν t - 2π ν_{o} t)

Note that one output of the quadrature detector gives the cosine and the other the sine of the rotating frame frequencies.

Copyright © 1996-2010 J.P. Hornak.

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