Telex ISP-100 manual Center Frequency, Bandwidth

Bandwidth can be displayed in terms of Q or octave fraction. See page

7-3 for information on changing the way filter bandwidth is displayed.

8-33

The EQ filters in the ISP-100 are full parametric. Each may be adjusted for center frequency, boost or cut, and bandwidth.

Center Frequency

The center frequency is the frequency at which the maximum boost or cut takes place. In the ISP-100 EQ filters the center frequency is continuously variable from 20 Hz to 20 kHz.

Bandwidth

The bandwidth is measured at the points on either side of the center frequency where the boost is 3 dB less than the maximum boost or the cut is 3 dB less than the maximum cut, whichever is appropriate. In the ISP-100 filters, bandwidth can be expressed in either octave fraction (fractions of an octave, or number of octaves if the bandwidth is greater than a full octave) or quality (Q).

The conversions between octave fraction and Q are:

⎧

⎡

1

1

⎤

⎫

⎪

⎢

+

+ 4

⎥

⎪

octave fraction = 2⎨log

2

Q

Q2

−1⎬

⎪

⎣

⎦

⎪

⎩

⎭

and

Q =

1

octave fraction

-octave fraction

2

2

−

2

2

Figure 8-15Octave Fraction vs. Q relationship.

The relationship between octave fraction and Q is shown in Figure 8-15.

Processing Components - Filter