Robotron Pty Ltd G9P 用户手册
WiNRADiO G39DDC User’s Guide
49
Audio Filter
The Filter button turns on the Audio filter. The audio filter is a bandpass filter
with continuously adjustable lower and upper cut-off frequencies:
with continuously adjustable lower and upper cut-off frequencies:
When the audio filter is enabled, its low and high cut-off frequencies can be
adjusted using the Low and High controls. The De-em control is used to
adjust de-emphasis, relating to the filter’s slope from the highest frequency to
the lowest, which is particularly important for FM signals (a typical de-
emphasis value for narrow-band FM-modulated signals is 6.0 dB/oct).
However, it can be also useful for AM signals: Gently sloping the filter
passband can sometimes make the signal easier on ears and avoid operator
fatigue.
adjusted using the Low and High controls. The De-em control is used to
adjust de-emphasis, relating to the filter’s slope from the highest frequency to
the lowest, which is particularly important for FM signals (a typical de-
emphasis value for narrow-band FM-modulated signals is 6.0 dB/oct).
However, it can be also useful for AM signals: Gently sloping the filter
passband can sometimes make the signal easier on ears and avoid operator
fatigue.
For wide FM modulation (broadcast FM), there are two standard de-emphasis
values to choose from, 50 and 75 microseconds:
values to choose from, 50 and 75 microseconds:
In North America, 75 microseconds is the standard value, while most of the
rest of the world uses 50 microseconds.
rest of the world uses 50 microseconds.
The audio filter passband is shown as a shaded area inside the Audio
spectrum, which is accessible by pressing the Audio button:
spectrum, which is accessible by pressing the Audio button: