MFJ MFJ-784B, Инструкция по эксплуатации, Страница: 54 / 74

MFJ-784B Instruction Manual
Filter Description 5-2
The following section describes the filters available in the various Filters switch
positions in detail. All graphs of the following filters show a line at the noise
floor of -55 dB. The response for these digital filters is typically much deeper
than -55 dB but circuit noise will generally mask any response below that point.
LR/HR Filter [1]
Use: Custom Voice, FSK, Wide CW Filter.
Passes medium to wide frequency width.
This position selects an adjustable low reject/high reject filter. The low reject
filter (
Low ) removes all signals below a user-selected frequency. The low reject
filter cutoff frequency can be varied between 200 Hz and 2200 Hz with the
Tunable Filters left knob. The high reject filter ( High ) removes all signals
above the selected frequency. The high reject limit is adjustable between
1400 Hz and 3400 Hz with the
Tunable Filters right knob.
For example: If the low reject filter is adjusted to 900 Hz and the high reject
filter is adjusted to 2500 Hz, all frequencies below 900 Hz and
above 2500 Hz will be rejected. In this case, the DSP filter will
only pass frequencies from 900 Hz to 2500 Hz.
Typical Low Reject/High Reject Filter Response
Frequency (Hz)
dB
-80
-70
-60
-50
-40
-30
-20
-10
0
0 500 1000 1500 2000 2500 3000 3500 4000