Yaesu FT-1000MP Operating Manual page 61

Operation
EDSP Auto Multiple Notch Filter
-
On page
34, we previously discussed basic IF notch filter
operation and how it is used to attenuate hetero-
dynes. EDSP offers multiple-notch capability
within the AF (rather than IF) bandpass with the
press of a button.
With the conventional (455 kHz 3rd IF) notch
filter, only a single offending heterodyne at a time
can be attenuated by pressing the
NOTCH
button
and slowly rotating the inner
NOTCH
control. Notch
tuning can sometimes be critical, as you have to
position the control for maximum "depth" by ear.
With the multiple notch, EDSP circuitry exam-
ines the AF bandpass and the correlation of the
signals present. After correlation parameters are
'
compared, unmodulated signals (heterodynes)
are identified and notched out. As EDSP dynami-
cally checks the audio, new heterodynes will be
identified and notched, one by one, as they ap-
pear. See the illustration below.
Desired Multiple Notches
Signal
QRM
I
(Multiple I
I I
EDSP
EDSP Auto Multiple Notch Action
Selectable
-
with EDSP off, functions
Theoretically, an infinite amount of notches
could be inserted to attenuate each new hetero-
dyne; however, the total notch bandwidth would
approach that of the audio passband, and, pro-
gressively notch all audio. One limitation of the
EDSP auto multiple notch feature is that it is only
for use with SSB modes.
It is important to realize that notch operation is
determined by two things:
The setting of menu selection 2-9.
If EDSP is active or not when the
NOTCH
button is pressed.
The
NOTCH
button still activates the IF notch
circuit, but you must determine which type of
notch (manual or EDSP-auto) will take effect via
menu selection 2-9 (see the box below). For the
auto notch feature (and all other EDSP functions),
the
EDSP
button must be engagedfor signal proc-
essing to occur.
page 59