Elecraft P3 High-Performance Panadapter Manual - Manual (Page 19)

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the preamplifier in the K3, the noise level displayed
on the P3 may decrease, rather than increase. That
is because the P3 automatically reduces its gain
when the K3 preamplifier is turned on, in order to
keep the signal levels the same.
Waterfall Display
The waterfall allows you to see a history of band
activity for the past few seconds. Like the spectrum
display, the horizontal axis is frequency but in this
case the vertical axis is time. Signal amplitude is
represented by colors, from dark blue for weak
signals, then brighter blue as signals increase in
strength, through shades of green, yellow and red
for the strongest signals. Each horizontal line
represents one update of the spectrum display.
As each new line is written the old ones are shifted
down, creating a waterfall effect.
While the spectrum display is better at accurately
displaying signal strength and the shape of a
signal's modulation, it can only show what is
happening right now. The waterfall is better for
showing transient signals, such as a DX station
running a pileup that only transmits for a few
seconds at a time. Often, you can easily see a weak
fading signal on the waterfall that is invisible on the
spectrum display.
The scaling of the waterfall is the same as for the
spectrum. That is, the bottom of the spectrum
display corresponds to dark blue on the waterfall
and the top corresponds to bright red. For maximum
visibility of signals on the waterfall, it is best to set
R E F L V L
so that the noise level is right at the
bottom of the spectrum display and then expand
S C AL E
as much as possible while keeping signals
of interest below the top of the spectrum display.
That improves the color contrast on the waterfall
and makes weak signals appear to pop out of the
noise.
Averaging and Peak Hold
Another way to make weak signals more visible is
averaging. Because noise is random in nature,
averaging reduces the jaggedness of the noise
spectrum trace, making signals easier to pick out.
The more averaging the better the noise reduction,
but at the expense of a slower response. To turn on
averaging and adjust the averaging time, hold
A V E R AG E
and then turn the knob. The averaging
time is in units of the spectrum update rate,
typically about 50 ms. You can apply averaging to
the waterfall as well by setting
MENU:Wfall Avg
to
On
.
Peak hold is a way to display a memory of past
signals on the spectrum display. It shows the
strongest signals that have appeared at each
frequency since the last time peak mode was
enabled. To reset the peak trace, simply disable
peak hold and then re-enable it. This mode is most
useful if you assign
MENU:Peak
to a FN key so you
can turn it on and off at the touch of a button.
One use for peak hold is to monitor a dead band for
activity while you are away from the operating
position. If you glance at the display every now and
then you can see if any signals have appeared in the
meantime. Peak hold is also useful to see the shape
of a modulation spectrum. Since the sidebands are
continually changing with modulation, the peak is a
better indication of the spectrum than the
instantaneous value.
Span
Adjusting the span is yet another way to make weak
signals more visible. As you narrow the span, there
is less noise within the range of each frequency
display point. That reduces the apparent noise level
while the signal levels stay the same, which
increases the signal-to-noise ratio. At narrow spans,
signals that are difficult or impossible to hear
become visible, especially on the waterfall.
As mentioned before, it is useful to keep the noise
level right at the bottom of the display. The P3 can
automatically keep the noise level constant as you
adjust the span by setting the menu
MENU:SpanScale: REF LVL only
. If you would
also like the level at the top of the screen to remain
constant as you adjust the span, set
MENU:SpanScale: REF LVL & Scale.
Fixed-tune mode
When the P3 is used with a K3 transceiver, the
center frequency on the P3 screen normally follows
along as you tune VFO A on the K3. This is called
tracking
mode. In this mode, the frequency
displayed at the top center of the screen is the
display center frequency, and the labels at the top
left and right show the frequencies of the left and