QRP Labs QCX 5W CW, Assembly Instructions Manual

Page: 86 / 138

QCX assembly Rev 1.08
86
5.3 Ampl. Avg.
60
The decoder maintains an amplitude threshold, which it uses to decide whether a tone is detected
or not. The level of this threshold must be varied automatically in order to cope with stations
having a wide range of different signal strengths. Other perils may include QSB (signal fading) of
the station you are listening to. The amplitude threshold is implemented via an exponential moving
average. The weighting of each new sample (every 4ms) added to the accumulated exponential
moving average value is the reciprocal of this parameter.
If the exponential moving average is too fast (the parameter value is too low) then noise etc will
too easily throw off the amplitude threshold and it may take time to recover to its proper level. If
the exponential moving average is too slow (the parameter value is too high), then it may take too
long to adjust to the received station
’s amplitude, resulting in missed characters while the decoder
slowly adjusts itself. It would also be too slow to automatically respond to QSB (signal fading).
5.4 Enable Rx
ON
An experienced CW operator may well dislike the CW decoder scrolling across the display all the
time. With this setting you can s
witch “Enable RX decode” to OFF and the receiver decoding is
disabled.
5.5 Enable Tx
ON
With this setting you can switch “Enable TX decode” to OFF and the transmit decoding is disabled.
When this setting is ON, the CW decoder will decode your own keying and display it on the screen
while you transmit. For an experienced CW operator that may be distracting too!
5.6 Enable edit
ON
This parameter enables CW decoding while editing. When ON, anything you key during editing of
NUMBER or TEXT type configuration parameters, edits the parameter. This is a really useful
feature that makes it very easy to enter frequencies or stored messages, for example.