Tony,
You should convert WPM to bauds to apply the formula.
Simpler, and hoping for the best, use a 1500 Hz keyed tone, it allows
for symmetric keying sidebands. As in PSK, do not overdrive anything
in the TX chain, and you should get a pretty decent signal.
With 1200 Hz wide sidebands, you must send quite snappy CW to exceed
that. With proper spectrum keying shaping done in the soundcard,
a 2.4 kHz wide filter should be enough to send what will be received
with another equal bandwidth filter, which is the most common thing for
weak signal receiving nowadays.
73,
Jose, CO2JA
Andrew O'Brien wrote:
*WHAT IS THE BANDWIDTH OF HIGHER-SPEED HSCW? ISN'T IT MUCH WIDER THAN
STANDARD FILTERS CAN PASS?
The formula given for the bandwidth of a standard CW signal, Bn=B*K, is
based on make-break ICW, the on-off keying of a carrier, with the leading
and trailing edge of the individual characters shaped by the keying
circuits, the bias of the following stages, etc. Thus the formula is usable
at the lowest HSCW speeds when make-break keying is used.
But today nearly all HSCW is done by keying an injected audio tone. This
means that if the transmitter is set up properly (i.e., processor off,
nothing overdriven, a proper tone frequency, etc.), the keying is not
shaped
by keying circuit components or adjustments of the transmitter. Rather, the
shape of the rise and fall of the individual characters closely
approximates
the shape of the injected sine wave audio tone. Thus, the above formula
does
not apply for tone-injection HSCW operation.
This is the reason that even the very-high-speed HSCW will fit in the
passband of a standard SSB filter. Of course, misadjusted or overdriven
audio or RF stages may cause spurious signals outside of the intended
range.
But it has proved to be quite easy to generate a good-quality HSCW
signal by
tone injection within the approximate bandwidth of a standard SSB filter.
On 5/26/07, Tony [EMAIL PROTECTED] wrote:
All:
Does anyone know the approximate bandwidth for
injected audio tone high speed CW? Is there a way
to calculate this?
Thanks,
Tony KT2Q
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