WHAT IS THE BANDWIDTH OF HIGHER-SPEED HSCW? ISNT IT MUCH WIDER THAN STANDARD FILTERS CAN PASS?

0
Posted

WHAT IS THE BANDWIDTH OF HIGHER-SPEED HSCW? ISNT IT MUCH WIDER THAN STANDARD FILTERS CAN PASS?

0

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 st

Related Questions