USKI-5 Universal Sequencer & Keying Interface
© Copyright 2015 QSK, llc
www.qskllc.com
Page 16
zero. Assuming the T/R switch and amplifier relays require 15 ms to switch, that amount of time
is accounted for in the sum of the VFO and transmitter start time. This allows the VFO time to
start before the transmitter (modern DDS VFOs are generally so fast that no delay is necessary
after starting before keying the transmitter). Again, as in previous examples, end delay
5
is
equal to the sum of the start delays so that the CW weighting of the transmitted signal correct
(intentional changes if weighting can be also be accomplished by proper choices of delays). End
delay
4
is set to 5 ms to allow the transmitter time to complete each CW symbol envelope
before turning off the VFO. If the VFO turns off its RF output quickly, the RX mute end delay can
be set to zero. If not, and sometimes for cleaner sounding QSK operation, sometimes a few ms
delay in the RX mute end delay may be necessary.
USING LONGER DELAYS
To minimize timing errors, the microcontroller is overclocked to the maximum frequency allowed
(32 MHz) in programs (A), (B), and (C). For the programs
as written, every delay or “pause” is
limited to a maximum of 8191 ms. If longer delays are desired, up to 65535 ms, the
microcontroller can be set to operate at its default frequency (4 MHz) by “commenting out” the
command line that sets the clock frequency to 32 MHz. This is done by simply adding a
semicolon in front of t
he line with the “setfreq m32” command. The START-DEL and END_DEL
lines should also have the “8 *” removed as shown here:
If even longer delays are required, refer to the PICAXE© programming manual.