Richard,

Lets look at a real case. A 7 MHz square wave contains no energy at 14 MHz.
Now change the duty cycle so that the signal is ON for 25% and OFF for 75%
of the time. Now you have energy at 14 MHz. One way to look at what we have
done is to think of the 25/75 signal as being a 1/2 cycle of 14 MHz every 2
cycles of 14 MHz. Obviously, the rise and fall times have to be short enough
to transmit these narrower pulses. The faster the rise and fall times, the
more higher frequencies you get.

Tam/WB2TT
"Richard Fry" wrote in message
...
Reg Edwards wrote
The shape of the pulse, the width of the pulse, the time interval
between pulses, all affect the harmonic frequency spectrum.
They act both independently and in conjunction with each other.
________________

Please explain the reason why the bandwidth characteristics needed to
generate a single transition from one DC level to another is different
than
when repeating that same transition any number of times before or after.

RF