RE: Is this correct?

[Macy]

CORRECTION!

just tested the premise and indeed the argument for the sine wave MUST ramp 
from ?? up to half value and then STEP up to one to cause the frequency to ramp 
up and hold that final value??
N=100000;fc=100e6;dt=1/fc/100;
ord=[ [0:round(N/2)-1]/N, ones(1,round(N/2) ];
makes a ramp up to half value, then abruptly jumps to one.
sig=sin(2*pi()*(100+100*ord).*t);
that produces a spectrum from 100MHz to 200MHz with a spike at 200MHz, where it 
sits for half the time. The waveform is surprisingly well-behaved, with no 
abrupt changes.  does seem to ramp the frequency up to 200MHz and then HOLDs at 
200MHz. Although, if the definition of frequency is dphase/dt, not sure what 
the step in the middle did. perhaps the step occured when not looking. oops may 
be ok, because the argument of sin is the integral of phase, and thus the step 
is allowed? gack! this gets confusing to explain. Easier to just work with it 
and get on with the task at hand. or maybe use ramp up ramp down in the packet 
and see if that's better definitely no abrupt steps anywhere. 




--- address@hidden wrote:

Now I have to go reconcile what happens when the frequency stops at the end:
sig=sin(2*pi()*1e6*(300+100*[0:N/2-1]/N));
and by that erroneous inspection the 'frequency' looks like it ramps up to 
350MHz and then stays there, but as shown earlier the frequency ramps up to 
400MHz, then what? snaps back to 350MHz for the last half of the time packet. 
Arrggg! feel like Calvin and Hobbes, ...brain will explode.