Recent content by samski

no it actually takes the difference in phase between the input and the output sinusoids. that's why there is a "phase detector". think about it, if what you said is right, then when the input frequency and the LO frequency are the same, there would be no voltage, so what is driving the VCO...

i guess its badly phrased. but anyway, they are oscillating terms on the input to the PLL.

re-read. x and y are the input signals

sounds unlucky, but unless you have downloaded any files from this forum, i doubt you've got a virus from here. some browsers can help with keeping ur pc protected so have a look at that. i use AVG but there is a lot of hate out there for that. i tend to manage to stay relatively free of nasties...

i made it up to try and make the maths work right lol. i wondered if it made sense in the rest of the maths

so the differential says that over time the frequency is changing and wobbling i think these show it well http://www.wolframalpha.com/input/?i=plot+Real%282*pi*50*x+%2B+20*e%5E%28i*%2810*x%29%29%29+x%3D0+to+10...

this is why i thought up the formula of: \theta_0 = 2 \pi f t + e^{j(\omega t + \theta)} (note 2*pi*f =/= omega) differentiating gives: differential = 2 \pi f + j \omega e^{j(\omega t + \theta)} which is a constant frequency of f with a wobble in the frequency, omega

agreed, the theta_0 at the beginning is wrong. ok, so what do we say theta_0 should be to make the final maths work? it must be a phase that gives a frequency of f, but is wobbling at omega. ie the intention is that the frequency, f, is wobbling at frequency omega

These notes are EXACTLY what the professor gave us (as these are his writing from the online uploaded version of the notes) I am quite familiar with eulers formulae and i know how multiplication and powers work, bear in mind that this is a 3rd year engineering degree course. the formula for...

do you have any more info on the lightbulb? you are putting a little too much current through it, but it sounds like you won't get much improvement in performance as 9V don't have a lot of capacity. The top end ones have ~570mAh of capacity for the disposable kind. This means that if you take...

could be talking about electron flow rather than conventional current...

that's not quite true. have a look back at the original formulae. i spoke to my lecturer today and he agreed that this maths doesn't quite work. please try to differentiate the equation for \theta_0 given in the original formulae. you will see that we don't get 2 \pi f. I'm wondering how we...

i think i might have mentioned this in my 2nd post, omega is NOT the input frequency, omega is the wobble in the input phase. edit: or at least i think it is, its the only way to make formula 1 make sense. omega is different to f

i think enthalpy's reply was on the sarcastic side

sorry are we getting confused here, i mean \theta_0 = e^{j(\omega t +\theta)} which definitely IS a function of time. i think the phase function should look more like \theta_0 = 2 \pi f t + e^{j(\omega t +\theta)}, because then, differentiating we get frequency = 2 \pi f + j \omega e^{j(\omega...