Recent content by paul_harris77

Hi all Sorry if this is quite a basic concept, but I am confused about RF signals. The way I currently understand it is that radio waves in space are an oscillating electric and magnetic field at 90 degrees to each other traveling through a medium. However, when you pass a radio wave into a...

Thanks for the reply. Ok, that's fine, but now I have a question about obtaining the PSD of a signal that is continuous in the frequency domain. I have read it is simply the square of the magnitude of the spectrum. If we assume that the spectrum was obtained with the Fourier Transform, surely...

Does anyone know the difference between the power spectrum of a signal and the power spectral density (PSD) spectrum of a signal? I've read on the net lots of things ranging from: i) They are identical ii) Power spectrum is units of Watts, power spectral density spectrum units of Watts/Hz...

Sorry for the delayed reply. I think I understand what your saying - instead of using two IIR filters and subtracting their outputs (one delayed), you can use one IIR filter and subtract it's inputs. I can't do a block diagram because I don't have any webspace to host the image at the...

Thanks for the reply. I think I understand the jist of what your saying. I'm not sure but would h[n]_{iir} be: h[n]_{iir}= x[n] + h[n-1] In which case would: h[n]= x[n] + h[n-1]-x[n-N] - h[n-N] be correct?

Sorry for the confusion, I should have written it in a clearer form with all the conditions. The h[n] = {1, 1/2, 1/4, ...} for n>=0 was wrong. There should not have been a "..." at the end. The example, even in the hard copy of the notes, specifically states: h[n] = (\frac{1}{2})^n for...

Hi rbj The first h[n] is the correct one i.e. (FIR). Sorry if this caused any confusion. Thanks! Paul

Hi rbj Thanks for your replies. I don't have much experience in DSP (as you can probably tell). [SIZE="4"]1) Perhaps I should give more context. I was just trying to relate two concepts from my lecture notes and they may or may not be indirectly linked to truncated IIR filters. I...

I've been told that to calculate the difference equation of an LTI system, you simply take the sample values of the impulse response as the coefficients of the x[n-k] terms in the difference equation. i.e. if h[n] = {1, 0.5, 0.25, 0.125} for n>=0, then y[n] = x[n]...

Dear All I am trying to measure the spectrum of an incandesant 6V 15W tungsten microscope lamp. I have a reasonably old scanning monochromator (diffraction grating based) coupled to a fibre optic cable and it has given me the spectrum...

Dear All I am having problems with how to draw band diagrams with band bending for Schottky Barriers and PN junctions. My issue is that I don't know how you determine which Fermi level remains fixed at its equilibrium level and which Fermi level moves to align with it when the two materials...

Dear all I am slightly confused over the equations for skin depth. My university notes give me the equations: \delta = tan-1 (tan\delta) = \frac{\sigma}{\omega \epsilon} (loss tangent) where \delta is skin depth and \sigma is conductivity. I am also given the equation: \delta =...

Thanks for the reply viscousflow :) I see what your saying for the most part. But surely for a fixed imaginary part (+/- jwd) moving the poles left would decrease the angle and cause dampening to INCREASE since it's cosine ? Thanks Paul

Dear All I'm stuck on something that seems to be contradictory. I was under the impression that the further the 2 closed loop poles are in a 2nd order system to the left of the root locus, the higher the damping. Surely high damping means longer rise time? But other sources say that the...

Hi Klondike Thanks for the reply. Glad I'm on the right track :) We've been chucked in at the deep end with no prior experience in SP of any kind and just a load of notes with definitions and no explanation! There was a previous exam question like this yet no examples on how to do it...