Questions regarding signal processing in octave

[Ahmed Husain ?Abbas Mohamed Sahrab]

We are a group of college students doing a project about signal processing.

We would like to compute the PSD(Power Spectral Density) and the Power Spectrum, our question is how to find the Power Spectrum and how to use different frame sizes e.g. 128, 256, 512.

We used this following code to find the PSD

NFFT=32768;

F=fft(y,NFFT);

F_Shift=fftshift(F);

Px=F_Shift.*conj(F_Shift)/(NFFT*L);   

We tried using a NFFT of 1024 but we literally got two intersecting lines

Our Second question is about sine waves, we have a wave with the following specification

x = A1*sin(2*pi*f1*t)

Sampling Frequency = 100 kHz =Fs

Frequency = 10 kHz = F1

Amplitude = 0.1 = A1

We need to generate 1000 samples of this wave, we were given an equation which is 

(fs=f*N) in which f is the frequency and N is the amount of samples needed. but in the question we already have the fs which is 100kHz so how are we supposed to generate 1000 samples?

Should we use

 t= 0:ts: Tfinal

until we have 1000 values in the t variable?

Best Wishes

Students of Polytechnic Bahrain