Hi there. Summer over and so is my work with the company RENKO ITH. IHR. LTD. STI.. Worked for peanuts doing lots. Proud of it. Paid my school tuition with the peanuts. I think this makes my school a three ring circus 
.
Work was good and honest in RENKO. I wore three hats at all times ;
I’ve been mulling over an idea all winter. Trying to come up with different projects that could be done using Beagle-board and Arduino. The project is (you hear drum-roll here) “Building An Intelligent Robot”. I know it’s already been done however I have some additional ideas to put in project. All code will be open source. So if you want to build your own you could read up in this site.Oh and I really do need help. Especially financially. So if you are interested please drop me a line. My doodling is as below to give you an idea.
It’s been a long time since I coded in C. I needed to change the size of an array within the program. At first I just simply tried;
int ab=10; int array[ab];
And surprisingly it didn’t work. (I mean it works in C++ and C#)
Anyway I was thinking of ways on how to do this thought of using malloc() however I really didn’t know how hence I did some Google’ing around. And found this neat piece of code.
int *resize_array(int *a, size_t new_size)
{
int *save;
save = realloc(a, new_size);
if (save == NULL) {
fprintf(stderr, "Memory exhausted\n");
exit(EXIT_FAILURE);
}
return save;
}
int *user_old_array; // the array
int new_array_size=10;
user_old_array = malloc(initial_array_size * sizeof *user_old_array); //resized array
Quite neat isn’t it. I thought I should probably write this somewhere so I won’t forget. Hence the post.
Enjoy!
We once had a homework way back when decided to share it. I edited this script which is in Matlab. I hope you like it. It simply is an analysis of AM and DSB-SC Modulation and Demodulation of a Periodic Square Wave.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 | %Amplitude Modulation with a periodic sqare wave and its spectrum analysis %Show the time domain and frquency domain representation of DSB-AM and %DSB-SC modulations %By : John Roach – 6 March 2009 %visit my site at http://johnroach.info N = 1024; %N point FFT N>fc to avoid freq domain aliasing fs = 4096; % Sample frequency t = (0:N-1)/fs; fc = 600; %Carrier Frequency fm2 = 80; %Message Frequency Ec = 20; %Carrier Amplitude Em2 = 5; %Messagae Amplitude % Try changing the message and carrier amplitudes to see the effect in % DSB-AM modulation %———Double SideBand Full Carrier Modulation (DSB-FC(AM)) A = Ec + Em2*square(2*pi*fm2*t);%Envelope/eliminate the carrier amplitude m = A.*sin(2*pi*fc*t); %to convert DSB-AM to DSB-SC Mf = 2/N*abs(fft(m,N)); f = fs * (0 : N/2) / N;%Since the fft result is symmetrical, only the %positive half is sufficient for spectral representation close all; figure(’Name’,'Time/Fequency domain representations of DSB-AM signals’); subplot(2,1,1); %Time domain plot plot(t(1:N/2),m(1:N/2),t(1:N/2),A(1:N/2),’r',t(1:N/2),-A(1:N/2),’r'); title(’Time Domain Representation’); xlabel(’Time’); ylabel(’Modulated signal’); subplot(2,1,2); %Frequency Domain Plot plot(f(1:256),Mf(1:256)); title(’Frequency Domain Representation’); xlabel(’Frequency (Hz)’); ylabel(’Spectral Magnitude’); %———-Double SideBand Suppressed Carrier DSB-SC———- A = Em2*square(2*pi*fm2*t) ; %Envelope/eliminate the carrier amplitude m = A.*sin(2*pi*fc*t); %to convert DSB-AM to DSB-SC Mf = 2/N*abs(fft(m,N)); figure(’Name’,'Time/Fequency domain representations of DSB-SC signals’); subplot(2,1,1); %Time domain plot plot(t(1:N/2),m(1:N/2),t(1:N/2),A(1:N/2),’r',t(1:N/2),-A(1:N/2),’r'); title(’Time Domain Representation’); xlabel(’Time’); ylabel(’Modulated signal’); subplot(2,1,2); %Frequency Domain Plot plot(f(1:256),Mf(1:256)); title(’Frequency Domain Representation’); xlabel(’Frequency (Hz)’); ylabel(’Spectral Magnitude’); text(15,60,’Carrier’); %——————————————————————– |
The long awaited Beagle board has arrived.
The CVS code is as follows
cvs -d:pserver:anonymous@theblackbox.cvs.sourceforge.net:/cvsroot/theblackbox login
cvs -z3 -d:pserver:anonymous@theblackbox.cvs.sourceforge.net:/cvsroot/theblackbox co -P modulename
I am sorry to say due to some weird problem you can not view the CVS modules from Sourceforge. You will need to use some kind of client. I am currently using Eclipse as my development IDE hence all my CVS materials comes from that. I have heard that TortoiseCVS is quite neat in its own way (for Windows) but I’d rather use Eclipse your choice.
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![[img src=http://johnroach.info/wp-content/flagallery/beagleboardarrival/thumbs/thumbs_image025.jpg]](http://johnroach.info/wp-content/flagallery/beagleboardarrival/image025.jpg){kind=link}