John Roach » john roach

A pretty picture

John Roach — Thu, 13 May 2010 19:27:05 +0000

Hi. Got to take a photo that I actually am proud of. I hope you like it.

If you are viewing this in a link in a other than my own site you may not able to see the bigger picture. Please view this in my own site. (http://johnroach.info/2010/05/a-pretty-picture/)

Blogger Is Closing Down FTP service… So what… I’ve got WP

John Roach — Tue, 02 Feb 2010 21:01:15 +0000

: Image by whiteafrican via Flickr

It seems blogger.com is closing down it’s FTP service. Good thing I already transferred my site to WordPress before hand.

My blogging life has been quite the roamer. It seems I like my individuality. My road started with LiveJournal.com. One day I opened my LiveJournal account to find it blocked by the firewall of our school. Some people used to put their nude pictures on their LiveJournal so it was banned. I got angry at this. Thus I transferred everything to Blogger.com. But guess what! Turkey blocked Blogger for about four to five months this got me mad. So what I did was make Blogger.com send the info to my FTP host. I even bought a domain for this host. A little coding and voila! My was site was back up and running. However this got me thinking. What if Blogger was totally banned? What would I do than? Hence I started looking for blogging scripts and that is how I met WordPress. I must say I’m very happy with it. I even integrated Zemanta with my browser to bring in even better content. In fact the picture here was found thanks to Zemanta. Anyhow…

So Blogger is closing down it’s FTP service. So what. It seems Blogger is thinking the same way. The mail they sent me states :

FTP remains a significant drain on our ability to improve Blogger: only .5% of active blogs are published via FTP — yet the percentage of our engineering resources devoted to supporting FTP vastly exceeds that.

It seems Blogger started cutting out the rotting flesh. The hoards of zombies that try to live on old tech. And this also shows Google‘s business management. If it doesn’t work, cut it out. Which I believe is one of the best ways to do management. Look at HP Labs present condition. Actually look at any big corporation. The only way you can go big is use this kind of thinking. I know… I know… It probably meant that the current FTP “engineering resources” our out of a job. But still… The show must go on.

Oh and for the people asking, the snow effect will still be here for a while. It is still snowing in Ankara, Turkey.

Setting up a CVS server for the BlackBox project

John Roach — Sun, 13 Dec 2009 09:05:28 +0000

Following the previous posts in this category you will notice that I was using Sourceforge.net as the code hosting. We had to change that because we really didn’t want to share every bit of code. ( A big sorry to open source developers. I am truly a sell out. ) So had to set up CVS server. Never done that before. Should probably add it to my CV. Anyways to business.

How to set up a CVS server using SSH :

Step 1 : Install CVS to Fedora. My Fedora distro came with CVS since I chose developer properties during installation. However you may not have it to install simply say;

sudo yum install cvs

Step 2 : Create a cvs user and group! Just follow the code below;

useradd cvs


groupadd cvs
mkdir /home/cvs
cvs -d /home/cvs init
useradd cvs
groupadd cvs

mkdir /home/cvs
Step 3 : Set permissions and add /home/cvs directory to cvs by using the following;

cvs -d /home/cvs init


chown -R cvs:cvs /home/cvs
chmod -R 770 /home/cvs

chmod 700 /home/cvs/CVSROOT

Step 4 : Now you have to add your project to the CVS server. I assume you have a ~/project directory on the server. Just follow the following commands;

cd ~/project


cvs -d /home/cvs import -m "Initial Import" project myname release

cvs -d /home/cvs checkout project

Step 5 : Add an account to the CVS server (preferably with the same username and password of the user acount you have created for the CVS server that will connect through SSH.) Use the following by replacing and

echo ":" >> /home/cvs/CVSROOT/passwd

Step 6 : Make sure you have created a user to connect through SSH give him CVS group permission.

And that is that. It should work. Though you may need to do some changes in Step 3. To connect you can simply use the following code or just use Eclipse’s IDE ( that is what we are using. )

export CVS_RSH=ssh


cvs -d :ext:user...@repository.host.name:/home/cvs login

cvs -d :ext:user...@repository.host.name:/home/cvs co moduleName

I hope it will be helpful. Peace!

AM and DSB-SC Modulation and Demodulation of a Periodic Square Wave (Matlab)

John Roach — Sun, 15 Nov 2009 15:49:00 +0000

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.

%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 site has been updated

John Roach — Tue, 20 Oct 2009 08:52:56 +0000

Yes, at last. Free of Blogger/Google. I won’t be blocked!! Thanks to Turkish blocking sites I have decided to carry EVERYTHING to my OWN host. And voila! What you see is what has happened.

I am using WordPress for people who are wondering and I know the theme is a little dark. But it is simple and I like simple.

And just to wet your appetites I shall post a tech related video.