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GitHub

As WordPress tends to mangle code that I post, I’ve started moving it to GitHub. As I move code to GitHub, I will replace the code within the article to a link to the code on GitHub.

You can find my GitHub here.

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Installing GIMP on Mac OS X with ELA Script-Fu

This article will walk you through installing GIMP on OS X with an ELA (Error Level Analysis) plugin to detect editing.

To learn more about reading ELA results, read this:
      http://fotoforensics.com/tutorial-ela.php

First, download GIMP from here: https://www.gimp.org/downloads/

Next, grab elsamuko-error-level-analysis.scm from the bottom of this page: https://sites.google.com/site/elsamuko/forensics/ela – Save it for later.

GimpElsamuko

After downloading this .scm file, open it in your favorite text editor and locate the following line:

SF-STRING      "Temporary File Name"   "error-level-analysis-tmp.jpg"

Change it to the following:

SF-STRING      "Temporary File Name"   "/tmp/error-level-analysis-tmp.jpg"

And save the file. This fixes an issue with images not being able to be processed as the default location is not writable by GIMP.

Now double-click the GIMP .dmg file you downloaded, and copy GIMP to your Applications folder as shown:

CopyGimpToApps

Once you have it copied over, you will want to open the package contents by alt-clicking and selecting “Show Package Contents“.

GimpShowPackageContents

From here, navigate to Contents > Resources > share > gimp > 2.0 > scripts and drop in the elsamuko-error-level-analysis.scm file you download earlier.

GimpScriptsElsamuko

Now, run GIMP. Because of security-related things and stuff, the first time you run you will have to alt-click on GIMP and select Open. After doing this for the first time, you won’t have to do it again.

GimpOpen

GIMP will appear to freeze for about 5 minutes while it builds its initial caches. This will cause GIMP to appear unresponsive. Do not force-kill it during this time, simply be patient until it opens.

Now, you can perform ELA on an image by opening it, and selecting Image > Error Level Analysis from the menu.

GimpELA

 

Once you’ve done that, running it against an image will produce an ELA mask as an additional layer, which you can use to analyze an image.

You can toggle the ELA layer visibility by clicking the eye shown in the following screenshot.

GimpToggleELALayer

(Sample image from http://fotoforensics.com/tutorial-ela.php, retrieved April 11th, 2016)

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Changing Piwik delimeters

If you wish to change the Piwik delimiters to break away from any treeing of your pages on the action and titles reports, you can use the method described on http://piwik.org/faq/how-to/faq_62/, but that method doesn’t describe both of the delimiter tags you may wish to apply.

There are two delimiter settings that you may wish to change, which get added to your config.ini.php file under [General]

action_title_category_delimiter = "::"
action_url_category_delimiter = "::"

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Installing Munin on Linux

I read several articles on how to install the Munin monitoring tool for Linux, and they all seem to over-complicate the install, or end up with an install that doesn’t work.

This article will walk you through installing Munin for a local monitor/node setup on Debian 8 64-bit. Tweak it to your liking. This also assumes that you are running as root. Prefix commands with sudo where appropriate.

Start by making sure your system is up to date:

apt-get update
apt-get upgrade

Next, install apache, munin, munin-node, munin-plugins-extra and dependencies.

apt-get install apache2 apache2-utils libcgi-fast-perl libapache2-mod-fcgid munin munin-node munin-plugins-extra

Now, edit the munin config file /etc/munin/apache24.conf

nano /etc/munin/apache24.conf

Change the <Directory /var/cache/munin/www> section as follows:

...
Require all granted
Options FollowSymLinks SymLinksIfOwnerMatch
...

Do the same with the <Location /munin-cgi/munin-cgi-graph> section, adding the Options line if it’s not preset.

Now restart both apache and munin-node.

/etc/init.d/apache2 restart
/etc/init.d/munin-node restart

You can now view munin data at http://<server IP>/munin

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ARRL Baofeng testing revisited

A while back I wrote a post called “Why FCC tested transceivers should matter to Ham Radio operators.” As part of this post, I drew attention to testing performed by the ARRL on used ham radio transceivers. One of the highlights of this article was that the Baofeng HTs performed exceptionally poorly due to a high level of spurious emissions.

However, I recently stumbled onto an article on PD0AC’s Ham Radio blog called “Baofeng UV-5R Spectrum Analysis Revisited,” in which Hans (the author) looked into comments about the UV-5R’s suspected spurious emissions. I quote:

“But wait, we did this(link) already … and the UV-5R wasn’t too bad at all. All of his bothered me enough to pick up a few of my own UV-5R’s and repeat the measurements… The only way I could replicate his [failing] results was by reducing external attenuation to such a low level that the linearity of the spectrum analyzer was compromised”

In his initial testing, Hans and Tom (PA2TSL) used a 30 dB attenuator for the spectrum testing.

So I went back to the original QST article (November 2015, page 74) and re-read it. It’s important to note that the following quote appears under the test results table on page 75:

“Specific makes and models in which the majority of the units tested were noncompliant: Baofeng, UV5R, UV5R+…”

I found the following description of their test equipment and setup:

“Our convention tests measured … using a test fixture consisting of a Bird Model 43 RF Power Meter, a Bird Model 8322 30 dB power attenuator, a Hewlett-Packard HP355C 0 to 12 dB step attenuator, and a Rigol DSA-815TG spectrum analyzer. … First, the power output … was measured using the Bird Model 43 meter. … Next, with the radio push-to-talk (PTT) button pressed and held, the Rigol DSA-815TG spectrum analyzer was used to perform a sweep…”

So, I went to the FCC’s testing setup. They’re the ones who initially gave the UV-5R a pass, so let’s see what they used to do it. Starting on page 37 of the FCC’s published test results, you can read for yourself the detailed setup and testing of the transceiver, including the directly-connected spectrum analyzer test. Note that they specifically show that the signal from the radio passes through an attenuator (if I’m reading the report correctly, the attenuation is 13 dB).

On page 76, of the QST article, Figure 3 shows a borderline result of a tested UV-5R. The attenuation displayed on the display of this figure shows an attenuation of 10 dB, below either of the previous two test setups.

Let me say that I appreciate what the ARRL does, and I don’t believe for a minute that they are unfamiliar with their equipment, but testing at the informal environment of a convention could lead to simple mistakes in the test setup. I would have really liked to see a clear spelling out of what level of attenuation, if any, was between the equipment and the spectrum analyzer. It’s also important to note that the ARRL clearly mentions in their article that this testing was performed on used equipment, not newly-manufactured units specifically submitted for testing. In light of the two previous articles I mentioned above, and the lack of clearly-mentioned attenuation between the radio and spectrum analyzer, I have to say that, in my opinion, the ARRL’s testing is inconclusive.

Your comments are welcome below. Thank you for reading. 

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Counterfeit radio programming cables and Windows 10

If you have purchased a cheap programming cable for your radio from Amazon, eBay, or another dealer, you’ve probably run into an issue where the cable initially won’t work, and someone (perhaps the vendor) told you that you have to use an older driver to get it to work. What you have is a cable that uses a counterfeit chipset. The Prolific chips seem to be the most problematic, while FTDI chipsets work very well. This page on miklor.com offers some background information on this subject.

The Miklor Cables & Drivers page talks about this and offers the older Prolific drivers that work well with cables that feature those counterfeit Prolific chipsets. You will run into one of two problems while dealing with them, however.

Under Windows 8 and previous Windows versions, Windows will offer the newer, non-working driver through Windows update. It is sufficient to go in and block the update, as described here, but you may have to do that each time you plug the cable in to a different USB port.

Under Windows 10, it’s a whole different situation. Windows 10 will install all updates offered through Windows Update, and you have the option to defer upgrades, but not to block individual updates. Windows 10 will continue to install the updated driver, which will continue to cause your counterfeit chipset cable to stop functioning.

So, if you’re using the counterfeit chipset cable under Windows 10, do yourself a favor and get a genuine programming cable. You’ll save yourself a lot of headaches and frustration.

A good source for programming software and cables is RT Systems, as they offer both cables and software for radios they support. If you’re only interested in the cable, and you want to use it with the factory software or the open-source software Chirp, look for cables that mention using genuine FTDI chipsets. They aren’t hard to find, but they will cost a little more. For the Baofeng 2-pin models, this cable from Amazon works well. This cable should work for all Baofeng 2-pin cable compatible radios, such as the UV-5R (and variants), the BF-F8+ (and variants), UV-B5 and UB-B6, and UV-82 (and variants). This should also work for all 2-pin cable compatible radios from other manufacturers, as long as they use the same pin out.

You could also try replacing the chipset with a $3 adapter, as described here. A good eBay seller for that adapter is here. Many other people report success. but I tried it with a counterfeit cable for my Baofeng and couldn’t get it to work.

Questions and comments are welcome below.

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Sound not playing in AllStar Web Transceiver under Linux

A problem exists when trying to access AllStar’s Web Transceiver under Linux where no sound is played.

This is due to issues with Java under Linux.

A workaround is documented here.

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Sound not working in Java apps in Ubuntu Linux

I tested Ubuntu 14.04 LTS in VMware. I started with a clean install. I made sure sound was working in the VM, then updated everything using this command:

sudo apt-get update && sudo apt-get upgrade

I then checked Software Updater and found a few more packages that didn’t get updated, and updated them.

I then made a backup of the VM to have a good baseline. I then installed OpenJDK 7 and the icedtea-7-plugin, using the following command:

sudo apt-get install openjdk-7-jre icedtea-7-plugin

I did not have openjdk-6, icedtea 6, or Oracle Java installed. If you do have any of those installed, try removing them to prevent any conflicts.

You can test your Java sound output any trying any Java applet that produces sound, such as this SoundApplet demo. If you don’t hear sound from it, you have an issue. If you have more than 1 sound device, check the other sound device for the sound output. In my case I only had 1 device (through virtualization), but it worked fine.

I also tried AllStar and was able to hear audio from the node announcements just fine, albeit with occasional crackle, perhaps due to the limited resources of the VM. I tried transmitting but did not get a reply from the few nodes I tried.

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If you have something to add, please feel free to comment below.

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Weather Underground forecast data in text display

One of the uses I found for my Raspberry Pi was using it to display weather data. I retrieved the weather data from Weather Underground using their API, parsed it, and displayed it on my RPi’s small LCD. This gave me an always-on view of the weather, which was nifty, and it was done all in bash scripting with a few external programs to parse the data.

This script is very customizable and extensible. You could use it to do any number of weather-related tasks.

I reduced the font size on the LCD to Terminus 6×12 using the following command:

sudo dpkg-reconfigure console-setup

This helped make room for all the forecast data on the tiny LCD. If you are running this on a PC, it’s not necessary.

For the smoothest updates, I have found it ideal to run the script under ‘watch’, as so:

watch ./weather.sh

I tired doing a ‘while true; do… clear… done’ loop, but the refresh rate was too low and the updates were not smooth.

Here is the script:

UPDATE : This has moved to github, here.

Last updated: 11-21-2015

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Installing and configuring Samba on Raspberry Pi

If you want your Raspberry Pi to share its files and folders over the network, you want to install and configure Samba.

Start off by installing the basic Samba requirements:

sudo apt-get install samba samba-common-bin

Edit the samba config file

sudo nano /etc/samba/smb.conf

edit the workgroup= line to match your network. workgroup=WORKGROUP is the default and usually fine. It needs to match what your Windows PCs are set to.

[pi]
path=/home/pi
browseable=Yes
writeable=Yes
only guest=no
create mask=0777
directory mask=0777
public=no

Add the pi user to samba. Use the same password for the pi user:

sudo smbpasswd -a pi

It takes about 2 minutes for the changes to take effect, but after this you should have no problem exploring files over the network. Note that some may be owned by root and you may have an issue writing to them.

If you have trouble logging in under Windows (password errors), try using “raspberrypi\pi” (raspberrypi-backslash-pi) as your username (without the quotes)

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