Adding virtual desktops to Windows with VirtuaWin

Most Linux users are very familiar with virtual desktops (a.k.a. workspaces), which enables you to organize your opened applications in more than one desktop that you can switch over from one to another using hotkeys or mouse clicks.

Though virtual desktops feature is not bundled in MS Windows OS, its availability in the form of 3rd party software, either free or commercial, has been around for many years. Microsoft also provides a virtual desktops Powertoy called Virtual Desktop Manager (MSVDM), which many find it is slow, lack of functionality, and not performing as good as the 3rd party counterparts.

If you are looking for an open source virtual desktops for Windows, Virtual Dimension used to be a popular and good one, but its development seems to have ceased around 2005.

The virtual desktop I'm using now is VirtuaWin. It is free and licensed under GPL version 2, and latest release is Version 4.1 dated 09-09-2009.

VirtuaWin has been around since 1999. It can run in all version of modern Windows OS including Win 95, Win 98, Win ME, Win NT, Win 2000, Win XP, Win 2003, Win Vista and Win 7.

It is very lightweight, fast in desktop switching, modular with features expandable by loading more modules into it. It even has a portable version which doesn't need any prior installation to use.

VirtuaWin is very easy to install and run. By default, you will get 4 virtual desktops (2 x 2) which you can navigate by pressing Ctrl-Alt together with one of the arrow keys on your keyboard. If you don't like this hotkey setting, you can always change your preference in its setup.

You can increase or reduce the number of virtual desktops by configuring its Desktop Layout, up to a maximum of 20. The more virtual desktops you use, the more amount of memory will be consumed.

With VirtuaWin, now you can use, for example, one desktop for web browsing, one desktop for graphics editing, one desktop for document writing, one desktop for network monitoring, ... this is of course more organized than cluttering all of them in a single desktop in Windows.

If you are a developer, and find any feature lacking in VirtuaWin, you can in fact make the feature by yourself using the VirtuaWin module SDK. Being open source and modular, the feature list of VirtuaWin is believed to be able to expand unlimitedly with the support and contribution from the developers community.

In fact, some of the fancy features in other virtual desktops software has been made available to VirtuaWin via module contributions.

The threat and vulnerability of GPS

The critical reliance and important usage on GPS nowadays, both in civil and military, has recently brought up a hot discussion again for the concerns in its threat and vulnerability.

Anyhow, this issue is not new, and has been discussed among technology experts for many years. Just that when GPS usage become more and more widespread, its threat and vulnerability need to be brought to its users' awareness, especially in the military, government and business sectors.

The GPS operation relies on signals from some 30 over orbiting satellites surrounding the earth in the space. In order for a GPS receiver to triangulate its position on earth, it needs to get signals from at least 3 GPS satellites.

GPS signal is known to be exceptionally weak. Each satellite transmits a signal equivalent to the power of a 25W light bulb from an distance of about 20,000km away. Such a weak signal can be readily interfered with or denied by unintentional or deliberate radio wave interference.

Portable GPS jammer devices such as the one shown in the diagram below have been made available for quite some times.

Some car security system and transportation logistic system make use of GPS to keep track on the position of the vehicle. It has been reported that car thieves make use of GPS jammer to disrupt the GPS signal and defeat the vehicle tracking system, therefore render the vehicle unlocatable.

Employees who drive vehicles that are tracked by their companies can also make use of the GPS jammer to hide their tracks.


In Germany, it is believed that some drivers are using GPS jammer to evade GPS-based road charging system.

Robbers can also easily spoof the GPS signal and guide the target vehicle to drive to their trap location.

Imagine what would happen if terrorists make attack on the GPS function of air traffic and/or naval traffic.

Beside its global positioning function, GPS is also used as a time server for time synchronization in certain infrastructure. This function can also be defeated by the jammer, and time critical system could be hacked in this way.

The GPS signal used by the US military is different from the civil signal, and is encrypted. However, it is also vulnerable to GPS jammer and subjected to interferrance from the enemy.

Imagine a GPS dependent missle being mislead by the enemy to attack on wrong target, or worse still, to attack to ally target instead of the enemy.

By intercepting the GPS signal, the position of military GPS user could be exposed to the enemy.

In the video below, you can see the GPS jammer in action and how it defeated the civil and military GPS.



So, what can we do to minimize the threat to GPS? Beside waiting for the US to strengten on the signaling, when we want to make use of GPS, also use some other alternative methods so that GPS could not be a single point of failure.

What are CPM, CPC, CPA, CPE, etc in online advertising

You might have noticed that my blog currently serves ads from Google Adsense and Innity Performance Network.

If you are familiar with online advertising, you should know about CPM, CPC, CPA, CPE, etc. If you are new to it, you might wonder what are these jargons about.

Well, they actually refer to the model in which you will be paid for ads running on your website or blog.

• CPM - Cost Per Mille or Cost Per Thousand Impressions. This is the easiest model to generate earnings, as every time the ads appear to a visitor to your site, you will get an amount of money. The rate is at 1,000 ad served. If your site produces less than 1,000 impressions for the ad, you will get a proportion of it. Google Adsense reports the estimated CPM rate you receive based on your earnings with Effective CPM (eCPM).
• CPC - Cost Per Click. You'll generate earnings when your visitors click on the ads displayed on your site.
• CPA - Cost Per Acquisition. You will be paid for leads generated on your site (e.g. product trial sign up, submission of survey, etc.)
• CPE - Cost Per Engagement. You will be paid for engagements generated by visitors from your site. Engagement is defined when a user response to the ad through the act of experiencing the features of the ad format. These features include advergames, videos or even social sharing.

Currently, you can get CPM and CPC ads from Google Adsense, while Innity Performance Network supports more models including CPM, CPC, CPA and CPE.

The rule of thumb: No matter what the revenue model is, visitor traffic is the key for you to get some earnings from online advertising.