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Archive for the ‘PC Software’ Category

Identify Busy Wi-Fi Channels in Windows 7

June 15, 2010 1 comment

When several wireless networks and other wireless devices operate at the same frequency, there can be a significant amount of noise and crosstalk that result in lost packets and network disconnections. To identify channels with larger numbers of networks and higher signal strengths, there are several programs available to display this information in a graphical interface such as:

  1. Vistumbler
  2. WirelessNetView
  3. inSSIDer

It is also noteworthy that the wireless channel bandwidths overlap, since channels are 5 MHz apart and the bandwidth of each channel is 22 MHz. To avoid overlap, channels 1, 6, and 11 are used most often.

802.11 b/g Wi-Fi Channel Bandwidth Overlap

Often times it is desirable to perform this task quickly without installing new software. The wireless channel and signal strength of nearby wireless networks can be displayed in Windows 7 or Vista by entering the following command in the command line:

netsh wlan show networks mode=bssid

This results in the following command line output:

Interface Name : Wireless WUSB600N
There are 5 networks currently visible.

SSID 1 : 2mix
Network type            : Infrastructure
Authentication          : WPA-Personal
Encryption              : CCMP
BSSID 1                 : 00:22:6b:73:aa:5a
Signal             : 100%
Radio Type         : 802.11g
Channel            : 1
Basic Rates (Mbps) : 1 2 5.5 11
Other Rates (Mbps) : 6 9 12 18 24 36 48 54

SSID 2 : BELL078
  Network type            : Infrastructure
  Authentication          : Open
  Encryption              : WEP
  BSSID 1                 : 00:26:50:34:1e:51
       Signal             : 36%
       Radio Type         : 802.11g
       Channel            : 1
       Basic Rates (Mbps) : 1 2 5.5 11
       Other Rates (Mbps) : 6 9 12 18 24 36 48 54

SSID 3 : linksys
    Network type            : Infrastructure
    Authentication          : Open
    Encryption              : None
    BSSID 1                 : 00:18:f8:ef:93:af
Signal             : 32%
Radio Type         : 802.11g
Channel            : 6
Basic Rates (Mbps) : 1 2 5.5 11
Other Rates (Mbps) : 6 9 12 18 24 36 48 54

SSID 4 : Killa
    Network type            : Infrastructure
    Authentication          : WPA2-Personal
    Encryption              : CCMP
    BSSID 1                 : 00:1c:df:39:81:f6
Signal             : 16%
Radio Type         : 802.11g
Channel            : 11
Basic Rates (Mbps) : 1 2 5.5 11
Other Rates (Mbps) : 6 9 12 18 24 36 48 54

SSID 5 : 5mix
    Network type            : Infrastructure
    Authentication          : WPA2-Personal
    Encryption              : CCMP
    BSSID 1                 : 00:22:6b:73:aa:5b
Signal             : 100%
Radio Type         : 802.11a
Channel            : 149
Basic Rates (Mbps) : 6 12 24
Other Rates (Mbps) : 9 18 36 48 54

Open Source Router Firmware

If you are able to use open source firmware on your router, it is also helpful to use the Tomato firmware to perform a wireles survey. The device web page gives a detailed report like the one below:

Tomato Wireless Survey

Tomato Wireless Survey

References

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Categories: Electronics, PC Software

StarCraft colors in Windows 7 and Vista

April 11, 2010 1 comment

Thanks to Warlord_7 on the Battle.net forums, I’ve managed to fix the issue with the StarCraft and Brood War menus being discolored in Windows 7 and Windows Vista. The best way to fix the bug is to make the following change in the Windows registry:

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectDraw\Compatibility\Starcraft116]

is changed to

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\DirectDraw\Compatibility\Starcraft116]

StarCraft Brood War title screen displaying colors correctly

StarCraft Brood War title screen displaying colors incorrectly

Warlord_7 uploaded the registry files to RapidShare here for free download. There is a 32-bit and a 64-bit version:
http://rs741.rapidshare.com/files/351487789/www.starcraft2.pro.rar (Original link expired)
http://www.4shared.com/file/_xPuNmx-/SC-Win7-Fix.html

file name: sc116-x64.reg
--------------------------------
Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\DirectDraw\Compatibility\Starcraft116]
"Flags"=hex:00,08,00,00
"Name"="Starcraft.exe"
"ID"=hex:ca,89,65,49

file name: sc116-x86.reg
--------------------------------
Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DirectDraw\Compatibility\Starcraft116]
"Flags"=hex:00,08,00,00
"Name"="Starcraft.exe"
"ID"=hex:ca,89,65,49
Categories: PC Software

Associating MATLAB with *.mat files

April 7, 2010 1 comment

MATLAB uses the *.mat extension to save exported workspace data, and this is the most common use of the file format[1]. However, Microsoft Access uses the *.mat extension for shortcuts to Micorosoft Access tables, and changes settings in addition to the normal Windows file extension properties:

  1. File association cannot be changed under the Tools > Folder options menu
  2. File extension is hidden even when “Show extensions for known file types” is checked.

The easiest way I’ve found to fix this file extension association is to use the following MATLAB command in the command window:

commandwindow; cwd=pwd; cd([matlabroot ‘\toolbox\matlab\winfun\private’]); fileassoc(‘add’,’.mat’) ;cd(cwd); disp(‘Changed Windows file association. MAT-files are now associated with MATLAB.’)

This link from the Mathworks website has more information:
http://www.mathworks.com/access/helpdesk/help/techdoc/matlab_env/f8-8880.html#bq4h655-1

Categories: PC Software

Disabling HP On Screen Volume Display

December 10, 2009 2 comments
New HP laptops, such as the dv6, are shipped with HP software that displays the volume on screen when it is changed with the TouchSmart buttons above the keyboard. The on-screen volume display (OSD) and the way it is displayed on the desktop is shown below:

While this sort of feature could be useful if it were handled separately from other Windows programs, this display can cause problems with causing programs to minimize or even crash when the volume is changed. To disable the on screen display, perform the following change in the Windows startup tasks:

1. Run msconfig: click the start menu and type ‘msconfig’ in the search box or press WIN+R and type msconfig, then press enter.
2. Select the Startup tab. You should see something like this:
Sort the Startup Item column by name and look for one of the following items. The name may vary by software version:
  • HP MediaSmart SmartMenu
  • HP Quicktouch On Screen Display
Disable the startup feature by unchecking the box next to the name of the volume on screen display program.
3. Click OK and restart. That’s it!
Categories: PC Software

Frequency power spectrum of Sine, Square, Sawtooth, and Triangle Waveforms

June 22, 2009 1 comment

Today I came across an interesting MATLAB code example today from the University of Maryland: http://terpconnect.umd.edu/~toh/spectrum/HarmonicAnalysis.html. Prof. Tom O’Haver did a wonderful job with this example, but I had some problems with MATLAB crashing while running it. The program may be more resource-intensive than it appears.

My screenshots can be seen in a Picasa web album for higher resolution here: http://picasaweb.google.com/kruckenberg.1/FFTOfWaveformPower

Sine wave:
The frequency analysis of a basic sine wave shows that it consists of only a single frequency at 250 Hz.

Square wave:

A square wave with the same frequency has its highest peak at the fundamental frequency and the power is reduced by 1/4 at each odd harmonic of the fundamental frequency.

Sawtooth Wave:

A sawtooth wave includes both odd and even harmonics, and the power reduces by half at each harmonic.

Triangle Wave:

A triangle wave has a similar set of harmonic frequencies to a square wave (odd harmonics), but each one is distributed over a wider range rather than focused at a specific frequency. At each odd harmonic, the power is reduced significantly.

A triangle wave was not included in the original post, but I added one for my own purposes. In MATLAB, a triangle wave is created using the sawtooth function as shown:

y=sawtooth((f1+f2/100)*x,.5);

Categories: Math problems, PC Software

Current Project: Using Excel for macro scripting in a spreadsheet

Current Project: Using Excel for macro scripting in a spreadsheet

Real-time USB in Matlab (2 of 2)

December 24, 2008 1 comment

Posting history:

Real-time USB in Matlab (1 of 2)

Real-time USB in Matlab (2 of 2)
Last month I had started a project using a TI MSP430 to communicate over USB with MATLAB and Simulink, and today I finished the real-time display of room temperature in Simulink.

Here is the end result. It’s a simple display and scope at the top level, but I used a roundabout method to choose data from the stream of USB data.

The completed files for displaying temperature from the USB MSP430RF2500 can be downloaded here: