Category Archives: Technology

Posts that relate to technology. Reviews, HOWTO’s, problems & solutions.

Fixing IPW2200 system hang with WEP 802.11

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After installing an IPW2200 mini-pci 802.11g wireless card, my wife complained that her system would freeze for a minute while attempting to connect to an 802.11 (WEP) network for the first time. After the initial time-out and failure, wireless network connections would work fine until the computer was rebooted. 

As it turns out, I was experiencing the same problems with my laptop, but I hadn't noticed it because I use suspend/resume a lot more than my wife, and I would go a week or so before doing a full reboot. (One failure to connect to a wireless network per week is a lot less noticeable than one every morning.)

After doing a lot of rebooting and troubleshooting, I isolated a few lines in my /var/log/syslog that appeared to be associated with the freezeup:

eth2: could not initialize WEP: load module ieee80211_crypt_wep
ieee80211_crypt_wep: could not allocate crypto API arc4

Even though my system (Ubuntu 7.04) had the arc4 crypto module, it didn't appear to be loading correctly. I added "arc4" to my /etc/modules file to force it to be loaded, and that appears to have fixed the problem.

3Com Bluetooth PCMCIA card (3CRWB6096) with Ubuntu

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3Com Bluetooth PCMCIA cardTo get a Motorola Bluetooth wireless PC card (PCMCIA)  (version 2) working with Ubuntu linux, all I had to do was download the windows driver from Motorola and extract (using unzip) the Drivers.W2k/BT3CPCC.bin file to /lib/firmware/BT3CPCC.bin.

This card works correctly, but I am able to get faster transfer times using a USB bluetooth adapter (from ellink). For example, transfering a 1.1MB file from my phone via the USB Ellink adaptor takes 27 seconds, while the same transfer takes 47 seconds using the 3com PCMCIA adapter. It is possible that this adapter is a Bluetooth 1.0 or 1.1 device as opposed to a 2.0 device.

Freeing my V3xx phone from Cingular

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After getting ATT/Cingular to take the subsidy lock off my phone, I decided to flash it with the generic International Motorola firmware. The advantages:

  • The Motorola firmware is not “branded” and gets rid of all of the “Shop Cingular” links, menu items, etc.
  • The quadband firmware claims to support all 4 GSM bands (instead of the 3 that the Cingular firmware supports).

The downsides:

  • The Motorola firmware is not “branded”, and I had to re-configure any Cingular specific settings that I like, such as the MediaNet connectivity settings and Cingular Video bookmarks.
  • The Cingular version of the phone has a slightly different button layout than the Motorola generic version (the Clear key is swapped with the Cingular Video key) and I had to remap those keys back to match the custom key layout.
  • Because I flashed the phone, all of my previous SEEM edits and java fixes were lost, so I had to repeat them.

As daunting as the downside list is, I have to say that getting rid of all of the Cingular branding was like a breath of fresh air. You really don’t notice how bad the branding was until it’s gone. Then you just notice all of the extra room in the menus, bookmark lists, etc.

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3G is better than EDGE for me!

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Some idiot makes the claim that EDGE is just fine and you don't need 3G for web-browsing. The author claims that pure bandwidth doesn't matter, and that latency is more important to the user experience (which I totally agree with) but then goes on to state that 3G has worse latency than EDGE, which is completely bogus.

I can't imagine the author had ever used a (working) 3G network, because in my experiance (using a Motorola Razr V3xx on AT&T/Cingular), the 3G network has ping times of 200ms, while the EDGE network has 800ms ping times. This means that when you click on a link using EDGE it takes about a second for the page to start loading, but if you are using 3G the web pages respond much faster! 

Using my phone's WAP/HTML browser is MUCH more responsive on the 3G network than on the EDGE network. (I switch to edge in some subway stations). The same thing applies to Google Maps (J2ME on the phone) which is much more usable on 3G, so this applies for apps that do intelligent caching as well as web browsing.

Bottom line, if you can get 3G instead of EDGE, do so!

Unlocking my Cingular / AT&T phone

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AT&T Death Star

AT&T allows some customers to "unlock" their phones. This allows the use of a SIM card from a different provider (for example, VodaFone) while traveling. (It also allows you to use the phone with another GSM provider in the US after your AT&T contract is finished, which is one reason AT&T and other carriers lock the phones they subsidize.) 

I don't know exactly what makes a customer "eligible" to have a phone unlocked, but I suspect that you have to have made several payments on time and be in good standing. When I am under a new contract with a subsidized phone I typically wait a few months (in this case, about 6) before calling in to ask to have my phone unlocked. I've had T-Mobile unlock three phones (under 2 different contracts) for me in the past, but this was the first time I tried it with AT&T.  

I suspect that AT&T has an official policy of making it difficult to unlock your phone. Here is my experience:

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D-link DWL-G122 with WPA under Linux

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The D-Link DWL-G122 USB 802.11g (revision B1) wifi adaptor works great for open or WEP encrypted networks and is supported by Ubuntu out of the box. Unfortunately, the open source driver doesn't support WPA2 (and only supports WPA via non-standard iwpriv settings, and even then, the support is flaky).

I was able to get it to connect to a WPA network once, following Jermey's instructions. But the network connection was not reliable (as in, I never got it to connect again).

To make it work with the standard wpa_supplicant package, I had to break down and use ndiswrapper to wrap the windows XP drivers. (I also had to blacklist the default rt2570 kernel module). Hopefully the Open Source rt2x00 kernel module will start to support this device (and others based on this chipset) in the future for WPA/WPA2 security.

Even after I used the ndiswrapper, it would only connect to a WPA Personal / TKIP access point. (I could not get it to work with the AES or AES+TKIP settings on WPA or to work with WPA2 at all.)

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Screen Scraping Amazon Album Art for MythTV

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mythtv icon

I wanted to get Album Art for all of my (newly ripped) songs on my MythTV box. 

Thierry has a nice perl script which finds album art on Amazon and automatically downloads it, but unfortunately for me the music plugin for MythTV has upgraded their database schema and the script no longer worked.  I am using the trunk SVN code, so it's a bit more up-to-date than the latest packaged release, but this means that scripts designed for the packaged versions may not work. (This specific script had a problem finding the correct directory to store the album art, so all the album art was stored in the root directory, overwriting itself with each album.)

Luckily, I know just enough SQL and Perl to be dangerous, so I whipped up a few changes to his code that fixed my problem (after exploring the new database format). The updated script is here if anybody needs it.

UPDATE: I also added features that allow you to run the script multiple times (if an albumart.jpg file already exists, it will skip that album) and improved the searching (if "album by artist" is not found, it will try searching by "album" name only).

Updated New File: amazon_album_art_scraper.txt (Thanks to Mike Wilson for updates to Amazon’s HTML!)

OLD FILE: Amazon Album Art Scraper Script

Saving a mms streaming video to a file using mencoder

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Copying a streaming video to a file using mencoder.

I wanted to watch Randy Pausch's last lecture on my home media PC as opposed to my laptop. It has MythTV, which can be used to watch any file on the hard disk. Unfortunately, you can't just download the a file, as his lecture is hosted by a streaming server. The specific URL is:

mms://wms.andrew.cmu.edu/001/pausch.wmv  

wget won't work, so I had to use mencoder to download the stream and copy it to a file on my hard disk. The command line I used was:

 mencoder mms://wms.andrew.cmu.edu/001/pausch.wmv -o randy.wmv -oac copy -ovc copy

(The -oac and -ovc are the output audio and video codec specfiers, and I have set it to just copy. If you would prefer the file be transcoded to a different format, you could specify a specific codec (xvid with ogg vorbis sound, for example) and mencoder would transcode the file (possibly losing some quality) at the same time. 

 

Encrypted home directory under Ubuntu linux 7.04 & 7.10

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Lock on doorUsing directions from Felipe Alfaro Solana, I set up an encrypted home directory in Ubuntu 7.04. I only had one problem, that exhibited an error message as follows:

Command failed: Incompatible libdevmapper 1.02.08 (2006-07-17)(compat) and kernel driver

This was caused by the dm_mod module not being loaded. I fixed it for the session by issuing a  modprobe dm_mod command, and fixed it forever by adding dm_mod to my /etc/modules file.

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