Laptop Battery Refill update

Posted on July 31, 2008 by Jay

I refilled the Li-ion cells in my laptop battery about 18 months ago.The battery has worked as expected since then. The only "special" treatment this battery gets is that it travels in my laptop (as opposed to being the extra battery in my backpack) when traveling through TSA security checkpoints. (I figure it's better the have the battery with the fully applied IBM label sticker visible in the backpack, and the battery where I pulled off the label sticker to dissasemble it safely integrated with the laptop.)

Laptop Battery

Over the last 18 months, the battery capacity has reduced itself to 44% of the original value (This happens with LiIon cells as they age). My last full capacity ACPI reading is now 21060 mWh, and provides 1-2 hours of working time on my IBM X31 Thinkpad. In a few more months it will be time to replace the Li-Ion cells again. Luckly, a friend gave me an IBM T60 extended battery (containing 8 cells) that had failed. When I took it appart, it appeared that 6 of the cells worked fine, and two of the cells were dead (killing the entire battery). TaDa! 6 free replacement cells!

Who watches the watchmen?

Posted on July 7, 2008 by Jay

A system downtime announcement I received today (slightly anatomized to protect the guilty):

Summary:

On Tuesday, July 1, 2008, at approximately 6:30 PM, the XXXX XXXXXXX server instance, which monitors the availability of XXXX servers and network devices, went offline. This outage was not noticed until Monday, July 7, 2008. After discovering the outage, the server was brought back online and was again monitoring services at 6:00 PM on July 7.

If you have any questions, please contact the XXXX Help Desk (XXXXXXXXXXXX). Thank you.

Motofone F3 (North American version)

Posted on June 26, 2008 by Jay

I purchased a north American version of the Motofone F3 (Manufactured in Brazil), which operates on the 850/1900 Mhz GSM bands (used almost exclusively in North America) for $34 including S/H from dakmart.com. After plugging my SIM card in the phone it reported that it was on the AT-T network. My original Motofone F3 from India worked only on the 900/1800 bands, and wouldn't work on the AT&T network (or any other North American network).

Continue reading →

Compressive Sampling: Beating the Nyquist Limit for certain signals

Posted on June 12, 2008 by Jay

Compressive Sampling is a new field of sensing theory that sidesteps the traditional Nyquist sampling limit. The Nyquist limit is an information theory result that says to perfectly capture a signal which is bandwidth limited at a certain frequency, X, you must take 2 times X samples per second. So for example, if you want to perfectly detect a 20Hz sine wave, you must take 40 samples a second. To perfectly represent audio that humans can hear (typically understood to be sounds in the 20-20,000Hz range) we must use 40,000 samples per second (40kHz). CD audio uses 44.1kHz, and professional audio systems typically sample at 48kHz a second. [Note that the number of samples per second has nothing to do with the quantization, or accuracy of the samples, so audio that is sampled at 20 bits per sample has more information (and less noise) than audio sampled at 16 bits per sample.] Continue reading →

Encrypted home directory with Ubuntu 8.04

Posted on May 18, 2008 by Jay

My encrypted home directory worked well with 8.04, I only had to make one change caused by the new xml format of the pam_mount.conf.xml file as follows:

After I installed 8.04 from scratch I had to mount the directory and chown the files to the new user.

MythTV / MythDVD movie ripping / playback problem (Solved!)

Posted on April 28, 2008 by Jay

I have used Myth to rip a large number of my DVD's to AVI files (using either the Excellent or Good setting). Now that I am starting to play back the movies, I have found something that is very troubling.

On many of the movies, the first 95% of the movie (e.g. 1:13 min of a 1:26 movie) plays flawlessly. However, near the end of the movie, the audio and video starts to speed up and get jerky. (Audio/video sync is also thrown off.) Continue reading →

Connecting to non-broadcasting SSID networks with IPW2200

Posted on April 20, 2008 by Jay

I have been having problems connecting to a wireless network that does not broadcast its SSID. (A so-called "hidden" network.) I am using an Intel IPW 2200 802.11b/g mini-pci wireless card that uses the ipw2200 wireless module.

I found that reloading the ipw2200 module before attempting to connect to the network fixed my problems (but only if I put a pause between the unload/load/connect sequence). I use wifi-radar to manage my wireless connections, and was able to call my unload/reload script using its "before" connection command.

The script is simply:

sudo rmmod ipw2200

sleep 1

sudo modprobe ipw2200

sleep 1

This does add two seconds to the connection time, but this is not a terrible penalty to pay as without the above pause the connection would usually only work about 25% of the time.

DPMS monitor control via remote control on Myth TV

Posted on April 13, 2008 by Jay

I am using an LCD monitor as the display for my MythTV box, connected via an analog RGB (a.k.a. VGA) cable. This allows me to use DPMS (Display Power Management Signaling) to turn the monitor on and off from the MythTV box.

Instructions for setting this up with MythTV are here , but I found that I had to make a few changes to get things to work correctly. I modified one line of the shell script as follows:

STATUS=$( xset -q | grep "Monitor is" | awk '{print $3}' )

To trigger the monitorpowerbutton.sh script, I placed the following into my /etc/lirc/lircrc file:

begin
 prog =  irexec
 button = TV_POWER
 repeat = 4
 config = /usr/local/bin/monitorpowerbutton.sh
end

Now my TV_POWER button toggles the power state of the monitor!

Fixing a missing bluetooth icon, battery charge indicator, and update notifier in Ubuntu

Posted on March 25, 2008 by Jay

For the last week my battery indicator and bluetooth icons had been missing from my top panel in Ubuntu. When I did Bluetooth stuff the pop-up "speaker balloons" from the bluetooth applet would still appear at the corner of my screen, but the Bluetooth applet itself was "invisible". I finally figured out that what I was missing was a "Notification Area" for these applets to "live". Right-Clicking on the Panel, Selecting "Add to Panel" and then adding the "Notifcation Area" (from the Utilities category) fixed my problems. Indeed, I then found out that the Software Update notification icon had been trying to tell me about software updates, but I hadn't seen it, so I had to install several software updates!

Ipod Touch (8GB) Review

Posted on March 23, 2008 by Jay

An Apple iPod Touch review, with special attention paid to use with Linux and open formats:

Pros:

Very nice high resolution screen. (480×320 at 163dpi)
User interface is very slick and easy to use after a minimal learning period.
Built in WiFi (802.11b/g) with very good mobile browser (Safari).
Methods to hack (jailbreak) it and install 3rd party software are widely available, and many 3rd party applications are already developed for it.
Base model has a generous 8GB of storage, 16GB and 32GB models are available.
Design: Aesthetically, it's solid. Hardware, software, feel and aesthetics, everything is great!
Battery life is good (5 hours of video, 22 hours of music, use of WiFi reduces this significantly).

Cons:

It's expensive. Almost $300 for the base model. (I won mine in a raffle, otherwise I wouldn't be reviewing it!)
Funky machine readable file-system format for storing music: Why is F03/KLJE.m4a my Spin Doctors – Cleopatra's Cat? What's wrong with a human readable filename, Artist/album/song storage paths, etc…)
Doesn't support music encoded with Ogg Vorbis.
Doesn't mount as a standard USB file-system. (You need iTunes, or a iTunes clone to move music/photos to it, and can't use it as a USB drive.)
Uses a non-standard (not a mini-USB) connector. (Yet another cable to carry around.)
Integrated battery prevents easy customer replacements.
Lacks many features of the full iPhone (Bluetooth, camera, cellular data/radio, speaker, microphone).
Chrome on the back scuffs MUCH to easily. I've carried mine in dedicated hip pockets and after only a week I still have visible scuffs and scrapes on the "chrome" back. Hopefully the glass on the front will resist scratches better than the "chrome" on the back. I still have the plastic protective cover that it shipped with over the glass screen, and am considering buying a static stick screen protector after my experiences with scuffs on the back.