US GSM Bands (T-Mobile, AT&T)

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AT&T and T-Mobile are the two main providers (in the USA) who provide GSM service. Below are the main cellular bands they use.

AT&T:
GSM: 850 and 1900
3G: 850 and 1900

T-Mobile:
GSM 1900
3G: 1700 (AWS) and 2100MHz

GSM bands not supported in the USA, but active in other countries: 900 and 1800.

Internationally, you may need the 900 and 1800 bands, especially in Europe and Asia (many south American countries work on the 1900 GSM band). If you have a “quad-band” phone it will work everywhere.

Sometimes these bands are called by acronyms instead of frequencies:
UMTS: 2100
PCS: 1900
DCS: 1800
AWS: 1700 (or simply AWS)

The advanced wireless system is a new block of bandwidth that has been opened up for use in the USA. AWS Overlaps with UMTS and DCS (1700/1800 and 2100) The convention appears to be labeling AWS with the number 1700, because 1800 and 2100 are already used to indicate other things.

Different channels on different tuners (MythTV)

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My SiliconDust HD HomeRun has a relatively good HD tuner, but it’s not quite as good as the built in tuner on my TV at picking up stations that are extremely strong and have multi-path reception problems. Although the signal My MythTV box reception of Fox TV would intermittently cut out as the SNR would drop too low to enable reception (even though, or, because the power level was pegged at 100%).

I purchased a Skywalker 16db attenuator, and it successfully lowered the signal strength of the (overpowered) Fox channel so that my HD HomeRun’s tuner chip could receive it with an acceptable SNR and no dropouts.

The only problem with attenuating my signal was that one of the two PBS channels (8, GPB-HD) was too weak to be picked up through the attenuator.
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Ubuntu 9.04 (Jaunty Jackalope) Annoyances

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I upgraded to Ubuntu 9.04 from 8.10 over the weekend.
The good:
Faster boot up. (worth the upgrade all by itself)
New notification “bubbles” that appear and then disappear again without any fuss.
OpenOffice 3.0 and other software upgrades.

The Bad:
Required tweaks to my pam_mount.conf.xml file to get my encrypted home directory to work. (Not an issue for most users.)

Bluetooth communication ports (serial over bluetooth) started giving errors because standard users no longer had permissions to use them. Adding the following code to an /etc/udev/rules.d/rfcomm.rules file allowed all users in the “dialout” group to access the /dev/rfcommXXX serial over bluetooth ports. (Ubuntu developers know about this problem and it will be fixed eventually.)

KERNEL=="rfcomm*", GROUP="dialout"

Java support for MIDI music failed until I installed timidity again with the following command:
sudo apt-get install timidity pmidi

The Annoying:
The hardware buttons on my thinkpad (brightness, volume, etc) still work, but no longer have an on screen display. I could fix this by installing the tpb (thinkPadButtons) package, but it takes up extra CPU cycles and power. I found that the packagers are actively discussing this issue and have decided to wait until they fix the issue within the default packages.

When running Pidgin (IM client), an “envelope” icon appears inside a “indicator-applet 0.1” to show that it’s running. Of course, Pidgin itself pops up another icon to show that it’s running on my gnome panel at the same time. I’ve thought about removing the indicator-applet from my panel to remove the duplicate items, but worried about what else I may miss if it’s not there to “hold all of the system indicators”. I eventually decided to go into the Pidgin preferences and select “Show System Tray Icon” only “on unread messages” which mostly fixed this annoyance, although now I need two button clicks to bring the IM window to the top instead of just one.

The ATI M6 graphics processor on my IBM X31 laptop was not automatically configured to use hardware acceleration. To use ppracer and other applications that require hardware acelleration to work well (such as the new version of lyx!) I had to edit my xorg.conf file following directions I found here.

Ubuntu 8.10 bootup time compared with 9.04 and Windows Vista

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One of the claimed features that made me upgrade to Ubuntu 9.04 was the boot-up speed increases. Before the upgrade using Ubuntu 8.10 it took my computer 55 seconds to boot up to the login screen. Including a very fast (2 second) login, it took 1:25 until the desktop was “usable”. Starting Thunderbird and Firefox immediately took until 1:55 to bring up both windows.

After I installed Ubuntu 9.04 I timed the login. I was impressed with the speed increases. It took
35 seconds to get to the login screen. Including a very fast (2 second) login, it took 1:05 until the desktop was “usable”. Starting up both Thunderbird and Firefox were ready to use by one minute and thirty seconds after bootup.

The bootup time of Ubuntu 9.04 is identical to that of Windows Vista (the shutdown time is approximately 5 seconds faster)

DM-Crypt encrypted volume upgrade problems to Ubuntu 9.04

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I just used the distribution upgrade option to move from Ubuntu 8.10 to 9.04. My dm-crypt encrypted home directory initially refused to load, and I had to change my volume entry in the /etc/security/pam_mount.conf.xml to make it work again.

Specifically, a few of the defaults had changed, so now I had to specify the old (8.04) defaults (ripemd160 hash).


< volume user="summetj" fstype="crypt" path="/dev/sda6" mountpoint="/home/summetj" options="cipher=aes,hash=ripemd160,fsk_cipher=aes-256-ecb,fsk_hash=md5" keyfile="/home/summetj.key" / >

Printer Ink, $9507 a gallon

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Just replaced an HP 74 black ink cartridge and purchased another backup cartridge for $13.11 (well below the standard price). Difference in weight between the full (28g) and empty cartridge (23g) is 5 grams. Assuming ink has the same density as water, that is $9507 a gallon. Assuming the 200 page per cartridge yield from HP is accurate, that’s also 15.26 cents a page.

Daylight Savings Time MythTV wakeup failure

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When I set up my MythTV box to suspend itself (and wake up whenever a show needed to be recorded) I followed the directions on the MythWiki ACPI Wakeup page, which suggested that I disable writes to the hardware clock as follows:

“Disable hwclock updates

On most machines it’s required to make a small change to the Linux shutdown procedure. When your machine goes down, most linux distributions write the system time/data back to the bios. On MANY machines, the machine never wakes-up after a time/data update. It’s recommended to make this change before you start. See below for more details (distro specific),

The reason for the recommendation above is that most linux distributions write the current system time back to the bios when shutting down the machine, and with some BIOSes, the machine will not wake up if the hardware clock is modified after the alarm timer has been set. To avoid that, it is necessary to disable the writing of the current system time to the hardware clock in the system shutdown scripts.”

This had no negative effects until daylight savings time kicked in. My MythTV box syncs itself over the internet, so it updated itself to daylight savings time with no problems. However, the system BIOS clock (hwclock) was not updated because I had disabled hardware clock updates! After a week of recording the very ends of shows instead of the full shows, I figured out what was happening and issued a “hwclock –systohc” command to re-set the BIOS (hardware) clock from the (correct) system time.

However, this will only work until daylight savings time ends, so I am investigating if I really need to disable the write to my hardware clock after the system sets the wakeup time. It may be that my BIOS handles that correctly, in which case I can take out the “HWCLOCKACCESS=no” line I added to my “/etc/default/rcS” file.

Getting 20,000 skymiles

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The Delta Airlines Skymiles American Express card will offer 20 to 25 thousand bonus Skymiles (Frequent Flier Points) when you first sign up. However, once you have signed up for a card, collected the miles, and then canceled the card, they no longer give you bonus miles for signing up again.

However, Northwest (NWA) and Delta are now in the process of merging. If you have a worldperks account, you can transfer it’s miles (points) at a 1 to 1 ratio into your delta account (after linking the two accounts). NWA also offers a WorldPerks Visa that gives you a 20,000 mile bonus for signing up. So, if you apply for the WorldPerks Visa, and purchase something with it, you get 20,000 miles in your NWA account, which you can then transfer into your Delta Skymiles account. (If you decline to give them an email address, you get a flier with a URL in your first bill that offers another 500 bonus miles if you register an email address.)