Thursday, March 31, 2011

Bi-centennial of Robert Bunsen's Birth


Reminded by Google's search page, Today is the 200th birthday of Robert Bunsen.  Known to high school students for his invention of the eponymous gas burner,  Bunsen did a lot more.  His burner invention was a means to an end.  To study the emission spectra of heated elements, one needs a source of clean and transparent heat -  either a hot, clean flame (no soot , just hot gas),  a source of hot inert gas heated by other means, or a source of directed light (e.g. UV) that energizes the sample without damaging it.  The simplest method is to use a flame containing only hot water and CO2. 
Google's doodle for today looks like this

Monday, March 28, 2011

Blogger App for Android

Here we go-mobile blogging. Story

NY police: Suspect dies after swallowing drugs
NYC Wire Published: Yesterday UNIONDALE, N.Y. (AP) -
A Long Island man who was being apprehended by police died after authorities say he swallowed what appeared to be crack or cocaine and went into cardiac arrest. Newsday reports that police say they witnessed 43-year-old Benjamin Jackson involved in a possible drug deal early Sunday and approached him on Planders Avenue in Uniondale. The newspaper says officers heard a crunching noise and saw Jackson spit out the suspected drug. The officers placed Jackson in handcuffs and called an ambulance. Police say Jackson went into cardiac arrest before the ambulance arrived. The officers performed CPR and regained a pulse, but Jackson was later pronounced dead at Nassau University Medical Center. Newsday says Jackson's family and friends declined to comment Sunday. The medical examiner's report is pending. ___ Information from: Newsday, http://www.newsday.com

Wednesday, March 23, 2011

My New 4G Mobile Broadband Data Service

LG's VL600 USB 4G Modem
Click to enlarge
Last week,  I ordered new mobile broadband internet service from Verizon Wireless.   I installed their access manager software which also installs device drivers for the USB modem (made by LG).  The modem kit includes a short cable and a clip which allows the device to be moved around a bit for best reception.  Typically, one would clip it to the upper edge of a laptop screen.  

The service is Verizon Wireless' "4G" service based on "LTE" .  Although marketed as 4G,  LTE does not meet the ITU requirements for  true 4G (IMT-Advanced) which includes low and high mobility access (pedestrian and static vs. car and train).  Verizon's LTE uses the 700 MHz band which was previously allocated to analog terrestrial television broadcasting. The switch to digital TV broadcasting has opened up valuable spectrum for mobile services with better urban transmission characteristics.

Verizon is claiming up to 12 Mb/s downlink and and up to 5 Mb/s up link.   This service is only available in 39 urban areas today but will expand to several hundred over the next few years.

Mobile broadband is not cheap -  most providers offer plans with data limits- such as 5GB/month. and charge for usage above that at about $10 per GB.  Verizon encourages use of their free WiFi availability with a database of WiFi locations available to their subscribers.  

Even wired (static) services (DSL, Cable-modem, FiOS) are beginning to impose monthly data usage limits:  Comcast has a 250 GB limit.   AT&T's limit is 150 GB plus $10/50GB.  High quality dowloaded video at  10Mb/s  would use about  36 GB/day at 10 hrs/day - on a monthy basis this is about 1,000 GB!  A lot.  More reasonable usage would be about 20-200 GB/month - still way over what's offered in the mobile space.

In the mobile space,  streaming media at 1 Mb/s would still be excessive at 10 hours/day.  So, the network speeds offered are really for fast loading of rich web pages, sporadic fast file downloads  (buying music/video etc.) and moderate use of low-rate video.  With 150 MB usage per day (4.5 GB/month) ,  at peak network speed,  less than 100 minutes is needed to reach the daily limit.   Low bit rate streaming at ~10kb/s could be supported continuously.  Clearly, at future higher speeds,  per bit costs will have to go way down - a kind of Moore's law for communication.

Utility Pole Replacement in Cambridge (Riverside)

Last night a wooden  utility pole  cracked at the base and fell toward the neighboring pole across the street. This caused the wires to d...