Show of 11-07-2015

Tech Talk

7 November 2015

Best of Tech Talk Edition
  • Segments replayed from previous shows
Email and Forum Questions
  • Email from Tina in Ohio: Dear Tech Talk. I am trying to scan some old photographs for digital storage and am getting confused by the terminology. Please explain the relationship between bytes (resolution), pixels (understood as size), and dpi (e.g. 300 dpi resolution for scanning purposes) Thanks for your help. Tina. Enjoy the show here in Ohio.
  • Tech Talk Responds: Let’s start with the simplest idea. Pixel is short for Picture Element and it represents a dot in a digitally stored picture. Computer display devices, like the screen on which you’re reading this, are composed of nothing but a rectangle of dots – so many to each horizontal line, and so many lines. For example, my laptop screen has 1,200 rows of pixels with 1,920 pixels in each row. If you multiple that together, you get over 2.3 million pixels, or 2.3 megapixels. A camera may have images that are 4,288 by 2,848 pixels, or a little over 12 megapixels. 
  • To figure out image size, we need one more fact. Each pixel has color, which is represented by three numbers (red, green, blue). If we allow each color to have 255 distinct levels, it takes on byte (8 bits) for each color. Thus each pixel is three bytes in size. Thus a 12 megapixel camera would require 36 MB for each picture uncompressed. This is just the number of pixels times the bytes per pixel.
  • You can compress this file using several methods. JPG format is an example of a lossy compression format; when the file is saved, the user can select the quality of the image. PNG is a good example of a loss-less image compression format.
  • Remember that pixels are dots, so when we talk about dot per inch, we’re really talking about how tightly packed the pixels are when they’re displayed or scanned.
  • For example, many LCD displays present around 75 pixels (or dots) per inch. It actually varies widely, depending on the physical size of the screen, the maximum resolution capability, and the resolution setting. The “Retina” display on Apple’s MacBook Pro currently distinguishes itself by having an exceptionally high DPI: 220 pixels per inch. Printers often offer 300 pixels per inch, and professional printing may go as high as 600 or 1200 pixels per inch.
  • You can resize the image for that target use. Make it as big as necessary for that use, but no bigger. Want your picture to be around five inches on screen? Then around 400 pixels wide is a great start. Five inches on paper? Then maybe 1500 pixels wide. 
  • Email form Mai Lynn in Oakton: Dear Doc and Jim. My Android has been infected with ransomware and I don’t know what to do. Please help me. Love the show. Mai Lynn in Oakton.
  • Tech Talk Responds: Mai Lynn, there is an aggressive ransomware spreading in the US. Simplocker was the first Android ransomware to actually encrypt user files. A new ransomware has been found that resets the PIN lock. In the new Android ransom-lockers, Lockerpin.A, users have no effective way of regaining access to their device without root privileges or without some other form of security management solution installed, apart from a factory reset. 
  • In the latest versions, the Trojan obtains Device Administrator rights with a clever ploy. The activation window is overlaid with the Trojan’s malicious window pretending to be an “Update patch installation”. As the victims click through this innocuous-looking installation they also unknowingly activate the Device Administrator privileges in the hidden underlying window. Not long after making this mistake, the user will be prompted to pay a $US500 ransom for allegedly viewing and harboring forbidden pornographic material. The only practical way to unlock is to reset to factory defaults – if device is not rooted. The device is now permanently locked and it’s impossible to unlock it without root privileges.
  • You can protect yourself from this Trojan by only installing properly vetted applications. Don’t install apps from third party markets, warez forums or torrents. Finally, Tech Talk strongly advises to your Antivirus software up-to-date.
  • Email from Alice in Alexandria: Dear Tech Talk. I recently downloaded iOS9. I have heard that it includes ad blockers, but I can find anyway to activate this service. How can I use it? Love the show. Alice in Alexandria
  • Tech Talk Responds: With iOS 9, Apple introduced what they’re calling “Content Blockers”. These function primarily as ad blockers, but they can also be used to block tracking data if you’re concerned about privacy. Once installed, they’ll block ads, tracking attempts, and more. These only work in Safari and only on 64-bit iOS devices (so the 5s and newer, iPad Air and newer, and iPad Mini 2 and newer).
  • While lots of mobile ads are obnoxious, please remember that ads are how sites like us make enough money to run. So unless you want to see all your favorite sites go out of business, whitelist the sites you like.
  • Content blockers aren’t enabled by default, and they take two steps to set up. Download your content blocker of choice from the iTunes App Store. Open Settings > Safari > Content Blockers and enable the blocker you installed.
  • Here are a couple of ad bloc programs (Blockr and Purity). The best ad block, Peace, was withdrawn from the app store after a few days. The author had a change of heart.
  • Blockr (99¢) is a content blocker has a few optional settings. It has individual toggles to block ads, media (like images or video), cookies, social buttons, and a more general privacy button. You can also easily add sites to a whitelist. Blockr’s powered by its own ad blocking list. I am using Blockr
  • Purify ($3.99) gives you toggles for ads, images, scripts, and fonts, while letting you whitelist any sites you want. Purify doesn’t list where it gets it ad blocking list from, but its list seems pretty extensive so far.
  • Email from Tom: Dear Dr. Shurtz, Can you explain in a fairly simple way why the direction from one point on the earth to another is not 180 degrees when going in the opposite direction? For example, when I check the distance between New York New York and Los Angeles California I find that it is 2462 miles or 2139 nautical miles.  The direction is given as 274.0 degrees or very slightly north of due west.  However, the direction from Los Angeles California to New York New York is given as 66.1 degrees with the distance remaining the same .It seems to me that if I stretch a string between these two cities on a globe the shortest distance between them should be 180 degrees opposite. Why am I wrong? I listen to your program every week and enjoy it very much. I’ve been listening since the WMAL days. Thanks, Tom
  • Tech Talk Responds: If you draw the shortest distance between two points on a sphere on a map which has been flattened (conformal mapping of coordinates), the line will be an arc rather than a straight line. This curvature is what causes the deviation from 180 degrees. If you are a pilot, you must also account for the rotation of the Earth. Also, the Earth is actually an oblate spheroid (fatter at the equator). 
Profiles in IT: Reid Hoffman
  • Reid Hoffman is best known as the founder of LinkedIn, a social network used for business connections, and considered to a super angel.
  • Reid Hoffman was born August 5, 1967 in Stanford, CA and grew up in Berkeley.
  • He attended high school at The Putney School in Vermont, a liberal arts high school.
  • He received a BS from Stanford University in Symbolic Systems and a Masters in philosophy from Oxford University.
  • Symbolic systems is a combination of artificial intelligence and cognitive science.
  • Initially seeking to be a philosopher, he switched to business and entrepreneurship.
  • After working at Apple Computer and Fujitsu in product management, Hoffman co-founded his first company,, an online dating service.
  • While at SocialNet, Hoffman was a member of the board of directors at the founding of PayPal and later joined the firm as a full-time employee.
  • At the time of PayPal’s acquisition by eBay in 2002, he was Executive VP of PayPal.
  • During his tenure at PayPal, Hoffman was instrumental to the acquisition by eBay and was responsible for partnerships with Intuit, Visa, MasterCard and Wells Fargo.
  • Hoffman co-founded LinkedIn in 2003. It was one of the first business-oriented online social networks. He was LinkedIn’s founding CEO for the first four years before becoming Chairman and President, Products in February 2007.
  • LinkedIn currently has 80 million members in over 200 countries.
  • In July of 2010, Tiger Global Management bought 1% of the company, valuing it at $2 billion.
  • After the PayPal sale to eBay, Hoffman became one of Silicon Valley’s most prolific and successful angel investors.
  • He made 80 angel investments in technology companies. In 2010 Hoffman joined Greylock Partners and runs their $20 million Discovery Fund.
  • According to David Kirkpatrick’s book The Facebook Effect, Hoffman arranged the first meeting between Mark Zuckerberg and Peter Thiel, which led to Thiel’s initial $500,000 angel investment in the company. Hoffman invested alongside Thiel in Facebook’s very first financing round. Facebook is valued at more than $14B.
  • Hoffman personally invested and joined the board of directors in Zynga’s first round of funding. Hoffman and Zynga CEO Mark Pincus co-own the Six Degrees Patent.
  • Zynga (known for Farmville and other online games) is currently worth $5 billion.
  • His other investments include Tagged, IronPort, Flickr, Digg,, Nanosolar,, Knewton, Kongregate,, OneKingsLane, and shopkick.
  • He serves on the boards of (a micro-finance organization), Mozilla (creator of Firefox), and Endeavor Global (supports entrepreneurship in emerging markets).
  • Twitter address:
  • He has lobbied for government support of entrepreneurship, including: micro-financing for startups, welcome foreign innovations, raise H-1B Visa cap, match VC funds.
  • According to Hoffman, entrepreneurs are the fertile soil for job growth and recovery. Small companies represent 99.7 percent of all employer firms. They pay nearly 45 percent of U.S. private payroll and have generated 60 to 80 percent of net new jobs annually over the past decade.
New Twitter Application: Fast Food Truck
  • Twitter recently became the communiqué of choice for the almost popular Kogi BBQ trucks, a taco vendor in LA.
  • Kogi uses Twitter to alert customers of its location.
  • The trend is spreading to other wheel meals as more food are using the social networking site to draw customers.
  • While it’s not clear which truck Tweeted first, the Kogi folks have shown themselves to be the most effective at turning tweets into effective marketing.
  • “Kogi special at the trucks and the Alibi! Grilled asparagus with Yellow Nectarines and Sesame Seeds!” read one recent Kogi Tweet.
  • Since Kogi’s launch in November, hungry herds of have been following the pair of white trucks that rove the city selling tacos, burritos and other gourmet tidbits steeped in traditional Korean flavors.
  • In short order, the Kogi name has become recognizable to foodies around the country.
  • No small accomplishment for a pair of taco trucks all due to Twitter.And she thinks the success of food truck Tweets likely will inspire a broader use of Twitter across the food world.
  • “Chefs will be Tweeting from the farmers market about the mushrooms they just picked up and will be part of their mushroom pasta that evening,” she says.
The Grilling Calculator – For Nerds Who Barbecue
  • Web site:
  • Click on Cookout Calculator Tab
  • Enter all meats to be cooked (Type, cut, thickness, degree on doneness)
  • Create cookout timeline
  • Print timeline and put by grill
Book of the Week: Cooking for Geeks
  • Real science, great hacks, good food.
  • Cooking for Geeks by Jeff Potter (Publisher O’Reilly)
    • Think like a Hacker
    • Initialize the Kitchen
    • Your Inputs: Flavors and Ingredients
    • Your Variables: Time and Temperature
    • Air: The Baker’s Key Variable
  • Fun with Hardwaree
  • One Example Lesson
  • Baking Soda: Bicarbonate which needs acids to form CO2. Used when the ingredients are acidic
  • Baking Powder: Baking soda plus acid. Self-contained for CO2 generation. Used when the ingredients are not acidic.
Flight Controlled Move toward GPS Guidance Systems
  • The System We Have Now is Antiquated
    • Radar plane detection and tracking
    • Planes have no knowledge of other nearby aircraft
    • Currently, a plane is guided to its destination via a series of radar handoff’s.
    • With today’s radar, it can take up to 36 seconds to get an accurate read on a plane’s position and a longer time for an aircraft flying 500 mph.
    • So safety buffers err on the conservative side: The minimum distance between planes is 5 miles horizontally and about 3 miles on landing and approach.
  • NextGen is designed to change all that by providing air traffic controllers and pilots with much more accurate and detailed real-time information
    • Instead of radar, the new system relies on ADS-B, or automatic dependent surveillance-broadcast.
    • An aircraft equipped with ADS-B receives GPS signals via an on-board receiver to determine its position in the sky.
    • That information, plus data on the plane’s identity, position, speed and intended flight path, is broadcast to other aircraft and ground stations within 150 miles. For the first time, both pilots and controllers will see the same real-time displays of air traffic.
    • Planes will be able to fly closer without jeopardizing safety, so more flights can be scheduled, easing congestion.
    • This procedure is known as self-separation.
  • Several airlines aren’t waiting for government action
    • Cargo carrier UPS Airlines has already equipped nearly 300 of its planes and its main airport hub in Louisville , Ky. , with ADS-B technology.
    • By shortening flight times and using more efficient approach paths, UPS expects to save about 800,000 gallons of fuel annually.
    • Next year, Southwest will install a similar system.
    • Southwest is forecasting big fuel savings when it re-equips its fleet of 520 737s next year
How Does GPS Work?
  • The Global Positioning System (GPS) is a world-wide radio-navigation system formed from a constellation of 24 satellites and their ground stations.
  • GPS receivers use these man-made stars as reference points to calculate positions accurately to an accuracy of meters using unclassified data.
  • GPS Satellites
    • Name: NAVSTAR
    • Manufacturers: Rockwell International
    • Orbit: 12 hours, 55 degrees to the equatorial plane
    • Ground stations in: Hawaii , Ascension Islands , Diego Garcia, Kwajalein, and Colorado Springs
  • Three satellites are needed for triangulation, but the receiver must have an atomic clock
  • Four satellites provide the time information and allow for cheap receivers.