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Sunday, June 25, 2017

Random Garage Door Openings

Posted by admin on December 14, 2011

Last year, my garage doors started opening and closing randomly. At first, I thought one of the neighbors had changed to use the same code, so I changed my code. But, the random openings continued, sometimes I would come home and find the left door open, sometimes it would be the right.

After some research, I came to suspect that the nearby Air Force Academy had switched to using Land Mobile Radio System (LMRS) radios, which operate on the same frequency, 390 MHz, and are known to cause interference. My opener, a Chamberlain 700WHC, has 9 dip switches with + 0 and – positions, allowing 19,683 possible combinations. It seems, though, that the new LMRS transmit 25,000 bits per second, and, sooner or later, the opener senses the right combination of bits and opens. My fix was to retrofit the opener with a new receiver with billions of possible combinations. Unfortunately, the old receiver continued to work; installing the new receiver did not stop the random openings and closings. With online searching revealing that there was no easy way to disable the old receiver, I resorted to good old fashion, tried and true methods, attacking the circuit board with a soldering iron!

Image of Circuit Board

Altered Circuit Board

Conveniently, the circuit board is manufactured with a test point between the radio receiver and the open/close logic. Just above the down force adjustment variable resister, labeled “DNF” (click on the photo to see the large version), you can see where I unsoldered one end of a wire to disconnect the receiver from the remainder of the circuit board. Disconnecting this jumper wire disables the radio receiver. If you don’t want to unsolder it, you can cut it.

Genie Retrofit Kit

New Opener Kit

The new receiver kit uses rolling codes and many more symbols to avoid interference. Installation is simple following the supplied instructions.

Parts Supplied in the Kit

Parts Supplied in the Kit

The new kit comes with a receiver, remote. “wall wart”-style power supply, and wire. You fasten the receiver to the ceiling near the existing opener, connect the wires, plug into power, and train it to the remote.

This change solved my random garage door opening problem. This is a much simpler, less expensive, and less time-consuming solution than replace the whole garage door opener just to get around a radio interference problem!

Course Announcement: Algorithms!

Posted by admin on June 27, 2011

I will be teaching CS265, Algorithms, at Colorado Tech starting next week. There are still openings available. Here is the course information:

Course Description

  • Students are introduced to the basic concepts of algorithm design analysis, including searching and sorting, hashing and information retrieval.
  • Average and asymptotic behaviors are discussed.
  • Complexity issues are explored.

Course Objectives

  • Describe and in basic problems apply the methods of analysis to the algorithms that solve those problems. This includes the derivation of sequences, series and recurrence equations that define the growth function for a pseudo code fragment.
  • Find the bounding asymptotic functions for various growth functions. Much dependency will be placed on applying relevant theorems and formulas without requiring their proof.
  • Classify algorithms according to their bounding big oh or theta functions.
  • Recognized what algorithm design type might be applied to solve a given problem type.
  • Trace the execution of an algorithm based on a given design type as applied to a specific problem solution. The student will use representations of data structures to display clearly how the algorithm works.

Sign up here!

Why Is Virtualization Hot?

Posted by admin on March 2, 2010

This whitepaper provides an introduction to virtualization. It gives an overview of the history of, the underlying technologies used in, and the business case for virtualization. Finally, it explores the question, “Is VM ready for the casual user?”


Course Announcement: Enterprise Information Systems

Posted by admin on March 1, 2010

As enterprises grow, integrating the variety of legacy, custom, and commercial package applications involved has become increasingly complex.  New approaches to development and integration of organization-wide systems are necessary to guide and manage the enterprise information system.  This course is designed to train those managers who will be responsible for planning, implementing and managing large scale enterprise information systems.  The use of information technology to achieve competitive advantage, efficient operations and effective decision-making is explored.  Technical architectures to achieve strategic enterprise goals will be investigated.  Students will analyze the functions of information technology and its impact on competitive strategy and organizational operations.

Course Objectives:

Upon completion of this course, the student should be able to do the following:

  1. Identify potential design risks resulting from inconsistent or contradictory technical requirements
  2. Identify enterprise technical requirements to satisfy user’s functional requirements as well as those of outside agencies such as the government
  3. Effectively communicate technical material to non-technical people
  4. Develop, manage and maintain a technical architecture across the enterprise to achieve organization strategic goals as well new system integration
  5. Be able to resolve technical buy, make or rent solutions to increase efficiency and strategic advantage across the enterprise
  6. Be able to use technology to increase the efficiency of business processes while taking into account legal and ethical requirements such as Sarbanes-Oxley and HIPPA

This course is a 4-credit graduate-level course offered on-line though Colorado Technical University, Colorado Springs. Please e-mail me at geekydewd <at sign> if you would like my assistance to enroll.

Introduction to Service-Oriented Architecture

Posted by admin on

The rapidly-changing business environment and the ubiquity of the Internet and the World-Wide Web have led to the emergence of platform-independent, web-based technologies as the standard building blocks for enterprise integration.  These technologies are called “Service Oriented Architecture” (SOA).  Fundamental to SOA are the concepts of Web services and the Enterprise Service Bus (ESB).  But SOA is also the enterprise Information Technology (IT) infrastructure – Web portals, networks, common software services, web-enabled legacy applications, and databases that support delivery of Web applications.  My e-book explores the evolution and concepts of SOA in both contexts, the enabling technologies and as an enterprise IT infrastructure.  You can download it here:

Introduction to SOA