…in the App Store.

I have been using Autodesk (previously, Alias) SketchBook for years. How did I not know about the iPhone app? It works pretty well I must say. I am one of those people who draw a lot so this will come in handy for many reasons: ideation, concepting, explaining, and passing time when I am in meetings. It works similarly to the desktop application aside from replacing my Wacom tablet pen with my big fat fingers… but thanks to the brush selection, I can control the thickness of my lines easily. Touch sensitivity works for creating nice fine lines or thick, chunky lines too.

For designers: You can import a photo from your Photo Library and sketch over the top of it. Comes in handy when you want to make some quick notes or sketches over an image.

I can’t believe this thing has been out for a year. Which goes to show you; marketing an app in the App Store is a lot harder than you would think.

So I finally gave in and bought Wolfram Mathematica.  It’s the home edition but that’s where I will be using it so it’s all good.  Having probably milked the Free Trial Version thing long enough, using multiple computers and email addresses to register, I figured what the hell?  Not only is this program pretty dang awesome, the Wolfram website is probably one of the best-designed technical sites I have seen in a long time.  The amount of content this company produces is amazing.  IBM might have them beat, but Wolfram’s site is much more aesthetically pleasing.  The support for the application is some of the best I have seen for such a technically-oriented program.

And really, when you are out of school, and you don’t have tests to study for, and massive assignments to complete, the bottom line is: Math Is Fun!

What finally made me pull the trigger on throwing down the three hundred bucks?  I give you:

I’m a sucker for old-school oscilloscopes! Even virtual ones.

Yeah, I have been working long hours (and playing even longer hours) so I have not been too involved with the ol’ “updating of the blog thing.” But that’s ok because lots is happening around my technology planet.

Briefly, just to throw up some fresh news, I have been working on some cool stuff and, as the summer weather begins to change ever so slightly into fall – the mornings cooler, the light just a little further south – the grand to-do list for the long winter months begins to grow. As my day job demands, I work with a team who is rolling out a pretty extensive Data Management Platform called Idea2.  The web-based application is really a framework that allows different industries to build custom Master Data Management solutions for their own databases.  And, with that, integrate with all sorts of web services and other applications to basically create a unified data tool that does lots of fancy things.   My role is to try to keep the wheels on this bus.  Bug tracking, integrating with outside applications, supporting the developers, supporting the administration, and supporting the customers.  It’s an all-day kind of thing, with meetings, and bullshit, and email, and phone calls.  Just like a real job.  You want technical specifics?  The app is written in Python, uses Redis, MongoDB, with nginx on the Tornado Web Server. It is hosted on Amazon EC2. We are still playing with disk sizing and all that stuff to determine the best setup for handling massive database loads. Once the thing has stabilized, I will post more about the technical specifications. The whole thing is a pretty fun learning experience so far.

Other things going on? How about if I just throw up some links to “things” I have been researching:

http://mobile.designnews.com/blog/Mechatronics_Zone/39065-PIC32_Kit_Simplifies_Ethernet_Connections.php

http://yaler.org/

http://mln.sourceforge.net/

http://pycon.blip.tv/file/1947528/

As far as MisterHouse stuff is concerned, I need to update the site to reflect that I have totally abandoned it. It was a fun project to get started in home automation but I don’t like Perl. Never have. Never will. I am finding new ways to integrate the home systems using much cooler interfaces and code. So long, MisterHouse.

I am also researching solar energy for an entirely different application and project that may or may not be coming up on the event horizon.

So there you have it.  A summary of stuff I care about.

I am always happy to come across someone who is combining engineering and art in interesting ways.  Today, just by chance, I found the work of Rob Seward on Vimeo only because I was doing some random stuff on that site for work.

I was immediately interested in what I was seeing.  Rob Seward is an artist and programmer who lives in New York.  His stuff can be seen here.

What caught my eye, and what drove me to his site, was his video called, Four Letter Words, which documents a piece that displays algorithmically generated word sequences.   You can watch it on his Vimeo site , or, just watch it here on this page:

Four Letter Words from Rob Seward on Vimeo.

He’s an Arduino guy, but I won’t hold that against him.   His blog is full of project references and concept pieces he is doing or has completed.  I can truly appreciate his ideas and his execution and will be watching his website from now on.  Nice work Rob!

What if a disaster wipes out your community’s wireless infrastructure?  Would you be able to get it back online using whatever was left of the original equipment?  No matter what caused the disaster – natural or man made  -  if your communication links are severed, your chances of recovery and getting assistance drop to nearly zip.

In thinking about being prepared for said disaster, I find myself thinking about the communication problem first and foremost.  Of course there are immediate needs like medical supplies, water, food and shelter to consider first, but without a communication system, however rudimentary, even those seemingly standard survival issues could be too difficult to coordinate.

A few years ago, I came across an interesting site who’s mission is to provide knowledge and expertise for building wifi networks in developing communities around the globe.

As part of this, they put together a very informative book (free PDF download, 425 pages) called Wireless Networking in the Developing World – 2nd Edition

This is a great book to have around.  Keep it stored locally on your computer or – probably smarter – print it out.  In the event you lose your connectivity to the web, you can most likely use the information in this book to re-establish that connectivity.  It is full of basics as well as advanced, practical DIY how-tos.  It walks the reader through the entire design and installation of various 802.11 infrastructures with the goal being to get a fairly advanced communication backbone using available resources and equipment up and running quickly.  There is even a section on using solar power to run your mesh, complete with some basic circuits that will provide a nice AC-DC, regulated output as well as sizing panels for a given output.  All fairly important things to know when nice, conditioned 120V or 240V RMS sine waves have stopped flowing out of the wall.

Why 802.11?  Because the equipment will be strewn everywhere.  It is by far the most popular protocol for wireless networks and most people will have access to basic network gear that can connect to this protocol.  The idea is to quickly get the infrastructure back up.  You won’t be inventing a whole new state-of-the-art communication system here.  You and your neighbors are trying to survive.

I’ll bet this:  No matter what your level of hacking ability is, this book will include  information you have never thought of or used in a real-world setting.  I have a lot of respect for the authors of this book.  Many of them are leaders in community wifi projects as well as researchers and elite hackers.  There is a vast amount of engineering experience crammed into these pages.

The book was obviously intended to assist those with limited resources and without access to expensive, brand new commercial hardware with a means to create and use a wireless network in their community.  The book is really not a “survival guide” or “disaster recovery” plan per se.  But, looking at recent events such as Katrina and Haiti, the need for this type of information to translate to the idea of citizen-powered disaster recovery is not only vital, it is probably a skill any good hacker or engineer should keep a close eye on.  I believe in the power of connecting to the developing world and giving everyone fair and equal access to the world wide web (and that’s ABSOLUTELY NOT for the FCC to decide but that’s another matter…).  The author’s cause is just and good.  I just think, the way this book has approached the problem of building an ad-hoc infrastructure in third-world conditions will be very similar to recovering a destroyed network after a natural disaster or worse.

One more thing:  There is a link on the http://wndw.net page that points to http://wirelessu.org/.  Follow this link.  And learn.

photo credit

I just installed the WPtouch theme that creates a pretty cool formatting for iPhones and other smart phones when you visit these pages via one of those platforms.  The theme itself is very customizable and works quite well.  Nice work Brave New Code!

[click on the image above to view larger]

I was able to score a case of Perim-Alert SR-1 Sensing Units from one of my obtainium sources and have been looking for a cool (and useful) way to incorporate them in a perimeter security system.

The units are brand new ( I’m guessing they were built in the mid 80s?), in-the-box, and come complete with hose clamps that are used to mount the units on standard galvanized fence posts.  These units, according to the box, were manufactured by Air Space Devices (16624 Edwards Road P.O. Box 7500, Cerritos, CA  90701) and were distributed by Norton Safety Products.  From what I can tell, Air Space Devices is no longer doing too much anymore or  is deeply “off the grid.”

The cool thing about these things is their extreme sensitivity.  The slightest jiggle causes a switch to open and, in conjunction with a latching relay, can be used to monitor and protect any barrier that needs to be accessed (a gate, door, stairway, ladder, etc.) by someone approaching a structure or property line.

When you open the sensor, you see a pretty simple setup:

The orange blob in the center is a vibration sensor that is sealed in an epoxy case.  The normally open (NO) contact terminals on the left and right of the unit are wired into your monitoring circuit.  The vertical screw in the center is used to adjust the sensitivity of the device.  It acts as a simple counterweight.  Loosening the screw makes the lever arm of the accelerometer longer, which, creates a larger moment of inertia to act upon.  Tightening the screw creates a shorter moment, enabling smaller movements of the device to shake the spring steel that the accelerometer is attached to.

The unit is unpowered meaning it requires no external power source to operate.  It is merely a switch.  Movement shakes the unit, and the circuit opens, causing the interruption of electrical flow which can be easily turned into a signal that activates alarms.

The usual installation of these devices would have probably entailed connecting a number of these units around an entire fence line or some type of perimeter structure in a continuous series circuit along with a central power supply.  Thus, a 24V or whatever control voltage would be sent around a loop, passing through each sensor on the perimeter and creating one, large circuit that would be monitored for continuity at a base (or guardhouse)  somewhere.

If any part of the perimeter circuit was either moved or cut, the circuit would activate some alarm and a crew of henchmen carrying machine guns and riding on snowmobiles would sprint out along the perimeter, looking for the intruder.  Evidently, with this type of setup, it would be hard to pinpoint the exact breach in the perimeter unless you used a sophisticated time domain reflection algorithm similar to old-school telephony fault analysis to pinpoint where the break in the circuit occurred.

Fast forward to today, where we can now use low-powered microprocessors and Wi-Fi networks….

My project will incorporate these units to monitor a perimeter as they were designed.  However, instead of hard-wiring each device together in a chain, I want to install each unit independently of each other and have them report back to me if they are disturbed in any way.

Using simple embedded control and an 802.15.4 star topology encrypted wireless mesh, I can monitor each unit not only for movement and/or tampering, but also track which unit is under attack.  The logic is simple.  The hardware is cheap.  The low-power, 3.3 Vdc operating voltage is minimal.   And you don’t have to run hundreds of feet of copper around a perimeter to control the system.  A simple battery powers each unit and radio.   A low-battery sensor alerts me when a unit’s power supply is getting below a safe threshold and needs to be changed.   Even the communication protocol can be set up to “wake on event” and go into sleep mode until it needs to broadcast the disturbance.

I am thinking:

The Perim-Alert Sensor
A PIC18LF4620 MCU (This is an 8-bit processor;  one bit more and you have reached overkill status.)
Some MRF24J40 transceiver/transceiver modules
A MiWi P2P Wireless Protocol
A battery
A couple of other things.

The PAN coordinator can report to either a web-based app that can notify and trigger some security devices (you know, like a loud alarm or a 500MJ 1.5MA homopolar generator or something…) or a stand alone system that can be accessed through a touchpad like a traditional alarm system that sends SMS messages to a mobile device along with a call to a 911 system.  I don’t know yet.

The first hole you could punch in this design is the fact that all networks are vulnerable to attack and wireless networks are the most vulnerable.  Because this system relies on node autonomy as well as self-organization, RF jamming and packet-level intrusion could easily make the system worthless.  I hear ya…

As this design progresses, I will discuss some ideas and real-world strategies to defend against this type of take-down and additionally, talk about how this is applicable to defending our very own Smart Grid from similar attacks.

Details coming…

In the meantime, check out an application note on the Microchip MiWi P2P wireless protocol here.

I sometimes post little blurbs about cool books from my library as a nod to the time when information had to be searched out, checked out, bought, and pored over.  I’ll admit I have a soft spot for old technical how-to and reference books.

I remember going to the library and digging through the periodicals in the science and tech sections and spending a day and $35.00 in dimes to copy articles of interest that I thought would come in handy down the road.  I still have a copy of Fred Cohen’s paper, Computer Viruses – Theory and Experiments written in 1984, which had just been published and that, at the time, I considered a minor coup in obtaining.

For me, the access to information is what keeps me excited about everything.  I have been a collector of information my whole life.  My engineering and design library is pretty extensive but, as the Internet becomes the repository for information, my technical book-buying has diminished.  The last book I have recently purchased is Python Web Development with Django, which, truth be told, the information contained therein could easily be found on the web with a few minutes of Google searching.  We all have our reasons for choosing to purchase a bound copy of information which, most likely, is readily available online, but, for me, the physical manifestation of information, presented in a book that lies open on your workbench or beside your computer, always seems to be preferable to flipping back and forth between your project and a PDF open on your screen.

I digress.

Bob Middleton’s Handbook of Electronic Time-Savers and Shortcuts (Prentice Hall Electronics Library)  is one of those books you simply must have in your hands as a physical book.  This is one of those handbooks so useful and so full of little-known tricks that to own it instantly makes you a better engineer.

Published in 1987, this book is solidly based in the analog world but also includes and extensive Digital Section in part two.

Now, what makes this book classic is the fact that Middleton presents solid, hands-on troubleshooting, testing, gotchas, and insider tricks for digging deep into circuits (at the component-level) that may (or may not) be faulty.  For anyone who hacks old gear or restores surplus equipment, this book is an absolute must.

Not only does the book cover troubleshooting in detail, it also shows you how to build bench-top test equipment and circuits from the stuff you have lying around.  Middleton shows you how to use your Multimeter, Ammeter, VOM, and signal sources to actually find circuit breakdowns the old-school way.  Engineering school never once showed you these techniques.  Trust me.  Case in point? Measuring Inductance.  Do you know how to get a quick measurement of the inductance of a transformer winding?

In the figure below, the inductor to be checked is connected in series with the resistor decade box.  You measure the voltage across the inductor and the voltage across the decade box with and AC DVM.  Then you compare these readings and change the resistance value until the two voltages are the same.

This gives you a quick and easy way to find the inductance which is sufficient for most electrical work.  Of course, EE will show you how to measure this value to the 1000th of a henry but who the hell cares?  When you are attempting to resurrect an old 150W tube amp, you don’t.

Here is another:  Turnover is often encountered in troubleshooting AC circuits.  Turnover occurs in a test situation if the meter reading on your AC voltmeter changes when its test leads are reversed. Look at the waveform in the picture:

Since this is an AC waveform, there is just as much electric charge in its positive excursion as in its negative excursion.  The average value of the AC waveform is zero. When the meter leads are applied one way, you may measure the positive-peak voltage.  When you reverse the meter leads, you will then  be measuring the negative-peak voltage of the waveform.  However, since the positive-peak voltage is greater than its negative-peak voltage, neither of the readings is the actual peak voltage of the waveform, because it has two different peak voltages.

The book is full of practical circuit analysis examples such as these.  I find myself, to this day, going back to this book when working on any type of circuit.  The cover price in 1987? $16.95.  Money well-spent considering my student budget-lifestyle back then.  Middleton also provides incredible depth to his digital section, even though you would imagine that a book written in ’87 on digital circuits would be hopelessly out of date.  Not so.  Aside from the BASIC programs illustrating solving RC integrating networks – a feat of programming prowess that is almost laughable at this point in time – there are still plenty of TTL and CMOS packages out there and the ability to find burned pinouts or problems with circuits exposed to high humidity using digital mapout troubleshooting procedures will make you the hero of your hackerspace today.

This is a book you can find used sometimes;  I’ve seen copies for as low as $3.00. Unfortunately,  it’s been out-of-print for awhile.  A quick Google search didn’t produce the results I was hoping for.  I found the book listed here but, until I uploaded the cover photo to this link, there really is no other information available about this piece of information gold.

[click on image to see full size]

Well, this should be interesting…

Read more about Andy’s house here.