μblog: engineering from the trenches

Last week, the rest of my family moved from Yalta, Ukraine to Washington D.C., USA, bringing with them their cat. Ukraine is known for various corrupt activities, including pirating games and replacing everything with mods to make it look like a Ukranian game. This is often done very poorly, and sometimes the pirated game DVDs contain crapware and possibly malware. In discussion with my brother (pictured), I got to remember the days when I did some network engineering/security work.

For the past four-five years, I have maintained a constant subscription with several security-focused email lists, however, I have probably only read a handful of messages. To make security easier to deal with, the National Vulnerability Database, working with DHS and CERT, have released some feeds that can be compatible with an RSS reader. Their statistics page is pretty handy too, the queries there will generate bar plots of vulnerabilities and relative percentages of vulnerabilities that meet the search criteria. Hopefully this will help me keep up with security in the background.

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My family is moving from Yalta to Washington D.C. so I am taking some time off to get their house ready. I have some spare time to explore the “advanced” features of my mobile phone. Below are a few tools that I found very handy in getting the most of my Verizon smartphone.

• BirdieSync – This tool synchronizes your Windows Mobile phone with Thunderbird. It is quite good for maintainging your address book as well as your tasks. Since Thunderbird can integrate with Google calendar, you can maintain an on-line calendar for your coworkers that syncs with your phone.
• PdaNet – This tool allows you to use your smartphone (with a data plan) as a broadband internet connection. I have had good functionality when I connect my phone with ActiveSync over bluetooth and then initiated the connection. See results.
• Yahoo! Go – This tool is meant to give your phone access to the Yahoo! network of sites. I use it mostly to upload images to flickr. I figure that is easiest to put them on-line for easy access so I don’t have to drag and drop them when ActiveSync connects.
• Google Maps – No triangulation, however, this Google Maps is still very useful. Integrates well with the i760 touchscreen.

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This weeks entry is the 20-bit delta-sigma DAC from TI.

dac1220-10x-stitch.jpg

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In a rare turn of events, I have plagiarized a figure from one of my own writeups. As I have promised before, I wrote up a basic introduction to the necessary electromagnetics and the Yagi-Uda design. This is the first version, so please feel free to comment where I can make some improvements. Thanks goes out to my colleague Eric for helping me proofread this.

( yagi-uda )

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I am spending the first half of this week in Cleveland, Ohio at the 2008 Neural Interfaces conference.

The first day was spent mostly discussing neural stimulation as an interface paradigm. Judging from the presentations, deep brain stimulation (DBS) is the most popular in both the research and medical communities. There are about five devices on the market that are FDA approved for DBS so many clinicians are looking to use these stimulators in various off-label applications to stimulate many targets within the brain as well as the vagus nerve in the periphery. The primary success story for DBS is continuous stimulation in the sub-thalamic nucleus and globus pallidus to alleviate effects of Parkinson’s disease. The same techniques are being applied with marginal success as a treatment for epilepsy, depression and obsessive compulsive disorder. It is still tough to show significant improvement for some of these latter diseases. Furthermore, it is equally tough to prove that the turning on the stimulation has any beneficial effects for those diseases. In some cases, implanting the stimulating electrode is good enough.

The second day has had some excellent coverage of the state-of-the-art prosthetic devices. One of the novel mechanisms that I was not aware of is nerve re-direction in the case of amputation. For example, there are surgical techniques to re-route nerve bundles that control arm movement in the case of amputation near the shoulder. The muscle groups on the chest become the targets and in some cases, the amputee can control those muscles by attempting arm movement and feel arm sensations through mechanical stimulation of their chest. If this type of surgery is successful, there are examples of external prosthetic arms which are controlled by electrically tracking muscle contraction on the chest and provide basic tactile feedback through mechanical stimulation.

On a side note, there was a luncheon focusing on commercialization of neurological devices. Translating an implantable device from academia to “mass product” seems to be a process that will test the designer’s patience and humility. The general feeling on the commercial side is that the academic designer should already have a working design that is undergoing human clinical trials when they approach a company for commercialization. Even then, the commercialization company will evaluate their potential for revenue generation and may provide a 0.25-0.5% royalty for the academic designer to take over the mass production of their product. This is while keeping in mind that the path from specifications to clinical trials is at least ten years. This may be the reason that many researchers try to create start-up companies and commercialize their own products to see more fruits of their labors. This approach, however, is perilous and may end up being unrewarding. This is clearly seen with the bankruptcy of Cyber-Kinetics, the company that has been receiving media attention for years for allowing several paraplegics control of an on-screen cursor by thought alone. (Their website has not been updated recently to disclose this.)

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Today’s entry is the LMC6042 dual-op amp from National Semiconductor. The layout of this device is a bit different from a standard op-amp due to the inclusion of some periodic components. It can also be noted that this die is mostly the same as the LMC6044 except that the two op-amps on the bottom-right side of the chip don’t have most of the metal deposited.

lmc6042-10x-stitch.jpg

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It looks like Siemens Energy and Automation has a has made their Seimens Technical Education Program (STEP!) courseware available (PDFs). Topic range from basic electronics, to motor control, to power distribution. What really caught my eye was the abundance of easily understandable safety information in the power distribution course section. The surge protection section is easy to understand and seems to contain enough information on properly wiring a residence to avoid certain catastrophes. Basically, this place seems like a good place to start for those who would like to do some minor work on their home’s power system but don’t have the required training. (This is not to say that STEP has all of the required training either!)

On a side note, I am in the middle of writing a document up to overview the Yagi antenna. I am more than half of the way done, however, I am going to the Neural Interfaces Conference next week. Consequently, the full version should be up next Thursday. If anyone else is there and has a desire to meet up then send an email.

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Apple has released the iPhone 2.0 at their world-wide developer conference touting new and improved data speeds via AT&T’s 3G network. As a smartphone user on the Verizon network, I became curious to see how my data speeds compared. I accessed the mobile speed test at dslreports.com via my phone and noted a 758Kbit/s download rate while in State College, PA. I then quickly tethered my laptop to the phone via USB cable and used speedtest.net to obtain the following two results:

Next, I tethered my laptop to the phone using Bluetooth to obtain slower connection speeds to the same test servers:

I tested the connection rates at another location on the outskirts of State College and found similar results. In contrast, it seems that the new speeds of 215Kbit/s are not impressive, even substandard. I would really like to give Apple and AT&T the benefit of the doubt here and write this off as a side-effect of high network congestion at the WWDC. I would be interested to see if any reader has experience with AT&T’s 3G data speeds and can post their apparent transfer rates.

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As I had hoped, I finished the 100km charity ride this past Sunday in a little over four hours. The organizers did an excellent job providing refreshments and snacks and the track layout was pretty flat. Near the end of the ride, the sun was out and my bike computer indicated that the temperature was above 40C/105F for the last 1.5 hours, peaking at 45C. I can truly say that I slept like a baby on Sunday night.

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This weeks entry is the INA2143 differential amplifier from Texas Instruments. This is a dual diff-amp and the partitioning is pretty apparent. It is also apparent that most of the device is constructed using a bi-polar process, which matches well with the decreased quiescent current with increased temperature in the datasheet.

ina2143-10x-stitch.jpg

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