Thursday, May 31, 2012

Makers and Defense

Last weekend marks the seventh year that we have attended the Maker Faire. During this time it has changed from a rag tag little show to an event with over 100,000 attendees.  The growth shows how the  Maker themes are becoming more mainstream.  Still, there was one talk at the MakerFaire that I did not anticipate.  Lietenant Colonel (LTC) Nathan Wiedenman, Ph.D. talked about the importance of the Make movement to national defense.  This fellow from DARPA describes how the technologies being developed by Makers can help the military and also make the world safer (go figure).  Normally it takes a significant amount of time to develop a new technology for the military.  The agile Maker community is much faster. Instead they have the raw materials to build just the parts they need when they need them.  Imagine a mobile force that doesn't need to carry every spare part they could possibly need. Imagine a developing country that can build their own pumps to create a safe water supply and avoid tribal conflicts over water.
DARPA has created some awesome challenges like the DARPA Grand Challenege and the DARPA Network Challenege.  They are just finishing up a challenge about quadcopters (you know we love quadcopters).  Who knows, the next challenge may be even more maker related.

New Ice Cream Scoop

We've all faced this problem.  Everything about ice cream is wonderful except for the calories and scooping it up.  Am I right?  Well, some folks have put together a new scoop to address some of the issues you may have run into while scooping.  First, there is the serrated edge that makes it easier to dig into the sweet frozen goodness.  Next is the funny dimply things on the inside of the scoop to allow it to easily fall off the scoop into your bowl.  Easy deployment is always a plus.  Finally it has a comfy handle and is dishwasher safe.  I say its revolutionary.

Wednesday, May 30, 2012

Convergence of Video and Still Imaging

Last year when we were looking to replace out video camera, we decided to get a Sony NEX-5 camera.  It is actually a still camera that doubles as a video camera.  We've seen this convergence of video and still imaging coming, but it is only recently that its gotten to the point where it made a difference to us.  It's true that the NEX-5 isn't quite as flexible of a video camera in some respects, but the image quality is great and the ability to have both the still camera and the movie camera available to me without carrying two cameras is fantastic.
I've always thought of this convergence as still cameras swallowing up video cameras, but the video above takes a different view.  It gives a Red Epic (an awesome film (video) camera) to a portrait photographer who is used to using a fancy, high-end Hasselblad still camera.  His reaction is very interesting.  Take a look and see for yourself.

The Little Dude on Your Shoulder

Some researchers at Yamagata University have developed a way to let a friend remotely sit on your shoulder so that you don't have to go through the day alone.  They created a little animatronic humanoid form that can gesture and look around via remote control.  This way, your friends can be there with you even if they can't... well sort of.

Its very clever, and you can tell it took a lot of work, but I just don't know that it is what I'm looking for.  I've seen too many cartoons where the angel is sitting on one shoulder and the devil is sitting on the other.  I can just imagine the conversation...
"Should I or shouldn't I?" I think out loud.
"Go on!  Do it!" says the devil.
"No Don't do it!  You'll regret it later," says the angel.
"Come on Roger, just press the button.  Post it!  Its just a blog post!" says the devil.
"You'll be sorry!" says the angel.

Thanks Phil!

What Happens When Two Black Holes Collide?

When I give talks, I make sure that there are no second graders in the audience for just this reason.  You know they always ask the hard questions.

Tuesday, May 29, 2012

Area of a Circle

OK, I admit that I did have to rewind and watch the last part twice to get it, but I really liked this proof without words of the area of a circle.  Take a look.

If you have trouble seeing what is going on, remember, the outer strand is the circumference, and as we unfold the circle the point of the triangle ends up being where the center of the circle was.  Thus the height is exactly the the radius of the circle.  Nicely done!

Golden Gate 75th Anniversary

We didn't make it up to the Golden Gate Bridge for the 75th Anniversary celebration this weekend.  Luckily, this video seems to capture the moment nicely.

Happy Birthday Golden Gate.  You're looking great!


With summer coming up, you are likely to be around a few water activities. The pool/lake/beach are always great on hot summer days. That is why we decided to post this article about drowning. The stereotypical person yelling or thrashing about in the water that you see in movies is NOT usually what really occurs when someone is drowning. It is important to be able to recognize drowning's more common silent characteristics.  You never know, what you learn may just save someone's life.

This article does a nice job of laying out the facts.  It could be the most important thing you read this summer.

Friday, May 25, 2012

9 Year Old Takes on the Game of Life

9 Year old Nick Packard tells it like it is.

Shadow QRCode

This is clever.  A company in Korea had low sales during the lunch hour, so they introduced a shadow QR code promotion.  They created a sculpture whose shadows create a QR code (those 2D bar codes you see everywhere) at a certain time of day (around lunch time).  Shoppers who scan the QR code with their cell phones find special deals waiting for them.  Its quite brilliant really.  Watch the video and see.

Thursday, May 24, 2012

Mixing Virtual and Real

A group at MIT has created a cool set of tools for interacting with virtual objects in the real world.  They use iPads, a special glove and head tracking to create the experience of holding a window into another universe.  You can reach into this world and create, destroy and manipulate objects in this word with your hands.  Multiple people can interact with these virtual object simultaneously making it possible to collaborate.  Very cool stuff with interesting possibilities.  I especially like the collaborative nature of it.

More information is available here.

Slinky on a Treadmill

What will happen?  Will it fall off?  Will it stop?  Will a cat jump onto the treadmill with it?  Watch and find out.  This just goes to show you that the proper music can make anything dramatic.

Wednesday, May 23, 2012

No More Anticipation

In the 1970s, Heintz ketchup had an advertisement that featured the Carly Simon song "Anticipation."  In a brilliant marketing move, they decided to feature the fact that their ketchup took forever to slide out of the bottle rather than see it as a problem.  Its a sign of quality... right.

Well, now some scientists at MIT have made the slow ketchup a thing of the past with special LiquiGlide coating for bottles that can make the ketchup flow right out.  Take a look at the two videos below.  First is a standard bottle.  The second is the same ketchup in a LiquiGlide bottle.

This coating is something they call a structured liquid.  It has features of both a liquid and a solid.  It should work for a whole host of applications, but just for sauces in glass jars, the implications are pretty large.  They estimate that if all sauce bottles used this treatment, they could keep a million tons of food from being thrown out every year.  It sure seems like it would make it easier to get the bottles ready for recycling.
Read the complete story here.

Tuesday, May 22, 2012


Ben & Jerry's has come out the perfect accessory for their ice cream.  Its called the Euphori-Lock.  Why would you need this?  Because there is no "u" in "my pint."

via Laughing Squid

Eclipse Photos from Around the World

We got a couple of good eclipse photos, but they are nothing compared to some of the amazing shots from around the world published by the Atlantic.  Take a look at them here.

Monday, May 21, 2012

Looking for a Slightly Used Kidney

A friend of mine is in need of a kidney.  His name is Eric Dishman, and he is looking for someone with O-type blood and one too many kidneys.  I worked with Eric a few years ago and learned to really appreciate his creativity, wit and energy.  He is a great guy, and I'd really like to help him find a donor.  Read his story here.
Also, please repost this story or pass it on to spread the word.


If you want the short version...Need kidney from a live donor; you rock for even considering it; you must be generally healthy with Type O blood (positive or negative); it all starts with a confidential questionnaire you can get from the very friendly Margie Marksthaler, RN, who is the Kidney Donor Coordinator at Legacy Transplant Services in Portland, Oregon at 503-413-7349 or Cookies involved.

Me (on the left) and my wife Ashley, on snowy Mount Hood in February of this year, trying to hike the pounds (cookies) off my stomach to make room for a new kidney on board!
If you want the long-winded version for more context...For those who know me well, I am rarely at a loss for words--on paper or in person. But I've sat down to write this letter more than a dozen times. How do you ask someone to voluntarily go through surgery to donate his or her kidney to you? What is the protocol for asking someone to be a hero, without sounding melodramatic? What is the perfect sentence that gets across the sense of humor you want to have about the whole ordeal while also signaling the serious urgency of the need for this kidney? I am not sure of the protocols or perfect sentences, so I have to simply ask you to please learn about the process of donating a kidney and to consider the possibility of donating that kidney to me.
So how have I ended up needing a spare kidney in the first place? My journey started in 1987, the year I graduated from high school. A routine pre-college physical revealed a "problem" that eventually became "some rare kidney diseases," followed by a couple decades of drug therapies (and a couple of painful biopsies) to try to stop the kidneys from failing. We always knew my kidneys would eventually give out, but we had hoped it would be in my 70s or 80s, not age 44. Nonetheless, my regular visit to my kidney doctor a few months ago revealed that the old filters need to be changed because my body can no longer adequately clean its own blood. It's time to get a new model!

The kidneys. Okay, a drawing of the kidneys. You have two. I only need one. You can live long and prosper without your spare! Lose weight--donate a kidney! : )
After a couple of months of tests to show that I am a good candidate for a kidney transplant, I was put on "the list" on May 11, 2012. I recently had surgery to put an "AV fistula" (no, not THAT kind of fistula) in my left arm to get me ready for dialysis, but I am trying to hold off from starting dialysis since kidney transplants work more effectively if you haven't yet started dialysis. That means I am feeling sicker--daily fatigue, nausea, dizziness, blood pressure challenges, headaches, and a taste in my mouth that makes even chocolate chip cookies taste horrible--as toxins build up in my blood that my kidneys can't deal with. The hope is that I will get a transplant before needing to be on dialysis, but only time will tell. None of it is so bad at this point--I am able to work and garden full time--just at a much slower pace.
The average wait time in Oregon right now for a cadaver kidney (from "the list") is about two years. But the doctors and I hope, especially for someone as young as me, that we can find a live donor since those kidneys tend to be accepted by the body better and to last longer. (As much fun as this is, I don't want to repeat it when I am 64!) I found it pretty amazing that donating a kidney can be a relatively quick, laparoscopic surgery in many cases, with minimal risk and recovery time. You can learn more at or check out And to hear from a good friend of mine's donor, Chip, who recently wrote about his experience, click on  If you would like to speak with Chip or other people I know who have been through the kidney donation process, email me at and I will put you in touch with them. There are many myths about donating a kidney that are important to see through.

The cookie. Okay, a photo of the cookie. Save a taste bud--make these taste wonderful again--donate a kidney today!
As for the details about donating to me specifically, you need to be generally healthy, preferably close to my age (in your 40s or 50s, or less), with Type O blood (positive or negative) to match mine. If you don't know your blood type, you can donate blood to your local Red Cross or other nearby blood bank, and ask them to tell you your type. Then, you can fill out a confidential questionnaire which you can get from the very friendly Margie Marksthaler, RN, who is the Kidney Donor Coordinator at Legacy Transplant Services (where I will have my surgery eventually) in Portland, Oregon at 503-413-7349 or All of your information given to Margie and the Legacy staff is confidential (I won't even know you called them), and please know that just because you volunteer to be tested doesn't mean you will end up donating a kidney. There are numerous milestones and "exit strategies" for potential donors to pass all along the way. Finally, you should know that my insurance pays to have one candidate at a time to go through all of these tests, if you and the transplant team decide to proceed with a workup.
So, with inadequate and still-too-many words, I have to say that I appreciate you even considering this request and, perhaps, sharing this letter with your friends and family members who might be open to volunteering to be tested. I don't know what inspires people--sometimes complete strangers--to donate a kidney, but I promise you I will live a full and powerful life with the gift you provide. (And I will surely come to enjoy chocolate chip cookies again with you in sugar-filled celebration.) Even if you don't match with me, I hope you will consider being a live donor to someone else, or an organ donor on your driver's license, or a blood donor within your community. So much many ways to give many ways to be truly heroic.
Eric Dishman
Kidney Patient, in need of a Hero, or if that's too much, a dear, dear Friend

Eclipse at Digital Diner

Bix, Monika and Widdakay stare at the Sun
Nature put on quite a show here yesterday.  The eclipse was quite spectacular!  We had special glasses for viewing directly as well as a pinhole camera setup for recording the motion across the sky.  These glasses were specially designed for viewing the eclipse directly as well as the transit of Venus which is coming up on June 5 & 6.  We just have to take very good care of the glasses between now and then to make sure they don't get any scratches or pinholes in them.

Maximal eclipse was around 6:34 local time.
I was even able to get a few pictures through the glasses.  This is approximately maximal coverage from our location.  It was surprising that even with such a significant portion of the sun covered by the moon, that it was still very light outside.

Draw quickly or the image moves before you finish
We were also surprised at how quickly the sun and moon moved across the sky.  We recorded the shape and position of the elipse every 5 minutes.  You had to draw quickly because image was moving as you drew it.
Eclipse shadows danced on the walls
When the eclipse was near its height, we noticed little eclipse projections everywhere.  This pattern danced on the wall as the light filtered through the trees and the blinds on the window.

It eventually turned to a giant PacMan in the sky

In the end, we got a nice plot of the shadow of the moon moving across the sun.

Thursday, May 17, 2012


Some folks at MIT Center for Bits and Atoms have made an object float.  Ok, I have a little trouble with them talking about this in terms of "no gravity," but still it is quite cool.  Some time ago I thought of doing exactly this experiment.  The idea is that an electromagnet it controlled by a computer that has sensors (video cameras in this case) to sense the location of a metal ball.  If the ball is too low, crank up the electromagnet above it.  If it is too high, repel a little.  With the appropriate algorithm (probably a PID algorithm) you should be able to get the ball to float just as the MIT folks in the video did.

You can find the complete story here.

Club Jameco

For many years now, we've gotten electronic parts for our various projects at a local supplier called Jameco.  I know, how exciting can a place that sells resistors really be?  To us its much more than that.  When Widdakay started in on electronics, he had a special relationship with Liz, the lady at the Jameco front desk, who would always look out for interesting little parts that might be useful to budding young engineer.

Widdakay, age 6 getting parts for a project from Jameco

One thing that many hobbyists love is to see other people use their designs.  One issue, no matter how good your instructions are, is that it is often difficult for people to get together the right set of parts to reconstruct your project.  Well, Jameco has just announced something new which they call "Club Jameco."  The idea is that hobbyists who have a cool design can post it and instructions to Club Jameco.  If it is approved, they will put the parts together in a kit along with your instructions and then others can easily get the parts to build your project.  ..and you, the designer, get a commission for each sale.

So basically, you can share your designs with the world,   Jameco makes it easy for others to build your designs, and you get paid.  Its an interesting business model and nice way to spread projects for hobbyists.

If you have a project, try it out.  Go post it to Club Jameco.

Wednesday, May 16, 2012

Why you should test your backups (rm *)

This is a story about how a Toy Story 2 got deleted and the backups were no good.  Fortunately, a work from home mom saved the day.  After seeing this video, I think I'll go double check my own backups at home.

USGS Open House

If the Maker Faire and and Solar Eclipse aren't enough to keep you busy this weekend, you may also be interested in checking out the USGS Open House.  The US Geological Survey in Menlo Park will open its doors to the public this weekend from 10am to 4pm on both Saturday and Sunday.  There will be exhibits, hands on activities, presentations, live music and chances to talk to actual scientists from the USGS.  It really looks like they have put together quite a program this year and best of all the event is free.  They only do this once every three years, so it is a unique opportunity.

For me, I think I'd like to see the presentation, "Potential Inundation in the San Francisco Bay Region Due to Rising Sea Levels" then maybe wander over to the "Dress like a Scientist" booth, then over to find out how close I live to an earthquake fault.  I have a feeling that I could fill up a whole day here without too much trouble.

The event is this weekend, May 19 & 20 from 10am-4pm at 345 Middlefield Rd, Meno Park.  You can find a flyer for the event here and detailed information about the event here (be sure to wander through the tabs on the site to see all the different events).

Remember that you can always find events like these on the Digital Diner calendar.  
Drop us a line or leave a comment if you have suggestions for the calendar.

Annular Solar Eclipse, Sunday May 20

This weekend there will be a Annular Solar Eclipse.  A Solar Eclipse is the kind where the Moon gets between the Earth and the Sun.  It is Annular because with the positions of the Sun, Moon and Earth, the Moon does not completely cover up the Sun, so at its maximum, there will still be a ring of the Sun visible around the moon.  It looks like the shadow will start in China, move over Japan, then head out over the Pacific Ocean, before arriving at the US west coast and ending somewhere in the western states.
Never Look Directly at an Eclipse!
Never Look at an Eclipse Through Sun Glasses
We recommend building a Pinhole Projector.  It is easy and fun, and by far the safest way to view the eclipse.

Tuesday, May 15, 2012

3D Printing

One of the more interesting changes that technology is providing us right now is the promise of affordable home fabrication.  There are various technologies like laser cutters and CNC machines that are dropping in price dramatically, but perhaps most compelling is the 3D printer.  This magic little device allows you to turn the virtual into reality.  It can take a design from your computer and turn it into a physical object that you hold in your hand.  

Solidoodle 3D Printer

The implications of this technology are far reaching.  Imagine being able to fax a 3D part to someone much as we fax paper today.  Imagine companies providing plans for products or spare parts that you can print yourself.  My colleague, MIT professor Neil Gershenfeld, believes that taken to the extreme, this implies that some day the price of most everything will be based on weight.  Once you have the plans, the cost of the object will boil down to the cost of the material required to make it (weight).  It could certainly change the economics of distribution.  

At a previous job, I was lucky enough to have one of these printers that could make high quality plastic parts incredibly cheaply.  It was very compelling.  It works by heating then extruding high quality plastic out a small nozzle that is mounted to a "print head" that can move in the X and Y dimensions on a flat plane.  As that first layer begins to solidify, the mechanism moves up very slightly in the Z dimension to add another layer.  By building up layer upon layer, the entire object can be created.  One of the downsides to these devices is that the higher the resolution in the Z dimension, the slower the printing process goes because it increases the motion required of the print head by making more layers.  There are other technologies that work by spreading out a layer of special plastic "sand" and then using a laser in the print head to fuse together the plastic grains.  Then another layer of "sand" is laid down and the laser fuses together that next layer.  When the piece is done, The sand is poured out and what remains it the fused together grains that make up the object you were printing.  This can be faster than the extruding method, but still has a trade-off with Z dimension resolution.  This technique is not as refined, so there aren't very many of these printers available.    

One of the really exciting ideas is that you can recycle your objects locally.  If there was a shredder that allowed you to break appart the objects you printed and melt/form them back into the source material required for building, then you could build as many different things as you like just for the energy costs of printing and recycling.  Very cool.  

There are several manufacturers making printers now.  Prices start around $500 and go up from there.  Only a few years ago similar functionality would have cost upwards of $100,000. 

Makerbot Replicator
I expect to see many 3D printers at the Maker Faire this weekend.  If you are coming, you may want to check out Makerbot.  As you can see from the video below, they will be showing off some robots that they have printed up on their 3D printer.


To those of you in the Bay Area this weekend (May 19 & 20), plan to come to the Maker Faire.  If you are not in the Bay Area, consider coming for a visit this weekend or attending one of the other Maker Faires around the world.
The Maker Faire is a place where hobbyists, tinkerers and makers of things get together to learn from each other and to show-off their talents.   They have everything from giant, artistic, fire-breathing dragons to quadcopters and rockets to 3D printers to crafts.  Best of all, there is a Do-It-Yourself vibe to it all.  You could do many of these projects yourself.   If you see something interesting, it is likely that the person who created it is sitting right there and you can talk to them about how they did it.  And, there are classes and activities that let you get your hands dirty creating something right there at the show. If you attend, you can see people performing music with giant Tesla coils:

You will find strange combinations of art and technology.

Our old family friend Fritz Grobe (half of EepyBird) will be there performing his famous Coke and Mentos tricks

The Maker Faire is a truly inspirational event.  We have been there every year since the very first one in 2006 and had things to show more often than not.  But, this year we will go as spectators, and I'm really looking forward to seeing what is in store this year.

See you at the Maker Faire!

Monday, May 14, 2012

Hackers and Unintended Gadget Music

I've been reading through the 25th Anniversary addition of the book Hackers by Steven Levy.  It chronicles the early days of the computer revolution and tells the story of some of the lesser known visionaries and revolutionaries that provided us with the technology that we take for granted.  It's quite a compelling view of an exciting time of change.

One of the stories that struck me was the first (or second depending on whose account you believe) meeting of the Homebrew Computer Club in 1975 where Steve Dompier managed to get his MITS Altair 8800 to play the Beatles song "Fool on the Hill" and  "Daisy Bell," the classic bicycle built for two song made famous by early computers and the film 2001. Actually, saying that it played the songs is a bit misleading.  You see Steve had noticed that his computer was causing interference on his nearby AM radio.  By figuring out exactly what actions in software caused particular tones on his AM radio, he was able to fashion together a scale and then play an entire piece of music.  He used a set of toggle switches on the front panel of the computer to enter in the the binary code required to play the music.  No keyboards here.  No MIDI.  No computer sound cards.  This was hardcore.

What I love about this story is that its all based on the unintended consequences of the system.  Nobody designed the Altair to make music, but Steve noticed some quirky behavior and followed it.  The result, in 1975, was a group of hobbyists were inspired, as were the people who saw Steve's program published later on.  They were inspired to go play with this new technology themselves.  They were inspired to explore and find out where it would lead.  These were the people who shaped the personal computer industry later - Steve Wozniak, Steve Jobs, Bill Gates, etc.

The whole idea of finding music in technology where it wasn't intended was refreshed in my mind by the much more modern video below, which has 8 rocking floppy disk drives playing "What is Love." The rhythm of data - pretty awesome and pretty dancable I think.

FYA, Below is a reconstruction of the original Altair playing Daisy

Sunday, May 13, 2012

Rocket Launch!

Bix with her Rocket, Buttered Bacon
Buttered Bacon
on the
Launch Pad

A few months ago, Bix had built a model rocket and we finally got a chance to launch it.  Yesterday we went to NASA AMES for the LUNAR rocket club launches.  Its pretty spectacular to actually launch your own model rocket from a NASA facility.  Widdakay launched one a couple of years ago, but this time it was Bix's turn.  Of course, it's not good enough to be just like her brother, so  Bix's rocket, "Buttered Bacon," was a complex, two stage rocket with a payload section.  The first launch went flawlessly with both stages burning and the rocket shooting straight up almost out of sight.
With one solid launch under our belts, Bix and Widdakay decided to go for a second launch, but this time they included a special high-tech payload.  While Bix designed her rocket, Widdakay designed and built an electronic payload that packed 11 sensors into ~12 grams and fit in the payload compartment of Bix's rocket.

For those of you unfamiliar with model rocketry, these rockets are made mostly of cardboard and balsa wood parts.  The run off of a small solid propellant that is remotely fired with an electronic igniter.  The rockets then launch themselves up into the air.  The propellants are designed to push for a period of time and then "coast" for a while before firing a small ejection charge in the opposite direction which effectively puts pressure into the tube which causes the nose cone to pop off and pull out a parachute which allows the rocket to gently return to earth.
Widdakay's Sensor Payload Unit
Widdakay's was designed specifically to measure the flight of these small rockets.  The tiny payload included 3 accelerometers, 3 magnetometers, 3 gyros (for each of the three dimensions) as well as a temperature sensor and lastly a barometric pressure sensor.  The little package was designed to log all this telemetry data to a microSD card for later analysis.  For those of you who are interested, Widdakay built this on an Arduino ProMini and had some fancy software to poll all the sensors about ten times per second and even do a little bit of complicated math to calculate quaternions, which are a fancy way to represent the orientation of the rocket.

This second launch was a bit nerve racking because another person with the same two stage rocket design had just had his rocket explode on separation of the first stage.  After all the work that had gone into it, we didn't want to lose our rocket or payload.  Our analysis of the failure was that there was too much pressure when the ejection charge went off on the first stage, and it caused the catastrophic failure.  We were concerned that this problem could affect Buttered Bacon, so we quickly cut a couple breathing holes in the first stage to allow it to vent the ejection charge.

The chute didn't fully deploy, so the rocket descended quickly
The launch went smoothly with both stages firing smoothly and the rocket seemed to go nearly as high as it did in the first flight, even with the added weight of the payload.  At its apogee, the ejection charge fired and the chute came out, but it never fully deployed, so the rocket came down much more quickly than we wanted.  It landed pretty hard onto the concrete runway of NASA AMES.  Thankfully, on inspection we found very little damage to the rocket and only a few bent pins on the payload.

On site data analysis
Next it was time to interpret the data.  It seems that due to occasional glitches in the hardware, occasionally data would get corrupted.  While the data loss was minimal, it did mess up the formatting enough that it made it difficult to interpret the data right there on the tarmac.  Instead we decided to head back to the Digital Diner and do our analysis there where we have access to tools like Google Refine which helps immensely in cleaning up raw data.

After we trimmed away all the data from the rocket standing on the launchpad and the corrupted lines, we were ready to start our analysis.  Of course, one of the first things we wanted to find out was how high did the rocket fly?  To do this, we looked at the data from the barometric pressure sensor.

The data shows a beautiful dip in atmospheric pressure starting just at liftoff, continuing for about 6 seconds and then over the next 20 seconds or so, returning to its original reading.  This is just what we would hope to see.  It shows that the barometric pressure dropped as the rocket shot up in altitude.  Thankfully, since the relationship between pressure and altitude is well understood, there is an equation that can convert this to value to altitude of our rocket. 
By applying this to our data, we get the following curve:
According to this data, the height at apogee was 483 ft and it happened about 5.6 seconds into the flight.  Pretty cool!  We got this information from just one sensor.  We have plenty more to analyze.  We'll do a complete analysis in a short paper, but for now, lets just look at the accelerometers to see what we can learn.  Below is a view of the accelerometer data for the first few seconds of flight.

At first, what you see is two accelerometers (accel X & accel Z) reading zero, while accel Y(the blue line) reads about 1 G.  This is just what you would expect from a rocket sitting still on the launch pad.  The X and Z accelerometers were horizontal, while the Y accelerometer is pointing up and down, so it is being pulled toward the earth at exactly 1 G.  When the rocket engine fires, we see a big burst of acceleration in the same orientation as gravity (ie the Y direction) as the rocket lifts off.  This maxes out at about 6 Gs worth of acceleration and then begins to drop off.  Within about a second, this engine has died out and the second stage starts to burn.  Now with a much lighter rocket, the acceleration reaches nearly 10 Gs.  By the end of this burn, the rocket has reached it's top speed.  As this second stage burns out, you can see the rocket begin to coast.  

At the beginning of the coasting phase, there is a slight negative acceleration on the blue line, as the friction of the air slows the rocket down.  Eventually, as the rocket reaches its apogee you will notice that all the accelerometers read approximately zero.  This is because as the rocket is in free fall, which to the sensors (and you if you were in the rocket) is indistinguishable from weightlessness.  If you are falling at the same speed as everything around you and nothing is stopping you from falling, you will experience weightlessness.  This is what astronauts feel as they are in orbit.  Essentially, they are continually falling towards the earth (and missing) and they experience weightlessness in just the same way as the sensors in this little rocket.  

Eventually this weightless bliss is violently interrupted by the ejection charge.  You can see that the nose cone (with the sensors in it) is pushed away from the body, but then gets caught on the rubber tether that holds body and the nose cone of the rocket to the parachute.  It looks to me as if it bounces around a couple of times before the chute unfurls which shows up as a nicely dampening oscillation in the acceleration.

We have plenty more sensors to analyze, but this post is getting a bit long.  We will try to write up a little paper and publish it here for those of you who are interested in such stuff.  Stay tuned. 

In the mean time, thanks for reading this far.

Friday, May 11, 2012

The Real Terry Gross

This one is for those of you who fans of Fresh Air on NPR.  Terry Gross is one of the most amazing interviewers on the radio.  This short film gives you an idea of what she is like after the interview.  If you've ever heard Terry Gross, you really need to see this short film.  Trust me on this.

Lets Dance...

For your entertainment:
Dubstep is a genre of electronic music that seems to spawned a very interesting dance style to go with it.  I must say, I haven't seen anything like it.  Take a look at this video and let me know if you agree.

As an aside, The section where one of them is dancing with a shadow reminds me of an old post here on Digital Diner of a young woman playing violin and dancing with her shadow.  Well, Just to follow up on that... Lindsey Stirling, the violinist in that video, has now gone off to Kenya and played violin to the Ven Tribe, many of whom had never heard a violin before in their lives.  Certainly makes for a cute video.

Anyway, back to the Dubstep dancing... If you like the guys at the top, you may want to check out a few of these other videos.  You'll find plenty on YouTube.

Mirage Table

Microsoft has been playing with their Kinect 3D sensor to create interesting, collaborative, virtual 3D spaces in a system they call the Mirage Table.  In the process they found a new way to play with dominos that I didn't mention in our recent post.  I think the most compelling part of this demo for me is the idea of sitting across the table from a remote person and sharing a 3D space.  Pretty cool stuff.

Wednesday, May 9, 2012


I remember always wanting an Etch-a-sketch as a kid.  The simplicity of controlling the cursor with two knobs; horizontal and vertical.  Drawing smooth curves with these two controls was an exercise in motor control.  I'm pretty sure that it helped me understand circle drawing algorithms later in life.  They were so much fun to play with and they were so process based.  Once you drew something, it would inevitably get bumped and then your work of art was lost forever.  Plus it was made by a company called Ohio Arts, which was a big plus for me as a kid growing up in Ohio.

Well, a friend of mine is involved in a project to try to bring some of that pleasure into the 21st century with an accessory to the iPad.  Its Etch-a-sketch for a new generation.

Check out the Kickstarter for Etcher: Etch-a-sketch for iPad


Dominos (Not the pizza place with the cool delivery scooter - the little rectangular blocks).  I hear there is a game that you play with them, but I think they are best known for lining them up in a row and then tipping the first one so that they fall like... well... dominos.  The world record is apparently over 33,000 dominos in a single spiral.

Dominos are also used to make pool shots.

It turns out however that there are a lot of other things that will fall over like dominos when lined up properly.  For example, how about human's tied to mattresses?

Or how about shot glasses?
or beer bottles?

You can find more at Yahoo Games

Monday, May 7, 2012

Sea Lions

Just outside of San Simeon California, across the street from the Hearst Castle, there is a beach where elephant seals gather.  Over the course of a year, these seals travel thousands of miles, but they always return to this one spot for birthing, breeding, molting and rest.  We stopped by there last week to see the seals and take these pictures.  The big bull seals (14-16 ft long - the size of a Volkswagen bug) were not there, but there were plenty of moms (only 9-12ft long) and babies (<5 years old).  They were busy doing what people do on the beach in California - soaking up the sun's warm rays.  Truth be told, I really think they look like giant slugs lying there on the beach and they sound like they're burping all the time.  It's not really so pleasant.  But, when you watch them in the water, it is entirely different.  They are graceful and beautiful.  Its no wonder they spend most of their lives at sea.  Although they are air breathing mammals, they dive down to 5000ft and can hold their breath for over an hour.
The web cam
The seals on this beach have their own website,  There is plenty of information there about these amazing animals, including a live web camera that lets you watch them right now.

Throwing warm sand on my back feels good.
Boys will be boys



DSLR Simulator

For the last thirteen years, here at Digital Diner, we've taken an average of nearly 1000 pictures per month.  As a kid growing up, I remember getting interested in photography, but finding that the slow turn around between taking the picture and developing it and seeing the results to be de-motivational.  Digital cameras changed all that.  With instant feedback and meta information that tells you exactly what your settings were, there is immediate gratification.  I learned so much more, so much more quickly once I could easily tie my actions to the results.  I had used a film Single Lens Reflex (SLR) camera for years before I started taking digital images.  Early digital cameras were fairly simple and actually not very good.  It was several years before I switched to Digital Single Lens Reflex (DSLR), and interestingly, it took a little while to get good pictures out of the DSLR.  These cameras can be a bit daunting.  Like driving a sports car, these cameras require some extra attention, but the results can be well worth it.

That is why I was interested to see that someone has created a DSLR simulator on the web.  Its an interesting little web page that lets you play with the different parameters to see how they affect your image.  Give it a try.  I think it can help make the transition to DSLR a little easier.

Sunday, May 6, 2012

Jailbreaking the Degree

Monika and I were talking a bit today about what the changes in the educational system will mean to future generations.  What happens when classes from Stanford, MIT, Harvard and other top tier universities are available for anyone to take.  Suddenly admissions to the university changes completely.  In a sense, everyone who wants to try is admitted, just by signing up for a class.  The value then is in the degree.  There may be a future world where students just take classes as they see fit.  Then eventually they bring their transcript and a large check to the dean and say, "I'd like a degree please."  Only then would the university actually scrutinize the student's accomplishments, take their money, and grant them a degree.  Under this model, you can take all the courses you want, but ultimately, to get the degree, you have to write that $200k check to get your Stanford degree.  It reminds me of a conversation a colleague had with his professor at a high end university about degrees.  He asked, "why is it that you let so many kids go through several years of work only to let them fail out at the end?  Why not just give them the degree?"  The professor responded, "Each degree that we give out just cheapens all the ones we've already given."  That professor clearly sees the degree as the scarce, and thus valuable, resource.

Interestingly, the folks at TechCrunch started thinking along the same lines, but instead saw a parallel to how the music industry has changed in the last few years.  They think that the current degree-based educational system is analogous to albums in the music industry.  iTunes has been a major force in changing the music industry (for better or worse) toward a pay-by-the-song economy.  You can read about their ideas for jailbreaking the degree here.

InstaPoem for Mother's Day

Mother's Day is coming up in a week.  For those of you at a loss for what to do for the woman who brought you into the world, here's an idea.  How about writing her a poem?   What's that you say?  Poetry isn't your strong point?  Well, the internet comes to the rescue again.   There is a site that asks you a few questions and then composes a personal poem just for you.  OK, OK, so maybe this isn't the most personal approach one could take to Mother's Day, but it is an interesting concept.  Take a look.

Saturday, May 5, 2012

RWC Super Moon

This is what the "Super Moon" looked like in Redwood City.  It was indeed very big and bright.  I hope you got to see it... It always makes me feel good to know that people I care about who are far away can look up and see the same moon as me.