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Posted by Jack Crossfire | Jul 05, 2015 @ 05:15 PM | 2,311 Views

This was the ducks guts for getting stereo with cheap electrets.

July 4 fireworks in San Francisco (3 min 44 sec)

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Posted by Jack Crossfire | Jun 28, 2015 @ 05:13 PM | 2,691 Views
After waking up expecting to see another rocket barely miss a barge or delayed launch, was surprised to see it exploded during liftoff. Of the 3 camera angles, the best one came from NASA TV, then was rereleased with banner ads & annotations.

Falcon 9 explosion from 3 cameras (1 min 13 sec)

The 2nd stage oxygen tank was the scene of many launch delays. Stuck valves, leaky pipes abounded. Not surprising that it finally blew up, probably from a stuck valve.

It's now been 2 consecutive failures in reaching the space station. The last successful mission was April 14. The Soyuz on April 28 failed. The last Cygnus attempt failed on Oct 28, 2014. Only 4 of the last 7 missions made it. The chance of reaching Mars has been better than reaching the space station.

The increasing rate of failures as rocket companies reach ever higher valuations makes you wonder when something has to work to be worth $10 billion & when it just has to be worth $10 billion to prevent a recession.
Posted by Jack Crossfire | Jun 20, 2015 @ 05:45 PM | 2,379 Views

NASA's last space shuttle external tank to complete Endeavour L.A. exhibit

Another win for Calif*. Now only the boosters will be fake, if the exhibit is ever funded. Completion was once envisioned in 2015, then it was 2018, but it was always based on donations & refinancing. If ever delivered, it'll be another spectacle as its transported down the streets of LA. Too bad some water can't be delivered in the tank.

Nearly a year after its inception, the travel fan has been highly successful at defeating the heat. It hasn't chopped any limbs off, hasn't tipped over. Keeping it close & blocking off the area around it has kept kids away from it. Humans are strangely attracted to putting their hands in spinning blades, especially Americans. Limiting the power to 1/4 power has left enough airflow on 12V.

On the downside, it became clear Chinese RC motors aren't capable of running continuously for days. It wasn't long before its RPM fluctuated, then it sometimes stalled & clicked. The bearings failed. Frequent lubrication has kept the bad bearings going.

Also, it's still noisy, despite every effort to silence PWM noise. The commutation noise & shaft resonance are deafening at low RPMs.

The 15 year old squirrel cage blower would make a comeback if not for the fact that it needs to be hosed down with a high pressure nozzle & the outdoor water was shut off.
Posted by Jack Crossfire | Jun 19, 2015 @ 11:33 PM | 2,566 Views
Posted by Jack Crossfire | Jun 18, 2015 @ 01:40 AM | 2,525 Views
Finished it in 32 miles of pounding up & down the trail. The title alone conjured the imagination. Long ago, Carl Segan said one day we would find life on Mars & the martians would be us. The title was obviously a play on that nugget.

It definitely has a few flaws. The mathematical descriptions sometimes get tedious, yet some of his solutions to problems are over simplified & wouldn't really work. It's technical sounding enough to sound like everything is factual. Sounding accurate is what it does better than any other book.

Otherwise, it works. It's easy enough to see how the general direction in the hacking of the various parts could work in real life. It's interesting to see how many different ways the oxygenator & water reclaimer could be basterdized to do virtually any task & to imagine a world where NASA produced stuff that really did work. If the movie is done right, it could invigorate a lot of interest in funding a space program, for a time. A book isn't accessible enough to reach enough people, but a movie might.

There were many attempts to make a movie about traveling to Mars. None got it right, showing how hard the task was. This one might get it right.

In other news, Fitbit finally had their IPO, but more importantly in today's terms, was valued at $4 billion. In creating unlimited free credit, Old Yellen solved the problem of monetizing private data that companies had no right to sell. They would just sell...Continue Reading
Posted by Jack Crossfire | Jun 14, 2015 @ 10:46 PM | 2,488 Views

The decision was finally made to retire the 4 original, low efficiency monocopters & the world's greatest battery charger to the landfill.

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Posted by Jack Crossfire | Jun 13, 2015 @ 01:57 AM | 2,103 Views
Realtime running form feedback

There was the vaporware, which claimed to capture running form for viewing at a later time. Fitbit & all the other uprated pedometers captured step rate for viewing at a later time. The trick is none ever provided realtime feedback. They were all intended to gather data for the company to sell to advertizers, not focused on providing any realtime feedback to the user.

A metronome is very good at providing realtime stimulus for step rate. The same thing hasn't been achieved for kinematics. Step 1 is capturing the body positions. Maybe accelerometers or autonomous drones could do it.

Step 2 is stimulating the athlete to adjust positions. A key stimulus would be moving a leg vertically or leaning at the right angle. Maybe pager motors could be strapped to the limbs. Nowadays, they're called "haptics" & worth many billions of dollars. To a child of the 80's, they will always be pager motors. There are also ways of creating brief pushing & pulling forces, by moving weights. Actuators for training body movements could be too heavy.

A kinematic simulating device would allow you to feel how a famous athlete poses. Famous performances could be recorded & played back through the pose stimulators. Reproducing a dance move with subtle pushing forces from actuators might be extremely slow & tedious, but something repetitive like running might be more practical.
Posted by Jack Crossfire | Jun 10, 2015 @ 12:20 AM | 2,877 Views
Posted by Jack Crossfire | Jun 08, 2015 @ 11:44 PM | 2,608 Views

So after running to the Apple store & waiting 30 minutes for a guy to finish with the 5k monitor, it became quite clear that I didn't have enough money to develop a 4k user interface. Had created a mockup to test out asset sizes, based on downloadable screenshots. It was too small on the 5k monitor. The screenshots were for a completely different monitor that the author had no idea of the resolution of.

The original plan was to make assets double the size of a 2.5k monitor, but the downloadable screenshots showed them using 1.5x the size. In the end, 2x size was probably right. Also, instead of making a fully functional interface, it would be best to just mock up a screen with the desired sizes. It's still completely impractical to design a user interface by loading mockups in an Apple store.

The standard resolution of the next generation of monitors will probably be 5k instead of 4k, just as it was previously 2.5k instead of 2k. The extra pixels allow a complete video frame to fit in a user interface. It makes sense when going from 2.5k to 5k to double the asset sizes. It's also much easier than making them 1.5x. It may be necessary to have double size assets for 5k & 1.5x size assets for 4k.

Unfortunately, I grew up in a time when the best monitors consumers could get were $200. Now, the crappiest 4k monitors are $400. The 5k Apple monitor has a $1900 tag & requires also paying for the embedded computer. Paychecks are getting smaller & rent is going up by amounts that would pay for a new 5k monitor every month. It's 1 of those times you realize the limits of mortality. Mortals can't save money or have everything.
Posted by Jack Crossfire | Jun 07, 2015 @ 01:52 AM | 2,511 Views

After much debate, finally built it. The RC fan shroud was noisy & reduced airflow. A screen which allowed air through might do better than cardboard. The motor is still too noisy, so the debate is on about reverting to the larger motor.
Posted by Jack Crossfire | May 31, 2015 @ 09:00 PM | 3,556 Views
Solar powered rover photovore thing:

These were popular, 10 years ago. They have no purpose besides reusing parts. There are some giant electrolytic caps & solar panels are slightly cheaper than the old days. The mane problem is all wheeled vehicles get stuck. There was a ramp up in photovore videos when they were popular, then nothing more to do with them was found.

Bluetooth sliding door lock:

The mechanics are simple, but the encryption is hard. Keyless entry systems have been around forever, but are actually an interesting problem. You can't just send a fixed packet to unlock them. The receiver & transmitter contain a pseudo random number generator which is synchronized. Every unlock command uses a different code from the random number generator. If an unlock command is missed, the receiver tests a certain number of future codes. The receiver can only miss a certain number of commands before it requires resynchronization.
Posted by Jack Crossfire | May 30, 2015 @ 11:45 PM | 2,943 Views

The 1st video card. It was PCI. None of this AGP, PCI-E nonsense. It's not about the performance as much as the memories. It was upgraded to some ghastly amount of memory for its time. The day it was upgraded, there was a geeky old guy in the same room, slobbering over a dual Pentium II he just received. It was the seed for the idea of a dual CPU. In the meantime between then & the dual CPU, this card went from 16 to 24 bit color. What an improvement.

The 2nd video card was for the dual CPU & had a lot of issues. After this came the era of freebie's which lasted until 2006. The next video card will be the 1st one bought since 1999.

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Posted by Jack Crossfire | May 27, 2015 @ 11:17 PM | 2,576 Views

Recycled the last of the through hole components.

After recycling most of 2 old power supplies, it became clear that more through hole components had been reclaimed than would ever be used in the rest of my life, so many parts were left.

The 20 year old Soundblaster had some through hole. A lot of memories came from that card. It was a miracle for a computer to play any amount of PCM audio, in those days. This card still had a muddy sound, compared to the best. It was a rare one which could do full duplex, with enough coaxing.

It only did 44.1khz. Had to upgrade to a new one when 48khz DVD's came along. The 48khz couldn't record higher than -3dB. It gave up a 24khz crystal, which makes the 44.1khz limitation seem like a driver issue. It would never have been replaced if that was known.

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Posted by Jack Crossfire | May 25, 2015 @ 07:18 PM | 1,991 Views

Decided to revive the XV-11 LIDAR, after failing to find a convenient way to wear a sonar transmitter. It wasn't expected to work in daylight. The XV-11 remanes to this day the only 2D ranging device for a comprehensible cost. 4 years of kickstarter projects could do no better. 2 of the LIDAR modules were probably salvageable, with the 3rd taking some doing.

After a year since the XV-11 arrived, it was finally rebuilt & plotting 2D scans as designed. The error rate bottomed out at 250rpm. Below & above, it increased. It depends on stable motor movement as well as speed. The scan resolution is limited to 360 points. You'd get higher resolution scans by sending a fake photo interruptor pattern down the TX line to the photo interruptor pad. Clock it as fast as possible & spin it with a hobby motor being driven in stepper mode.

After building up the software to assemble images & the dual power supply, it was completely useless in sunlight. If the camera got pointed at the sun, it shut down until power cycled. It couldn't detect any surface lit by the sun. In shade, things got more interesting. It could resolve a concrete path, grass on 1 side, & a curb on the other side.

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Posted by Jack Crossfire | May 17, 2015 @ 10:09 PM | 3,851 Views

Fired up a segment of the last sonar circuit, built 3 years ago. Stepped up the voltage to 41V with a 43k 100k parallel resistor network & after a period of fits & starts at 500mA, it ran off 2.5V 100mA just fine. It drove a pulse every 50ms. The voltage hitting the transducer would have been slightly less than 41V.

The next steps are building up a new receiver & recording the waveform on an actual drive. Skepticism keeps progress slow.
Posted by Jack Crossfire | May 16, 2015 @ 02:48 AM | 3,490 Views
It's quite clear that there's not enough time to do any projects at home, anymore. After 3 hours of commuting, the amount of stretching & high vegetable eating required to do all the things this body does consume about all the time.

There's an idea for a monocopter based on a single chip for the radio & computer, with a hacked ESC for silent operation. There's an idea for path following.

Tracking the athlete once again presented a better solution than tracking the path. Sonar presented a better solution than vision, because of the problem of consistent lighting of a target. It would depend on GPS to get the direction of the path. It would use the athlete's position to get the sideways position on the path.

For all the times sonar appeared, it has never worked. The ambient noise on the receiver side is too high. It's too directional. There are too many echos. There aren't any echos outside. The athlete would have to stay in a cone of directionality.

But there are times when staring at a schematic for the day job when you remember staring at schematics as a young boy. They were neat looking drawings of which you knew nothing of the function, only that the collection of lines did something important & better than any human could.

Now, sometimes, you do get paid to stare at the schematics of complete consumer products & know the functions of most of the parts. A lot of livelihoods depend on you to make the once mysterious drawings work, sometimes rework them, sometimes design them. There are still a few mysteries in the analog stages & it's not long term at the rate prices are rising, but for now it's what you want to do, you run along the waterfront every day, you get free lunches, & your boss isn't completely crazy.
Posted by Jack Crossfire | May 14, 2015 @ 11:25 PM | 8,330 Views

So do you feel like an idiot for spending $1400 on a 30" 2560x1600 monitor, 7 years ago? Of course not. The 30" provided $1400 of content. It's going to continue doing so until a system capable of producing 4k video becomes affordable.

Making software look right on a 4k monitor is another matter. For now, it amounts to doubling the font size which looks right on a 2k monitor & hoping for the best. There's also examining the software in the Apple store. These monitors are 3840x2160, only 1.5x the resolution. There's no interest in slowing a program down with dynamically scalable assets.

No-one wonders anymore what technical challenges had to be overcome to make a 4k monitor. They just magically appear from South Korea.
Posted by Jack Crossfire | May 13, 2015 @ 11:08 PM | 2,480 Views

Photos of the world wars get more fascinating as they drift farther into the past. Germans of WWI look absolutely alien, nowadays. Part of it might be the alien gas field they're fighting in.

The ruins of WWII still surround us every day. They are a reminder that a world war in what was perceived as a modern age was fought with nothing more than crude sticks & stones. That was the best they had.

Why hasn't something like that happened again in almost 100 years & when will we have to fight something like that again? As long as 1 country held a dramatic advantage no-one else could win against, there was no world war, but the field is leveling again. The happy time won't last forever. It mathematically can't. All armies must regress towards the mean & have a chance against each other, eventually.
Posted by Jack Crossfire | May 12, 2015 @ 01:29 AM | 3,929 Views
Another day of testing path footage revealed the mane problem is detecting the horizon. The RALPH algorithm requires the camera to be pointed down from high enough to fill the frame with some distance down the path. The Tamiya is too low. Even with GPS aid, it was still unsolvable without spherincal LIDAR. 10 years on, spherincal LIDAR is still more than the cost of a new car.

It turns out all the LIDAR modules GOOG uses are made by 1 company, invented by 1 guy in search of a use for a real estate investment that went bust in 2001. There was a nifty video about it.

Velodyne: On Sound, LiDar, and Marine Technologies (25 min 7 sec)

A good reminder that if a real estate investment had to go bust for the innovation to happen, how much innovation can happen in a world without recessions, where there is no interest on credit, no limit to borrowing, any invention no matter how small has infinte valuatioin.

Also a good reminder that 10 years on, no-one at the Goog has a clue how to make an audio limiter. They just know how to recite 50 path following algorithms in interviews.
Posted by Jack Crossfire | May 11, 2015 @ 12:35 AM | 2,832 Views
Goog produced many videos vaguely describing how their self driving car worked, in 2013. Then, they stopped discussing how it worked & focused more on philosophy. No matter who the employee is, whether it's a marketing guy, middle manager, or an engineer, they all show the same slides, show the same videos, read the same lines. It's a perfect corporate machine.

Embedded Linux Conference 2013 - KEYNOTE Google's Self Driving Cars (24 min 27 sec)

They reveal hardly anything about how it works. The mane nuggets are it uses GPS to get a rough position fix. Then it matches the current LIDAR image with a 3D map of the world to get the exact position. LIDAR detects landmarks & pedestrians. Radar detects metal objects like cars. They have to manually drive every route the computer drives, to make a 3D map of the world, manually entering all the traffic rules, all the lanes, all the traffic light positions.

It doesn't use vision for anything besides traffic light color. They made no mention of vision detecting lane markings, unlike lane keeping systems. Lane keeping systems must have proven too unreliable for a fully autonomous car.

Infiniti Q50 Active Lane Control - Selfdriving Car (2 min 6 sec)
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