recent stereoscopic images

For my nearsighted friends, here’s another batch of images. So take off your glasses, look into the distance and hold you smartphone about 18″ from your nose!

winging it

the wood lot

Nick found a chew bone

finished mowing

new red shoes

a Raspberry Pi iGate which meets performance specs

My supply of OLPC XO-1 laptops has really dried up. I currently have two – the one that has faithfully been running my iGate for the past 3 years and a backup just in case.

Over the past 9 months, I built 15 iGates using that design. eBay was a good provider Smile

I still get requests for iGates. Given the laptop was the only “used” item, I started looking for a solution that was 100% off-the-shelf new parts. The Raspberry Pi was the logical choice.

pigate

After months of experimenting with combining a Raspberry Pi with and SDR (software defined radio), I concluded the design worked but required strong, nearly perfect radio transmissions. Since APRS is predominantly transmitter in motion, the signals are rarely perfect and seldom strong. Eventually, I caved to the realization that – while I could build such an iGate – it would not perform.

I went back to the drawing board and took my tried and tested iGate design. The laptop has four useful components built it – a computer, a screen, a keyboard, and wireless. While I could add all of those to a Raspberry Pi, it didn’t work from a cost stand point. With some basic computer skills, a “terminal” connection using SSH from a regular computer can access the Raspberry Pi to do the minimal configuration needed. That eliminated the need for a screen and keyboard. The network option of a wired connection vs a wireless connection was nearly 50:50 with the people who wanted and iGate – thus I consider it an option rather than a required part.

In the end, I was able to create an iGate using a Raspberry Pi that has the same software architecture of the XO-1 Laptop. I used Debian as the base linux operating system. I Used Soundmodem which turns a sound card into a TNC. I used APRX for the iGate software. I used a low cost handheld HAM radio to receive the transmission.

Here is a list of all the components which can be sourced from Amazon.com. If you had nothing lying around and you had to purchase everything, the cost is 47+5+4+5+4+30 = $95. Included in these prices is the antenna adapter for the radio. I included it because nearly everyone who asked for an iGate needed that adapter. FYI – The pictured system has an beefier radio (+$9) and WiFi (+$9).

I have an image of the final SD card. After I run it for a week as my primary iGate, I will de-personalize it, compress it, and try to post it to this blog.

Addendum: If you want more USB ports and want to avoid the SD card sticking out, there is the new Raspberry Pi Model B+ ($46) which uses a microSD card and has 4 USB ports. It does require a different case which have limited choices but expect the availability of the B+ and cases to become more prolific in the near future.

Advanced yoga balancing posture

This is for my yoga friends, here is an advanced balancing pose for you to try !

It requires one sock. Place the sock on the floor right in front of you. Take a deep breath and move into the tree pose as you’re starting position. Next, transition to half downward dog. Pick up the sock. Transition back to tree pose. Now move the hand holding the sock down toward the bent knee. This is where it gets tricky …

maintain you balance while your dog attempts to wrestle away the sock before you can put it on your foot!

I call this “tug of warrior” pose :-)

Photo testing the Nexus 7

sunrise photo using Nexus 7 camera (click for original)

sunrise photo using Nexus 7 camera (click for original)

 

I’m in the process of evaluation the Google / ASUS Nexus 7 tablet. This is the 2013 or 2nd generation model.

The primary test is as a aviation flight planning and navigation device. I’ll be comparing it to the iPad Air. (The iPad Mini would be a better test from a size or portability perspective but I don’t own an iPad Mini.)

While I have the Nexus 7 I decided I should also test it as a general purpose mobile device since most people would not buy it as a unitasker.

The camera takes pictures which are 2592×1944. I decided a sunrise would be a good test with its extreme dynamic range. You can see the full size by clicking on the picture.

Note: this blog automatically recompresses images to 85% quality so the original image on the devise is a larger file size and is somewhat less grainy than the copy on this blog.

Personal drones – who gets to decide ?

Someone created a video of fireworks using one of the growing populations of quad-copters. This is not actually a drone. It’s really an remote control aerial craft. (I’ve decided to differentiate RC craft from drones by the presence of autonomous flight capabilities – which are now available on some of these personal devices.)

Anyway, the video shows a professional fireworks display recorded from the quad-copter and the operator flies the craft right into the display.

There are lots of comments on the video and most fall into either "beautiful" or "safety". However, there is another category I did not see voiced – "who gets to choose?"

Here is my first line of questioning …

Can people attending the event see the quad-copter in the fireworks ? Does it detract from the visual display? I’m guessing a few people may have seen it as it was illuminated by one of the bright explosions but probably not too many people actually noticed it.

Here is my second line of questioning …

The operator of the quad-copter thought it was cool to fly his craft into the fireworks. OK, unless there is some regulation, let’s assume he is within his rights.

Now, in 2015 and 10 million people have seen the video and think it is really cool. 1% of those want to make their own video of fireworks up close. 1/10 of 1% of those happen to choose the same display. There are now 100 quad-copters flying within the same fireworks display.

What happens when 100 RC craft are flying in close proximity to each other ? Will 100 quad-copters be visible to the public ? Will 100 quad-copters run the risk of colliding and crashing? What happens the next year ? Or at some other event ? What happens when those quad-copters are upgraded to drones ?

I’m not answering any of the questions I pose.

the video that got me asking these questions

What’s It #22 – commercial coffee grinder burrs

Grindmaster 875 - 5lb coffee grinder
Grindmaster 875 – 5lb coffee grinder

I've had a Grindmaster coffee grinder for a few years. Recently, while getting a tour of Eastern Shore Coastal Roasting Co., I spotted a similar (but much newer) Grindmaster. It turns out they had recently picked it up on the used market and it was in need of a good cleaning and tuneup.

I offered to take it home and go over it completely.

The machines are made to be easy to work on. I disassembled the outer housing and found lots of old coffee grounds inside. Add some humidity over a few years and there was caked on crud in random corners.

After getting it all clean on the outside, I removed the motor and disassembled the grinding unit. Once it was clean, I inspected the burrs.

One thing seemed odd. The burrs seemed to fit better than I had recalled from my own grinder. Curiosity got the better of me and I had to pull the burrs from my own unit and compare. Indeed they are different.

difference - ignore that the auger is attached to my burrs
difference – ignore that the auger is attached to my burrs

I finished the cleaning and reassembled the grinder (and put mine back together too). I polished the hardware and the grind setting knob for good measure. I then adjusted both grinders and ran a test grind at different settings to compare.

While the burrs of my unit are newer, the ESCR grinder actually runs easier. My grinder tends to want to clog at the finest setting.

grind test
grind test