When we first started hearing about software-defined radio hacks (which often use USB dongles that ring it at under $20) we didn’t fully grasp the scope of that flexibility. But now we’ve seen several real-life examples that drive the concept home. For instance, did you know that SDR can be used to track ships? Ships large and small are required by may countries to use an Automatic Identification System (AIS) transponder. The protocol was originally developed to prevent collisions on large ships, but when the cost of the hardware became affordable the system was also brought to smaller vessels.
[Carl] wrote in to share his project (which is linked above). Just like the police scanner project from April this makes use of RTL-SDR in the form of a TV tuner dongle. He uses the SDRSharp software along with a Yagi-UDA. The captured data is then decoded and plotted on a map using ShipPlotter.
This is [Paul Mandel’s] Ground-truth velocity sensor. That’s a fancy name for a device which tracks the movement of a vehicle by actually monitoring the ground its travelling over. This differs from simply measuring wheel rotation (which is how traditional odometers work) in that those systems are an indirect measurement of motion. For us the interesting part is the use of an ADNS-3080 single-chip optical mouse sensor on the left. It’s cheap, accurate, and only needs to be ruggedized before being strapped to the bottom of a car.
[Paul] designed a case that would protect the electronics and allow the sensor to mount on the uneven underbelly of a vehicle. The optical chip needs to be paired with a lens, and he went with one that cost about ten times as much as the sensor. Data is fed from the sensor to the main system controller using the PIC 18F2221. One little nugget that we learned from this project is to poll a register that always returns a default value as a sanity check. If you don’t get the expected value back it signals a communications problem, an important test for hardware going into the vibration-hell that is automotive technology.
Instead of walking his kid to the bus stop like he used to, [Paul Wallich] lets this quadcopter watch his son so he doesn’t have to. It is quite literally an automated system for tracking children — how wild is that?
The idea came to him when wishing there was a way to stay inside the house during the winter months while still making sure his kid got to the bus stop okay. [Paul] picked up a quadcopter kit and started looking at ways to add monitoring. He found the easiest technique was to include a cellphone and watch via a video chat app. But that is only part of the build as he would still have to fly the thing. After searching around he found a beacon that can be placed in the backpack. It has a GPS module, an RF modem, and runs a stripped down Python scripting shell. Whenever the GPS data changes (signaling his son is on the move) it uplinks with the quadcopter and gives it the new coordinates.
This goes a long way to making your family a police state. May we also recommend forcing the children to punch a time clock?
[G. Eric Rogers] is a radar-systems engineer who just happens to live within sight of the aircraft approach path for the local airport. We wonder if that was one of the criteria when looking for a home? Naturally, he wanted his own home-based system for tracking the airplanes. He ended up repurposing a motorized telescope for this purpose.
The system does not actually use Radar for tracking. Instead, the camera strapped to the telescope is feeding a video experimenter shield. A tracking algorithm analyzes the video and extrapolates vector data. From there, the base unit can be controlled by the Arduino via an RS232 interface.
There are some bugs in the system right now. The Arduino has something of an ADHD problem, losing interesting and going to sleep in the middle of the tracking process. [Eric’s] workaround uses the RS232 board to periodically reset the Arduino, but he hopes to squash this bug soon.
Check out this solar-powered Stirling engine (translated). The build is part of a high school class and they packed in some really nice features. The first is the parabolic mirror which focuses the sun’s rays on the chamber of the engine. The heat is what makes it go, and the video after the breaks shows it doing just that.
But the concept behind the mirror makes for an interesting challenge. The light energy is focused at a narrow point. When the sun moves in the sky that point will no longer be at an efficient position to power the engine. This issue is solved by a pair of stepper motors which can reposition the dish. It’s done automatically by an Arduino Uno which makes readings from four LDR (photoresistors) in that cardboard tube mounted at the top of the dish. If the light intensity is the same for all four, then the tube is pointed at the sun. If not, the motors are tweaked to get the best angle possible.
Continue reading “Sun-powered Stirling engine with automatic tracking”
Many of the hacks featured here inspire others to build on the creator’s work, and on occasion the positive feedback brings the hack to market. Last year we told you about [Wayne’s] creation, a system aimed at tracking down would-be game console thieves. He received a bunch of requests to document the tracker in full, so he decided to revise his creation and release it as Open Source Hardware.
As you might remember, his original tracking device was powered by an Arduino, which monitored an accelerometer and GPS sensor, reporting coordinates and movements to his mobile phone on demand. He combined the disparate components together on a single board, and started a Kickstarter for the project.
Aside from his original purpose of tracking stolen goods, he lists off an array of other uses, such as tracking the driving habits of your newly licensed teen, geofencing objects in certain areas and more.
If an SMS controlled all-in-one tracking system is something you might be interested in, check out his Kickstarter, or take a look at the documentation and build one of your own.
One of [Wayne’s] relatives had their house robbed during a blizzard/extended power outage, and as is typically the case, none of the stolen items were recovered. His nephew’s PS3 was among the pilfered belongings, which didn’t sit well with him. Taking a cue from police “bait cars”, he thought it would be cool to fit a dummy game console with a tracking device, should anything similar happen in the future.
He bought a hollowed out PS3 shell on eBay, filling it with an Arduino, an accelerometer, a GPS sensor, a small GSM modem with a prepaid SIM card, and a reasonably sized LiPoly battery. The system usually sits in a sleeping state, but when the accelerometer senses motion, the Arduino powers up the GSM modem and sends an SMS security alert to his mobile phone. Using his phone to control the tracking system via SMS, he can request GPS coordinates and directional information, which can then be relayed to the police.
His tracking system is a great idea since hawking stolen game consoles are easy money for thieves. If there happens to be a string of robberies in your neighborhood, you could certainly rest a little bit easier knowing that your Playstation doppelganger will let you know if someone is looting your house.