UPDATE: Roll your own GPS can now track twice as many satellites

diy-gps-module

[Andrew Holme] wrote in to tell us about some work he’s done to improve his scratch-built GPS receiver. He figured out a way to use the same hardware but double the number of satellites it can track to a total of eight. When we looked at the original hardware about a year ago it was limited to monitoring just four satellites. That’s the bare minimum for calculating position data. This will not only help increase the accuracy, but remove the problems that would have been cause if just one satellite was dropped because of an obstruction or other issue.

His solution is based entirely on using the FPGA in a different way. He had taken up almost all of the gates available in the Xilinx Spartan 3 chip. Now he’s implemented a CPU on the chip and is able take some of the work off of the hardware gate design by running code on it. He also found and squashed a bug in how the data was processed. He says his original work wasn’t taking into account the rotation of the earth when determining position. All of these improvements put his accuracy at +/- five meters even when he’s not tracking all eight satellites!

Reverse geocache based on STM32 and GPS wristwatch

reverse_geocache

[Renaud Schleck] somehow got lucky enough to find a GPS wristwatch in the trash. It had a broken LCD screen so its wouldn’t be of much use on that next hiking trip, but he knew it still had potential. He used the GPS module and a few other parts to build this reverse geocache box.

Reverse geocache is a container that is locked, opening only in a pre-defined geographic location. We’ve seen plenty of these projects around here, like this one that talks, or this one which was given as a Christmas gift. They’re popular projects both because of the unique method of getting at the prize inside, and because it doesn’t take a whole lot of hardware to build one. Once [Renaud] had the GPS module he simply need a user interface, locking mechanism, and a microcontroller to pull it all together.

The interface uses a screen from an old cellphone and one push button. The latching system is a tiny geared motor salvaged from a Laptop optical drive. These, along with the GPS watch board are all monitored by the STM32 microcontroller which he programmed using OpenOCD and the Bus Pirate.

[via Reddit]

Man tracks children using a quadcopter

child-tracking-quadcopter

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?

[via: theGrue]

Arduino data logger maps out the potholes on your morning commute

Now you can prove that you have the bumpiest commute in the office by measuring how rough your ride actually is. [Techbitar] calls the project the Bump-O-Meter. It uses an Arduino, GPS, and accelerometer to map out rough roads.

The hardware was built on a breadboard and [Techbitar] goes into detail about connecting and communicating with each module used. Once it’s running, the logger will read up to six sensors and record them to an SD card. In the video after the break he shows the method used to dump and graph the data. He starts by looking at the data in a spreadsheet. There are many fields included in the file but only three of them are needed to graph what is seen above. After narrowing down the number of columns he heads over to GPS Visualizer and uploads the data set which is then automatically plotted on the map.

In a Utopian society all city owned vehicles would have a system like this and the bad sections of road would automatically appear on the road crew’s repair list.

[Read more...]

Stacking GPS, GSM, and an SD card into an Arduino shield

A few years ago, [Phang Moh] and his compatriots were asked by a client if they could make a vehicle tracking device for oil tankers all around Indonesia. The request of putting thousands of trackers on tanks of explosives was a little beyond [Phang Moh]‘s capability, but he did start tinkering around with GPS and GSM on an Arduino.

Now that tinkering has finally come to fruition with [Phang]‘s TraLog shield, a single Arduino shield that combines GPS tracking with a GSM and GPRS transceiver. There’s also an SD card thrown in for good measure, making this one of the best tracking and data logging shields for the Arduino.

The shield can be configured to send GPS and sensor data from devices attached to an I2C bus to remote servers, or a really cool COSM server. [Phang] is selling his TraLog for $150, a fairly good deal if you consider what this thing can do.

Seems like the perfect piece of kit for just about any tracking project, whether you want to know the location of thousands of oil tankers or just a single high altitude balloon.

Tip ‘o the hat to [Brett] for finding this one.

Spoofing GPS and getting your own UAV

A couple folks over at the Radionavigation Lab at UT Austin successfully spoofed GPS to take control of a small helicopter drone this weekend. Of course, this attracted the attention of the Department of Homeland security, so you’d better stock up on GPS spoofing equipment while there’s still time.

The DHS, CIA, and US Military have a huge interest in spoofing GPS; Iran stole a drone late last year using the same method. The UT Austin team used only about $1000 worth of equipment to take control of an autonomous drone and pilot it away under unauthorized control. Of course with matters of homeland security, the open-source hacker scene has yet to publish how this spoofing attack was actually done, but here’s a paper covering what is needed to remotely control up to four GPS-guided drones.

While waiting on the details of this build to be made public, feel free add your own insight in the comments as to how this attack was actually performed.

How do atomic clocks work?

[Bill Hammack] aka [Engineerguy] is back again with another fantastic informational video. This time around he’s describing exactly how an atomic clock does what it does. He starts off with a great analogy of jello jiggling when poked. He explains how this is similar to the quartz crystal inside the clock oscillating due to the electrical “poke” we give it.  He goes on to explain how GPS satellites rely on this accuracy when determining physical locations on the ground.

As usual, [Bill] does a fantastic job of delivering the information quickly and packed full of detail, while still keeping it simple enough that even those unfamiliar with the technology can follow along.

[Read more...]

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