If you dabble in the ham radio hobby we’re sure you’ve heard of GPS position monitoring or tracking using APRS packet data commonly transmitting over the VHF ham band and FM modulated. One of the issues you’ll face using this common method is range limitations of VHF. [Mike Berg] a.k.a [N0QBH ] tipped us off to his latest project to greatly increase the range of a standalone APRS system utilizing the HF bands on single-sideband (SSB).
There are some unique challenges transmitting packet data using SSB over HF bands. High Frequency APRS has been around for decades utilizing FSK AX.25 packet transmissions at 300 baud, but it was quite susceptible to noise and propagation aberrations. More recently PSK-31 at the slower 31 baud speed helped alleviate many of these issues. [Mike] utilized the somewhat updated APRS with PSK-63 and the “APRS Messenger” program to overcome these challenges. [Mike’s] hardware solution consists of a PIC 16F690 micro which is coded to receive data from a GPS receiver, convert it into PSK-63 and then transmit on 30 meters over an attached HF radio. A second receiving station or stations at great distances can pick up and decode the transmission using the “APRS Messenger” program connected to the receiving radio over the computer’s soundcard. The program can then forward the tracking information, if good, to tracking websites like FindU.com and APRS.FI.
You can build your own FreeTrak63 by downloading [Mike’s] parts list, assembly code, HEX file, manual and schematic. The PCB is available on OSH Park if you don’t want to make your own or wire point-to-point. Let’s not forget to mention how hackable this hardware is, being really just an eight bit DAC, micro, serial in and radio out. One could reprogram this hardware to do other modulation schemes like AX.25 packet or MFSK16, the sky’s the limit. If short-distance on VHF with existing Internet linked receiver networks using an Arduino compatible platform is more to your taste, then checkout the Trackuino open source APRS Tracker.
After seeing an autopilot for a kayak a few days ago, [Mike] thought he should send in his version of a water-borne autopilot. Compared to something that fits in a one-man kayak, [Mike]’s creation is a monstrous device, able to keep a largeish sailboat on a constant heading.
To keep track of the ship’s bearing, [Mike] is using a very cool digital compass that uses LEDs to keep a steady heading. Also included is an amazingly professional and very expensive 6 axis IMU. To actually steer the ship, [Mike] is using a linear actuator attached to the tiller powered by a huge 60 Amp motor controller. The actuator only draws about 750 mA, but if [Mike] ever needs an autopilot for a container ship or super tanker, the power is right there.
For control, [Mike] ended up using an Arduino, 16-button keypad, and an LCD display. With this, he can put his autopilot into idle, calibration, and run modes, as well as changing the ship’s heading by 1, 10, and 100 degrees port or starboard.
From a day of sailing, [Mike] can safely say his autopilot works very well. It’s able to keep a constant heading going downwind, and even has enough smarts to tack upwind.
Continue reading “Sailing With An Autopilot”
[Andrei] is cruising in style thanks to his Raspi-powered CarPC project, which is a steal at $200 considering all the functionality it provides. This is an update to the work we saw from him back in March. Rather than completely replace his car’s head unit, [Andrei] simply relocated it to the trunk, permanently set it to the “aux input” source, and connected the Raspberry Pi’s audio output. The Pi runs a Raspbian Wheezy distro with XBMC and is mounted in the storage area beneath the middle armrest. [Andrei] filled the hole left by the old stereo with a 7-inch touchscreen display, which connects to the Pi through both HDMI and USB. If you throw the car into reverse, the Pi automatically selects the touchscreen’s AV input to display the car’s backup camera, then flips back when put in drive.
The unit also provides navigation via the open-source Navit software using OpenStreetMap data. An ST22 SkyTraq GPS receiver grabs coordinates and feeds them into the Raspi, which updates the on-screen map once per second. You’ll want to watch the video after the break (Audio Warning: Tupac) to see for yourself just how well the CarPC came together,
Continue reading “Using a Raspberry Pi to give your car more features”
GPS is really fun to play with in your projects. But when [Trax] decided to build a GPS chip into his design the fun ended abruptly. Above you can see the section of the board devoted to the hardware. Unfortunately this PCB fails to provide any GPS location data whatsoever.
Continue reading “Fail of the Week: GPS module design”
[Colin] and [Fergus] have been working with GPS for years now, and like most builders of really cool things, they’re often limited by the precision of off-the-shelf GPS units. While a GPS receiver is usually good for meters of accuracy, this just isn’t good enough for a lot of projects. What you need is centimeter-level accuracy, something the guys have managed to do with their Piksi GPS receiver.
Where most GPS receivers only look at the data coming from the GPS satellites orbiting overhead, the Piksi uses another technique, real-time kinematics (RTK), to determine the receiver’s location with exacting precision. The basic idea behind RTK is to look at the carrier frequency of the GPS signals at 1575.42 MHz. This frequency has a wavelength of 19 cm, compared to the alternating 1s and 0s of the that are transmitted at around 1 MHz, or about 300 meters between each bit. While centimeter-level precision isn’t possible with only one receiver, two of these Piksi boards – one base station and one on a vehicle, connected via radio link – can make for a very exacting high-accuracy GPS receiver.
Previously, commercial RTK GPS systems have cost thousands of dollars – making a quadcopter or other homebrew project that relies on this level of precision nonsensical. [Colin] and [Fergus] have built hardware that can bring the price of this setup to under $1000. As a bonus, the Piksi board can also receive from other constellations such as Galileo and GLONASS. A very impressive piece of hardware, and we can’t wait to see the applications.
Although the thrill of launching rockets is usually found in their safe decent back to Earth, eventually you’re going to want some data from your flight. Everything from barometric pressure, GPS logging, and acceleration data is a useful thing to have, especially if you’re trying to perfect your craft. [zortness] over on reddit created a data logging board created especially for amateur rocketry, a fabulous piece of work that stands up to the rigors of going very fast and very high.
The design of the board is a shield for the Arduino Mega and Due, and comes with enough sensors for over-analyzing any rocket flight. The GPS logs location and altitude at 66Hz, two accelerometers measure up to 55 G. Barometric, temperature, and compass sensors tell the ground station all the data they would need to know over a ZigBee 900MHz radio link.
Because this is an Arduino, setting up flight events such as deploying the main and drogue chutes are as easy as uploading a bit of code. [zortness] built this for a 4″ diameter rocket, but he says it might fit in a 3″ rocket. We just can’t wait to see some videos of it in action.
[Radu] spend the first portion of this year building and improving upon this wireless rover project. It’s actually the second generation of an autonomous follower project he started a few years back. If you browse through his old postings you’ll find that this version is leaps and bounds ahead of the last.
He purchased the chassis which also came with the gear-head motors and tires. Why reinvent the wheel (har har) when you’ve got bigger things on your plate? To make enough room inside for his own goodies he started out by ditching the control board which came with the Lynxmotion chassis in favor of an AVR ATmega128 development board. He also chose to use his own motor controller board. Next he added a metal bracket system to hold the battery pack. Things start to get pretty crowded in there when he installed his own Bluetooth and GPS modules. Rounding out his hardware additions were a set of five ultrasonic sensors (the grey tubes on top), a character display, as well as head and tail lights. The demo video shows off the control app he uses. We like that tic-tac-toe design for motion control, and that he added in buttons to control the lights.
Continue reading “Wireless rover with Android control”