As a follow up to my previous post, I built some simple SMA dielectric probes using PCB edge mount connectors. The probe interface surface is rather rough and the short was made using some soldered copper tape. This is definitely not the ideal set of probes. Nevertheless, I was curious how the probe would compare […]Read More »

Adding dielectric materials to electromagnetic simulations can be a pain if the correct dielectric properties are not known. To solve this I decided to build a poor-mans dielectric probe. The probe consists of a coaxial interface that is placed flush with a material under test. From a single reflection measurement of your material and a […]Read More »

Early 2016 was the year Tesla started showing off their new Model 3 electric car. Unfortunately, my financial situation did not allow me to own such a vehicle. As a result, I settled for the next best thing, building an incredibly overpowered electric skateboard. Most of the drive system was ordered as a kit from […]Read More »

It has been two years since I have touched this project. However, it has lingered in the back of my mind ever since. The significant issues with the previous design were positioning accuracy, skier safety and propulsion. Two of these hurdles were due to over optimising cost in the prototyping stage, which I now realise was […]Read More »

Last year I started building an intelligent ski-course, which was basically a set of buoy drones that would swim to there positions in a public river to form a ski course. This would then allow tons of interesting possibilities such as easy setup and effortlessly changing the shape of the course. Most of the project is […]Read More »

Since the last post, we have completed a year of successfully RF measurement campaigns. Sadly, the quadcopter featuring in the previous post (FEMU 1.0) underwent an autopilot failure during a measurement dry-run which caused it to fly straight up into the air until its battery died. It has never been seen since. This forced us […]Read More »

I decided it would be a good idea for our lab, and for me, to have a 3D printer at our hands. After some consideration, I ordered a kit from a local supplier DIY Electronics whom I would gladly recommend. The kit, a relatively new design, is named a Prusa i3. Up to now, after […]Read More »

Here is the MG close to our favourite kite-boarding spots Langebaan and Shark Bay. This was taken at the mill house close to the local Club Mykonos casino.Read More »

After about 3 weeks the Raspberry Pi RFM22B has arrived. The boards have been soldered and tested. There is some setup needed to get the SPI interface working, this is all explained at the top of some example code I am attaching at the bottom of this post. I built a total of 3 of […]Read More »

The 32-bit spectrum analyzer has been used for multiple tasks in its prototype form. However, it has been decided to slightly change the final design. This choice is motivated mainly by the application I am using for my Master’s degree. Therefore, this is the end of the development for the 32-bit analyzer and the birth […]Read More »

With a lot of help from a friend, Johan Frank, new legs and a platform was built for the quad copter. These legs allow for an antenna to be mounted below a platform supporting a spectrum analyzer and single board computer. This platform was specifically built for a measurement campaign at the SKA site which […]Read More »

The RF shielding effect of a berm was measured using a Multi-copter as part of my PhD program. LS of SA from LS telecom generously helped us with these measurements with their own Multi-copter measurement platform. The measurements were done with a transmitter located on the far side of the berm transmitting 9 vertically polarized frequencies, […]Read More »

After flying in loiter mode for a while the quad-copter suddenly flipped over. I immediately switched to Stabilize mode and increased throttle in an attempt to save the situation. It stabilized itself just before hitting the ground but sadly had too much horizontal velocity. As a result, the quadcopter snagged and rolled in spectacular fashion. The […]Read More »

In the beginning of 2011 my grandfather gave me his 1968 MG midget MK III. The car is still in almost perfect condition as can be seen in the photo taken in Stellenbosch. I will dedicate this part of my webpage to give updates on my MG. The bottom photo shows my grandmother and grandfather […]Read More »

Upgraded to the APM 2.5. Height and GPS accuracy are significantly better than the APM 1.0. The APM 2.5 also has a much higher telemetry data throughput due to some of the signal processing happening off of the Atmel chip. Below is a photo of the new neat setup containing the APM 2.5.Read More »

After receiving my raspberry pi camera, I thought it to be a good idea to take some aerial photos with the quadcopter. The first few photos are from Stellenbosch University campus followed by the last few which are from a farm near Worcester, South Africa.Read More »

After getting the quadcopter to fly in loiter and auto missions with confidence, it was decided to use the quadcopter for measuring RF signal propagation. This measurement was done with a transmitter on one side of a 13m high human-made berm. Flying a vertical path up to 50m on the far side measuring the diffraction of […]Read More »

It is time to revisit the RS232 spectrum analyser. Below is an image of some prototyping on a breadboard followed by a soldered working version including an SMA connection. The problem with the previous spectrum analyser was mainly in the computation of the frequency set registers which involved large 9 digit values, a hard feat […]Read More »

After the vibration issues were sorted out it was time to test the loiter and auto modes. A video of the first successful loiter test can be seen below. The APM 1.0 seems to hold its position reasonably well given that there was a slight breeze that day. The quad-copter was also instructed to land […]Read More »

After the quadcopter was fully assembled including ESC’s, accelerometers and radio calibrated it was ready for its maiden flight. This flight was carried out at the back of our Engineering building, Stellenbosch, on an insufficient piece of grass. A short video from the flight can be watched below. After some time flying the altitude hold function was tested which seemed to work. However, […]Read More »

After a number of flights in stabilize mode with a very stable vehicle, it was decided to test the rest of the flight modes. Our goal was to build this into a measurement platform which necessitates the use of the auto modes. Therefore, we went to an open test field near Stellenbosch where we switched […]Read More »

After a long break moving to another city, I restarted my efforts on the quadcopter build. This time adding the motors and finalising the construction to the point of a maiden flight. Some changes to the previous thought process were incorporated: channelling the high current ESC wires through the aluminium tubes. The latter meant disassembling the whole quadcopter. The […]Read More »

Before being able to do some wireless tests, the sensors and telemetry radio need to be powered. In this first phase of assembly, the power distribution board, IMU board along with the telemetry was mounted on the frame. Thereafter a single electronic speed controller was connected to power the IMU board and radio. As of […]Read More »

Here are some screenshots of the spectrum analyser graphical user interface. Please note that the levels shown have not yet been tested with proper equipment. Proper tests and calibration will be done in the next hardware iteration.Read More »

Another sensor needed during navigation and control was added to the IMU board. This sensor, a magnetometer, is responsible for measuring the orientation using the earth`s magnetic field. In a plane setup, the current heading can be easily determined by making use of consecutive GPS measurements.  On the other hand, a quadcopter does not need to stay […]Read More »

A new GPS arrived today, all the way from 3DRobtics, as a replacement for my previously dead on arrival GPS unit. This time around the GPS worked as soon as it was plugged in and even started acquiring satellites from indoors.Read More »

This project came from the idea that I needed a simple, light spectrum analyzer which could be easily interfaced to embedded applications. This design was a proof of concept which made use of an RFM22B radio module and a PIC16F690. A simple GUI was also constructed for initial testing purposes. Photos of the prototype can be […]Read More »

For this project a constant data communication will be needed from the vehicle and its payload to a ground station. Therefore, a telemetry radio needs to be present. Fortunately, the APM 1 kit discussed earlier makes provision for a telemetry module. The telemetry modules I opted for was from 3DRobotics running at 433MHz 100mW. Due […]Read More »

The flight controller is the brain of the vehicle and will contain most of the essential sensors.  To save time I opted for a Ardu-Pilot Mega 1.0. The main reason why I opted for the 1st generation and not the newer second generation is to have the option of replacing the 8 bit micro-controller with […]Read More »

The NXF-4 frame was bought from Netram in Durban (now in Cape Town), South Africa. It took 24 hours from order to delivery which I was quite impressed with. After it was delivered it took me a couple of hours to assemble with some spare parts. All in all the frame feels sturdy and has an interesting colour scheme. […]Read More »

This was my final year project for my BEng degree. The idea for this project came from the problem that certain South African prepaid meters bill the residence for the power they generate into the grid. This project investigated a temporary workaround for this problem, by diverting the net outflow of power into a resistor […]Read More »

This project was done by myself for a company called TFDesign, the software is in phase 1 at the moment and is capable of reading data from a Siemens PLC, processing the data with some thermodynamic libraries and finally plotting the data on a psychometric and pressure-enthalpy graph. The software has extra functionality such as […]Read More »

This is a project I did for a company called TFDesign. The software is used to calculate certain parameters of a Heat Exchanger given certain specifications. The calculation runs over a given amount of heat exchanger rows to help the user determine the optimum design. The project was written in java to enable its use over multiple platforms. […]Read More »