Carjacking - shortening the path for justice

As automobiles become more sophisticated, direct theft by tampering with the ignition system becomes a nearly impossible task. This narrows down the choices left for the criminals, who end up adopting the only choice where successful access to the vehicle is guaranteed: threatening the occupant(s) with a weapon in exchange for the car.

In general the criminals can get away with this type of crime if they are efficient and careful, leaving the victim with few evidence to help in the investigation and tracking of the vehicle.

However, once again we can put technology on our side, and in an attempt to be resourceful enough, take advantage of two broadly available devices: a cell phone and a GPS module. These devices
are becoming cheap enough to have dedicated in a discrete location inside the car for a single purpose: on demand location.

By being able to query the location of the car just by sending an SMS message to it and get a reply with the corresponding GPS coordinates, this could be a useful tool in the police work, as real time location would always be possible.

Following this idea, I've decided to attempt a simple implementation of one such system which I have designated "Vechicle Finder". Having as a platform a Nokia smartphone and a Bluetooth GPS device (both sitting on a board for convenient fixation of the apparatus), I have developed a Java application which reads the GPS coordinates and sends it as an SMS to the originator of the request SMS:



Upon receiving an SMS containing a special command and some optional parameters, this onboard device will reply with another SMS containing the following data:

The meanders of OBD-II protocols

As we travel through the history of automotive technology back and forth, we realize that at the heart of the machines that enable us to go from point A to point B faster than our legs, are a number of components that essentially haven't changed too much: engines still burn fossil fuels and the vast majority are based on pistons that transform the explosive energy of the fuel combustion into movement.

Decoding ACARS transmissions

Just as with other radio related hobbies, this is quite an interesting one:

Long-haul WiFi - new developments

Returning to the WiFi topic, here is the new antenna development that I had promissed in the early post, once the dual "cantenna" design was finished.

The dual cantenna is quite efficient, as I realized by connecting it to reasonably distant access points (in excess of 200 meters, with many obstacles between, including houses). By verifying the antenna efficiency was the expected, I assumed that in better conditions the range could be far greater, by establishing a link between two antennas of this type or other type of optimal configurations.

However, I knew I could push it a little further, so I decided to buy a 12 euro 45 cm dish from a regular satellite TV system, and the materials to build a biquad feed. I installed the dish on top of the tripod used for the cantennas, and attached the biquad feed (built according to these instructions) to it:

Water Fuel Cell - DC voltage results

Today I performed some tests measuring gas production with DC voltage. The tests were performed in order to obtain aproximately the same consumed power, namely 22 Watts.

DC test performed:


High frequency test (100 KHz) at same voltage:


The DC test shows a clear increase in efficiency (almost 25%) relative to the pulsed electrolysis.
Still to compare these results with low pulse frequencies (it is likely that power losses are quite high at 100 KHz).

Water Fuel Cell - more results

For one measurement taken without the inductor coil, we have the following values:

Water Fuel Cell - measured results

I performed two consecutive runs without changing the conditions. The data obtained is as follows:

Considering that it consistently took 4 minutes to produce 80 ml of H2 + O2, this
gives a rate of 1.2 litres/hour of H2 + O2.