We all do it — park our cars, thumb the lock button on the key fob, and trust that our ride will be there when we get back. But there could be evildoers lurking in that parking lot, preventing you from locking up by using a powerful RF jammer. If you want to be sure your car is safe, you might want to scan the lot with a Raspberry Pi and SDR jammer range finder.
Inspired by a recent post featuring a simple jammer detector, [mikeh69] decide to build something that would provide more directional information. His jammer locator consists of an SDR dongle and a Raspberry Pi. The SDR is set to listen to the band used by key fobs for the continuous, strong emissions you’d expect from a jammer, and the Pi generates a tone that varies relative to signal strength. In theory you could walk through a parking lot until you get the strongest signal and locate the bad guys. We can’t say we’d recommend confronting anyone based on this information, but at least you’d know your car is at risk.
We’d venture a guess that a directional antenna would make the search much easier than the whip shown. In that case, brushing up on Yagi-Uda antenna basics might be a good idea.
Modern smart keys allow you to keep the key fob in your pocket or purse while you simply grab the handle and tug the door open. [Phil] decided he would rather ditch the fob altogether and instead implemented a passive Bluetooth keyless entry system with his Android phone. It’s probably unlikely for car manufacturers to embrace phone-based keys anytime soon, and [Phil] acknowledges that his prototype poses a landslide of challenges. What he’s built, however, looks rather enticing. If the car and phone are paired via Bluetooth, the doors unlock. Walk out of range and the car automatically locks when the connection drops.
His build uses an Arduino Mega with a BlueSMiRF Silver Bluetooth board that actively searches for his phone and initiates a connection if in range. Doors are unlocked directly through a 2-channel relay module, and an LED indicator inside the vehicle tells the status of the system. A pulsing light indicates it’s searching for the phone, while a solid ring means that a connection is established.
We hope [Phil] will implement additional features so we can make our pockets a bit lighter. Watch a video demonstration of his prototype after the break, then check out the flood of car-related hacks we’ve featured around here recently: the OpenXC interface that adds a smart brake light, or the Motobrain, which gives you Bluetooth control over auxiliary electrical systems.
Continue reading “Passive Bluetooth keyless entry system”
If you’re lofting a digital camera high into the stratosphere with a helium balloon, you really can’t do better than one of those key fob spy cameras. Being extremely lightweight with decent resolution, they’re the perfect camera to take to near space. If you’re bringing someone along to snap the pictures, that is.
[Román] wanted to take his 808 spy camera to new heights, but not wanting to manually reset the thing when it’s 100,000 feet in the air decided to use a microcontroller instead. An 8-pin PIC12F675 takes care of taking 60 pictures with a 4-second interval, then switching to movie mode and recording a 20-second video.
The entire device can be powered by 6 to 9 volts with the help of a voltage regulator. [Román] found the camera hangs after taking about 1600 photos, so a connection from the microcontroller to the reset switch was added. Everything works on the ground, so we can’t wait to see what happens miles above the Earth’s surface.