In 2016, a communications satellite will be launched into geostationary orbit somewhere over the middle east. Normally, this is fairly ordinary occurrence. This satellite, however, will be carrying two amateur radio transponders for hams all across europe, africa, the middle east, and India. [2FTG] is building a satellite transponder to talk to this satellite, and he’s doing it with junk sitting around his workbench.
The uplink frequency for this satellite will be in the neighborhood of 2.4 GHz, and [2FTG] needed a way to deal with the out of band interference in this part of the spectrum. The easy and cheap way to do this is with filters made for the WiFi band. Instead, [2FTG] had a few cavity filters in his junk box and decided to go that route. It meant he had to retune the filters, a process that should be annoyingly hard. [2FTG] did it in thirty minutes.
Antennas are another matter, but since [2FTG] has a supply of metal coffee cans, this part of the build was just a matter of soldering a bit of wire to an SMA connector, drilling a hole (using a log as a drill stop, no less), and soldering the connector to the can.
The project featured in this post is a quarterfinalist in The Hackaday Prize.
Continue reading “THP Semifinalist: Cheap Satellite Transponder”
For the sufficiently geeky aviation nerd there’s FlightAware, a website that tracks just about every airliner and most private planes currently in flight. The folks at FlightAware compile all the information with the help of a few thousand volunteers around the world that have a bit of hardware to listen to ADS-B transmissions and relay them to the FlightAware servers. Now you can do this with a Raspberry Pi, and as a nice little bonus FlightAware is giving away free enterprise accounts to anyone who does.
Listening in on ADS-B transponders is something Raspberry Pis have been doing for a while, but doing anything useful with the altitude, speed, heading, and registry numbers of various planes flying overhead is pretty much FlightAware’s only reason for existing, and the reason they’ve developed an easy to use software package for the Pi.
Setting everything up requires getting dump1090 running on the Pi, the only hardware required being an RTL-SDR USB TV tuner, a GPS module, and an antenna for 1090 MHz. From there, just send all the data to FlightAware and you get a free enterprise account with them. Not a bad deal for the aviation nerds out there.
FasTrak is the electronic toll collection system used by the state of California. Motorists can purchase a toll transponder for ~$26 and link the serial number with a debit account to have their tolls deducted automatically. Today at Black Hat in Las Vegas, security researcher [Nate Lawson] presented not just the privacy problems with FasTrak, but why absolutely no transaction from the tag should be trusted.
Continue reading “Black Hat 2008: FasTrak toll system completely broken”