Since the discovery that some USB TV tuner dongles could be used to monitor radio waves across a huge amount of spectrum, the software-defined radio world has exploded with interest. The one limiting factor, though, has been that the dongles can only receive signals; they can’t transmit them. [Evariste Okcestbon, F5OEO] (if that is his real name! Ok c’est bon = Ok this is good) has written some software that will get you transmitting using SDR with only a Raspberry Pi and a wire.
There have been projects in the past that use a Pi to broadcast radio (PiFM), but this new software (RPiTX) takes it a couple steps further. Using just an appropriately-sized wire connected to one of the GPIO pins, the Raspberry Pi is capable of broadcasting using FM, AM, SSB, SSTV, or FSQ signals. This greatly increases the potential of this simple computer-turned-transmitter and anyone should be able to get a lot of use out of it. In the video demo below the break, [Evariste] records a wireless doorbell signal and then re-transmits it using just the Rasbperry Pi.
Amateur radio is the only hobby that offers its licensed operators the chance to legally design, build, and operate high power radio transceivers connected to unlimited antenna arrays for the purpose of communicating anywhere in the world. The most complicated part of this communication system is the single-sideband (SSB) high frequency (HF) transceiver. In reality, due to the proliferation of low-cost amateur equipment, there only exists a very small group of die-hards who actually design, build from scratch, and operate their own SSB transceivers. I am one of those die-hards, and in this post I will show you how to get started.
The Fluid Site Specific Browser (SSB) is one of our favorite pieces of kit for Leopard. You can use Fluid to give web services you use constantly like Gmail, Facebook, Wikipedia, or Pandora their own icon and a browser tailored to that site’s specific workflow. Fluid based on WebKit and has plugin support among many other features. Embedded above is [Eric Eggert] showing how to create a reasonable Twitter client using it. The initial setup is identical to any other Fluid app: point it at https://twitter.com/. The clever bit is leveraging Fluid’s GreaseMonkey style userscripting support. He created a userscript to autorefresh. A second userscript is used to strip off all of the extraneous page elements leaving just the text field and the timeline. Every time you get a new message it generates a growl notification and you can even attach it to the status bar. Best of all: it avoids all API limitations since you’re accessing through the web interface.