Great Scott Gadgets has launched an accessory designed to boost the flexibility of the popular HackRF One software-defined radio (SDR) board — by piggybacking on top to provide antenna switching capabilities: the unusually-named Opera Cake.
"This add-on board has two primary ports, each connected to any of eight secondary ports, and it is optimized for use as a pair of 1×4 switches or as a single 1×8 switch," explains Great Scott Gadgets' Brittany "Straithe" Postnikoff of the device. "You can control Opera Cake for HackRF One manually with our command-line software
hackrf_operacake, or you can configure HackRF One’s firmware to automatically switch Opera Cake ports based on frequency or time."
When configured as a 1×8 switch, the Opera Cake work as a simple antenna switcher. Connect a range of antennas to a single HackRF and switch between then at will without having to fiddle with wiring, moving as required from high frequency (HF) to very high frequency (VHF) and ultra high frequency (UHF), omnidirectional to directional, or even a dish antenna for satellite work.
If using the Opera Cake as a pair of 1×4 switches, meanwhile, you gain an extra feature: the ability to set it up as a switched filter bank. "To do this, connect port A1 to B1, A2 to B2, A3 to B3, and A4 to B4 through physical SMA filters and cables of your choosing," Straithe explains. "This setup allows you to change your transmit or receive to be through the filter of your choosing without having to reconnect hardware every time you would like to use a different filter."
Control can be handled manually, switching using a command-line utility whenever required, or automatically. The latest official HackRF One software bundle includes integrated support for the Opera Cake, including the ability to switch automatically depending on the signal being targeted.