Back in April, Lime Microsystems unveiled their LimeFRE (Lime RF Front End) SDR power amplifier with filtering, designed to work with the company’s line of RF technology. After over two months of waiting, the SDR has officially launched on Crowd Supply. LimeFRE is touted as a ‘software-definable RF front-end module’ for Lime’s existing SDR lineup — the LimeSDR, LimeSDR Mini, and LimeNET Micro, and covers all HAM, mobile, and wide-band frequencies.
Lime explains, “A single LimeRFE covers three very different sets of bands: HAM, cellular, and wideband. The exact band used at any given time is software-selectable. By making the RF front end definable in software, LimeRFE is the next step in the evolution of software-defined radio.” While the company states the LimeFRE board can handle those frequencies mentioned earlier, additional filtering may be required for projects that utilize HF bands.
As far as features are concerned, the LimeFRE offers appropriate filtering for both Rx and Tx, selectable AM/FM notch filter, a 1 to 4000MHz power and SWF meter (external directional coupler required), and a cellular band’s Tx power meter (internal coupler). It also packs an ATmega328 microcontroller, FT232RL USB-to-serial converter, and host serial connection via USB Type-B connector.
Rounding out the specs is a 10-pin interface to SDR, with power/ground, I2C, two GPIOs (connected to ATmega328), and four bi-directional level shifted I/O (1.2/5V, individually switchable direction, and power Darlington drive stage for inductive loads). On the software side, the board makes use of Lime Microsystems’ LimeSuite tool package for SDR applications, as well as the Arduino IDE. The LimeFRE board is available for $499 (early bird pledge), $599 and $999 (bundled with the LimeNET Micro board).