A software radio that is so rad:
- Plenty of space for custom IP middleware: 500k gate FPGA
- Fast: 125 Msps ADC
- Plays nice: 50 ohm input impedance
- Pre-amplifies: 20 dB LNA
- Filters: 2nd-order low-pass
- 70 dB dynamic range
- IEEE 1149 JTAG BSP
- Fat pipe: 480 Mbps USB
- Reconfigurable: FPGA configures over USB
The hardware consists primarily of a field programmable gate array (FPGA), an analog-to-digital converter (ADC), and a USB 2.0 microcontroller.
RF from the antenna is amplified by a low noise amplifier (LNA) and filtered by a second-order low-pass filter. The ADC then digitizes the signal into the FPGA.
The FPGA can act as a conduit, in which case it simply clocks the digitized RF into the USB endpoint for transmission to the host Mac. The FPGA can also down-convert the RF using a cascaded integrator-comb (CIC) filter and numerically controlled oscillator (NCO), useful for sample rates beyond 10Msps.
The software consists of Cocoa / OpenGL applications which do visualization and demodulation. A user-space device driver is included with each application.
Two applications are currently available for sorad, a spectrum analyzer and a spectrogrammer.
Other applications, such as an oscilloscope, am/fm radio, etc. may be developed in the future.