Wideband UHF Radio Card (WURC)
High-power Software Defined Radio Front-end
The Skylark Wireless Wideband UHF Radio Card (WURC) is a Software-Defined Radio (SDR) analog front-end designed to operate at high power within the UHF radio band from 400-700 MHz with a maximum output power of 30 dBm (1 Watt), and within the 2.4-2.5 GHz ISM (Industrial, Scientific, and Medicine) band with a maximum output power of 26 dBm. The linear ultra-wideband power transfer network for the UHF band is specially designed using real-frequency matching techniques for optimal output power with minimal signal distortion.
The WURC implements the LMS6002D wideband transceiver IC, providing a full-duplex direct-conversion radio architecture, integrated 12-bit DAC/ADC with up to 50 MHz quadrature sampling rate, field-programmable anti-aliasing channel filters from 1.5 to 28 MHz, and fully-independent transmit and receive fractional-N frequency synthesizers. Programmable transmit (35 dB) and receive (61 dB) gain provide a wide dynamic range suitable for long-range outdoor UHF or ISM-band communications.
On-board LNAs complement the dynamic range of the LMS6002D with increased noise-figure performance. Dual-pole, dual-throw transmit/receive switches allow both time-division duplex operation from a single antenna per frequency band, or completely independent frequency-division duplex operation from two antennas. RF connection is provided from 2.4-2.5 GHz via 50 Ohm SMA female connectors, from 300-700 MHz via 75 Ohm F-type female connectors. An additional wideband (300 – 3800 MHz) wideband auxiliary input-only port provides wideband spectrum-sensing capabilities.
A standard HSMC (Samtec ASP-122952-01) connector provides an interface to the host baseband platform for Altera development kits, or to Xilinx baseband development kits via the HSMC/FMC adaptor also developed by Skylark Wireless. Power and clocking is derived from this host interface.
An on-board micro-controller provides initialization, calibration, and control macros via a scriptable serial 115200-baud UART interface to either the digital baseband host or a micro-USB host.
Each board is factory calibrated and tested for transmit and receive local-oscillator feed-through and IQ quadrature imbalance–no customer analog calibration is necessary.
Open-source reference designs have been implemented with the Skylark Wireless WAB 1:1 and WURC to provide real-time Automatic Gain Control (AGC), digital baseband IO and calibration, and digital interpolation/decimation filters for increased signal integrity and spectral mask compliance. A complete real-time Layer-2 SISO implementation of 802.11-2012 has been implemented as well as a rapid physical-layer prototyping framework based on the open-source Rice WARP SDR project.
Publications Using WURC
- S. Sur, X. Zhang, “Bridging Link Power Asymmetry in Mobile Whitespace Networks,” In proceedings of IEEE InfoCom, April 2015, DOI
- X. Zhang, E. Knightly, “WATCH: WiFi in Active TV Channels,” In Proceedings of ACM MobiHoc, June 2015, Hangzhou, China, DOI
- N. Anand, R.E. Guerra, E. Knightly, “The Case for UHF-Band MU-MIMO,” In Proceedings of ACM MobiCom, Maui, HI, August 2014, DOI
- R.E. Guerra, N. Anand, C. Shepard, E. Knightly, “Opportunistic Channel Estimation for Implicit 802.11af MU-MIMO,” In Proceedings of ITC 28, Würzburg, Germany, September 2016, LINK, DOI