![\"\"](\"http:\/\/www.cqdx.ru\/blog\/wp-content\/uploads\/2010\/06\/gemini-front.jpg\" "\\"gemini-front\\"")
<\/a><\/p>\nThe Gemini receiver features two RF inputs, each of them independently processed by a low-noise and high dynamic range RF front-end and sampled by a high speed, 14 bit, two channels A\/D converter operating at 200 MSPS.
\nEach of the two RF front-ends of Gemini are equipped with a six bands pre-selection filters bank ranging from 28 to 170 MHz, a high IP3 LNA and a 0-30 dB, 1 dB steps variable attenuator.<\/p>\n
Wideband Inputs for Direct Access to the A\/D Converter<\/strong><\/p>\n Gemini features two unconditioned wideband inputs (1-500 MHz, 3 dB bandwidth) which give a direct access to the A\/D converter inputs for multiple channel operations with external RF signal conditioning. For the maximum flexibility the wideband inputs are equipped with independent variable attenuators.<\/p>\n Meeting the Need of Higher Speed Digital Signal Processing<\/strong><\/p>\n The RF signals simultaneously sampled by the Gemini A\/D converter are numerically processed at 200 MSPS\/channel by a high speed multichannel digital down-converter implemented in a FPGA of Xilinx’s most recent Spartan6 family. The digital down-converter outputs are decimated down to 1 MSPS\/channel or less and streamed to the PC processing plaftorm through a high-speed (480 Mbit\/s) USB2.0 port.<\/p>\n Ultra Low Jitter Clock for the Highest Dynamic Range up to VHFs<\/strong><\/p>\n As the frequency of the signals to be sampled increases, the quality of the A\/D converter sampling clock needs to be higher and higher.<\/a><\/p>\n
\nGemini A\/D converter is driven by a sampling clock derived from the industry best crystal oscillator, a ultra low noise 400 MHz voltage controlled oscillator locked to an internal 10 MHz, 1 ppm TCXO.<\/p>\n