All receivers at the Arecibo telescope use local oscillators locked to the station hydrogen maser frequency/time standard. Commercial synthesizers in the dome and carriage house are remotely controlled to provide the first LO. The upstairs and downstairs IF chains are linked by optical fibers to bring the signal from the telescope to the control room, providing an instantaneous bandwidth of up to 1 GHz per polarization. Up to eight dual-polarization IF sub-bands (or all seven dual-polarization ALFA beams) can be selected for transmission to the observatory spectrometers, or other signal processing equipment. Doppler offsets can be applied at the first and/or second (downstairs) LOs.
Observers can select any of the receivers available in the dome feed turret or the carriage house from the control room. The selection process includes the routing of the LO reference signal, the IF signal, the positioning of the feed turret, and the loading of the appropriate pointing model.
To access detailed schematics of the IF/LO system, go to;
Robert Minchin 2017-10-30