Initially the project was to build a suntracker operating at 300MHz. The student was to build a suitable receiver which would output a voltage proportional to the input noise power. The circuitry is very similar to the 38.2MHz riometers which Lancaster University already operate (IRIS). Unfortunately the protected astronomy band in which the instrument was intended to operate was too noisy, with too little solar radiation at that frequency.
After experimenting with domestic satellite TV receivers it was decided to use a 10GHz satellite dish and LNB. At this frequency the solar radiation is much higher and the beamwidth much narrower so man-made interference is not a major problem. The whole 50MHz bandwidth from the LNB is output to a frequency analyser and the resulting power measured by some custom software on a PC running Linux.
The tracking hardware is computer-controlled and updates the azimuth and elevation of the dish approximately once a minute. During this time the sun will have moved approximately 0.25°, much less than beamwidth of the satellite dish.
|Time resolution||3 samples / second|
|Sampling resolution||4½ digits|
Ionosphere and Radio Propagation Group,
Department of Communication Systems,