Abstract
The original Nançay‐St. Santin incoherent scatter facility based on the radio astronomy antenna at Nançay and a CW transmitter located at St. Santin (300 km south) was improved in many ways between 1965 and 1970: doubling of the transmitted power to 140 kw, lowering of the receiver noise level down to 100 K, monitoring of the antenna and data acquisition through the use of a computer, rejection of the parasitic tropospheric echoes.However, the most important improvement brought to the system is the addition of two new receiving stations 100 km east and west of the transmitter. Each of the new stations is equipped with a three‐beam Cassegrain antenna (25‐m parabola) aimed to simultaneously intersect the vertical transmitted beam at three different heights. Both new receivers have wide band (38 MHz at 3 db) gaseous helium cooled parametric amplifiers and on‐line computers. While one of the two new stations is equipped with filter banks for the purpose of spectral analysis, a different choice has been made for the other station. For the latter the data acquisition will imply multibit correlators, for both the ionic spectrum and plasma line measurements.Most of the improved electronic equipment designed for the new stations has also been implemented in the Nançay receiver. The frequency and time synchronization between the four sites is now accomplished by employing a single 5‐MHz frequency standard in each station monitored by standard time and frequency signals from MSF and/or HBG stations.The observation procedure consists of tilting the different receiving antennas so as to gather the signal scattered from the ionospheric vertical column illuminated by the transmitter. For calibration purposes a standard ionosonde is operating at St. Santin.The main objective of the quadristatic system is to determine completely the ion drift vector in order to study the electric fields and the neutral tidal winds. Other capabilities offered by the new system are a determination of the plasma line and a higher data acquisition rate.The first observations with one of the new stations were performed in December 1972.
Published Version
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