Although regular sounding at the Chilton site started on December 1st 1993, there have been breaks in the records to allow maintenance and because of hardware problems. In the middle of December 1993, regular sounding was halted to allow calibration and installation by the engineers. This interrupted transmissions for about a week. Sounding then continued regularly and efficiently until June 17th 1994, when the main power supply failed. After the installation of a spare, which also failed, regular sounding became impossible. Before this however, nearly seven months of simultaneous data had been taken and it was decided to use the spring equinox in this interval to form the first part of this comparative study. As a result of the failure, the decision was taken to extend the period of the study into 1995 in order that data from the summer months could be compared. This period, from March to December 1995 forms the second half of this study.