Anomalous Long Distance TV Reception at Delhi

Abstract

Continuous monitoring of long distance TV receptions at Delhi has been done for channels 2, 3 and 4 in band I for 1 yr during 1978-79. Unexpected high occurrence of anomalous TV reception for channel and to a certain extent for channel 3 has been found. An occurrence peak around noon for channel 2 during summer months is ascribed mainly to the high occurrence of sporadic-E, while another peak each in the afternoon, for channels 2 and 3 during equinoxes and winter months has been interpreted as due to normal F-layer reflections over long distances with high values of <i>f_o</i>F2 and low F-layer heights, increasing the MUF factor. A third peak of occurrence a few hours before midnight in certain months has been considered for channels land 3 as propagation mainly via artificially modified ionosphere caused by heating due to high power, high frequency transmission under some special conditions. Tropospheric ducting may also play an important role in the anomalous long distance TV receptions.