On a preflare variations of solar decimeter radioemission fluctuations

The results of analysis of solar decimeter preface radioemission fluctuations observed in the Radioastrophysical Observatory of the Academy of Sciences of the Latvian SSR with 10-m telescope on frequencies 755 and 612 MHz during 1979-1984 are considered. Two kinds of preflare changes are detected. At first the evolutional ones manifesting themselves with growing fluctuation amplitudes in the 5 to 20 minute range during the time from one hour to two days before the flare itself. Secondly, more short periodic ones- precursors, emerging in one hour preceding the flare. Features of both kinds of preflare changes of short period fluctuations are considered