NOPR Collection: http://nopr.niscpr.res.in/handle/123456789/36925 2026-10-13T03:24:11Z 2026-10-13T03:24:11Z Fading of Simultaneous If Radio Signals for Two Propagation Paths with the Same Effective Height Sen, S K Ktrehan, S Sen, A K http://nopr.niscpr.res.in/handle/123456789/37083 2016-11-16T07:50:48Z 1979-04-01T00:00:00Z Title: Fading of Simultaneous If Radio Signals for Two Propagation Paths with the Same Effective Height Authors: Sen, S K; Ktrehan, S; Sen, A K Abstract: Simultaneous observations of the field strength of If radio signals on 332 and 280 kHz propagated over two paths for which the effective heights of reflection are the same, have been made at Berhampore, West Bengal. A preliminary analysis of the data indicated that the fading’s at the two frequencies are independent, the depth of fading being more at night than in daytime. There is a tendency for the fading depth at night to decrease abruptly after midnight, particularly for the propagation path at 332 kHz. The results have been critically examined in the light of the current knowledge about radio wave propagation in the lower ionosphere. Page(s): 91-92 1979-04-01T00:00:00Z Some Studies on Solar Radio Bursts & SIDs in Relation to Distinctive Visual Features of H<sub>ɑ</sub>-Flares Gupta, M K Das Das, T K Sarkar, S K http://nopr.niscpr.res.in/handle/123456789/37082 2016-11-16T07:49:22Z 1979-04-01T00:00:00Z Title: Some Studies on Solar Radio Bursts & SIDs in Relation to Distinctive Visual Features of H<sub>ɑ</sub>-Flares Authors: Gupta, M K Das; Das, T K; Sarkar, S K Abstract: Solar H<sub>ɑ</sub>-Flares reported under a scheme of classification based on their distinctive visual features have been examined for a period of about eight years. Flare-radio burst and flare-sudden ionospheric disturbances (SIDs) association and also the peak flux spectra of the associated bursts have been studied. The following important results are obtained, viz. (i) D-type of flares, compared to other types, are the most predominant and appear to concentrate more towards the disk limb; (ii) flare-burst association is frequency dependent and has the highest and the lowest values for H- and D-types of flares respectively; (iii) peak flux spectra of each type of flares reveal that the flux density shows a definite increase in the decimetric region; (iv) decametric type III bursts generally do not coincide with these types of flares; if they do, they accompany microwave and decimetre wave bursts in 30% and 43% cases respectively and (v) flare-SID association is highest for F-type and lowest for D-type of flares. Page(s): 89-91 1979-04-01T00:00:00Z Study of Geminid Shower Activity Using Meteor Wind Radar Devara, P C S Ahmed, Md. Iqhbal Rao, M Srirama http://nopr.niscpr.res.in/handle/123456789/37081 2016-11-16T07:46:25Z 1979-04-01T00:00:00Z Title: Study of Geminid Shower Activity Using Meteor Wind Radar Authors: Devara, P C S; Ahmed, Md. Iqhbal; Rao, M Srirama Abstract: The meteor wind radar at Nagarampalem field station of Space Research Laboratories, Andhra University, Waltair, (lat., 17° 43' N; long., 83° 18' E) was operated continuously during 11-16 Dec. 1977 covering the peak activity of Geminid meteor shower and nearly a total of 1,763 radio meteor echoes were observed in 24 hr during shower maximum period. The diurnal variation, of echo rates is discussed and compared with 'the visual and radio meteor observations of earlier workers at Waltair. The activity during shower and non-shower periods is compared and found to agree with the results of meteor forward scatter communication experiment between Waltair and Dehra Dun. The variation of elevation of the shower radiant with time is estimated and the observed meteor rate is discussed in relation to the elevation of the shower radiant. Page(s): 85-88 1979-04-01T00:00:00Z On the Influence of Sunspot Activity on Sporadic Radio Meteors Rao, M Srirama Jyothi, K K http://nopr.niscpr.res.in/handle/123456789/37080 2016-11-16T07:45:12Z 1979-04-01T00:00:00Z Title: On the Influence of Sunspot Activity on Sporadic Radio Meteors Authors: Rao, M Srirama; Jyothi, K K Abstract: The effect of sunspot activity on sporadic meteor rates has been investigated. The data of Christchurch (lat., 43°37'S) for the periods Feb. 1960-Jan. 1961 and 1963-65; of Ottawa (lat., 45° N) for the period 1958-62 and of Waltair (lat.; 17°43'N) by forward scatter of radio waves from Dehra Dun (lat., 30030'N) for the period Dec. 1974-Nov. 1975 have been considered. The lowest recorded mean hourly meteor rate on any day in a month is considered to be typical of sporadic meteor activity for that month, and the corresponding value of sunspot number on that day is considered for this correlation study. In no case the correlation has been found to be significant at <i>p</i>=0.01 level. The data for Ottawa for five years have been divided into four seasons each year and an analysis similar to the above is carried out in respect of all echoes or only long duration ones. In all the cases the correlation has been found to be insignificant. Finally, the plots of <i>N </i> (the normalized percentage deviation) against sunspot activity also reveal no preferential alignment for the scatter of the points. Hence it is concluded that there is no correlation between sunspot activity and sporadic meteor rates. Page(s): 82-84 1979-04-01T00:00:00Z