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A further note on “sweepers”
Research notes
The research reported in this note has been sponsored by the Electronics Research Directorate of Cambridge Research Center, Air Research and Development Command, United States Air Force, through the European Office, ARDC, under contract AF 61(052)-08. \ K. W. ERIKSEN Norwegian Defence Research Establishment 0. HOLT Kjeller, Norway B. LANDMARK I
REFEREWES LITTLE C. CT.and LEINBACH H. HULTQVIST B. and ORTNER J.
1958 1959
Proc. IRE 46, 334. Pkmet. Space Sci. 1, 193
A further note on %weepers”
The phenomenon reported recently by GERSON and GOSSARD (J. Atmosph. Terr. Phys. 17, 82) was brought to my attention late in December, 1959. By using a conventional communications receiver and a rhombic antenna directed east from Boulder, Colorado, the signals could be readily identified. However, an interesting feature was noted that was not reported. Many of the signals, as they swept through the receiver pass-band, were observed to be modulated, having the characteristic sound of a poorly filtered plate supply. Analysis by a sound spectrograph of a few of them showed the modulation frequencies to be predominantly even harmonics of 60 c/s, which would be expected from a full-wave rectifier operating from a North American power line. This additional feature of the observations puts an entirely different light on the phenomenon and, although it may still be a subject for investigation by those engaged in interference identification and suppression, it seems unlikely that it must be explained as a newly discovered natural phenomenon. J. M. WATTS Ionospheric Research Section Radio Propagation Physics Division Boulder Laboratories Boulder, Colorado, [J.S.A.
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81
The research reported in this note has been sponsored by the Electronics Research Directorate of Cambridge Research Center, Air Research and Development Command, United States Air Force, through the European Office, ARDC, under contract AF 61(052)-08. \ K. W. ERIKSEN Norwegian Defence Research Establishment 0. HOLT Kjeller, Norway B. LANDMARK I
REFEREWES LITTLE C. CT.and LEINBACH H. HULTQVIST B. and ORTNER J.
1958 1959
Proc. IRE 46, 334. Pkmet. Space Sci. 1, 193
A further note on %weepers”
The phenomenon reported recently by GERSON and GOSSARD (J. Atmosph. Terr. Phys. 17, 82) was brought to my attention late in December, 1959. By using a conventional communications receiver and a rhombic antenna directed east from Boulder, Colorado, the signals could be readily identified. However, an interesting feature was noted that was not reported. Many of the signals, as they swept through the receiver pass-band, were observed to be modulated, having the characteristic sound of a poorly filtered plate supply. Analysis by a sound spectrograph of a few of them showed the modulation frequencies to be predominantly even harmonics of 60 c/s, which would be expected from a full-wave rectifier operating from a North American power line. This additional feature of the observations puts an entirely different light on the phenomenon and, although it may still be a subject for investigation by those engaged in interference identification and suppression, it seems unlikely that it must be explained as a newly discovered natural phenomenon. J. M. WATTS Ionospheric Research Section Radio Propagation Physics Division Boulder Laboratories Boulder, Colorado, [J.S.A.
6
81