منابع مشابه
International Comparison of Atomic Frequency Standards Via VLF Radio Signals
A study was made of data obtained over an 18-month period (July 1961 to December 1962, inclusive) on the comparison of atomic frequency standards located in seven laboratories in the United States, Europe, and Canada, using the VLF signals of GBR (16 kc/s), Rugby, England, and NBA (18kc/s), Balboa, Canal Zone. Each laboratory observes the accumulated difference in phase over a 24-hr period (the...
متن کاملDecrease in the electric intensity of VLF/LF radio signals and possible connections
In February 2002, a receiver was put into operation at the Department of Physics of Bari University (Southern Italy) to record VLF-LF radio signals. The intensity and the phase of the signals transmitted by GB (f =16 kHz, United Kingdom), FR (f =20.9 kHz, France), GE (f =23.4 kHz, Germany), IC (f =37.5 kHz, Island) and IT (f =54 kHz, Sicily, Italy) has been monitored with a 5 s sampling rate. T...
متن کاملVLF/LF Radio Sounding of Ionospheric Perturbations Associated with Earthquakes
It is recently recognized that the ionosphere is very sensitive to seismic effects, and the detection of ionospheric perturbations associated with earthquakes, seems to be very promising for short-term earthquake prediction. We have proposed a possible use of VLF/LF (very low frequency (3-30 kHz) /low frequency (30-300 kHz)) radio sounding of the seismo-ionospheric perturbations. A brief histor...
متن کاملDaytime ionospheric D region sharpness derived from VLF radio atmospherics
[1] We described and applied a technique to measure the local midlatitude daytime ionospheric D region electron density profile sharpness from the Earth‐ionosphere waveguide mode interference pattern in the spectra of radio atmospherics (or sferics for short), which are the high‐power, broadband, very low frequency (VLF, 3–30 kHz) signals launched by lightning discharges. VLF propagation simula...
متن کاملIonospheric D region remote sensing using VLF radio atmospherics
Lightning discharges radiate the bulk of their electromagnetic energy in the very low frequency (VLF, 3–30 kHz) and extremely low frequency (ELF, 3–3000 Hz) bands. This energy, contained in impulse-like signals called radio atmospherics or sferics, is guided for long distances by multiple reflections from the ground and lower ionosphere. This suggests that observed sferic waveforms radiated fro...
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ژورنال
عنوان ژورنال: Nature
سال: 1974
ISSN: 0028-0836,1476-4687
DOI: 10.1038/248472a0