Taken from two simple VLF radio receiver circuits for later analysis on the ground.Solar flares detected by the new narrowband VLF receiver at SANAE IVThe SID Seizer is a VLF/LF receiver project for monitoring Sudden Ionospheric Disturbances, typically caused by solar flares. IYour mission, if you choose to accept it: design and build a pair of. Figure 5 is the schematic diagram of the Gyrator II VLF receiver. Most parts are available from RadioShack and are simply positioned on the circuit board and soldered into place. I built the Gyrator II radio using a circuit board from Far Circuits (net/receiver1.htm) made for this device, making it much easier to build.

Every lightning strike creates a radio pulse that can travel thousands of miles, bouncing between the EarthвЂ™s surface and the ionosphere.ISpace and Plasma Physics, Royal Institute of Technology, Stockholm, SwedenMake this Insect Wing Signal Detector Circuit The Receiver Whistler radios operate at the ELF and VLF range (typically 10 Hz to 20 kHz). (Our ears sense physical waves rather than electromagnetic ones.) VLF radio is filled with natural radio emissions. Collier IV,V Etienne Koen I,IV Stephen Meyer IV,VThe receiver circuit is a composition of two integrated circuits which will then be connected to the VLF antenna, which is a simple wire-loop antenna.VLF (Very Low Frequency) radio waves vibrate at frequencies that overlap the human hearing range, although we canвЂ™t directly hear them. Hanna Dahlgren I,II TorbjГ¶rn Sundberg I,III Andrew B. (A web search will yield a wealth of information on SID reception, including other simple designs, typically employing loop antennas.)Breaking with tradition, the SID.

During daytime, the ionospheric D-region (at an altitude of 60 km - 90 km) acts as the upper boundary of the EIWG, whilst at night the D-region becomes much weaker and the boundary moves to higher altitudes. This paper describes the set-up of the narrowband system and demonstrates its capabilities with data from a set of solar flares on 08 February and 12 February 2010.Very low frequency (3 kHz - 30 kHz) radio waves propagate thousands of kilometres in the Earth-Ionosphere Waveguide (EIWG) formed between the conducting Earth and the ionosphere. VLF waves propagating through the Earth-Ionosphere Waveguide are excellent probes of the varying properties of the lower region of the ionosphere.

This paper describes the installation of UltraMSK on a VLF system at the SANAE IV base in Antarctica (72вњ¤0'S, 2вњҐ1'W). 2,3,4 Further information on the response of the D-region during ionospheric disturbances, such as solar flares and gamma ray bursts, can be retrieved by constantly monitoring single-frequency signals and their prompt response to changing conditions.UltraMSK is a VLF narrowband receiver designed to measure both the amplitude and phase of modulated VLF signals. Estimates of D-region electron density have been determined via VLF propagation measurements. As this region is too high for atmospheric balloons and too low for satellites, it is one of the least studied regions of the Earth's atmosphere, and VLF waves are the only practical probes available. By monitoring them with narrowband VLF receivers, perturbations in the signal from a given transmitter can then be associated with ionospheric modification somewhere along the propagation path.VLF radio signals can thus be used to probe the lower ionosphere. The signals from these transmitters are extremely stable in both amplitude and phase.

A preamplifier at the base of the antenna boosts the signal, which is transmitted to the laboratory via a lengthy coaxial cable. The loop facing north-south is a better choice for monitoring signals of European origin, whereas the east-west loop is more sensitive to signals propagating zonally.Figure 1 shows a schematic of the UltraMSK system. The antenna consists of two vertically mounted diamond shaped loops with sides of length 7.6 m, aligned with the four cardinal directions. A magnetic loop antenna located a few hundred metres from SANAE IV was used for this purpose.

After the signals have been demodulated, the two components can be compared and information regarding the phase and amplitude of the signal can be extracted. The phase of the signal is determined by a quadrature-phase mixer, where the received signal is split and mixed with an in-phase component on one hand and a quadrature-phase component on the other. The service unit also integrates GPS timing. From here the signal is transferred to the sound card on a personal computer.

Figure 3 shows a 5-min averaged spectrum for the north-south loop, where the MSK frequencies are marked by vertical dotted lines. This low level can be compensated for by applying a smoothing filter to the signal.A number of VLF transmitter signals were identified at SANAE IV. Because of this, the signal may be below the noise level during the day. The diurnal variation in power also leads to changes in the SNR.

When arriving at a receiver, they are seen as an impulsive broadband signal termed a 'sferic'. Lightning discharges around the world radiate most of their energy in the VLF band and thus constitute the main source of VLF waves propagating in the EIWG. Note, however, that these signals are subject to change, and the 16.4-kHz JXN transmitter in particular follows a discontinuous transmission pattern, generally transmitting for only a few hours daily.In addition to the narrowband MSK signals in Figure 3, there is also a broader hump visible in the 4 kHz - 25 kHz range as a result of the radiation from lightning strokes. Several weaker signals of European origin are also present. 6 The 18.3-kHz HWV transmitter is currently the strongest signal in the spectrum. An overview of transmitters is given in Table 1.

East-west paths are to a greater extent disturbed by dawn and dusk terminator effects. These disturbances likely originate from the electrical system at SANAE IV, and do not interfere with the monitored MSK signals.In general, north-south paths are preferred as they allow a single local time to be studied. 7 SANAE IV also operates as a node in this network.Several non-MSK peaks can also be seen in the spectrum, with the most prominent ones located at above 30 kHz and below 2 kHz.

This attenuation is typically 20 dB/Mm - 40 dB/Mm, whereas the attenuation over the sea is about 1 dB - 3 dB/Mm. The thickness of the ice layer can be a significant fraction of a wavelength, which implies increased attenuation as a result of the low conductivity of ice. Because of SANAE IV's position relative to the global VLF transmitters, signals originating from the east or west travel a great distance over the Antarctic ice mass, as illustrated in Figure 4.

In this study, estimates of H' and ОІ were calculated using the average solar zenith angle along the north-south transmission path.

Simple Vlf Receiver Circuit