The picture on the left provided by curtesy of Mr. This antenna type has been selected as the 'perfect' fit for our broadband VLF SID monitor.Ī detailed technical describtion written by the developer Mr. The buffer amplifier has been optimised for good strong signal handling performance. To prevent receiver overload, maximum output has been set to about – 20 dBm. Following this line of thought, tests have been performed to find the optimum dimension for the pa0rdt-Mini-Whip. A small die-cast aluminium box can also be used, with the buffer amplifier mounted inside. a small piece of copper clad printed circuit board. If it is accepted that a whip is a capacitance coupled to the electric field, shape becomes irrelevant, as long as the required capacitance is available. This is an electric field active antenna in a small package. More about that and the general theory of loop antennas is extensively explained by Lionel Loudet. So one must compute the direction of the in-coming signal and orientate the area of the loop antenna perpendicular to this direction. That means that the area of the loop must be perpendicular to the transmissions magnetic field vector in order to obtain strongest signal strength. That means that the loop antenna can be orientated towards the direction of the transmissions magnetic field vector.
A vertical antenna responds mainly to the electrical component. A properly designed Loop primarily responds to the magnetic component of the radio wave. On the other hand it has much less noise (electrical component) to pick up. The easiest solution is to use air.Ī disatvantage of the loop antenna to the longwire is that the gain is much less. As core material one may choose from air or a powdered iron compound (Ferrite). It may be either box (solenoid), any solenoid (e.g.
#VLF RECEIVER CIRCUIT LISTEN TO METEOR HOW TO#
There are many ways on how to wind the loop form. The same may be archived by using a loop antenna, which is a small multi turn loop of less than 1/10th wavelength in length. For the InFlaMo project we utilize the FiFi-SDR (see picture beside).Īt first one must ask what is a loop antenna (see picture on the left) and why use it? For LF and VLF radio wave receiving one would need in principle very long metal wires (to build a large di-pole). This makes the SDR the (almost) perfect ionospheric phenomena measurement device. While we are used to listen to just one radio channel on our FM radio, it is possible to record (listen) a continious spectrum with a SDR receiver at a high temporal resolution. ~10Hz till 60 MHz) for ionospheric studies aiming to investigate VLF and LF waves. This sudden development has made it possible to utilize SDR receivers also with broader bandwidth (e.g.
#VLF RECEIVER CIRCUIT LISTEN TO METEOR SOFTWARE#
Such a design produces a radio which can receive and transmit widely different radio protocols (sometimes referred to as waveforms) based solely on the software used.įirst SDR systems have been developed in 80ies and were aimed primarily for military use.Today SDR systems start to be affordable and radio amateurs have developed low priced and high quality hardware suitable for science applications. Significant amounts of signal processing are handed over to the general-purpose processor, rather than being done in special-purpose hardware. Other users from the world wide web can also access this data-storing facility or even upload their data for further science projects.Ī basic SDR system may consist of a personal computer equipped with a sound card, or other analog-to-digital converter, preceded by some form of RF front end. An user can now analyse the data (manual or automated) and/or store them at data-storing facility. After processing this signal once more with a low-pass filter one has only an analog signal as left-over and can convert it via an 8 Bit analog-digital-converter (ADC) into digital informations, which can be transmitted for processing to a Linux-micro-PC. This results in a DC voltage level, which is equal to the signal strength. A demodulation of the remaining signal follows. Here the target transmitter frequency together with a narrow frequency band surounding is extracted from the main spectrum. This process is followed by narrow band-pass filter. This RF signal is at first processed by pre-amplifier, which enhances the signal. So let us assume this means that the input signal (RF) is a signal consisting out of all possible frequencies.
LF and VLF signals are transmitted on a broad spectrum and are detected by a, e.g. How does a narrow band VLF radio receiver works? Obviously is the world not as narrow as we would wish in this matter.
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