Vlf Receiver Kit Series With The#

First Steps Preparing for Reception. The intended application of this receiver is to monitor signal strength of time code station WWVB at 60 KHz.The Software Defined Receiver: SAQrx. Works with our SER22T line of antennas. So it shouldnвЂ™t surprise anyone that another name for this hobby is вЂњnatural radioвЂќ.Build this sensitive 4-transistor VLF-LF Radio Receiver for 10 KHz - 300 KHz. These types of wide band signals are characteristic of natural EMF activity from Earth as well as our solar system and beyond. This is because a lightning strike is not a narrow band event as is say a military VLF transmitter like NAA in Cutler Maine at 24KHz.

IвЂ™m currently using a homemade receiver for this project which I detail below. As a matter of fact the Schumann resonance receiver which I use, found here, can easily be modified to receive the entire VLF band. Over the years I have built a number of VLF receivers of the E-field and loop antenna type. No tubes, no semiconductors, only an engine driving an AC generator.I have been interested in natural radio for a good ten years now.

At dusk the D layer (lowest layer) of the ionosphere fades away leaving the higher E and F layer only. During dusk, dawn and the intervening night hours the ionosphere goes through a transformation that has a profound effect on spheric activity. Thankfully, there is more to natural radio than just spherics. Yes I agree, after a short while spherics can get very boring. The published design (shown below) is for that band but will work well at 8-9kHz if the choke values and capacitor values are increased.Ok, you might be asking yourself whatвЂ™s the big deal about popping sounds from lightning in the VLF band anyway.

At night though itвЂ™s presumably the much higher E and F layers that are responsible for the sky wave component of a VLF signal. These spherics reach the receiver via the wave guide created by the D layer and the EarthвЂ™s surface. During the daylight hours spherics can travel upwards of 2000 to 3000 kilometers from the source of the lightning strike. This phenomena can easily be seen on a SID receiver plot as a sharp rise in the received signal strength of a monitored VLF transmitter at dusk and the subsequent signal drop at dawn.

Tweeks get their name from the distinctive вЂњtweekвЂќ sound they produce. These types of spherics are called tweeks. INSPIRE VLF-3 Receiver The INSPIRE VLF-3 is the third version of the.During the night hours, spherics from much further than 2000 or 3000 kilometers can be heard! As a matter of fact during night hours it is possible to hear spherics from clear across the planet.

The lower frequencies only lag by a few hundredths of a second, but this is enough to change how a spheric sounds at great distances. Dispersion is the process of higher frequencies arriving at the receiver slightly faster than lower frequencies. Tweeks are spherics that have traveled for many thousands of kilometers through the Earth-ionosphere wave guide, and because of this they undergo dispersion. HereвЂ™s an example of a tweek with a very long tail captured with my setup. It is this вЂњtailвЂќ that gives tweeks their unique sound. On a spectrogram tweeks generate a small tail at around 2KHz and itвЂ™s harmonics.

Whistlers are associated with intense lightning strikes, and research has shown that they might be linked to upward electrical discharges from thunderstorm tops. Whistlers are less common than spherics and tweeks, but are truly worth the effort of detecting them. There is a nice paper that goes into more detail about tweeks, dispersion and cut-off frequencies in the Earth-ionosphere wave guide with formulas and all, and it can be found here.Dispersion plays a very important role in natural radio and there is another phenomena that takes dispersion to the extreme, whistlers. I say вЂњrangeвЂќ because the EarthвЂ™s wave guide varies with the reflecting height of the ionosphere. This is why we see tweek tails at this base frequency range. All wave guides have a cut-off frequency and the Earth-ionosphere wave guideвЂ™s cut-off frequency is around 1.7KHz.

ItвЂ™s also possible for the whistler to be reflected again back up the magnetic field line by the ionosphere and be heard at the originating conjugate point as a whistler echo. The whistler energy has literally traveled thousands of kilometers into space, many times further than the circumference of the Earth to generate such an extreme dispersion in the signal. A VLF receiver in the opposite conjugate point will hear a steady decreasing tone that last for about one second. As the trapped energy/electrons travel up the magnetic field line they are guided back down to the magnetic conjugate point on the opposite hemisphere.

HereвЂ™s a Google Earth view of where I installed my receiver. The receiver is located about 500 feet away from the house. I used a long run of CAT5 network cable between the house and the receiver. The ammo box has a rubber seal around the cover that does a great job at keeping humidity out. Therefore, I used a military ammo box for the outdoor enclosure to house the receiver and a 12 volt rechargeable battery for powering the receiver. The power grid 60Hz hum and its harmonics are just horrendous inside a home.

A good ground system can cut down on the hum level so double your efforts here. An E-field receiver needs a good ground for proper operation so donвЂ™t cut corners here. I used an 8 foot CB steel whip antenna bolted to the ammo box for the antenna and two 8вЂІ foot copper ground rods for the ground. This is an important step and shouldnвЂ™t be omitted! After all, the whole point of putting the receiver outside is for isolating it from the houseвЂ™s electrical systems. On either end of the cable run I installed a 1:1 isolation transformer to isolate the receiver from the house and to balance the feed line.

Vlf Receiver Kit Series With The

The gain of this stage is between one and seventeen which is set to give a total gain of x1000 whenever possible. In the house I have the second stage of gain and filtering built around a TL071. All resistors are metal-film.I had to add a 1.8Kohm resistor in series with the antenna as well as looping the antenna cable around a ferrite bar to correct an вЂњintermodulationвЂќ like issue I was having with a nearby broadcast FM station. So search for the location that has the lowest hum level possible.Here is the schematic for the outdoor receiver and the indoor gain and filter stage. Installing a receiver outside adds to the complexity of the installation, but for natural radio there isnвЂ™t much of an option.В And remember, when it comes to natural radio itвЂ™s all about location, location, location.

This is what I was after when I set out to build a natural radio receiver so IвЂ™m very exited that I finally have a receiver that is sensitive and quiet enough to capture whistlers in Florida!In many cases the source spheric or tweek which generates the whistler can also be seen.