Vlf Receiver Full Test Of
It needs a full test of functionality, but I leave that to someone in the VLF community with the appropriate test equipment. This board was built and verified by listening through headphones. Some filtering is desirable to limit the bandwidth and cut the noise of mains hum.An open source version of Renato Romero’s portable E202 VLF radio receiver, made with permission. For an electric field receiver all that’s essentially required is a whip antenna and a high input impedance, high gain, audio frequency amplifier. The close-up of the VLF receiver below shows a 363k resistor and 750 pF capacitor from the antenna (Fahnstock clip) to the gate of the J201 JFET (or any type suitable for low voltage application).RefQtyDescriptionDigikey PNBNC1 BNC2 BNC33CONN BNC JACK R/A 50 OHM PCBA97555NDC11CAP CER 0.033UF 50V C0G RADIAL4458490NDC101CAP CER 10000PF 50V C0G RADIAL4458384NDView 29 more rowsI’m doing a little more on a simple handheld VLF receiver I’ve been working on. The original baby monitor antenna is the short gray one and the VLF antenna is the longer black telescoping type.
But it does have what I was looking for. BBB-4 VLF Receiver for broadband 0.1 to 11 kHz reception of naturally-occurring ELF-VLF radio phenomena.A quick google later, found this rather nice poster on NASA’s site, “ Building and Testing a Portable VLF Receiver“.It doesn’t have the schematic – I expect it’s one of their INSPIRE models. McGreevy's BBB-4 (Bare Bones Basic) Natural VLF Radio Receiver Schematic REVISED RELEASE COPYRIGHT 1996 to1998 S. Impractical to constantly listen for and record VLF emissions, as they can occur at inconvenient times and may never happen again for months Often times, a listener can listen with their portable receiver forStephen P. 14 VLF or Very Low Frequency 153 Radio Receiver 22 Radio Receiver Genius Radio.Automated VLF Reception Systems VLF Natural Radio emissions often occur randomly and can’t be predicted reliably. But I’d forgotten a key consideration, how much overall gain the thing should have.Portable HD Radio Receiver iHD transmitter or receiver these days.
Hmm, gain of 1500, that’ll be tempting to stability problems.When I was looking for the gain requirements yesterday, I opened a bunch of the results in browser tabs. I also need to check roll-off at the frequency extremes (call it 20Hz & 20kHz). I can figure out the gain bits from there, and simulate. There’s a feedback resistor change in my near future.First though I reckon I’ll draw up the circuit as it stands (in KiCAD).
The major problem with VLF reception is interference noise, so ideally you want to situate the receiver a long way from sources of that – eg. One piece of utter genius jumped out at me. It features a variety of simple receiver designs. While vlf.it is the site for all things Radio Nature, I did stumble on some material I hadn’t seen before.This page is notable : VLF Natural Radio Reception at techlib.com.
I must admit, it does have a bomb-like appearance! It spent the rest of the night under an overturned flower pot with the VLF antenna sticking out the little drain hole in the bottom.“.Another very promising site I ran across, have still to read, is Larry’s Very Low Frequency Site. That turned out to be a questionable location, by the way! Not only did several neighbors become alarmed by it, but a couple of police officers also spotted the thing. Voila, instant remote receiver.“ The antenna was horizontal and near the ground under my truck for this recording. Here the author bends a baby monitor transmitter, replacing the mic with a VLF preamp.
Vlf Receiver Plus A 3
I’ll come back to this is a while – I need to research & buy the gyro & accelerometers. As such, while they should be ok for picking up seismic data, they fall far short for the ELF/VLF radio capture which should really go up to the region of 20kHz.On the seismic side, I think a first pass worth trying is a home-hacked sensitive, one axis sensor, plus a 3 axis gyro and a 3 axis accelerometer. These are quite limited – 10 bit ADCs with bandwidth that at best may go up into a few kHz. An Arduino Uno has 6 analog inputs, and the ESP8266 WiFi card which I plan to use has one.
It seems that as well as the 50Hz fundamental, there’s also a significant amount of the 3rd harmonic at 150Hz. It’s a relatively simple 2-transistor design, with a high impedance FET input followed by a bit of further amplification provided by a regular BJT.A major problem, as mentioned here before is mains hum interference. A good starting point for this seems to be the BBB-4 VLF Receiver. This will be some kind of antenna, picking up the electric field with a frequency range from somewhere probably in the 100s of mHz up to around say 200kHz.
Pretty much decades in the audio range seem a reasonable starting point. Yes, this project is experimental…I intend to do a bit more examination of the signals that appear in VLF before going further, though whatever, the choice of frequency bands at this point has to be fairly arbitrary. But keeping things simple is a major consideration here, so I’ll stick to somewhere a bit below audio up to a bit above. Radio frequencies from the milliHertz right up to microwave are mentioned, may contain useful information. Alas, it seems that research is fairly inconclusive (and in places contradictory).
For the top end of (1.), a straightforward two op amp LP filter should be fine. Effectively just DC blocking. But it is possible to make pragmatic educated guesses. I intend using general-purpose op amps for implementation.At the bottom end of (1.), I suspect it’ll be more effort that it’s worth to worry too much about LF roll off, a simple buffered CR filter, should be adequate.
Pretty straightforward for Arduinos. The kind of values that are probably close enough to the decades above to usefully split ranges, but (hopefully) offcentre for the 50Hz harmonics.I don’t know if I’ve mentioned it before, but as the radio receiver needs to be as far away as possible from power lines (which will likely be determined by my WiFi range), I’m intending using little solar panels feeding rechargeable batteries for power.While on the subject, I reckon it’ll also be worthwhile adding data from other environmental sensors, notably for temperature and acoustic noise (a mic). Using the Sallen-Key circuit (this is a low pass, but shows what I’m talking about):This gives fc = 15.9 kHz and Q = 0.5, subject to component tolerances (typical inexpensive capacitors are +/-10%). But I’m hoping that using standard value/tolerance components will make enough offset to alleviate the hum harmonics. + are at multiples of 50Hz. Regarding the steepness of their curves, Butterworth configurations (maximally flat in passband) keep design straightforward.You may notice that 3.
I’ve given myself two major constraints: it should be simple it should be low cost. Author Danny Ayers Posted on FebruCategories Analog, Arduino, Hardware, Radio, Seismic Leave a comment on Arduino front end ideas Arduino – initial experiencesSkip to Arduino/WiFi bit, also Issues Raised and a Cunning Plan Requirements & ConstraintsOn the hardware side of this project, I want to capture local seismic and ELF/VLF radio data. My hope is to get a Deep Learning configuration together that will in effect subtract this from the signals of interest.
Vlf Receiver Software Licensing Issues
So the plan is to hack something. I’m taking rather a scattergun approach to the hardware – find as many approaches as are feasible and try them out.Both the seismic and radio sensor subsystems have particular requirements when it comes to physical location. Note that project non-constraints are absolute measurement, calibration etc. I want to capture 3D data, and want to keep the price comfortably under $100. Unfortunately, these gadgets start at $375 USD, and that’s only for one dimension (and there may be software licensing issues). For example, on the seismic side, a simple approach would be to purchase a Raspberry Shake, an off-the-shelf device based on a Raspberry Pi and an (off-the-shelf) geophone.
(WiFi range may well be an issue – but I’ll cross that bridge when I come to it). For my own installation this will probably mean bolting the seismic part to my basement floor (which is largely on bedrock) and having the radio part as far up the fields as I can get it.What seems the most straightforward starting point is to feed data from the sensors into a local ADC, pass this through a microcontroller into a WiFi transceiver, then pick this up on the home network.
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