e GEM-2 'ski' is a hand-held, digital, multi-frequency broadband electromagnetic sensor. It operates in a frequency range of 30 Hz to 93 kHz, and can transmit an arbitrary waveform containing multiple frequencies. The unit is capable of transmitting and receiving any digitally-synthesized waveform by means of the pulse-width modulation technique.
A frequently-asked question is the "Depth of Investigation." This is a very complex question because the answer depends on many factors, particularly on ground conductivity and ambient electromagnetic noise. Based on many analyses and field data, we estimate the GEM-2 should be able to see about 20-30m in resistive areas (>1000ohm-m) and about 10-20m in conductive areas (<100ohm-m). This figure assumes an ambient noise level of 5ppm.
The noise level is generally high in urban areas and low in rural areas. For typical applications, we do not recommend the GEM-2 for depths deeper than 30m.
The GEM-2 ski contains three coils: transmitter, bucking, and receiver coils. For frequency-domain operation, the GEM-2 prompts for a set of desired transmitter frequencies. Built-in software converts this into a digital "bit-stream," which is used to construct the desired transmitter waveform (Figs 1 and 2). This bit-stream represents the instruction on how to generate a complex waveform that contains all frequencies specified by the operator.
Figure 1. A three-frequency transmitter waveform.
Figure 2. First 33 points of Figure 1.
Figure 3. The base period of the bit-stream for the GEM-2 is set to 1/30th of a second for areas having a 60-Hz power. The TX switches at 192 kHz and, therefore, the bit-stream contains 6,400 steps within the period. Through a Fourier transform of the transmitter current waveform above, we obtain a power spectrum of the primary field, which shows each transmitted frequency.
Figure 4. With multiple frequencies, one can determine layered conductivity structure of the earth, conceptually shown below. This is called "frequency sounding" method.
Canadian rivers are known for its gold findings. Once again we received fantastic pictures of a happy gold seeker. With his Black Hawk metal detector he was looking for natural gold streams on the riverside in British Columbia/ Canada. The result you can see here - wonderful gold flakes. The OKM Black Hawk is available with different search coils for the detection of natural gold and buried metal objects.
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New research out from the journal Current Biology discovered that different movement patterns of elephants (walking stomping, charging) create unique ultra low frequency seismic waves.
Paired with earlier evidence that elephants are able to detect low energy seismic waves, scientist hypothesize that these self created seismic waves might be used communicate with other elephants up to 6.4 kilometers away!
Listening for elephant vibrations would certainly be one of the more unique use-cases for our Geode Seismograph, but it is totally possible given this research. It only goes to show that there are still many undiscovered use cases for seismographs like our Geode!
Aquapulse was the tool used for this amazing find!
The crew of a boat known as “Capitana” recently discovered over 350 gold coins! The Capitana is part of the 1715 Fleet-Queen’s Jewels, LLC historic shipwreck salvage operation. The famous 1715 fleet sank in the year 1715, with millions of dollars in lost treasures. The vast amount of coins just recovered were found on exactly the 300th Anniversary of the 1715 Fleet!
According to Brent Brisben, the co-founder of of the 1715 Fleet-Queen’s Jewels, LLC, there were 9 rare coins also found, known as “Royals”. Those coins are valued at $300,000 a piece!! Brisben also mentioned, in a recent press release, that the coins were meant for the King of Spain and these make up 30% of all the known Royals out there! Brisben said that all the artifacts were discovered in shallow waters, about 6 feet deep, off the coast of Vero Beach, Florida. The treasure hunter that made the amazing find was William Bartlett, near a location where Co-Captain, Jonah Martinez chose.
You can order your aquapulse here