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GrievousAngel

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  1. “What you will find is there is no singular answer to the question you are seeking because the variables in play are simply too complex. I get the impression you are looking for the optimal frequency to detect . . . “ No not that at all. I found the science interesting, and I guess I was looking for a 'meaningful understanding' that made sense to me. I understood what -3db half-power was about in electrical power transfer and impedance matching, so I set out to see if my intuitive feel was accurate as applied metal detectors. It helped me understand why a specific frequency is better for a specific target, as opposed to accepting and putting to memory. Like why a dime reacts better to 2.7kHz than say 15kHz? Other than the manual says so. I'm kind'a weird in that way. I like understanding as opposed to running on 'blind faith' one may say. As you have mentioned, be careful to not get trapped in the technology thing. And you are right. The bottom line is to get outside and go detecting! I appreciate your comments. I need those 'checks and balances' to stay focused. Later, Billy BTW . . . I would really enjoy traveling to Nevada and detecting with you and others in that area. I've lived in CO's Eagle River Valley (I70) for over a year in 2013-14. I love the Western states. I'm hard to pinpoint at times, as I enjoy outdoor adventures and yet I'm into technical details, etc. I could learn so much out there! I live in SE Georgia, and raised my family on the Ogeechee River near Statesboro. I got a few articles to read now. Like I said, this is a great site to be part of. You and others have done an excellent job with it.
  2. Steve and the rest of us . . . Without any doubt, this site is the 'Top-Drawer' source of accurate information, in all aspects of metal detecting - technical to use in the field! I'm totally impressed. There are so many knowledgeable detectorist hanging out on this site, who are eager to share information. I have an OK engineering background, but I'm short on actual use in the field. Thanks to all, Billy
  3. Thanks for leads. I will knock on their doors soon. It is fortunate to be able to connect with others that truly have a 'meaningful understanding' of a given topic. Top-Drawer Experts! Later, Billy
  4. I agree. Yes it can be confusing for sure, as the terms are often used loosely. Due to time and avoiding over-stating an accepted law in a more casual setting, you have to be careful how one might explain a concept. Yep, it is the 'special off-set' frequency at which the R-response component is at maximum level (magnitude) in which the detector receives and processes. Conceptionally I think of it as shifting the center frequency intended to be transmitted, up or down so it's at maximum magnitude when received. In terms of electrical power, -3db frequency point is called the half-power level, in which maximum power transfer is achieved via impedance matching. This law is also critical in microwave waveguide design, i.e., used in many engineering fields. My definitions and concepts were taken directly from the articles below. I should have referenced the sources in more detail. The article Signal Frequency And Multiple Frequency as found on this site, https://detectorprospector.com/forums/topic/3193-selectable-frequency-and-multiple-frequency/ was the entry point for my thread. This article also referenced George Payne from his article found at http://jb-ms.com/Baron/payne.htm (2002). I would suggest reading these articles if not already done so. I certainly improved my understanding of the science behind VLF frequency selection, single or multiple. Cool stuff! Billy One of the experts in this arena is George Payne as referenced in
  5. Sad it is. I think about concrete covering up important finds more or less for ever! But they can surface 100's of years later.
  6. I would love to spend a month + checking it all out. I have been out that many times, but Time Won't Let Me! Have you gathered many finds in that area? Billy
  7. Ok Steve, I guess I'll go down Dimitar's Tarsacci rabbit hole . . . just knock on the door to keep me from getting too lost! I was not aware of his work in any detail. I've noticed his name about but that's about it. Billy
  8. Absolutely right Steve, it's held very close. Although, I wasn't chasing the received signal processing, e.g., electronic circuitry or the coding, I was more interested in understanding the science behind determining the optimum frequency (single or multi) to be transmitted for a given target. As I mentioned, I ran into the reference to George Payne's paper discussing the significance the -3db frequency shift up or down from the center transmitted frequency (per -3db half-power law ), where R magnitude is maximum and X magnitude is halved. Per Payne it turns out that the returned signal is maximum when at this -3db special frequency point. Therefore the VHF processing unit receives this optimum signal, in which improves it's performance substantially. (The amplitude(s) of these wave forms are easier seen in the frequency domain.) Thanks to your article Selected Frequency vs. Multiple Frequency, I have a much better understanding of the details surrounding the selection of a specific frequency for a specific target. That's the short version of why certain model detectors are better at certain targets ranges. The -3db Frequency point as a huge impact on the detectors design. A few days back, I did not have as clear of a understanding as I do now, but it ain't that clear . . . Steve your articles great. Thanks for sharing your knowledge of detectors, from use in the field to the technical aspects. I apologize for repeating some of my comments and references, but it's difficult to drop into a related thread without some premise. Later, Billy
  9. I emailed Minelab referring to my interest in the -3db frequency half-power level and it's impact on receiving the maximum returned signal for processing. I also referred to the George Payne article that was referenced in the article named Single Frequency and Multiple Frequency. I just got a reply from Minelab engineering stating that information is not available for public consumption. So maybe it is deeply woven into Minelab's Multi-IQ weighting algorithms. From my limited point of view, it would seem logical. I've taken this about as far as reasonable plus I learned a little along the way. Thanks for your advice. Moving on. Billy
  10. That's it. I would recommend detectorists to watch the series. Traces history throw there finds at certain locations. Thanks for the info. Billy
  11. . . . where two guys wandered around the USA detecting relics and coins? They used Garrett's AT detectors I think back. They would locate/research historical homes and other locations of interest, then ask for permission to hunt. There was a different story every week I think. I always thought that historic wagon train trails would cough-up great finds. I would assume one could travel the same pathway, either by road or off-round, with proper research and planning. I would like watch those shows again. Billy
  12. What was the last meteorite found in the USA Mainland? How 'bout worldwide? 'Falling Stars' are visible every evening somewhere on this planet I would think, but finding them is something else of course. I used to watch Meteorite Men on the Science Channel years back. What were those cats names? Gregory maybe and one other guy. It always interest me . . . how meteorites were located and hopefully found. I remember one they found that was huge like maybe 3' in diameter. It wasn't from a recent fireball that someone saw falling. I always wondered why they were looking on this particular large farm & pasture land? It was like 6' deep. I think they were using a custom 2-box detector on wheels. It lay along the side of a long fence line. Did anyone see that particular Meteorite Men? Anyways meteorites are cool! Later, Billy
  13. I gave my Garrett L&S PI to my grandson. I found it was basically a ‘dig everything’ detector that worked Well on saltwater beaches and most soils at good depth. Are there any other advice or tips I can pass on? i stopped using it has it a very heavy detector. Made like a tank but heavy! That is what led me to purchase the Equinox 800. Later, Billy
  14. What profile is typically better for wading or diving in freshwater? I am assuming no presence of black sand or other strong mineralization in soil or the water. I venture to say, the same settings that works on surrounding land! However I haven’t spent enough detector time to form a strong opinion. What have other Equinox users found to work well? Billy
  15. What is a good Equinox compatible headphone for wading in saltwater surf knee deep? I can easily see a larger wave splashing and covering detector and me for a second or so! So maybe the term water-resistant is applicable. Plus has good sensitivity to fast weak signals. I just posted a similar thread where I mentioned the advantage of a lower mass speaker component. Suggestions? Billy
  16. I’m looking an Equinox compatible water resistant headphones. I said ‘resistant’ because I don’t plan to dive, just wade in the ocean surf like knee deep. They need to be sensitive enough to hear fast dim signals. The more mass the speaker component has, the less sensitive they are. Larger mass speaker diaphragms are not as responsive to fast changing signals with weaker signal amplitudes. Wired or fast Bluetooth OK as long as they deal with saltwater and sand! The ML-80 headphone don’t appear water-resistant, so I am looking Suggestions? Billy
  17. I’m sorry Steve. For some reason I thought you where Andy S. My apologies Steve I understand it is a marketing thing and not to be referred to as technically correct. i was more interested in the -3db point of a selected single frequency as discussed on a different thread. Billy
  18. Actually it is similar to radar, but the transmitted magnetic waves cutting throw the target's eddy currents is what produces the returned 'radar-like' signals. I think I said that correctly. Billy
  19. Detectors don't just measure the reactive component of a target. If they did, a 13kHz machine ( decent all-rounder Fisher F75, for example ) would be hopeless at finding 1 kHz targets ( US silver dollars / half-dollars ), as the phase lag is about 86 degrees, with the reactive component way less ( 7% ) than the resistive component. Of course they don't. Returned data is in the form of X (inductance-like current momentum) and R (inversely related to conductivity). Of course that is a simplified analogy. I am not disagreeing with all you have said. You are correct. Billy
  20. "Now you're bringing multiple freqs into it ... and it sounds like you don't really understand the why's of multi-freq." by PimentoUK. Maybe so, but please refer to this article: Selectable Frequency and Multiple Frequency from this site. In which part is taken from an article by George Payne. See this link: http://jb-ms.com/Baron/payne.htm (2002). My comments was taken directly from these two articles. The -3db point yields max returned signal of a given center frequency. I then became interested and wondering if the -3db half-power data was somehow used in the different weighting algorisms used in Minelabs Multi-IQ. I would guess, very likely. I am hoping to get comments on this specific concept. Maybe I put this thread in the wrong forum. Thanks, Billy
  21. I think we are saying the same thing. In a previous thread I clarified what I was saying. Please refer to latest Equinox Manual. Frequency, p. 29. I was relating to this page. it's just a marketing thing. With v3.x and the addition of 4kHz (3,7kHz) as a single frequency (even though not included in Multi-IQ algorisms, it does expand the range or ratio to ~ 11, therefore the marketing graphic could/would 6Fx11 (800) and 4Fx4 (600). BTW, that was not the main idea I was interested in. Further into my comments I referred to -3db point of a given single frequency. I was relating [it] to the half-power level of the transmitted alternating wave and the resulting received alternating wave prior to being processed into a maximum magnitude. I think it is the R component. I was hoping someone would expand on the -3db point of a given frequency, as I understand it, that would yield the strongest returned signal for processing. Please refer to the article Selectable Frequency and Multiple Frequency, p. 1-2. This part of the article was taken from a previous work by George Payne at http://jb-ms.com/Baron/payne.htm. Thanks, Billy
  22. Thanks helping me clarify. Personally, I don't want to share information that is actually inaccurate, so I often ask if someone agrees or disagrees. I enjoy an awareness of technically correct background knowledge, but at times I go out on a weak limb which usually falls. Billy
  23. I think we are saying about the same thing. The 4kHz (3.7kHz) signal is available for use as a single frequency, but is not used the detectors algorisms for weighing in each mode/profile. Using 3.7 the ratio (range dependent) works out with proper rounding but is just a marketing thing, eg., Nox800 with 3.7kHz addition, the 5Fx8 could/would be considered 6Fx11. Billy
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