8/19/17 Report - New Video To Show How To Identify Target Shape From Audio Signal Alone. Tropical Activity and Predictions.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

Source: nhc.noaa.gov

Harvey is going to cut across the Yucatan and then back out into the Gulf again.

L92, which is the next one to the east of Harvey is headed towards us.  The question is how strong it will be.  It did not strengthen last night.  It has a ways to go yet though.

Right now the surf is only one to two feet on the Treasure Coast.  Nothing big is predicted at this point.

The tides are pretty big.  There are some nice negative tides.

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ATX Coil Over Broken Iron Shipwreck Spke.
Source: See link to video below.

I've talked a lot about how much you can tell about a buried target from the audio signal alone even if you are using an All Metals or Pinpoint mode.  The audio signal will tell you a lot about the target's shape, size and depth if you really understand your detector.

I made a video that demonstrates how you can tell something of the shape of a buried object from the audio signal alone.  In the video I used a quarter (just for comparison), along with a fairly large bolt, smaller screw, piece of an iron shipwreck spike, and an odd shaped piece of metal that responds a little bit like a fish hook.  I usually can identify fish hooks by the sound of the signal.

I used a Garrett ATX, although you would get the same type of results with many other metal detectors.  I used this same technique to identify target shapes before I ever got the ATX.  It worked exactly the same when using an Excalibur, for example.

I put the items on a board so you could see them well.  I also cut the sensitivity of the Garrett ATX down to less than half, just to temper down the signal, and used Motion mode, although the results would be similar using the Non-motion mode.

When you run your coil over a long straight object you will get a different type of signal depending upon the direction you move the coil.  You'll see that clearly in the video.

When you move the coil over the long object from one end to another, you'll get a double signal.  One towards each end of the object.  And if you move the coil over the object at 90 degrees to that, the signal will sound very much like a coin-shaped object.  So if you swing in one direction and get a regular signal and then change the direction of your sweep 90 degrees, you'll get something like a double signal.  You can also get an idea of the length of the object something by the amount of time between the double blips.  There will be more time between the blips when the object is longer.

Here is the link to the video.  There is really a lot of good useful information in this video if you really study the objects and signals they produce.  If you don't want to dig nails, you don't need a target ID meter on your detector.

https://youtu.be/Mu7sbkrLC1k

If you move the coil too fast, you might not always catch the double blip.  You can gather additional information by varying how fast you move the coil too.

All of this is does not have to take extra time.  You can do it while pinpointing.

If you dig all targets, you don't have to do it at all, but if you are at a site littered with nails or other long narrow objects, you might want to be more selective.  This is a type of target ID that does not require a ID meter or any particular metal detector mode or function.

Notice that on the last object, there is a break.  I don't know what to call that thing right off, but you get what I'm calling a double blip when you sweep the coil in both directions.  The latch on the object is open.  You get the double blip in both directions, instead of just one direction like you would get with a bolt or nail or other long thin object.

My main point is that if you learn to analyze your signals, you can get a lot of information from just listening to the audio signal.  I always say that the human brain is a better processor than the detector's circuitry.  You can also learn to get a good idea of the targets depth and size from just the audio signal.


Happy hunting,
TreasureGuide@comcast.net

8/18/17 Report - Developing Storm Headed Our Way. Metal Detecting and Electrical Interference. Sand Transport Prediction Model.

Written by the TreasureGuide for the exclusive use of treasurebeachesreport.blogspot.com.

Source: nhc.noaa.gov

Harvey is now a tropical storm.  It is headed towards Yucatan and Mexico.  There was another one not long ago that took about the same track.

The one behind Harvey (red) is the one that looks to be headed towards Florida.  At this point it has a 70% chance of developing into a cyclone in the next 48 hours.

As you can see, the third will probably head north and out into the North Atlantic.

There is a good chance that the one behind Harvey will affect out beaches.  We haven't had much of anything to stir up the beaches all year.

MagicSeaWeed predicts an increase in the surf up to three or four feet by Tuesday.  We'll see.

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If you've done much detecting around the Treasure Coast, you might have noticed that there are some places where your detector becomes very erratic or noisy.  There is a place like that south of Turtle Trail.  There is another south of the Rio Mar beach access.  There is another north of Amber Sands beach access.  And there are times when Pepper Park can produce some electrical interference, but not as consistently or as much as the other sites that I mentioned.

Wikipedia says, Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction. The disturbance may degrade the performance of the circuit or even stop it from functioning. In the case of a data path, these effects can range from an increase in error rate to a total loss of the data.  Both man-made and natural sources generate changing electrical currents and voltages that can cause EMI: automobile ignition systems, mobile phones, thunderstorms, the sun and the Northern Lights. EMI frequently affects AM radios.  It can also affect mobile phones, FM radios and televisions, as well as observations for radio astronomy.

You can also get electrical interference from electrical lines, underground utility cables and train engines.  The interference can be significant enough that you won't be able to detect some locations. Some metal detectors will be more sensitive to a specific source of interference than other detectors. Some detectors will allow you to detect much closer to overhead electrical lines or other sources of electrical interference than others.  That can be an advantage.

Some detectors have adjustments you can make that will allow you to work around various sources of interference.  Just the other day I took my Ace 250 and ATX to a yard that had overhead electrical lines as well as underground cables that caused interference.  Without making adjustments, the Ace could work much closer to the cables than the ATX, however the ATX has a Frequency Scan function that helped with that situation.

When working in the middle of the yard, the ATX was very noisy and sensitivity was severely reduced, but he ATX Frequency Scan function was able to find a frequency that eliminated much of the noise.  It then worked very well where there was previously way too much interference.

On the ATX you hold the searchcoil steady and away from any metal, and push the button to activate the Frequency Scan function.  It takes 35 seconds for the ATX to complete the scan and select a quiet operating frequency.  It worked well.

At the beach I've seldom used the Frequency Scan function, except a few times at some of the locations mentioned above.  There aren't as many sources of interference at the beach, but you'll find a good number in urban areas or residential neighborhoods.

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Darrel S. said the weight found by Grant of the Capitana a few days ago, Matches the weight found on Green Cabin Wreck several years, ago. It had 6M on it, and this one 4M.  

Thanks Darrel.  I didn't remember that.

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I noticed that in my videos and previous posts I kept typing Ace 150 when it should have been Ace 250.  I made those corrections.

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Here is a scientific article on cross-shore suspended sand and bed load transport on beaches.  It is very technical and difficult to read.

Here is the link.

http://onlinelibrary.wiley.com/doi/10.1029/2007JC004203/full

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Keep watching for weather news and a possible change in beach detecting conditions.

Happy hunting,
TreasureGuide@comcast.net