maxxkatt
Forum Supporter
When learning the Equinox 800 it caused me to dig down deeper into frequencies, what they were and why they were important to this hobby. This information may be useful for those of you considering which detector to purchase.
In this post I am limiting the scope to frequencies and not other weighting factors like roundness. This post is written for the detectorists who wants to learn more about their Equinox as well as other detectors where you can change the frequency within a range of frequencies. Or more importantly why you would like to buy a detector capable of searching using different frequencies.
Everything else being equal this is why when using detectors that you can change to lower frequencies and you can find deeper coins than other models say the AT Pro with a fixed frequency at 15 khz. (not picking on the AT Pro, one of the best machines ever made a number of years ago. But technology has moved forward.
In the Equinox 600 and 800 manual it is indicated that park one Park 1 Multi-IQ processes a lower frequency weighting of the multi-frequency signal. And Field 2 Multi-IQ processes a higher frequency weighted multifrequency signal. Lower weighing means it just uses lower frequencies in Park1.
I wanted to dig down deeper into the physics an understand why this is true. It is common knowledge on these forums that lower frequencies will go deeper and find high conductive silver and coins better than using high frequencies. Well I hit a wall getting down to the actual physics in my Google search, but I did dig up some useful information.
The Navy in the past employed extremely low frequencies of 3 – 30 hz to penetrate about 20 meters of seawater to communicate with their submarines on patrol. The Navy scientist knew that lower frequencies penetrated water and ground better. If my memory is correct these very long wave frequencies 1,000 to 100,000 km required very long buried antennas covering thousands of acres up in the Wisconsin an northern Michigan. As an aside the blue whale communicates over long distances at very low frequencies of 10 – 40 hz.
By digging deeper into the physics I turned to Vferrari on another forum and some articles I dug up on the internet using Google as my metal detector for information. But I basically hit a road block on getting down to the actual physics.
All I could dig out is that low frequencies with longer waves penetrate objects better. Higher frequencies with shorter waves then to reflect off the surface of objects. And an object can mean the ground or water.
As usual Vferrari took the time to go deeper into the question and he also stated there are some things about physics he just does not know when talking about frequencies and metal detecting. Well after my research, I can say the same thing.
Pulled up another good article on the subject by two developers of metal detectors, gentlemen named Mark Rowan & William Lahr. They work or worked for a metal detecting company designing metal detectors. I am not sure, but I think it is Whites. This article will probably go as deep into the subject of metal detector design that you will want to go.
http://www2.gi.alaska.edu/~jesse/treasure/misc/howdetector.html
There are many examples of the effect of frequencies on depth and a good test is at this link.
https://youtu.be/XTFMX1Xnxo4
by xpmetaldetector. He does a very good job at eliminating all variables in the test other than changing the frequency. The actual test starts at 2.45 minuite mark.
I never did have the actual physics explained, and I probably would not have understood it anyway. But there are useful bits for the detectorists. There are likely many of you guys who already know this, but this information recap is for those like me who are still learning.
Use low frequencies for hunting coins because they penetrate the soil better and give better signals on high conductive silver and copper coins. Go back over well hunted ground using a single low frequency like 5 or 10 khz. You may want to reduce your sensitivity some to go quiet down the chatter from many small near surface targets.
Go back over the same well hunted ground with a higher frequency because it is better at detecting a small footprint, eg a coin on the edge or not laying horizontal but vertical. Again reduce your sensitivity to eliminate many small near surface objects. Maybe find a diamond stud gold earring or small gold chain that also has a small footprint and is gold and thus more reactive to the higher frequency.
Low Frequency
• Have longer wavelength.
• Gets greater depth as long waves penetrate the ground more easily.
• Better for detecting high conductivity targets like silver and copper.
• Not good for finding smaller targets.
• Not good for low conductivity targets like gold or Iron.
High Frequency
• Have shorter wavelengths.
• Great for detecting small objects like tiny gold nuggets, earring studs hopefully with diamonds attached.
• Better for low conductivity targets like gold and Iron.
• Less depth is achieved than low frequency.
• Higher accuracy, closer to the surface.
• More sensitive to ground mineralisation interference.
If you have a detector that you can adjust the frequencies to a single frequency then you can change your frequency to suit your hunting plans. When you are working a site that has produced in the past, changing your frequencies can aid you in recovering items others have missed with their single frequency detector.
I am not sure that this is directly related to frequency, but it came up in my search.
Iron targets are orientation sensitive; so as the coil is moved above them, the calculated numerical value may change dramatically. This explains iron falsing. It is important to swing a target in different directions to identify iron falsing, eg iron reading like a high number good target.
Experience metal detectorist know this and this why a straight nail will give a different signal swinging from nail head to nail point than swinging cross the middle of the nail from one side to the other.
A good target like a coin will give the same signal from every direction if it is laying perfectly horizontal to the surface. If the coil is laying at an angle to the surface the signal can disappear on the 90 degree cross sweep at low frequencies. If the coin is laying next to an iron target this can and often will alter your target ID numbers on different swings. Changing your iron bias on the 800 can help, but not totally fix this problem.
If anyone finds errors in this post, please comment. If anyone wishes to add to this post, please do so. The intent of this post is to help newbies learn more about metal detecting as I am.
In this post I am limiting the scope to frequencies and not other weighting factors like roundness. This post is written for the detectorists who wants to learn more about their Equinox as well as other detectors where you can change the frequency within a range of frequencies. Or more importantly why you would like to buy a detector capable of searching using different frequencies.
Everything else being equal this is why when using detectors that you can change to lower frequencies and you can find deeper coins than other models say the AT Pro with a fixed frequency at 15 khz. (not picking on the AT Pro, one of the best machines ever made a number of years ago. But technology has moved forward.
In the Equinox 600 and 800 manual it is indicated that park one Park 1 Multi-IQ processes a lower frequency weighting of the multi-frequency signal. And Field 2 Multi-IQ processes a higher frequency weighted multifrequency signal. Lower weighing means it just uses lower frequencies in Park1.
I wanted to dig down deeper into the physics an understand why this is true. It is common knowledge on these forums that lower frequencies will go deeper and find high conductive silver and coins better than using high frequencies. Well I hit a wall getting down to the actual physics in my Google search, but I did dig up some useful information.
The Navy in the past employed extremely low frequencies of 3 – 30 hz to penetrate about 20 meters of seawater to communicate with their submarines on patrol. The Navy scientist knew that lower frequencies penetrated water and ground better. If my memory is correct these very long wave frequencies 1,000 to 100,000 km required very long buried antennas covering thousands of acres up in the Wisconsin an northern Michigan. As an aside the blue whale communicates over long distances at very low frequencies of 10 – 40 hz.
By digging deeper into the physics I turned to Vferrari on another forum and some articles I dug up on the internet using Google as my metal detector for information. But I basically hit a road block on getting down to the actual physics.
All I could dig out is that low frequencies with longer waves penetrate objects better. Higher frequencies with shorter waves then to reflect off the surface of objects. And an object can mean the ground or water.
As usual Vferrari took the time to go deeper into the question and he also stated there are some things about physics he just does not know when talking about frequencies and metal detecting. Well after my research, I can say the same thing.
Pulled up another good article on the subject by two developers of metal detectors, gentlemen named Mark Rowan & William Lahr. They work or worked for a metal detecting company designing metal detectors. I am not sure, but I think it is Whites. This article will probably go as deep into the subject of metal detector design that you will want to go.
http://www2.gi.alaska.edu/~jesse/treasure/misc/howdetector.html
There are many examples of the effect of frequencies on depth and a good test is at this link.
https://youtu.be/XTFMX1Xnxo4
by xpmetaldetector. He does a very good job at eliminating all variables in the test other than changing the frequency. The actual test starts at 2.45 minuite mark.
I never did have the actual physics explained, and I probably would not have understood it anyway. But there are useful bits for the detectorists. There are likely many of you guys who already know this, but this information recap is for those like me who are still learning.
Use low frequencies for hunting coins because they penetrate the soil better and give better signals on high conductive silver and copper coins. Go back over well hunted ground using a single low frequency like 5 or 10 khz. You may want to reduce your sensitivity some to go quiet down the chatter from many small near surface targets.
Go back over the same well hunted ground with a higher frequency because it is better at detecting a small footprint, eg a coin on the edge or not laying horizontal but vertical. Again reduce your sensitivity to eliminate many small near surface objects. Maybe find a diamond stud gold earring or small gold chain that also has a small footprint and is gold and thus more reactive to the higher frequency.
Low Frequency
• Have longer wavelength.
• Gets greater depth as long waves penetrate the ground more easily.
• Better for detecting high conductivity targets like silver and copper.
• Not good for finding smaller targets.
• Not good for low conductivity targets like gold or Iron.
High Frequency
• Have shorter wavelengths.
• Great for detecting small objects like tiny gold nuggets, earring studs hopefully with diamonds attached.
• Better for low conductivity targets like gold and Iron.
• Less depth is achieved than low frequency.
• Higher accuracy, closer to the surface.
• More sensitive to ground mineralisation interference.
If you have a detector that you can adjust the frequencies to a single frequency then you can change your frequency to suit your hunting plans. When you are working a site that has produced in the past, changing your frequencies can aid you in recovering items others have missed with their single frequency detector.
I am not sure that this is directly related to frequency, but it came up in my search.
Iron targets are orientation sensitive; so as the coil is moved above them, the calculated numerical value may change dramatically. This explains iron falsing. It is important to swing a target in different directions to identify iron falsing, eg iron reading like a high number good target.
Experience metal detectorist know this and this why a straight nail will give a different signal swinging from nail head to nail point than swinging cross the middle of the nail from one side to the other.
A good target like a coin will give the same signal from every direction if it is laying perfectly horizontal to the surface. If the coil is laying at an angle to the surface the signal can disappear on the 90 degree cross sweep at low frequencies. If the coin is laying next to an iron target this can and often will alter your target ID numbers on different swings. Changing your iron bias on the 800 can help, but not totally fix this problem.
If anyone finds errors in this post, please comment. If anyone wishes to add to this post, please do so. The intent of this post is to help newbies learn more about metal detecting as I am.
).
