Android app uses resonance test to detect fake silver coins

[Nikon]

Ok, so the traditional methods of detecting fakes are weighing and measuring the coin. But there are lots of good quality fakes out there which have the appropriate weight and size. That leaves visual comparison, which becomes more and more difficult with the ever improving fakes on the market.

There is ultrasound equipment which can be used to detect fakes, but it is expensive, and works better for bars than coins due to the lack of smooth surfaces on coins.
That basically only leaves us with the destructive test methods.

Some time ago I had an idea for a new method:
Why not make a smartphone app which tests the resonance frequencies of a coin?
The resonance frequencies of an object are determined by the objects shape and material. If a fake coin has the correct shape, but is made of the wrong material, then it will likely have different resonance frequencies.

As I see it, there are many advantages with this method:
* It is a cheap and easy test. Probably the easiest test of all.
* Silver plated fakes will make little difference. (Unlike when testing with acids and other surface-tests)
* Non-destructive.
* It examines an actual physical properly of the material.
* Requires no equipment besides your smartphone. Meaning the test can easily be performed "on the field".
* A new weapon in the arsenal against the ever improving fakes.
* The app is capable of measuring resonance frequencies outside the range of human hearing.
* Works even if you are partially or completely tone-deaf like me .

Here is a short demonstration video of how the app works:
http://www.youtube.com/watch?v=5pZnqp3bl3A
(Some Android devices with less sensitive microphones require that you tap the coin with a harder object than your fingernail to create a strong enough sound)

I just published the app on Google play. You can find it here or by searching for "Bullion Test".
Sometimes there are delays in the publishing process of google play. If you can't find it, wait a few hours and try again.
This initial version only supports a few different coins. I am working to add support for many more coins.

Important: This app should in no way be used as a replacement for other testing methods. It should only be used as a complement. You should always combine as many different testing methods as possbile to improve the chance of detecting fakes.

Let me know what you think!

 

[Gunna]

Awesome Idea, well done.

Let me put my conspiracy theory hat on:

Someone makes a similar app that enables the GPS and it logs the amount of coins/bars you test, then sends the results back to the creator. They now have GPS co-ordinates of your stack.

 

[Nikon]

Thank you!

Apps need explicit permission from you to access the GPS.
My app only asks you for two permissions: Ability to record sound, and ability to store data to the sd-card.

I will not, and can not, record your location. Promise

 

[Gunna]

I like it, I look forward to seeing more coins added.

Any chance of doing bars as well or are they too hard?

edit: If it were me, once I had a number of coins added I would charge $1. Might help you purchase additional coins to add

 

[willrocks]

Awesome Idea, well done.

Let me put my conspiracy theory hat on:

Someone makes a similar app that enables the GPS and it logs the amount of coins/bars you test, then sends the results back to the creator. They now have GPS co-ordinates of your stack.

You are one paranoid puppy.

 

[Gunna]

Awesome Idea, well done.

Let me put my conspiracy theory hat on:

Someone makes a similar app that enables the GPS and it logs the amount of coins/bars you test, then sends the results back to the creator. They now have GPS co-ordinates of your stack.

You are one paranoid puppy.

No more paranoid then the people in the safe thread claiming people working at the insurance companies could sell your information regarding insured coins/bullion

 

[SilverSpurs]

Just because you are paranoid doesn't mean they aren't after you.

 

[Chillidog]

Just because you are paranoid doesn't mean they aren't after you.

:lol::lol::lol:
Looks left looks right thinks he can hear something land in the back yard.
With the drop in precious metals they can't be after them(as they are now worthless according to some)
It must be me!!!

 

[BlackSheep]

Sounds like a clever idea Nikon, will download and have a look.

As mentioned above would be nice if it handles bars, although I'm guessing not?

Just because you are paranoid doesn't mean they aren't after you.

True dat :| :lol:

 

[Big A.D.]

Awesome Idea, well done.

Let me put my conspiracy theory hat on:

Someone makes a similar app that enables the GPS and it logs the amount of coins/bars you test, then sends the results back to the creator. They now have GPS co-ordinates of your stack.

You are one paranoid puppy.

How is that paranoid?

The number of apps that phone home to their publishers with the user's personal information apps is huge.

Even most of the phones out there now embed GPS co-ordinates into the photos they take by default.

 

[Nikon]

Awesome Idea, well done.

Let me put my conspiracy theory hat on:

Someone makes a similar app that enables the GPS and it logs the amount of coins/bars you test, then sends the results back to the creator. They now have GPS co-ordinates of your stack.

You are one paranoid puppy.

How is that paranoid?

The number of apps that phone home to their publishers with the user's personal information apps is huge.

Even most of the phones out there now embed GPS co-ordinates into the photos they take by default.

Well, they still need your permission to "phone home". Apps without gps and internet permissions can do no such thing.

 

[Nikon]

I like it, I look forward to seeing more coins added.

Any chance of doing bars as well or are they too hard?

Bars are certainly a possibility, depending on size.
Big and heavy ones are probably not going to have as distinct resonance frequencies as smaller ones. 1kilo bars could be problematic.
Any particular type and size of bars you'd like to see?

edit: If it were me, once I had a number of coins added I would charge $1. Might help you purchase additional coins to add

Yes, I will have to do something like that to be able to add support for any significant number of new coins (or bars).
Buying small numbers of many different types of coins costs me much money due to high premiums and shipping costs.
I have also had other expenses, such as the Google Play publishing fee and some outsourced graphics jobs.
It certainly adds up.

My current idea is to have one free version with support for a limited number of coins, and a full version with support for more coins. The income from the full version will hopefully be enough to enable me to add support for more coins.
I hope this sounds reasonable.

 

[Nikon]

The full version of the app supporting 12 different coins is now published on Google Play.
Link to full version
If/when the app has generated some income, I'll take requests for which coins/bars you'd like to see added next.

 

[Altima]

Oh man. Why am I stuck with an iPhone?

 

[Nikon]

Oh man. Why am I stuck with an iPhone?

You could pick up some old second hand Android phone for just a few bucks on ebay. Or perhaps you know someone who has an old phone they are not using? Old Android phones are not worth much. It is entirely feasible to have one around just as a "fake detecting droid"
The app should run on any Android phone with Android version 2.2 or newer.

In fact, the old original "HTC Desire" running Android 2.2 has the best microphone for picking up high resonance frequencies of all Android devices I have tried.
It beats my Nexus phone hands down.

But until now I have only come across one Android device where the microphone is weak enough to actually make it a bit difficult to use the app, and that's my Acer Iconia tablet.
I guess Android devices are not originally designed to be used to pick up faint resonance frequencies in the 20kHz range, so I can't really blame them.

 

[Altima]

Oh man. Why am I stuck with an iPhone?

You could pick up some old second hand Android phone for just a few bucks on ebay. Or perhaps you know someone who has an old phone they are not using? Old Android phones are not worth much. It is entirely feasible to have one around just as a "fake detecting droid"
The app should run on any Android phone with Android version 2.2 or newer.

In fact, the old original "HTC Desire" running Android 2.2 has the best microphone for picking up high resonance frequencies of all Android devices I have tried.
It beats my Nexus phone hands down.

But until now I have only come across one Android device where the microphone is weak enough to actually make it a bit difficult to use the app, and that's my Acer Iconia tablet.
I guess Android devices are not originally designed to be used to pick up faint resonance frequencies in the 20kHz range, so I can't really blame them.

That's a wonderful suggestion! Shall go hunting for a cheap android phone then.

 

[joebush]

Interesting concept, and it seems like a simple way to add an additional test. I have a question.

The list of coins to test is quite limited. Are there plans to allow user updated results? This would be interesting since empirical data would be massive.

Another interesting option would be to do a ping test and have the app TELL THE USER what coin it is, be it real or fake.

 

[joebush]

Btw, the point of the user updated results would be to add coins you don't already have listed. (couldn't edit previous post)

 

[Midnight Man]

The problem of allowing user added coins is that a user might unknowingly have a coin type in their stack that is fake - which (at least for a time) would become the accepted baseline for that coin type.

I also have a question for Nikon - assuming this app has been tested with several different coin types, is there much of a difference in the raw resonance data - enough to difinitively distinguish between various coin types, and further to that, have any fakes been tested? I ask because I could see the potential possibility for (as an example) a 2011 ASE fake having the same resonance as a genuine 2008 Panda (I will happily admit I am no expert on sound/audio, so this possibility is from a laymans point of view and may be absolutely a non-possibility).

In recent times, with an increasing number of fakes out there, I have purchased (and just received) one of these: http://www.ebay.com.au/itm/230968472069?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

I have yet to test it, that will be happening in the next couple of days - but I am envisaging a device I might build around this unit to hold a coin in place to allow for testing across its diameter (testing through its thickness will not be a very accurate test due to the limited distance involved).

 

[Nikon]

Interesting concept, and it seems like a simple way to add an additional test. I have a question.

The list of coins to test is quite limited. Are there plans to allow user updated results? This would be interesting since empirical data would be massive.

The problem of allowing user added coins is that a user might unknowingly have a coin type in their stack that is fake - which (at least for a time) would become the accepted baseline for that coin type.

Yes, that is the primary reason why I am hesitant to include such a feature.
I have a list of other features which would also help improving the number of supported coins, without the risk of introducing fakes as a baseline in the app.
When/if the features will be added depends on how much time I have to spend on improving the app.

The full version of the app currently supports 12 different coins. I am working to add more.
I do take requests for wich coins are most important to add first, but I can not make any promises for when and if they will be added.
Coin requests posted in the comment field of a (hopefully positive) review on google play for the full version of the app may be given some priority..

Another interesting option would be to do a ping test and have the app TELL THE USER what coin it is, be it real or fake.

I also have a question for Nikon - assuming this app has been tested with several different coin types, is there much of a difference in the raw resonance data - enough to difinitively distinguish between various coin types,

I originally had this feature in the app (before I released it), but there are many different coins which do sound the same way, so it made no sense to keep it.
All coins of the same material, weight and diameter are going to sound very similar, so it is not possible to tell them apart.
In additon, two coins of different material and different diameter and/or weight may also sound about the same.
For example: The 1oz silver ASE and the 1oz Perth mint gold kangaroo have very different diameters, and are obviously made of very different metals, but they sound the same. The difference in material is compensated for by the difference in diameter.
So a silver ASE would make a very good gold kangaroo fake from a resonance frequency perspective, until someone picks up a caliper and sees that the diameter is off by almost 10mm.

The resonance frequencies of a coin are primarily determined by three parameters: The material in the coin, the weight of the coin, and the shape of the coin.
The app should always be used in combination with size and weight testing.

... and further to that, have any fakes been tested? I ask because I could see the potential possibility for (as an example) a 2011 ASE fake having the same resonance as a genuine 2008 Panda (I will happily admit I am no expert on sound/audio, so this possibility is from a laymans point of view and may be absolutely a non-possibility).

Yes, fakes have been tested!
For example here: http://www.youtube.com/watch?v=5pZnqp3bl3A
You can verify the test yourself: Start the app, and hold your phone close to your computers speakers while playing the video on your computer. The app will record the sounds from the video and show you the results.

You can also verify the app in the same way based on the sounds of a different fake in this video:
http://goldsilver.com/video/special-report-how-to-avoid-fake-silver-and-counterfeit-gold-products/

But fakes are surprisingly hard to find when you actually want one. So I have only been able to test a small number of actual fakes, but the app has detected every fake so far.
I am always interested to learn what your results are if you happen to own a known fake.

In recent times, with an increasing number of fakes out there, I have purchased (and just received) one of these: http://www.ebay.com.au/itm/230968472069?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

I have yet to test it, that will be happening in the next couple of days - but I am envisaging a device I might build around this unit to hold a coin in place to allow for testing across its diameter (testing through its thickness will not be a very accurate test due to the limited distance involved).

I have also looked at those. Seems like a very good test, particularly for bars.
Larger bars are too massive to resonate sufficiently for the app to be useful. I even tried hitting a 1kg bar with a hammer to get it to resonate. No luck. Large bars will never work well with the app, but will probably work very well with a ultrasonic device like this.

I suspect that it might be a bit more difficult to use a ultrasonic device on coins since the relief on coins will make it difficult to achieve good physical contact between the ultrasound transducer and the coin?
The relief on coins also means that the thickness of the coin is somewhat uneven, which may be a problem since the ultrasonic device test depends on knowing the exact thickness of the coin. The diameter may be equally difficult to test due to the rounded nature of a coin, and even worse: Reeding on some coins.
I'd be very interested to hear what your results are!

The "Bullion Test" app and the ultrasonic meter both relies on the same physical property: The speed of sound in silver.