Demonstrating an RTL-SDR Based Metal Detector

Over on YouTube user Ancient Discoveries has uploaded a video showing a prototype of his RTL-SDR based metal detector. The metal detector appears to consist of a coiled detection loop antenna powered by an AM transmitter and an RTL-SDR running in Q-branch direct sampling mode.

Ancient discoveries uses SDR# to tune to a low medium wave frequency of around 898 kHz while in direct sampling mode. Then as a piece of metal is moved closer and further from the detection coil the signals on the spectrum move around in correlation with the metals distance. A whining sound just like a real metal detector is also produced by SDR#.

!!! RTL SDR Metal Detector !!! dancing with signals !!! modified latest project

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Though I may not agree with Ed, I also shake my head when I hear the “Educated” profess superior knowledge. I am also always taken back as to how quickly those highly “Educated” individuals are to call others who don’t share their point of view “simple minded” and “uneducated”. Gentlemen, we are all here at this website to gain a better understanding of a cool, and inexpensive little thing that can expand our thinking and knowledge. Let us appreciate the level of knowledge that others have, and applaud the individual desire to expand upon that knowledge, as opposed to those who would rather sit on the sofa, watch ballgames,and drink beer until bedtime. 73

Dr. Celalettin UÇAR

No 3d imagery we only created a time slice image. Buried water tank area detected thanks to matlab simulink as darked than its environment. Calculating the depth is impossible with rtl sdr because of its sampling rate.If you look at youtube videos description you will see all the equipments.

Dr. Celalettin UÇAR

I am sorry for this false post

Dr.Celalettin Uçar

Yes… ı am working on a sdr based gpr project. 450 mhz frequency and 25 watt signal power. Unfortunately i have not created a subsurface gpr image yet but the signal reflection increased in magnetic field (buried metal gasolina tube in 1.25 m death from the surface) and reduced in non metalic water contained field. The changings are visible on waterflaw screen perfectly. This means that my sdr based gpr can be use for finding metal and water. Congrulations my friend. Go on

vishal verma

Hello Dr Celalettin , Hope you are doing good with this project. Can you share a little more about this project. The schematics of this GPR , SDR is going to work as a reciever , what are you going to use as transmitter and how you gonna change the readings into 3d imagery. How would you calculate the depth , shape , material of different cavities etc found using this GPR

Mustafa ynr

Merhaba hocam, size ulaşmam mümkün mü birkaç sorum var, rica etsem yardımcı olur musunuz?

Dr.Celalettin Uçar

Yes ı am working on a sdr based gpr . 450 mhz frequency and 25 watt signal power. Unfortunately i have not created a subsurface gpr image but the signal reflection is introduce in magnetic area and reduced in non metalic water concertion area. The changings are visible on waterflaw screen. This means that my sdr based gpr can be user for finding metal and water.

Ancient Discoveries

this is Ancient Discoveries..
this project is so simple but ı do some improvements next few weeks
actually in this project ı just attached the rtl doungle antenna but next time will improve it
ı am going to holiday when ı turn back i will work for 24 hours to finish the project
25 khz and 6 khz
my aim is deepest metal detector for coins

Mustafa ynr

Merhaba hocam, am transmitterin devre şemasını paylaşabilir misiniz rica etsem?


Innovative uses for the RTL-SDR dongle continue, this one is exceptionally innovative, kudos to the author.


I would strongly disagree.

The commonly available metal detectors for $50, work as follows.

They are nothing more than 2 simple RF oscillators, with both designed to operate on the same frequency in the LF range. One oscillator is the reference, while other will vary in frequency, because it’s L-C tuned circuit, has it’s inductor located externally, such that when in proximity to metal, will change the inductance and tuned frequency. As a result, when the oscillators are no longer tuned to the same frequency, the difference will produce a audio beat note, that can be heard via headphones or speaker. Obviously, the beat note will vary, depending on the distance the pickup inductor is, from the metal object.

What’s the innovation in using a RTL-SDR and computer, just to hear the hetrodyned beat note?


Ed, your comment is exceptionally simple minded and gives me the impression that you don’t have much experience evaluating innovated ideas. The innovation here is not a simple metal detector, it’s stupid to think that. I immediately see two areas this RTL-SDR metal detector could open up:

1) Multi-frequency metal detectors (highly sensitive and tunable to individual elements such as zinc, gold, copper, silver, tin, aluminum, etc.)
2) Ground-penetrating radars (~10 MHz to 2 GHz)

Lots of potential here for the RTL-SDR thanks to this author.


Unfortunately, you’re not familiar with even the basics concepts of digital signal processing.
If you were, you should have know better, then to say this.

Hint – While there are multiple fields of spectroscopy and each uses very different and advanced forms of input spectrum and DSP computer analysis programs.

Only the uneducated will confuse such an example of SDR capability, with the innovations and science, that has since occurred.


no need to strongly anything, these are advanced hobbiests which covers any humans showing an interests to dig deeper than is currently dug with science and engineering. generally pretty bright people. play nice.