Is it possible to construct circuit to mimic this odd iPhone behavior?

[rfblackmagic]

I was reading this:

https://www.reddit.com/r/rfelectronics/comments/v9kbfi

In it the user claims, their iPhone picked up a random radio transmission while they were on a call. Is it possible to construct any circuit which will pick up the strongest radio transmission nearby? Regardless of the frequency or modulation

 

[Papabravo]

The microphone itself? No probably not since the microphone is mechanical and there is unlikely to be any RF source in the 20 Hz. to 20 KHz. range that would excite a mechanical device. There are a few VLF (Very Low Frequency) sources, but they usually have very high power and very long antennas.

FYI. For an RF signal, the wavelength in meters times the frequency in Hertz is equal to a constant. This constant c, the speed of light, is approximately 300,000,000 meters/sec. For example, at 10 KHz a half wavelength antenna would be 15,000 meters or approximately 9.32 miles.

There are instances where a very strong RF source, very close to a receiver, can cause the effect you describe, but it has nothing to do with the microphone. There are also cases where such a nearby source can render the receiver deaf.

To your question. It is possible to construct a receiver with a wide input range that will find the strongest signal and tune to that frequency. This would be a good application for an SDR (software Defined Radio). A typical public service band scanner will also do this.

 

[Nigel Goodwin]

Nothing 'odd' about it, it's perfectly 'normal' - radios of any kind (including mobile phones), or even other electronics, are designed to operate within certain limits - and excessively strong signals can overload them causing demodulation of those strong signals. The better the device, the less likely this is to happen, as quality improvements include better filtering and better high signal handling.

It's well known that this occurs even without electronics - a classic example is hearing radio signals in your head, which are being demodulated by the fillings in your teeth. An amalgam filling has similarities to the 'crystal' used in the old crystal sets, which was usually galena.

 

[rfblackmagic]

The microphone itself? No probably not since the microphone is mechanical and there is unlikely to be any RF source in the 20 Hz. to 20 KHz. range that would excite a mechanical device. There are a few VLF (Very Low Frequency) sources, but they usually have very high power and very long antennas.

FYI. For an RF signal, the wavelength in meters times the frequency in Hertz is equal to a constant. This constant c, the speed of light, is approximately 300,000,000 meters/sec. For example, at 10 KHz a half wavelength antenna would be 15,000 meters or approximately 9.32 miles.

There are instances where a very strong RF source, very close to a receiver, can cause the effect you describe, but it has nothing to do with the microphone. There are also cases where such a nearby source can render the receiver deaf.

To your question. It is possible to construct a receiver with a wide input range that will find the strongest sign and tune to that frequency. This would be a good application for an SDR (software Defined Radio). A typical public service band scanner will also do this.

I have an SDR but it I don't know any software which scans the entire frequency range provided by it and shows the strongest signal. There is probably some circuit connected to the mic in the iPhone which picked up the radio transmission.

Nothing 'odd' about it, it's perfectly 'normal' - radios of any kind (including mobile phones), or even other electronics, are designed to operate within certain limits - and excessively strong signals can overload them causing demodulation of those strong signals. The better the device, the less likely this is to happen, as quality improvements include better filtering and better high signal handling.

It's well known that this occurs even without electronics - a classic example is hearing radio signals in your head, which are being demodulated by the fillings in your teeth. An amalgam filling has similarities to the 'crystal' used in the old crystal sets, which was usually galena.

So you are saying a smartphone which goes for around $1000 has been made shoddily. I did hear about radio transmission being picked up by teeth filling, Lucille Ball talked about it, but it is very disputed, it is impossible to know if it is true or false.

 

[Nigel Goodwin]

I have an SDR but it I don't know any software which scans the entire frequency range provided by it and shows the strongest signal. There is probably some circuit connected to the mic in the iPhone which picked up the radio transmission.

No, that's complete nonsense.

So you are saying a smartphone which goes for around $1000 has been made shoddily.

Certainly, it's made down to a price (little of which has to do with the radio section anyway), and to highly constrained physical limits. The radio parts are nothing like high quality professional radio receivers, which come with much higher price tags.

I did hear about radio transmission being picked up by teeth filling, Lucille Ball talked about it, but it is very disputed, it is impossible to know if it is true or false.

No reason to doubt it, as far as I'm aware it's well tested, and the principle is perfectly sound.

 

[Diver300]

If you look at the microphones used in recording studios, you'll see that they are much larger than smartphones. A phone is made to give reasonable quality, primarily for voice communication, and to work in most conditions, but it has to be tiny, so the electrical signal it produces is tiny and needs more amplification, making electrical noise more of a problem.

Similarly, the manufacturer of a phone isn't going to waste space and money on filters that will only be noticed in the strangest of conditions.

 

[rfblackmagic]

No reason to doubt it, as far as I'm aware it's well tested, and the principle is perfectly sound.

Really? Do you have links? What is the principle?

 

[Nigel Goodwin]

Really? Do you have links? What is the principle?

Try looking up old crystal radios - as I mentioned previously, an almalgam filing is pretty similar to galena, or iron pyrites, which are two crystals used as detector diodes (many similar crystals will work).

 

[rfblackmagic]

Try looking up old crystal radios - as I mentioned previously, an almalgam filing is pretty similar to galena, or iron pyrites, which are two crystals used as detector diodes (many similar crystals will work).

That would explain the rectification of the signal, but how would that produce sound, would it vibrate?

 

[Nigel Goodwin]

That would explain the rectification of the signal, but how would that produce sound, would it vibrate?

It produces electric signals, which can be interpreted as audio - think crude cochlear implants.

 

[Diver300]

There could also be tiny amounts of movement. The ear bones are closely related to the teeth and jaw. https://en.wikipedia.org/wiki/Ossicles

When we hear a sound, the movement of the air moves the ear-drum, which in turn moves the ossicles, which move liquid in the cochlear duct. The movement of that liquid is picked up by tiny hairs.

We can hear very low energy sounds. For instance a house fly's wings at a few metres distance. That will be causing the most incredibly small movement of the ossicles.

There could easily be electrostatic forces that cause slight movement, or peizo-electric movement from the fillings or the teeth. I realise that the movement those forces cause would be tiny, but all hearing is detecting tiny movements.

 

[rfblackmagic]

It produces electric signals, which can be interpreted as audio - think crude cochlear implants.

How can electrical signals in mouth or outside cochlear be interpreted as sounds?

There could also be tiny amounts of movement. The ear bones are closely related to the teeth and jaw. https://en.wikipedia.org/wiki/Ossicles

When we hear a sound, the movement of the air moves the ear-drum, which in turn moves the ossicles, which move liquid in the cochlear duct. The movement of that liquid is picked up by tiny hairs.

We can hear very low energy sounds. For instance a house fly's wings at a few metres distance. That will be causing the most incredibly small movement of the ossicles.

There could easily be electrostatic forces that cause slight movement, or peizo-electric movement from the fillings or the teeth. I realise that the movement those forces cause would be tiny, but all hearing is detecting tiny movements.

Thanks for this information.

 

[Nigel Goodwin]

How can electrical signals in mouth or outside cochlear be interpreted as sounds?

Thanks for this information.

It's very close to the ear/brain, and human tissue is conductive.

If you don't believe it's possible, then don't believe it - no one really cares.

 

[rfblackmagic]

It's very close to the ear/brain, and human tissue is conductive.

If you don't believe it's possible, then don't believe it - no one really cares.

It's not about that, I want to know how it works, so that when I face similar skepticism, I'll be able to defend it. My personal theory is, unless the implant is in contact with auditory nerve, electrical signals produced by it will be ineffective, so I think the implant has to vibrate or make tiny movements which make the cochlear send electrical impulses up with the auditory nerve..

 

[Nigel Goodwin]

It's not about that, I want to know how it works, so that when I face similar skepticism, I'll be able to defend it. My personal theory is, unless the implant is in contact with auditory nerve, electrical signals produced by it will be ineffective, so I think the implant has to vibrate or make tiny movements which make the cochlear send electrical impulses up with the auditory nerve..

It's so rare, as it depends being in a very strong RF field, so why care?.

 

[rjenkinsgb]

I want to know how it works

It's a "signal breakthrough" effect, similar to when [illegal] AM CB radios were in use in the UK back with analog TV, where a vehicle transmitting an passing close to a house could cause their audio to be heard on a TV or HiFi, as the RF field strength was great enough to swamp the electronics and be rectified & detected.

It's an untuned effect that can only happen with extreme signal levels, not conventional or selective (tuned) radio reception.

How a tooth filling produces audio (rather than just a hypothetical electrical signal) under those conditions is anyone's guess - it could have even been some other piece of equipment in the vehicle producing audio and confusion about the source. Even a turned off radio could hypothetically produce some faint audio if the RF field strength was great enough.

 

[Dr_Doggy]

Also to note, is that I have had cellphone glitches where i have picked up other ppls phone calls, but only brief segments and only one side of the conversation was heard.

I had a quick look at how cells work, and basically they use the same frequencies, one for tx and one for rx, and there is some kind of modulation or encryption or something based off the sim card number. The above may be a skewed vision, but have often wondered if simcards could be hijacked.