Why do microphones start beeping when a phone is ringing next to it.
In: Technology
I am not sure if you are describing this well – a microphone can’t beep, nor should it produce any “ghost-sounds” via proximity to a phone.
However,there’s a similar phenomenon: radios can pic up a cellphones transmissions if in close proximity, resulting in a beeping noise. This is simply the radio picking up the cells transmissions and interpreting them wrongly as sound.
However, this should not happen to any playback devices, unless tuned for am/fm frequencies.
What you’re like describing is “GSM Chirp”.
Some background:
Audio signals inside of a sound system are just voltages that change over time.
All wires pick up radio waves and the result is……a voltage that changes over time.
So inside a wire, there’s no way to tell the difference between an audio signal and any other kind of signal.
However, most audio systems filter out any frequencies that are higher than 20kHz as humans can’t hear above that.
Ok Main Point:
Some cell phone technology used to blast out radio signals. Again they were very high frequency so normally, even if a wire inside a sound system picked it up, it would get filtered out.
HOWEVER! This specific cell technology used to pulse these signals. They would blast the signal for a very short of time and them turn it off, then blast against and turn it off.
It turns out that the frequency of blasting and turning off was lower than 20kHz and as a result it created an audible “chirp” in sound systems.
This mostly happened when phones were at the very edge of reception and would turn up their transmit power really high to try and make a connection to a tower.
Latest Answers