Recently, when I watched the video, I found that those old mobile phones had a very interesting function, and I would like to share it with you.
Its name is FM Transmitter Function.
More than ten or twenty years ago, mobile phones were not so popular, FM radio (commonly known as radio) was still a very mainstream way of entertainment, and many mobile phones would also have built-in radio functions.
However, ordinary mobile phone radios can only collect the sound from radio stations in one direction. However, the mobile phones of some international manufacturers, such as Nokia and Motorola, support the sound of the mobile phone to be transmitted by radio, which is the FM frequency modulation transmission function.
Simply put, the analog audio signal is converted into a digital signal through an AD converter, and then the signal is modulated and transmitted to the carrier wave, and the receiver receives it at the same frequency, converts it into an analog signal through a DA converter, and then amplifies the output to the speaker.
The operation is also very simple, set the transmission frequency, and transmit the mobile phone audio through the radio, at this time the mobile phone is equivalent to a small radio station. Then use another mobile phone or radio next to you, adjust to the set frequency, and you can receive the sound emitted by the mobile phone.
Doesn't it sound a bit like Bluetooth now? In fact, this function is mainly used in the design of car scenes, in the past, cars had radio functions, but rarely supported Bluetooth, with this function, you can share the music of the mobile phone to the car to play.
However, after Bluetooth became popular, I never saw the FM FM transmitter function appear on the mobile phone.
Compared with Bluetooth, the advantages of FM transmitter function are more convenient, only need to transmit, and do not need to be paired like Bluetooth. And it does not pick the receiving device, whether it is a car, a mobile phone, a radio, as long as it supports the FM radio function, it can be received.
Image source network
The disadvantage is that it is easy to interfere, the transmission distance is shorter, and the power consumption should be greater than that of Bluetooth.
Although this function has been eliminated now, it was definitely a black technology more than ten or twenty years ago.
Did you use this feature back then?