Quote:
Originally Posted by jbjb
Is there anything to suggest that the smartphones in question actually have all the hardware needed to receive and play FM, as opposed to just having a Bluetooth/Wi-Fi chip that also happens to have FM capability? There's more to an FM radio than just having a chip with an FM receiver - you'd need the appropriate antenna, associated circuitry etc.
/JB
|
You are correct.
A typical example in a higher end smartphone is that the FM antenna is the headset cord and the audio left and right conductors in that used as the antenna. In the phone there will be antenna impedance matching circuitry and electrostatic discharge (ESD) protection to match the antenna input to the receiver antenna input impedance in the connectivity IC which may be capable of supporting all or some of Bluetooth, Wi-Fi (WLAN), FM Receiver, FM Transmitter, UART. The headset cord conductors used as the antenna also have to be isolated from the connectivity ICs audio output as those conductors are common to both the connectivity IC's FM antenna input and its audio outputs.
The ESD, matching and isolation is all specifically required for the FM radio and, of course, also entails the cost of a more complex circuit board and higher costs of assembly.
So the people who are just describing the need as just being "switching the chip on" are dreaming. Also, of course, the phone manufacturer has to consider their markets and I suspect those are telling them that there is limited demand, or that the demand is only within certain geographic regions or price points; in which case including FM radio receiving capabilities is pointless.
There may, of course be other capabilities within the phone which are not enabled for similar reasons