FM Diversity and Phantom Power on Fakra B : USB Radio

Thread Starter


Joined Nov 5, 2019
My next project which Im hoping will give me USB Radio.

Certainly I've seen a reference for something that using a USB Microcontroller (C8051F321) and an Si470x device to provide FM Radio, however Im interested in adding DAB so looking at the Si468x chip.

It looks like it uses SPI for communication, but possibly not I2S for digital sound - though there some USB Microcontrollers that alledgedly support I2S for sound cards and microphones, so hey, how difficult can it be to cobble everything together.

I've mostly got the design complete, and Im reminded in my car, I have FM Diversity using a Fakra B and a Fakra K cable.

It seems to be nigh on impossible to get Automotive FM Radio chipsets such as the Si47903 to provide FM Diversity, so if needs be, is there another way to provide FM Diversity? And then there's the case that Fakra B is supposed to be Phantom powered. Now, Im not sure on the exact schematics of this, but I gather essentially 12v is provided over the central pin to the aerial. That's no problem. We can do that. What I don't know, is whether it then the central pin that provides the signal from the aerial and therefore whether I need to filter out the 12v prior to it hitting the RFIN on the chip, or whether the signal is provided through another means such as down the ground wire.

So I guess Im asking:

I2S over USB - possible?
Fakra B - Phantom Power - any schematics for both the cable and also for a phantom power circuit?
FM Diversity - anyway to achieve this? Do I need two Radio Chips, monitor and flip between the two? Any schematics to achieve this?