My 2 cents:
We are talking about 3 very different things in the same thread! (confusing) :S Let's clarify this:
I have spent literally months(!!) trying to figure out a radio + amplifier for my carpc. I own the CarTFT version but I'm not very happy about it. I can confirm that sometimes, there is enough interference from other things around it to mess up the reception so badly that it's not worth listening to the radio. This only started happening during winter for me, weirdly enough. Here is my research and I hope all of you can benefit from this.
CarTFT FM Tuner
This is what I posted on another forum recently regarding the CarTFT unit (which I own):
Quote:
Actually I don't think it's a silabs tuner. Whatever provides tuning and demodulation is controlled by a silabs cp210x serial interface i.e a USB<-->Serial(COM) converter.
I believe that the actual TMC chip is a TC5000 made by GNS.
Main Page - Wiki-TC6000
So basically, you send data through the COM port and that is interpreted by whatever mechanism is inside the unit to Scan, Change Freq, increase volume etc.
Picture of CarTFTFM Taken apart 1
Picture of CarTFTFM Taken apart 2And I think the closest commercial product they have to this is : (pdf (http://www.gns-gmbh.com/index.php?eI...fca52525100d7f))
My current problem is that I am really sick and tired of windows. And the only thing stopping me from moving to linux(gentoo) is the ability to use this as my radio! Grrr. GNS don't open their APIs either. I think the unit can do much more than it is advertised as, and I guess that the APIs might hint at that, which is why they don't open it up to everyone IMO.
Wish me luck.
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Following that, I managed to wrap the provided DLL, but since it's compiled for windows, there's no way to get it to work on linux natively. I've already made a simple network server app in C# for it that's compiled on windows and acts as an interface for commands sent to it over TCP/IP. i.e. my plan was radio hardware <---> CarTFTFM.dll wrapper <--> My Radio Server Interface App (win32 drunk on wine
) <---> My Gentoo Frontend. Yeah! It's a real pain in the rear!!!
Dumb Silabs usb radio dongles
There have been many other threads mentioning how bad the silabs chips were from consumer USB dongles. It's not surprising, as those were not automotive grade silabs FM tuners. Those were probably the reference design consumer FM tuners from silabs:
Si4701, NOT to be confused with this one which is a
Si4741
DigitalCaradio Silabs tuner
This one, as mentioned previously is a
Si4741, which is the automotive grade version of the silabs tuners. I can only assume that it's way better, being designed and manufactured for that purpose by silabs and is used by the automotive industry car manufacturers in their own systems. Silabs even produces better (very much more recent versions) of their automotive chips, namely the
Si4749 and the latest of them all
Si475x. The Si475x (which supports LW/AM/SW/FM/RDS/RBDS) is in fact so new that I couldn't really find any wholesalers stock them at the point I was looking into building my own together with the TDA7850 Amplifier. In fact, what DigitalCaradio provides through their
Amp and FM Tuner is the exact combination that I had in mind. I was just about to start designing the PCB for manufacture (where the soundcard, Silabs FM tuner, Amplifier would work as a single unit). I was also looking at hooking all of it through the ISO harness too.
The other great thing is that silabs tuners have kernel support in linux for the Si470x family. Not sure about this more recent one though. Questions to So the only things I would be concerned about before purchasing these are:
Questions to DigitalCar:
1. How does the Si470x chip appear to the computer?
----Is it hidden/interfaced by an RS232 converter?
--------If so, then is there a protocol I can use to talk to the Com port and issue commands to control the tuner?
2. Does the Amplifier Soundcard come with the ISO cables and splitters (because I need another 12v+ IGN and PERMANENT LIVE going to my existing carpc)?
3. Since both the Amp and the tuner seem to have their own USB sound interfaces, will it be easy to route FM audio via the AMP?
4. Can I take the AMP and tuner out of their cases and fit them back into my carpc casing, connecting them to internal USB and internal Audio headers (I've got enough space). Speaking of which, would you happen to have a neat audio header cable that could feed into the Amplifier?
5. Si4741 is said to have support for other modulations than FM, is that supported in any way?
6. Is there a chance that we could see a Si475x version any time soon?