Famicom doubles as an FM radio station

[133MHz]

I had this theory for quite some time that you should be able to listen to the Famicom's audio broadcast on a standard FM radio receiver in the US because the frequencies match and the TV sound channel is modulated in FM just like the radio stations. So I decided to put my theory to the test by connecting my Famicom's RF output to the antenna of an old radio cassette receiver, then tuning the dial to the right frequency should produce Famicom sound out of the radio speaker. So I tried that out and it worked!

Here's a video I've just uploaded to YouTube showing how it works: http://www.youtube.com/watch?v=UOXAN9TfUWQ

You can try it out with a Famicom system, an FM radio receiver and a single RCA cable. Just tune your radio into 95.75 MHz for Famicom CH1 and 101.75 MHz for Famicom CH2.

This works because even if Japan uses the same TV system as the US, their TV channel frequencies are different. US/World FM radio spectrum goes from 88 to 108 MHz , while JP FM radio goes from 76 to 90 MHz. The result is that all of the analog TV channels are in different places.

JP TV Channels 1 and 2 correspond to 91.25 and 97.25 MHz respectively, just above the JP FM radio band but right in the middle of the US FM radio band! A TV channel is 6 MHz wide, by adding 4.5 to the video carriers you get the sound carriers, 95.75 and 101.75 MHz respectively, still pretty in the middle of the dial.

US Cable channels 95 and 96 use these exact same frequencies, which is a blessing for us Famicom owners. These channels are seldom used in practice because of the interference with FM radio broadcasts (even though a cable TV system is completely isolated in theory, you'll always get some interference in real world usage).

This also explains why your import Famicom might look like crap on your TV if you're using the RF modulator and Channel 95. If there are strong radio broadcasts in your area in the vicinity of those frequencies, they'll interfere with your Famicom's video signal (and you have nobody to complain, since the Famicom is using an illegal frequency in the US radio spectrum). You could largely alleviate the problem by using thick coaxial cable between the Famicom's RF out and your TV's aerial socket, in order to keep those pesky talk shows from messing with your Japanese video games.

[ericj]

Just watched your video. That's awesome! 

[son_ov_hades]

This is so cool! I'm gonna try this for sure.

[JC]

*checks the "What are you listening to now?" thread*

[manuel]

Nice, man! I might just try that myself. 

[133MHz]

Nice, man! I might just try that myself. 

But unless you brought an FM radio from Germany to Japan with you or you can get hold of a dual standard Japanese receiver, you won't be able to do this, because you're in Japan and FM radio goes from 76 to 90 MHz there.

[b1aCkDeA7h]

Darn, this might have been a way to test the sound on the HK Famicom. But alas, I just sold it too. Oh well, hopefully ooxooxoo or whatever on DP can make something of it.

[manuel]

Nice, man! I might just try that myself. 

But unless you brought an FM radio from Germany to Japan with you or you can get hold of a dual standard Japanese receiver, you won't be able to do this, because you're in Japan and FM radio goes from 76 to 90 MHz there.

I should have my little portable radio from Germany somewhere...

[petik1]

Hey, how would this work for me? The previous owner of my famicom replaced to RF modulator so now it is switchless, or I think he put it as "automatic" or something like that. If I remember correctly, when you helped me mod my famicom, I explained that I get video on channel 93 and static for noise. Also, if you wanted to broadcast your fami- music to the world, couldn't you hook it up to an antenna? that would be awesome!

[133MHz]

You had the weird RF modulator right? If I recall correctly you had a picture but no sound, so this probably won't work for you.

As for the antenna thing, yes in theory it should work, but in practice I've noticed that the broadcast range is quite limited. I believe this is because of the already strong signals being put out by proper radio stations and also because of slight differences between frequency modulated TV sound and proper FM radio.

[PatMan33]

Hah! Fantastic!

I've noticed the Famicom interference with all sorts of electronics while fiddling about with the wires around back. Nice to know I'm not crazy!

[petik1]

You had the weird RF modulator right? If I recall correctly you had a picture but no sound, so this probably won't work for you.

Gotcha. What do you think the guy meant by automatic? He said

It's an automatic setting CH1 or CH2. It's depend on the TV system of your country.

Yeah, 93 and 13 I get the clearest signals, yet they are still extremely staticy and no sound from the console.
Aww, man. Right when I thought I could set up my own famicom radio station...