Are there technical limitations that prevent the integration of AM tuners into portable audio devices?

[Strifer]

I always see FM receivers included in portable media devices--most recently in the new Apple FM tuner for the iPod.

I know many people have forgotten about the AM band, but I listen to AM talk radio frequently. It would be nice to have that capacity on my iPod. What prevents electronics manufacturers including support for this band?

 

[dkozloski]

The amount of Radio Frequency Interference generated by a digital device is substantial. This is easily handled by an FM radio receiver but difficult with AM. Couple that with declining music availability on AM radio and you have the result you have observed.

 

[aaqubit]

AM signals are lower frequency and so have less energy. This makes them more susceptible to attenuation and so they are not popular anymore.

 

[Bassyhead]

It probably comes down to economics, not technology. AM radio is an added expense in which the majority of consumers may not use.

 

[bendixG15]

Anybody here ever build a "crystal" radio ???

 

[harrkev]

Also note that because AM is a very low frequency (around 1MHz), that you either need a VERY long rod antenna (never done), or you need a "bar" antenna". These antennas can be as small as a thin pencil and two inches long. But given the size of the current crop of MP3 players, that would be too large of a size hit. FM radio can use the headphone wires as an antenna. This would be EXTREMELY inefficient for AM frequencies.

So here we have the following factors:
1) Antenna would be huge compared to the other parts
2) Likely to be lots of noise created by the device itself
3) Not much interest

All of these combine to kill it.

 

[Bassyhead]

1) There are quite a few more parts and extra complexity involved with a digital tuning AM radio that is built into a MP3 player than a standalone crystal radio.
2) MP3 players with AM radios exist, so it can be done and they're rare. Sony made some MP3/CD/FM/AM/Weatherband/TV MP3 portable players before. The antenna for the AM radio was curved around the perimeter of the unit. I don't know of any other MP3/AM radio capable units off the top of my head.

 

[HannibalX]

Originally posted by: bendixG15
Anybody here ever build a "crystal" radio ???

Yeah when I was a kid for a science project.