This interview with Lieutenant Colonel R G Wells who constructed a radio receiver and transmitter in a Japanese POW camp during World War II has been making the blog rounds recently (via free103point via BoingBoing via MAKE). Though somewhat technical, the account is a fascinating example of what a simple technology radio is given that the prisoners in the camp had access to very little material except what could be scrounged, nicked or smuggled in.
In this digital era it’s important to remember that one can still build an analog crystal radio receiver that requires no external power, deriving all the juice it needs from the electromagnetic waves. That’s not what Wells and his fellow prisoners did–probably because they were working with more distant signals than a crystal set can receive–but so-called “foxhole receivers” based on crystal sets were used throughout World War II by both citizens and soldiers in order to stay in touch where powered radios were banned or impractical.
I remember building crystal sets both from scratch and from kits as a kid in the early 80s, amazed at the ability to listen to local AM stations without batteries or AC power. I wonder if this is something kids still do these days.
However a crystal set only works with analog, amplitude modulated signals; FM won’t work and neither will any digital signal. Well, you can pick up a digital signal, but it will just be a bunch of hash noise.
I think it’s important for analog radio to continue to exist exactly because of its technological simplicity and ability to transmit over long distances. That doesn’t mean digital or internet-based radio shouldn’t continue to be developed. Rather, keeping simpler, proven analog technologies in service provides a sort of insurance, even if most of our daily existence is highly electrified and digital.