Log in

No account? Create an account

Previous Entry | Next Entry


( 8 comments — Leave a comment )
Mar. 5th, 2011 05:55 pm (UTC)
re:last link, Hedy's frequency-hopping comms was one of the most underrated inventions of the 20th century.
Mar. 5th, 2011 10:08 pm (UTC)
Tell us more...
Mar. 5th, 2011 11:35 pm (UTC)
Ah, the link doesn't say much about it...

Well, the original invention was for torpedos. Previously they'd required a direct cable connection, which was obviously rather limiting. Hedy Lamarr suggested, basically, using a player piano roll as a shared secret for unjammable/uncorruptable/nigh-undetectable radio comms instead - the torpedos could go further, and faster. The 88 piano keys become 88 radio channels and, so long as both the sender and receiver know the song and remain synchronised, they can talk to each other secretly.

Aside from the military uses (which I can't comment on), pretty much all 3G/WIMAX mobile phones use that technique, as do the 802.11b/g/n WiFi standards. In those cases, the 'music' is from a PRNG with a known seed, and the number of channels is defined by standards, licences, and radio/antenna characteristics, rather than the number of keys on a piano, but it's the same principle as Hedy Lamarr's invention. Basically, every connected mobile device in use today owes her a little debt.

(And, obviously, she was also the inspiration for Dr Kleiner's debeaked pet headcrab...)
Mar. 5th, 2011 11:38 pm (UTC)
Oh and "underrated" because the US Navy didn't use it at the time. No implementation was made until 1962 - two decades after the patent was granted - yet now it's used almost everywhere.
Mar. 6th, 2011 12:04 am (UTC)
I'm impressed that you spotted the reason behind my icon choice...
Mar. 6th, 2011 12:19 am (UTC)

I love the HL games... but I'm really looking forward to Portal 2 at Easter.
Mar. 5th, 2011 09:02 pm (UTC)
I've heard that Wisconsin wasn't in deficit until Walker started, any libertarian or independent blogs on that?
Mar. 5th, 2011 09:53 pm (UTC)
He's only been governor for two months, so can't really be blamed for the current position. And while some of his policies are certainly libertarian (notably those to reduce union power), some aren't (he's "100%" anti-abortion, even in cases of rape and incest).
( 8 comments — Leave a comment )