Music, Tech, Women.

Let's celebrate the #International #Women's #Day with the story of an actress and a composer, who worked in secret for years, and created a system to safely transmit radio signals. The carrier was rapidly changing frequency ("hop"), across a spectral band of 88 frequencies, inspired by the 88 keys of a #piano. The synchronisation mechanism was based on player-piano rolls. The transmitter and the receiver could interpret the signal by following the same predefined sequence of frequencies, as a "melody".

The technology was called "frequency-hopping spread-spectrum", and it was patented. Developed in 1942 to help Allies during #WWII, surprisingly it went unnoticed for a while, as its inventors were an actress, the Austrian Hedy #Lamarr, and a composer, the American George #Antheil.

This idea then led to our modern spread-spectrum communication technologies, such as Bluetooth and Wi-Fi.

#music #tech #women
#Weltfrauentag
#frequencyhopping #spreadspectrum

Neuman-Hofman codes are named for Frank Neuman and Larry B. Hofman of NASA Ames who presumably derive them in their 1971 paper β€œNew pulse sequences with desirable correlation properties”
That took me too long to find so I thought I’d put it out there. I still need a copy of that paper if anyone has it.
#gnss #spreadspectrum #preamble

@tek So everytime someone uses a radio-based remote, Bluetooth and to some extend WiFi they use something based off her works.

Without #SpreadSpectrum there's no #OFDM...

@Wayne_Murillo @prepping I get so excited about #mesh networks! I did try Serval several years ago. Our current solution is #SpreadSpectrum wireless house phone system with an intercom feature. Slightly adjacent to this space is #LoRa. But that Cybiko looks really fun. 😊 https://en.wikipedia.org/wiki/LoRa
LoRa - Wikipedia