This build uses good old FSK (frequency shift keyring) technology sending 1′s and 0′s through the air. Although its applied using infra-red, the same concept is used for RF. Also Infra-red is still technically wireless (lol). So on to the build. Just in-case you want to brush up on your FSK I recommend just straight up hitting wikipedia. (If not, here’s the TLDR version; A steady pulse is used to represent a 1, and a variation in the pulse width is used to represent a 0)
On the transmitter side a 555 timer is set up as a Astable Multivibrator, the digital input (fed from say a microcontroller) pulls down the transistor which modifies the frequency of the 555 timer, causing a 0. Leaving the pin high (representing a 1) leaves the 555 timer alone. The data is transmitted via infra-red led.
On the receiver side, a 565 PLL (Phase Lock Loop) IC locks on to the frequency of the 555 timer and outputs a 1 or a 0 when the signal alternates between the 2 frequencies.
This is a great project but mostly as an educational one. Full post up on gadgetronicx.