HowTo: Using a Pager in the 21st Century
10010101101000111001001111111100 - T E S (7 bit/symbol) 11001010100000000000001111100011 - T . . And this is how the message looks on the radio spectrum: Bits are encoded with a frequency shift keying (FSK) modulation using 9 kHz bandwidth and 1200 bits per second speed, all this message is transmitting in about 0.5s. Looks simple, and it really is. I will skip the details, those who are interested can read the protocol specification. It is even easy to draw all these bits with pen and paper — these protocols were simple in the past, I think nobody can do it with modern GSM or WiFi. In POCS...
Source: medium.com