Basic Wireless Communication for Microcontrollers
Chapter 4 - Design Project 3: 900MHz Automatic Error-Correcting Data Link
Synchronization
In the last project we discussed the need for synchronizing the transmitter and receiver in a serial data link, so that the receiver knows when each bit begins and ends. Just like in the last project, the signal to noise ratio in this case should easily be high enough to allow the use of a simple synchronization procedure, based on the standard UART method of start and stop bits. Once again we will transmit a couple of synchronization bytes (hex FFs) and use flag characters to indicate both the beginning and end of each packet. Also, the bit slicer in the Linx RF modules does not require a balanced coding scheme, although it does require that there be transitions at least every 1/300 th of a second. Since we are transmitting at 4800 bits per second, the start and stop bits will guarantee transitions much more often than 1/300th of a second, so no special care is needed.