====== Exercise: Finalizing the FH system by implementing the sender ======

The last step will be to develop the sender of the "Frequency Hopping (FH)"-system. The sender is based on the Exercise [[network_protocol_programming_lab:15.3_4_exercise|4. Exercise: Packet Transmission]]. In addition to this exercise, the following extensions are needed:

  * the baud rate need to be reduced to 1.2 kBaude,
  * the preamble should be set to 1 Byte,
  * the frequency must be changeable and the sender should use the same frequencies as the receiver see [[network_protocol_programming_lab:fast_scan|Exercise: Scanning faster]] and
  * the sender changes the frequency after transmission of a packet.

===== Requirements  =====

This task requires 

  * Two ready BeagleBone Black equipped with the CC1200 operating at a symbol rate of 1.2 kBaude and a preamble length of 1 Byte.
  * no 4C

===== Tasks  =====

  * the programming is done by extending the source files of exercise [[network_protocol_programming_lab:15.3_4_exercise|4. Exercise: Packet Transmission]]. 
  * Test, if pre-calibration compared to normal calibration improves the stability of the system.

===== Hints  =====

  * For simplicity, the sender changes the frequency in round robin manner.
  * Sender and receiver should use tree frequencies.