Instruction Manual

Tentative
8
3 Communication Method
3.1 Frequency hopping
This wireless module employs an FH system as a diffusion method. In the FH system, diffusion signals
with a wide bandwidth are produced by hopping the frequency according to a certain pattern. The
pattern is called a frequency hopping pattern. This device has 31 types of frequency hopping patterns.
The same hopping pattern is set for the wireless machines that are intended to mutually communicate.
figure 4：frequency hopping
Even when the hopping pattern is the same, mutual communication is impossible when a wireless
module randomly hops the frequency. Therefore, in the frequency hopping system, one of the wireless
machines works as a standard, while other wireless machines synchronize the frequency and hopping
timing of each machine by receiving packets from the standard machine. This is called
synchronization.
3.2 Synchronization
The slave switches frequency while waiting for a wireless packet from the master. When a wireless
packet is received, it switches to the next frequency and waits for a wireless packet again. When
received, it is judged that the synchronization with the master was successful. After that, the
slave matches the timing and sends wireless packets to the master.
No timeout is set, even for cases when synchronization is unsuccessful due to a poor communication
environment. It continues receiving until synchronization succeeds. In the case when
synchronization fails during communication for some reason, a maximum of 1000ms is required to
re-synchronize.
figure 5：master and slave
frequency
time
master（transmitter）
slave（receiver）