The frequency hopping XStream and XCite modules have 7 different "channels" available: ''''HP''''=0, 1, ., 6. The frequency hopping system transmits on 25 individual frequencies in a specific hopping pattern. Each channel reuses the same 25 frequencies but navigates through them in a different pattern to minimize the interference between the channels. Data on each channel is encoded differently so it is impossible for a radio modem configured for channel 1 to receive data transmitted on channel 2 but there may be interference between two transmissions on different channels.
The XTend radio has 10 different "channels". The FCC requires that the XT09 utilize 50 frequencies instead of 25 for 1W transmission.
When two channels (networks) are being used in the same vicinity at the same time, the collision rate is predicted by the formula (N-1)/C; where N is the number of simultaneous networks and C is the number of frequencies in the hop pattern (in this case 25). In the case of two simultaneous networks the formula predicts (2-1)/25=0.04 or 4% collision rate in theory. In practice we see a collision rate of closer to 10%.
Aug 08, 2017