User's Manual

Document CAN04_08301_B (Repeater supervisor 915MHz RF System description).doc Page 5/

3.2. SUPERVISOR MODE CONNECTED TO A PC THROUGH A RADIO

FREQUENCY LINK

This mode is identical to the previous mode, with the difference that a second RF module

is used to transmit data to the PC on a radio frequency link instead of the wired serial link.

The second RF module is synchronised with the first RF module that is used to

communicate with slaves GPS-COM or CSP-COM. The two RF modules jump

synchronously on the following channel according to the same hopping frequencies table

but with a fixed offset (15 > offset > 5).

This prevents the two RF modules to transmit data at the same time on the same channel.

The system stays on a channel during 165ms (time slot). This time slot consists on three

parts:

1. Calibration channel (no TX, no RX)

2. Repeater/Supervisor data transmission to the slave through first RF module on

channel X. Repeater/Supervisor data transmission to the PC through second

RF module on channel Y (X≠Y).Transmissions on channel X and Y occurs

in parallel. Only one frame is sent by the Repeater/supervisor on channel X

during this period and only one frame is sent in parallel by the

Repeater/supervisor on channel Y during this period

4. Slave data transmission (only one slave is transmitting during a time slot),

Repeater/Supervisor is in reception state (no TX). Only one frame is sent by

the slave during this period.

Timing: 1- Calibration: 45ms

2- Repeater/Supervisor transmission on each channel: 60ms (dwell time =

17,3ms max.)

3- Slave transmission: 60ms

Time slot: 165ms

4. RECEIVER INPUT BANDWITH

The input bandwidth of the receiver is 40 kHz.