An apparatus comprises a platform, an optical transmitter associated with the platform, an optical detector associated with the platform, a sensor associated with the platform, a phase-locked loop circuit, and a processor unit associated with the platform. The optical transmitter is configured to transmit first optical signals. The optical detector is configured to receive optical signals. The phase-locked loop circuit is configured to indicate a presence of second optical signals in the optical signals indicating a time interval to transmit information in the first optical signals. The processor unit is electrically connected to the optical detector, the optical transmitter, and the sensor. The processor unit is associated with the phase-locked loop circuit. The processor unit is configured to transmit the information in the first optical signals using the optical transmitter during the time interval.