System and methods of detecting loss of signal in free space optical communications
The present application at least describes a system for detecting loss in free space optical communications (FSOCs). The FSOC may include a sensor located downstream of the power supply unit. The FSOC may also include a signal conditioning unit (SCU) located downstream of the sensor. The FSOC may also include a comparator located downstream of the SCU. The comparator may be configured to receive the first signal from the SCU and determine an indication of signal loss based upon the first signal being below a predetermined threshold. The FSOC may further include a photodiode located downstream of the sensor. The photodiode may be configured to receive power from the power supply, receive an optical signal from a source, and output a second signal based on the optical signal.
1 . A method comprising:
monitoring a current of a voltage supply being transmitted to a photodiode, wherein the current is associated with a communication link;
determining, via a comparator, a first signal associated with the current is below a predetermined threshold indicating signal loss of the communication link;
transmitting the indication of signal loss to a processing system; and
receiving, via the processing system, feedback that a second signal associated with the communication link was frozen at an instance prior to the indication of signal loss.
2 . The method of claim 1 , wherein the processing system includes an FPGA and a CDR circuit.
3 . The method of claim 1 , further comprising:
determining, via a comparator, the signal is above the predetermined threshold.
4 . The method of claim 3 , further comprising:
receiving, from the processing system, an indication the freeze of the second signal has been lifted.
5 . The method of claim 1 , further comprising:
transmitting, to the processing system, the second signal output from the photodiode.
6 . The method of claim 1 , wherein the indication of signal loss is associated with atmospheric fade.
7 . The method of claim 1 , wherein the comparator and photodiode are located in an optical receiver.
8 . The method of claim 1 , wherein the processing system is remotely located from the comparator and photodiode.
9 . The method of claim 1 , wherein the comparator receives the first signal from a signal conditioning unit (SCU).
10 . The method of claim 9 , wherein the SCU is an operational amplifier.