This application provides example optical receivers, and is applied to the field of coherent communication. One example optical receiver includes a local oscillator laser, a coherent receiver, and a signal processor. The local oscillator laser is configured to output a local oscillator laser signal. The coherent receiver is configured to receive a target optical signal and the local oscillator laser signal, and output a target digital electrical signal based on the target optical signal and the local oscillator laser signal. The signal processor is configured to obtain a current power value of the target digital electrical signal, and obtain a target frequency offset based on the current power value and a target mapping relationship. The signal processor is further configured to adjust a center frequency of the local oscillator laser when the target frequency offset is greater than or equal to a first threshold.

An autonomous mining system includes a real-time digital video transmission sub-system configured to obtain video streams from underground, and transfer the video streams to a control center located above ground; and an exploration and maintenance sub-system located underground, and configured to extract a resource and bring the resource to the surface, based exclusively on commands received from the control center through the real-time digital video transmission sub-system.

An optical receiver includes a parasitic current compensation circuit having a reference diode, a sense avalanche photodiode (APD), at least one DC voltage source, and a measurement node. The at least one DC voltage source is configured to generate a first DC bias voltage that varies over time and drives the reference diode, and generates a second DC bias voltage that varies over time and drives the sense APD. A reference parasitic current travels through the reference diode based on the first DC bias voltage. A sense current travels through the sense APD based on the second DC bias voltage and exposure of the sense APD to a light signal. The measurement node receives a sense photocurrent, which is generated by the sense APD in response to the exposure of the sense APD to the light signal, the sense photocurrent including the sense current less the reference parasitic current.