A signal transmission system, wherein the signal transmission system is configured to transmit a power signal and a superposed signal, and the signal transmission system comprises: a power supply, a power sourcing device, and a powered device; wherein the power supply is connected to the power sourcing device, and the power sourcing device is connected to the powered device through a coaxial cable; the power sourcing device comprises a first active inductor module, a first capacitor module, and a signal processing module connected to the first capacitor module; wherein the first active inductor module is configured to receive a direct current signal transmitted by the power supply, and transmit the direct current signal to the powered device through the coaxial cable; and the first capacitor module is configured to receive a superposed signal transmitted through the coaxial cable, and transmit the superposed signal to the signal processing module; the powered device comprises a second active inductor module, a second capacitor module, and a signal acquiring module connected to the second capacitor module; wherein the second active inductor module is configured to receive, through the coaxial cable, the direct current signal transmitted by the power sourcing device, and transmit the direct current signal to the signal acquiring module; the signal acquiring module is configured to acquire the superposed signal, and transmit the superposed signal to the second capacitor module; and the second capacitor module is configured to transmit the superposed signal to the power sourcing device through the coaxial cable, characterised in that the power sourcing device further comprises a first detecting module, wherein the first detecting module is configured to detect an operating parameter of the powered device, the first detecting module comprises a first detection resistor and a first voltage comparator; wherein one terminal of the first detection resistor is connected to an output terminal of the power supply, and the other terminal of the first detection resistor is connected to the first voltage comparator and the coaxial cable, respectively; the first detection resistor and the powered device are configured to divide a voltage supplied by the power supply; the first voltage comparator is configured to output a comparison result based on a first divided voltage detected at the other terminal of the first detection resistor and a predetermined reference voltage; and the control module is further configured to determine the operating parameter of the powered device based on the comparison result. the signal transmission system is configured to transmit a power signal and a superposed signal, and the signal transmission system comprises: a power supply, a power sourcing device, and a powered device; wherein the power supply is connected to the power sourcing device, and the power sourcing device is connected to the powered device through a coaxial cable; the power sourcing device comprises a first active inductor module, a first capacitor module, and a signal processing module connected to the first capacitor module; wherein the first active inductor module is configured to receive a direct current signal transmitted by the power supply, and transmit the direct current signal to the powered device through the coaxial cable; and the first capacitor module is configured to receive a superposed signal transmitted through the coaxial cable, and transmit the superposed signal to the signal processing module; the powered device comprises a second active inductor module, a second capacitor module, and a signal acquiring module connected to the second capacitor module; wherein the second active inductor module is configured to receive, through the coaxial cable, the direct current signal transmitted by the power sourcing device, and transmit the direct current signal to the signal acquiring module; the signal acquiring module is configured to acquire the superposed signal, and transmit the superposed signal to the second capacitor module; and the second capacitor module is configured to transmit the superposed signal to the power sourcing device through the coaxial cable, characterised in that the power sourcing device further comprises a first detecting module, wherein the first detecting module is configured to detect an operating parameter of the powered device, the first detecting module comprises a first detection resistor and a first voltage comparator; wherein one terminal of the first detection resistor is connected to an output terminal of the power supply, and the other terminal of the first detection resistor is connected to the first voltage comparator and the coaxial cable, respectively; the first detection resistor and the powered device are configured to divide a voltage supplied by the power supply; the first voltage comparator is configured to output a comparison result based on a first divided voltage detected at the other terminal of the first detection resistor and a predetermined reference voltage; and the control module is further configured to determine the operating parameter of the powered device based on the comparison result.