Abstract: A gas detection device is provided, including: a first inlet channel, a second inlet channel, a detection module, a switch valve and a control module. The first inlet channel is configured to input a sample gas. The detection module is configured to obtain a detected concentration value of a detection target from the sample gas. The switch valve is connected with the first inlet channel, the second inlet channel and the detection module, and the switch valve is switchable to communicate the detection module with the first inlet channel or the second inlet channel. The control module is communicative with the detection module and the switch valve and includes a processing unit and a setting unit. The setting unit is configured to set a setting concentration value, and the processing unit controls the switch valve according to the detected concentration value and the setting concentration value.

Abstract: A gas detection system includes a plurality of sampling assemblies, at least one detector and a control unit. The plurality of sampling assemblies respectively include at least one inlet channel, a first pump and a first valve. The first pump is communicated between the at least one inlet channel and the first valve, and the first valve is switchable between a sampling state and a pre-sampling state. The at least one detector is selectively communicated with the first valve of one of the plurality of sampling assemblies. The control unit is communicative with the plurality of sampling assemblies and controls said first valves of the plurality of sampling assemblies. When the first valve of one of the plurality of sampling assemblies is in the sampling state, the first valve of another one of the plurality of sampling assemblies is in the pre-sampling state.

Abstract: An testing method includes following operations: generating, by a signal generator, a multi-tone signal; transmitting, by the signal generator, the multi-tone signal to an input terminal of an under-test device; measuring, by a spectrum analyzer, the input terminal of the under-test device and an output terminal of the under-test device to acquire a plurality of input ripple intensities corresponding to a plurality of frequencies and acquire a plurality of output ripple intensities corresponding to the frequencies; and generating, by a control device, a plurality of power supply rejection ratios corresponding to the frequencies according to the input ripple intensities and the output ripple intensities.