A motion detector (200, 300) comprising: a radio frequency transmission circuit; an RF reception circuit; a controller that is electrically coupled to the RF transmission circuit and the RF reception circuit, the controller configured to send a first control signal to the RF transmission circuit in order to control the RF transmission circuit to generate an RF signal, control the RF reception circuit to receive a reflected RF signal from a target object in a predetermined time for reception after transmission of the RF signal; control the RF reception circuit to provide a Doppler signal based on mixing the received RF signal and a second control signal in a mixer and thereby setting a detection range for the motion detector (200, 300); adjust a sensitivity of the RF reception circuit during the predetermined time for reception; and activate an indicator based, at least in part, on a magnitude of the Doppler signal, wherein the RF reception circuit includes an amplifier, characterized in that the RF reception circuit further includes the mixer electrically coupled to the amplifier; a sample and hold circuit electrically coupled to the mixer; and an op-amp electrically coupled to the sample and hold circuit, wherein the RF reception circuit further includes a variable attenuator positioned between a reception antenna and the amplifier or between the amplifier and the mixer, wherein the controller is further configured to adjust the sensitivity of the RF reception circuit by adjusting the variable attenuator, wherein the controller is further configured to adjust the sensitivity of the RF reception circuit by normalizing the Doppler signal with the amplifier or the variable attenuator, and wherein the controller is further configured to, after a predefined delay after that the controller sends the first control signal to the RF transmission circuit in order to control the RF transmission circuit to generate the RF signal, send a third control signal to the amplifier or the variable attenuator in order to adjust the sensitivity of the RF reception circuit. a radio frequency transmission circuit; an RF reception circuit; a controller that is electrically coupled to the RF transmission circuit and the RF reception circuit, the controller configured to send a first control signal to the RF transmission circuit in order to control the RF transmission circuit to generate an RF signal, control the RF reception circuit to receive a reflected RF signal from a target object in a predetermined time for reception after transmission of the RF signal; control the RF reception circuit to provide a Doppler signal based on mixing the received RF signal and a second control signal in a mixer and thereby setting a detection range for the motion detector (200, 300); adjust a sensitivity of the RF reception circuit during the predetermined time for reception; and activate an indicator based, at least in part, on a magnitude of the Doppler signal, send a first control signal to the RF transmission circuit in order to control the RF transmission circuit to generate an RF signal, control the RF reception circuit to receive a reflected RF signal from a target object in a predetermined time for reception after transmission of the RF signal; control the RF reception circuit to provide a Doppler signal based on mixing the received RF signal and a second control signal in a mixer and thereby setting a detection range for the motion detector (200, 300); adjust a sensitivity of the RF reception circuit during the predetermined time for reception; and activate an indicator based, at least in part, on a magnitude of the Doppler signal, wherein the RF reception circuit includes an amplifier, characterized in that the RF reception circuit further includes the mixer electrically coupled to the amplifier; a sample and hold circuit electrically coupled to the mixer; and an op-amp electrically coupled to the sample and hold circuit, wherein the RF reception circuit further includes a variable attenuator positioned between a reception antenna and the amplifier or between the amplifier and the mixer, wherein the controller is further configured to adjust the sensitivity of the RF reception circuit by adjusting the variable attenuator, wherein the controller is further configured to adjust the sensitivity of the RF reception circuit by normalizing the Doppler signal with the amplifier or the variable attenuator, and wherein the controller is further configured to, after a predefined delay after that the controller sends the first control signal to the RF transmission circuit in order to control the RF transmission circuit to generate the RF signal, send a third control signal to the amplifier or the variable attenuator in order to adjust the sensitivity of the RF reception circuit.