Abstract: A traffic-monitoring system includes a gateway that includes a gateway radio and that is connected to a server and traffic-monitoring devices arranged along a road. Each of the traffic-monitoring devices includes a housing, a microcontroller that is located within the housing, at least one sensor that is located within the housing, that is connected to the microcontroller, and that collects traffic and/or environmental data, and a monitor radio that sends data to the gateway or an adjacent traffic-monitoring device. The microcontroller processes data collected by the at least one sensor to reduce an amount of data to be sent to the gateway or the adjacent traffic-control device and sends processed data to the gateway or the adjacent traffic-monitoring device in real time or near real time using the monitor radio.

Abstract: A traffic-monitoring system includes a gateway that includes a gateway radio and that is connected to a server and traffic-monitoring devices arranged along a road. Each of the traffic-monitoring devices includes a housing, a microcontroller that is located within the housing, at least one sensor that is located within the housing, that is connected to the microcontroller, and that collects traffic and/or environmental data, and a monitor radio that sends data to the gateway or an adjacent traffic-monitoring device. The microcontroller processes data collected by the at least one sensor to reduce an amount of data to be sent to the gateway or the adjacent traffic-control device and sends processed data to the gateway or the adjacent traffic-monitoring device in real time or near real time using the monitor radio.

Abstract: A duplexer includes a branch circuit connected to an antenna and arranged to branch to a receiving side and a transmitting side, a receiving-side LC parallel resonant-type filter connected to the receiving-side of the branch circuit and arranged to cause a reception signal to be passed and a transmission signal to be attenuated, a surface acoustic wave filter connected to the receiving-side LC parallel resonant-type filter defining a subsequent stage of the receiving-side LC parallel resonant-type filter and arranged to cause the reception signal to be passed and the neighborhood of the high-frequency side of the reception signal to be attenuated, and a transmitting-side LC parallel resonant-type filter connected to the transmitting-side of the branch circuit and arranged to cause the transmission signal to be passed and the reception signal to be attenuated.

Abstract: A duplexer includes a branch circuit connected to an antenna and arranged to branch to a receiving side and a transmitting side, a receiving-side LC parallel resonant-type filter connected to the receiving-side of the branch circuit and arranged to cause a reception signal to be passed and a transmission signal to be attenuated, a surface acoustic wave filter connected to the receiving-side LC parallel resonant-type filter defining a subsequent stage of the receiving-side LC parallel resonant-type filter and arranged to cause the reception signal to be passed and the neighborhood of the high-frequency side of the reception signal to be attenuated, and a transmitting-side LC parallel resonant-type filter connected to the transmitting-side of the branch circuit and arranged to cause the transmission signal to be passed and the reception signal to be attenuated.