Abstract: A concurrent dual-band receiver includes a front-end subsystem and a concurrent dual-band down-converter. The front-end subsystem supplies radio frequency signals in a first frequency band and a second frequency band. The concurrent dual-band down-converter includes a dual-band frequency synthesizer, a first down-converting circuit, and a second down-converting circuit. The dual-band frequency synthesizer simultaneously generates first local oscillation signals having a first local oscillation frequency and second local oscillation signals having a second local oscillation frequency. The first down-converting circuit mixes the radio frequency signals with the first local oscillation signals to down-convert the radio frequency signals to base band signals, and outputs the down-converted signals from the first frequency band.

Abstract: A navigation device includes a transceiver, a timer, an angle detector, and a processor. The transceiver is for projecting a detecting signal and receiving the detecting signal reflected from an obstacle in front of the transceiver. The timer is for calculating a time interval between projecting the detecting signal and receiving the detecting signal reflected from the obstacle. The angle detector is for detecting a projecting angle of the detecting signal projected from the transceiver with respect to the vertical direction. The processor is for calculating a horizontal distance to the obstacle according to a velocity of the detecting signal, the time interval, and the projecting angle.