Abstract: The present disclosure proposes a receiving device, an abnormality detecting method, and an abnormality detecting program, which are capable of detecting an abnormality related to a reference signal after the reference signal is outputted. The receiving device includes an output part, an input part, and processing circuitry. The output part outputs a first signal that is a periodical reference signal generated based on a positioning signal to a first transmission line connected to an external device. The input part accepts an input of a second signal that is a returning signal of the first signal of the first transmission line from the external device side via a second transmission line. The processing circuitry detects an abnormality related to the reference signal based on a signal characteristic of the second signal.

Abstract: A GNSS receiver includes a demodulation module, a position calculation module, a storage, and a determination module. The demodulation module receives the GNSS signal and acquires a navigation message. The position calculation module performs positioning calculation based on a propagation delay which is a time until a GNSS signal transmitted from a GNSS satellite reaches an antenna. The storage stores reception timing (reference timing) of a message of a predetermined type in the navigation message. The determination module determines that a GNSS signal including the navigation message is a spoofed GNSS signal when the difference between the reception timing of the next and subsequent messages of the same type predicted from the reference timing and the reception timing of the same type of message received after the reference timing is outside the scope of the time threshold.

Abstract: A GNSS receiver includes at least two antennas, a satellite direction acquisition module, an estimation module, and a determination module. A satellite direction acquisition module acquires the direction when viewing the satellite corresponding to the GNSS signal received by the antenna based on the satellite orbit information. The estimation module estimates the arrival direction of the GNSS signal on the basis of the difference in timing when the GNSS signal is received by the plurality of antennas. The determination module compares the direction in which the satellite is viewed from the antenna with the arrival direction estimated by the estimation module to determine whether the GNSS signal received by the antenna is a direct GNSS signal based on a direct wave from the satellite or an NLOS GNSS signal.

Abstract: To provide a reference frequency generating device that can output a highly accurate reference frequency signal even if a reference signal becomes unable to be acquired. The reference frequency generating device includes a synchronization circuit, a temperature sensor, and a controller. The synchronization circuit controls a reference frequency signal outputted from a voltage controlled oscillator, by a control signal obtained based on a reference signal. The temperature detector detects a temperature of the voltage controlled oscillator being used. When the reference signal is unable to be acquired, the controller corrects a voltage controlled signal in consideration of a distortion in the aging characteristic of the voltage controlled oscillator based on a rate of change with time in a slope of the oscillator temperature, and generates a holdover control signal based on corrected contents to control the voltage controlled oscillator.

Abstract: To provide a reference frequency generating device that can output a highly accurate reference frequency signal even if a reference signal becomes unable to be acquired. The reference frequency generating device includes a synchronization circuit, a temperature sensor, and a controller. The synchronization circuit controls a reference frequency signal outputted from a voltage controlled oscillator, by a control signal obtained based on a reference signal. The temperature detector detects a temperature of the voltage controlled oscillator being used. When the reference signal is unable to be acquired, the controller corrects a voltage controlled signal in consideration of a distortion in the aging characteristic of the voltage controlled oscillator based on a rate of change with time in a slope of the oscillator temperature, and generates a holdover control signal based on corrected contents to control the voltage controlled oscillator.