A navigation system including at least one pulse radar and a number of transponders which when receiving radar pulses transmit high frequency pulse modulated signals. When receiving an interrogating signal from the pulse radar the transponder transmits a response signal with a delay. The
A method for preventing a radar beacon's response to received pulses from a vessel which originate from the side lobes of the vessel antenna. The carrier frequency of the radar signal pulses to and received by the beacon is measured and a value of this frequency is stored when the amplit
A device for measuring the frequency of a pulsed carrier signal in which the carrier frequency is situated within the frequency range and to give a continuous signal whose frequency is equal to the measured carrier frequency. A frequency discriminator (3) gives an analog voltage via a
