Range measurement device, range measurement method, and storage medium
A range measurement device includes a signal processor configured to fit an intermediate frequency signal, obtained by mixing continuous waves which have been frequency-modulated and transmitted toward targets and continuous waves which have been reflected by the targets and returned, with exponential functions whose arguments have real parts and imaginary parts using Prony method.
1 . A range measurement device comprising:
a transmitter configured to transmit, toward targets, a first signal being continuous waves which have been frequency-modulated;
a receiver configured to receive a second signal being the continuous waves which are reflected by the targets and returned from the targets; and
a signal processor configured to:
fit an intermediate frequency signal, obtained by mixing the first signal and the second signal, with exponential functions whose arguments have real parts and imaginary parts using Prony method;
remove the exponential functions whose absolute values of the real parts in the arguments that are greater than a prescribed value, as noise, among the exponential functions obtained by fitting the intermediate frequency signal; and
acquire values of ranges between the range measurement device and the targets based on the exponential functions from which the noise has been removed.
2 . The range measurement device according to claim 1 , wherein the signal processor is further configured to acquire, from the exponential functions from which the noise has been removed, values of amplitudes of the exponential functions from which the noise has been removed, and values of the imaginary parts of the exponential functions from which the noise has been removed.
3 . The range measurement device according to claim 2 , wherein the signal processor is further configured to:
acquire top amplitude values from the acquired values of the amplitudes based on the exponential functions from which the noise has been removed, and including the acquired values of the amplitudes and the acquired values of the imaginary parts; and
acquire values of ranges between the range measurement device and the targets, the values of ranges corresponding to the acquired values of the imaginary parts of the exponential functions from which the noise has been removed of the top amplitude values.
4 . The range measurement device according to claim 3 , further comprising a display configured to display target information including the acquired top amplitude values and the acquired values of the ranges.
5 . A range measurement method executed by a computer, the range measurement method comprising:
transmitting, by a transmitter of a range measurement device, toward targets, a first signal being continuous waves which have been frequency-modulated;
receiving, by a receiver of the range measurement device, a second signal being the continuous waves which are reflected by the targets and returned from the targets;
fitting an intermediate frequency signal, obtained by mixing the first signal and the second signal, with exponential functions whose arguments have real parts and imaginary parts using Prony method;
removing the exponential functions whose absolute values of the real parts in the arguments that are greater than a prescribed value, as noise, among the exponential functions obtained by fitting the intermediate frequency signal; and
acquiring values of ranges between the range measurement device and the targets based on the exponential functions from which the noise has been removed.
6 . A computer-readable, non-transitory, storage medium storing a program for causing a computer to execute:
transmitting, by a transmitter of a range measurement device, toward targets, a first signal being continuous waves which have been frequency-modulated;
receiving, a receiver of the range measurement device, a second signal being the continuous waves which are reflected by the targets and returned from the targets;
fitting an intermediate frequency signal, obtained by mixing the first signal and the second signal, with exponential functions whose arguments have real parts and imaginary parts using Prony method;
removing the exponential functions whose absolute values of the real parts in the arguments that are greater than a prescribed value, as noise, among the exponential functions obtained by fitting the intermediate frequency signal; and
acquiring values of ranges between the range measurement device and the targets based on the exponential functions from which the noise has been removed.