초록 ▼

A method for a radar for detecting a noise floor level of an electric signal corresponding to an incident radio wave received by the radar, the incident radio wave including a return of a radar wave that is transmitted from the radar toward a measuring range of the radar to detect target object char

A method for a radar for detecting a noise floor level of an electric signal corresponding to an incident radio wave received by the radar, the incident radio wave including a return of a radar wave that is transmitted from the radar toward a measuring range of the radar to detect target object characteristic including presence of a target object within the measuring range of the radar, a distance between the target object and the radar, and a relative speed of the target object to the radar is provided. The method includes steps of: calculating a histogram of intensities of frequency components, the frequency components exceeding a predetermined value relating to the measuring range, and extracting an intensity having the maximum height in the histogram as the noise floor level of the electric signal.

대표청구항 ▼

What is claimed is: 1. A method for determining a noise floor level in analyzing an incident radio wave which is received and translated by a radar into an electric signal and which includes a return of a radar wave as having been transmitted by the radar and reflected from a target object within a

What is claimed is: 1. A method for determining a noise floor level in analyzing an incident radio wave which is received and translated by a radar into an electric signal and which includes a return of a radar wave as having been transmitted by the radar and reflected from a target object within a measuring distance range of the radar, comprising steps of: performing frequency analysis on the electric signal to derive a distribution of intensities of frequency components of the electric signal; calculating a histogram of the intensities of ones of the frequency components which are out of a given frequency range in which the return of the radar wave from the target object is to fall; and determining one of the intensities having a maximum height in the histogram of the intensities of the frequency components as the noise floor level. 2. The method according to claim 1, wherein the radar is a frequency modulated continuous wave (FMCW) radar that transmits a frequency-modulated radar wave whose frequency changes in time, the radar wave having an upward modulated section during which the frequency of the radar wave increase in time and a downward modulated section during which the frequency of the radar wave decrease in time, the electric signal includes a first beat signal and a second beat signal which are generated by mixing the incident radio wave received by the radar and the radar wave transmitted from the radar in the upward modulated section and in the downward modulated section, respectively, and at least one of the first and second signals is used to calculate the histogram of intensities of frequency components of the beat signal. 3. The method according to claim 2, wherein the FMCW radar has a plurality of receiving antennas to receive the incoming radio wave to generate a plurality of beat signals, each beat signal responsive to component of the incoming radio wave received by the corresponding receiving antenna, and the histogram of intensities of frequency components of the beat signal is calculated by using the plurality of the beat signals. 4. A frequency modulated continuous wave (FMCW) radar that detects a target object characteristic including at least one of presence of a target object within a measuring range of the radar, a distance between the target object and the radar, and a relative speed of the target object to the radar, comprising: a transmission signal generator that generates a transmission signal whose frequency is modulated so as to have a upward modulated section during which the frequency of the transmission signal increase in time and a downward modulated section during which the frequency of the transmission signal decrease in time; a transmission antenna that transmits the transmission signal as a radar wave in direction of the measuring range, the measuring range being limited the farthest distance thereof which correspond to a maximum measurement frequency; a reception antenna unit that receives an incident radio wave including a return of the radar wave from the target object located within the measuring range of the radar so as to generate a received signal based on the incident radio wave; a beat signal generator that generates a first and second beat signals with respect to each of the upward modulated section and the downward modulated section, respectively, based on both the transmission signal and the received signal; an frequency analyzer that performs frequency analysis on the first and second beat signals to obtain a first and a second frequency spectrum characteristic thereof which show distribution of intensities of the beat signal in frequency domain with respect to the upward modulated section and the downward modulated section, respectively; a histogram calculator that calculates a histogram of intensities of frequency components, which frequency components exceeding the maximum measurement frequency, based on at least one of the first and second frequency spectrum characteristic of the beat signal; a noise floor level detector that detects a typical intensity that has a maximum height in the histogram of intensities of frequency components as the noise floor level; a peak frequency detector that detect a first and second peak frequencies which has respective highest intensities in the first and second frequency spectrum characteristic, respectively, if the first and second peak frequencies are below the maximum measurement frequency and have their intensities larger than a value determined as a function of the noise floor level; and a target object characteristic calculator that calculates the target object characteristic based on the first and second peak frequencies. 5. The radar according to claim 4, wherein the reception antenna unit includes a plurality of receiving antennas to generate a plurality of received signals, each received signal being generated from the incoming radar wave passing through the corresponding receiving antenna, the beat signal generator that generates a plurality of first beat signals and second beat signals, each first beat signal relating to the incoming radar wave passing through the corresponding receiving antenna and the radar wave transmitted within the upward modulated period, and each second beat signal relating to the incoming radar wave passing through the corresponding receiving antenna and the radar wave transmitted within the downward modulated period, based on the plurality of received signals and transmission signal. 6. The radar according to claim 5 further comprising: an interference detector that detect occurrence of interference between the FMCW radar and some other radar based on a result of whether or not the noise floor level exceeds a predetermined interference threshold value. 7. The radar according to claim 4, wherein the FMCW radar is a vehicle-mounted radar. 8. A interference detecting device for a frequency modulated continuous wave (FMCW) radar which device determines whether interference between the FMCW radar and some other radar occurs, comprising: a transmission signal generator that generates a transmission signal whose frequency changes in time; a transmission antenna that transmits the transmission signal as a radar wave in direction of a measuring range of the FMCW radar, the measuring range being limited the farthest distance thereof which correspond to a maximum measurement frequency; a reception antenna unit that receives an incident radio wave including a return of the radar wave from the target object located within a measuring range of the radar, so as to generate a received signal based on the incoming radio wave; a beat signal generator that generates a beat signal based on the transmission signal and the received signal; a frequency analyzer that executes frequency analysis on the beat signal to obtain a frequency spectrum characteristic thereof which show distribution of intensities of the beat signal in frequency domain; a histogram calculator that calculates a histogram of intensities of frequency components, which frequency components exceeding the maximum measurement frequency, based on the frequency spectrum characteristic of the beat signal; a noise floor level detector that extracts a typical intensity whose intensity has the maximum height in the histogram of intensities of frequency components of the beat signal as the noise floor level; and an interference detector that detects occurrence of interference between the FMCW radar and some other radar based on a result of whether or not the noise floor level exceeds a predetermined value. 9. The radar according to claim 8, wherein the reception antenna unit includes a plurality of receiving antennas to generate a plurality of received signals, each received signal being generated from the incident radar wave passing through the corresponding receiving antenna, the beat signal generator that generates a plurality of first beat signals and second beat signals, each first beat signal relating to the incident radar wave passing through the corresponding receiving antenna and the radar wave transmitted within the upward modulated section, and each second beat signal relating to the incident radar wave passing through the corresponding receiving antenna and the radar wave transmitted within the downward modulated section, based on the plurality of received signals and transmission signal. 10. The device according to claim 9, further comprising: a peak frequency detector that detect a first and second peak frequencies which has respective highest intensities in the first and second frequency spectrum characteristic if the first and second peak frequencies are below the maximum measurement frequency and have their intensities larger than a functional value of the noise floor level; and a target object characteristic calculator that calculates the target object characteristic including a distance of a target object located within a measuring range of the radar and a relative speed between the target object and the radar based on the first and second peak frequencies.