JP2006258689A - Device for detecting moving velocity - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for detecting moving velocity, capable of easily and of surely obtaining the moving velocity of a moving station loaded on a vehicle and the like. <P>SOLUTION: Radio waves, having frequency Fo emitted by a moving state 21 on a vehicle and the like and reflected by surrounding structures 22, 23, are received by an antenna 101 and a receiver 102, and frequency-coverted by a frequency converter 103, digital-converted with an A/D converter 105 and temporarily contained in a data buffer 108. The data is fast-Fourier transformed with a TFT processor 109. Data under a specific threshold are removed with a TH detection processor 110, the maximum Doppler frequency Fmax and the minimum Doppler frequency Fmin are obtained by a frequency shift calculator 112, and the moving velocity of the moving station is calculated with a velocity component detector 113, based on these Fmax and Fmin. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a moving speed detection apparatus, and more particularly to a moving speed detection apparatus that calculates a moving speed of a radio wave emission source by receiving a radio wave of a moving radio wave emission source and detecting a Doppler frequency.

  There is a case where it is desired to quickly detect the moving speed of a vehicle (car, train, etc.), ship or airplane. For example, the speed of a vehicle traveling on a highway is detected to detect whether the vehicle is traveling at an appropriate speed within a predetermined speed limit. It is necessary to crack down on this. In general, the Doppler effect is used to detect the moving speed of such a moving body.

  When measuring the speed of a moving radio station, the Doppler frequency is measured from the reflected wave of the radiated radio wave as in the Doppler radar device, or the Doppler frequency of the radio wave transmitted by the mobile body is measured. However, in order to detect these moving speeds, it is necessary to irradiate the mobile body with a radio wave whose frequency is already known, or to know the transmission frequency transmitted by the mobile body.

  Prior art in this technical field or related is disclosed in several technical documents. A propagation path fluctuation estimation apparatus and a propagation path fluctuation estimation method that detect the maximum Doppler frequency of a mobile terminal using FFT (Fast Fourier Transform) technology and estimate fluctuations in radio propagation path characteristics are disclosed (for example, (See Patent Document 1). It also detects the fluctuation in the envelope level of the received power, counts the number of times the envelope level crosses the reference received power level upward, calculates the Doppler frequency, and averages the moving speed of the mobile terminal at regular intervals A wireless communication system or the like that seeks is disclosed (see, for example, Patent Document 2).

Japanese Patent Laid-Open No. 2002-290293 (page 5-6, FIG. 1) JP 2004-208001 A (pages 11-12, FIG. 1)

  However, the conventional technology as described above has several problems. First, when transmitting a radio wave like a radar apparatus, it is necessary to pay attention to radio wave interference to other apparatuses as well as to increase the scale of the apparatus. If the transmission frequency needs to be known, the speed of a mobile radio station whose frequency is unknown cannot be measured.

  Further, the radar device needs to transmit and receive radio waves. The reason is that even if the radio wave emitted by the moving target is unknown, it can be measured, but it is necessary to receive and analyze the radio wave reflected from the target, and the radio wave specifications need to transmit a known radio wave. It is. Further, when the moving speed is estimated using only radio waves from the mobile radio station, the frequency or wavelength of the radio station needs to be known. The reason is that it is impossible in principle to calculate the moving speed only by the observed Doppler frequency, and there is no method for determining the transmission frequency of the radio station from the received signal.

  The present invention has been made in view of the above-described problems of the prior art, and provides a moving speed detection device that overcomes or reduces the above-described problems, that is, measures the speed of a mobile radio station whose transmission frequency is unknown. The main purpose.

In order to solve the above-described problems, the moving speed detection device according to the present invention employs the following characteristic configuration.
(1) In a moving speed detection device for obtaining a moving speed of the mobile station by receiving radio waves emitted from the mobile radio station by an antenna and a receiver of the fixed station,
Data buffer means for storing data for a predetermined time including Doppler frequency components in which radio waves from the mobile station received by the receiver are reflected by surrounding structures, etc., and data stored in the data buffer means FFT processing means for performing a fast Fourier transform (FFT), frequency deviation calculating means for obtaining a maximum Doppler frequency and a minimum Doppler frequency from an output of the FFT processing means, the maximum Doppler frequency obtained by the frequency deviation calculating means, and A moving speed detecting device comprising speed component detecting means for determining a moving speed of the mobile station from a minimum Doppler frequency.
(2) In a moving speed detection device for obtaining a moving speed of the mobile station by receiving radio waves emitted from the mobile radio station by an antenna and a receiver of the fixed station,
FM detection processing means for measuring the frequency of radio waves reflected by surrounding structures or the like from the mobile station received by the receiver; data buffer means for storing data from the FM detection processing means; Frequency shift calculating means for calculating a maximum frequency and a minimum frequency from frequency data stored in the data buffer means for a predetermined time, and the movement using the maximum frequency and the minimum frequency calculated by the frequency shift calculating means. A moving speed detecting device comprising speed component detecting means for determining a moving speed of a station.
(3) The moving speed detection device according to (1), further comprising TH detection processing means for setting a threshold (TH) to be removed as noise in the output of the FFT processing means.
(4) The reception output of the receiver is frequency-converted to the intermediate frequency (IF) by the frequency conversion means by the oscillation signal of the local oscillation means whose oscillation frequency is controlled by the control processing means (1), (2) Or the moving speed detection apparatus of (3).
(5) The moving speed detecting device according to (4), wherein the IF signal frequency-converted by the frequency converting means is converted into a digital signal by an A / D converting means and further converted into a real part and an imaginary part by an orthogonal converting means. .
(6) The moving speed detecting device according to (5), wherein the output signal converted by the orthogonal transforming means removes high frequency noise by a low pass filter (LPF) means.
(7) The moving speed detecting device according to (2), wherein LPF means are provided in the preceding and succeeding stages of the FM detection processing means, respectively.

  According to the moving speed detection apparatus of the present invention, the following remarkable practical effects can be obtained. Since the Doppler frequency can be measured only by receiving radio waves from the radio station, the moving speed of the moving radio station can be easily detected. Further, since the Doppler frequency is calculated from the amount of frequency deviation from the mobile station, it is not necessary to know the transmission frequency from the moving radio station.

  Hereinafter, the configuration and operation of a preferred embodiment of a moving speed detection apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  First, FIG. 1 is a functional block diagram showing the configuration of a first embodiment of a moving speed detection device according to the present invention. The moving speed detection apparatus 100 includes an antenna 101, a receiver 102, a frequency converter (or frequency converter) 103, a local oscillator (or local oscillator) 104, an analog / digital (A / D) converter (or A / D conversion unit) 105, orthogonal transform unit (or orthogonal transform unit) 106, low-pass filter (or LPF unit) 107, data buffer (or data buffer unit) 108 for temporarily storing data, FFT processing unit (or FFT processing unit) ) 109, a TH (threshold) detection processing unit (or TH detection processing unit) 110, a control processing unit (or control processing unit) 111, a frequency shift calculation unit (or frequency shift calculation unit) 112, and a velocity component detection unit ( (Or velocity component detection means) 113.

  In this moving speed detection apparatus 100, the received signal of the antenna 101 is received from a receiver 102, a frequency conversion unit 103, an A / D conversion unit 105, an orthogonal conversion unit 106, an LPF 107, a data buffer 108, an FFT processing unit 109, and a TH detection process. Unit 110, frequency shift calculation unit 112, and velocity component detection unit 113 are sequentially connected to perform predetermined signal processing described later. Further, the control processing unit 111 is connected to the frequency conversion unit 103 via the local oscillation unit 104.

  In the moving speed detection apparatus 100 shown in FIG. 1, an antenna 101 and a receiver 102 capture radio waves in real space including a signal from a mobile radio station (not shown). The frequency conversion unit 103 converts the input signal from the receiver 102 into an intermediate frequency (IF) signal using the local oscillation signal from the local oscillation unit 104 and outputs the signal. The local oscillation unit 104 outputs a signal having a frequency controlled by the control processing unit 111.

  The control processing unit 111 controls the output signal of the local oscillating unit 104 so that a signal having a target frequency set by an operator (or an operator) is converted into an IF signal. The A / D conversion unit 105 converts the input signal into corresponding digital data and outputs it. The orthogonal transform unit 106 performs orthogonal transform on the signal input from the A / D conversion unit 105, separates it into a real part and an imaginary part, and outputs it. The LPF 107 filters the input signal to remove and output a high frequency component unrelated to the Doppler frequency.

  The data buffer 108 records and holds the signal input from the LPF 107 for a predetermined time. The FFT processing unit 109 performs Fourier transform (FFT) processing on the signal input from the data buffer 108 and outputs the result. The TH detection processing unit 110 removes data below the TH value as noise from the data after Fourier transform. The frequency deviation calculating unit 112 calculates and outputs the maximum frequency Fmax and the minimum frequency Fmin from the frequency data. Further, the speed component detector 113 calculates the moving speed of the radio station using the output of the frequency shift calculator 112 and outputs it from the output terminal 114.

  Next, the operation of the moving speed detection device 100 in FIG. 1 will be described. In FIG. 1, the operator inputs a frequency estimated to be used by a radio station whose movement speed is to be measured, to the control processing unit 111. The control processing unit 111 sets the frequency of the local oscillation signal in the local oscillation unit 104 so that the designated frequency is converted into an IF frequency and input to the A / D conversion unit 105. As a result of these controls, radio waves from the mobile radio station are converted to the vicinity of the IF frequency via the antenna 101, the receiver 102, and the frequency conversion unit 103 and input to the A / D conversion unit 105. Therefore, the A / D conversion unit 105 converts the input signal into digital data and outputs the digital data, and the output data from the A / D conversion unit 105 is orthogonally transformed by the orthogonal transformation unit 106 to obtain the real part (I data). And imaginary part (referred to as Q data).

  The data separated into I data and Q data by the orthogonal transform unit 106 is subjected to removal of high frequency components by the LPF 107 to extract data including Doppler frequency components, and stored or stored in the data buffer 108 for a predetermined time. The FFT processing unit 109 performs fast Fourier transform processing using the data stored in the data buffer 108, calculates the frequency distribution of the received signal, and sends it to the TH detection processing unit 110. In the TH detection processing unit 110, noise is removed by removing a signal equal to or lower than the TH value from the data after Fourier transform as described later with reference to FIG.

The signal from which the noise has been removed by the TH detection processing unit 110 (the hatched portion in FIG. 4) is expressed by the frequency shift calculation unit 112 using the maximum Doppler frequency Fmax given by (Equation 1) below and the following (Equation 2) The given minimum Doppler frequency Fmin is calculated and output to the speed component detection unit 113.
Fmax = Fo · C / (C−V) (Equation 1)
Fmin = Fo · C / (C + V) (Formula 2)
Here, C is the speed of light (constant), and V is the moving speed of the mobile radio station.

Next, the speed component detection unit 113 uses the Fmax and Fmin input in (Equation 1) and (Equation 2) and performs the calculation of (Equation 3) shown below, so that the mobile radio station The moving speed V is calculated and output as the final result.
V = C · (Fmax−Fmin) / (Fmax + Fmin) (Equation 3)

  Next, the principle of detecting the moving speed of the moving body by the moving speed detecting apparatus 100 of the present invention will be described in detail with reference to FIGS. FIG. 2 is an explanatory diagram in the case where a received radio wave from a moving body that emits radio waves is received by a fixed station. In FIG. 2, a vehicle (mobile station) 21 that emits radio waves of frequency Fo travels in an urban area having structures 22 and 23 such as buildings that reflect radio waves, and receives radio waves at a fixed station 24. In the specific example of FIG. 2, the vehicle 21 is approaching the structure 22 at a speed V and is moving away from the structure 23.

  In the state of FIG. 2, the frequency of the radio wave received by the fixed station 24 after being reflected by the structure 22 is Fmax, and is expressed by the above (formula 1). That is, when the frequency of the radio wave emitted by the mobile station 21 is Fo, when the vehicle 21 travels toward the structure 22, the frequency of the radio wave reflected by the structure 22 is maximized. On the other hand, when the fixed station 24 receives the radio wave reflected by the structure 23 opposite to the traveling direction of the vehicle 21, that is, the vehicle 21 moves away, the frequency of the radio wave becomes the minimum Fmin. expressed.

  FIG. 3 is a graph showing the time-frequency relationship showing how the reception frequency of the fixed station shifts in the case shown in FIG. In the situation shown in FIG. 2, the radio waves received by the fixed station 24 from the mobile radio station 21 are affected by Rayleigh fading because they receive radio waves reflected from the surrounding structures 22 and 23. As a result, the reception frequency shifts between the maximum frequency Fmax and the minimum frequency Fmin around Fo as shown in FIG.

  Next, FIG. 4 is an explanatory diagram of noise removal based on a waveform after FFT conversion of the received signal received by the fixed station 24 shown in FIG. 2 and TH (threshold) determination. The TH detection processing unit 110 shown in FIG. 1 performs processing for removing the waveform below the set TH value (the portion without hatching in FIG. 4) and leaving only the waveform portion indicated by the hatching exceeding the TH value.

  Next, a second embodiment of the moving speed detection device according to the present invention will be described with reference to FIG. FIG. 5 is a functional block diagram showing the configuration of the moving speed detection device 200 of the second embodiment. For convenience of explanation, similar reference numerals are used for components corresponding to the components shown in FIG. In the following description, the difference will be mainly described.

  The moving speed detection apparatus 200 includes an antenna 201, a receiver 202, a frequency conversion unit 203, a local oscillation unit 204, an A / D conversion unit 205, an orthogonal conversion unit 206, a first LPF 207, a data buffer 208, and a control processing unit 211. , A frequency shift calculation unit 212, a velocity component detection unit 213, an FM detection processing unit 215, and a second LPF 216. Then, the detected moving speed of the mobile station (not shown) is output from the output terminal 214 connected to the speed component detecting unit 213.

  In the moving speed detection device 200 of FIG. 5 described above, the reception signals received by the antenna 201 and the receiver 202 are the frequency conversion unit 203, the A / D conversion unit 205, the orthogonal conversion unit 206, the first LPF 207, and FM detection. The processing unit 215 and the second LPF 216 are sequentially connected. The second LPF 216 is sequentially connected to the data buffer 208, the frequency shift calculation unit 212, and the speed component detection unit 213, and is also connected to the speed component detection unit 213. The control processing unit 211 is connected to the local oscillation unit 204, and the local oscillation unit 204 is further connected to the frequency conversion unit 203.

  In this moving speed detection device 200, the frequency shift is further devised in the calculation technique with respect to the moving speed detection device 100 of the first embodiment described above. That is, the first LPF 207 removes high-frequency components, extracts data including Doppler frequency components, and outputs the data to the FM detection processing unit 215 in the same manner as the LPF 107 of the moving speed detection device 100. The FM detection processing unit 215 converts the input data into frequency data and outputs it to the second LPF 216.

  Next, the second LPF 216 performs low-pass filter processing on the data after the FM detection processing by the FM detection processing unit 215. Thus, only the Doppler frequency data is extracted, stored (or accumulated) in the data buffer 208 for a certain period of time, and output to the frequency shift calculation unit 212, thereby calculating the frequency shift distribution. In FIG. 6, (A) is a signal before passing through the second LPF 216 and contains high-frequency noise, while (B) is a signal after passing through the second LPF 216 and high-frequency noise is removed. .

  The configuration and operation of the preferred embodiment of the mobile station speed detection apparatus according to the present invention have been described above in detail. However, it should be noted that such examples are merely illustrative of the invention and do not limit the invention in any way. Those skilled in the art will readily understand that various modifications and changes can be made in accordance with a specific application without departing from the gist and spirit of the present invention.

It is a functional block diagram which shows the structure of 1st Example of the moving speed detection apparatus by this invention. It is explanatory drawing of the principle which the frequency shift of the received radio wave in this invention produces. It is a figure which shows the relationship between the frequency shift of the received electromagnetic wave in this invention, and deviation amount. It is explanatory drawing of a noise removal process by the waveform and threshold value (TH) determination after a fast Fourier transform (FFT). It is a functional block diagram which shows the structure of 2nd Example of the moving speed detection apparatus by this invention. 6A and 6B are explanatory diagrams of processing for extracting a Doppler frequency component from a waveform after FM detection processing by a filtering process in the moving speed detection device shown in FIG. 5, wherein (A) is a waveform before filtering and (B) is a waveform after filtering.

Explanation of symbols

100, 200 Moving speed detector 101, 201 Antenna 102, 202 Receiver 103, 203 Frequency converter 104, 204 Local oscillator 105, 205 A / D converter 106, 206 Orthogonal converter 107, 207, 216 Low-pass filter ( LPF)
108, 208 Data buffer means 109 Fast Fourier transform (FFT) processing means 110 TH detection processing means 111, 211 Control processing means 112, 212 Frequency shift calculation means 113, 213 Speed component detection means 215 FM detection processing means 21 Mobile station 22 , 23 Structure 24 Fixed station

Claims (7)

In the moving speed detection device for obtaining the moving speed of the mobile station by receiving the radio wave emitted from the mobile radio station by the antenna and the receiver of the fixed station,
Data buffer means for storing data for a predetermined time including Doppler frequency components in which radio waves from the mobile station received by the receiver are reflected by surrounding structures, etc., and data stored in the data buffer means FFT processing means for performing a fast Fourier transform (FFT), frequency shift calculating means for obtaining a maximum Doppler frequency and a minimum Doppler frequency from an output of the FFT processing means, the maximum Doppler frequency obtained by the frequency shift calculating means, and A moving speed detecting device comprising speed component detecting means for determining a moving speed of the mobile station from a minimum Doppler frequency. In the moving speed detection device for obtaining the moving speed of the mobile station by receiving the radio wave emitted from the mobile radio station by the antenna and the receiver of the fixed station,
FM detection processing means for measuring the frequency of radio waves reflected by surrounding structures or the like from the mobile station received by the receiver; data buffer means for storing data from the FM detection processing means; Frequency shift calculating means for calculating a maximum frequency and a minimum frequency from frequency data stored in the data buffer means for a predetermined time, and the movement using the maximum frequency and the minimum frequency calculated by the frequency shift calculating means. A moving speed detecting device comprising speed component detecting means for determining a moving speed of a station.   The moving speed detection device according to claim 1, further comprising a TH detection processing unit that sets a threshold (TH) to be removed as noise from the output of the FFT processing unit.   The reception output of the receiver is frequency-converted to an intermediate frequency (IF) by a frequency conversion means by an oscillation signal of a local oscillation means whose oscillation frequency is controlled by a control processing means. 3. The moving speed detection device according to 3.   5. The movement according to claim 4, wherein the IF signal frequency-converted by the frequency converter is converted into a digital signal by an A / D converter and further converted into a real part and an imaginary part by an orthogonal converter. Speed detection device.   6. The moving speed detection device according to claim 5, wherein high-frequency noise is removed from the output signal converted by the orthogonal transform means by a low-pass filter (LPF) means.   3. The moving speed detection device according to claim 2, wherein LPF means are provided in the front stage and the rear stage of the FM detection processing means, respectively.

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