JPH0815417A - Moving speed detector in frequency hopping method - Google Patents

Abstract

PURPOSE:To perform the high-efficiency detection of the relative moving speed between two stations by sampling the receiving levels of specified frequencies, comparing the sampling data and obtaining the counted value when the difference of the data becomes the specified threshold value or more. CONSTITUTION:A receiving means 2 receives the spectrum-diffused radio wave from an antenna 1, and the inverse diffusion of the spectrum is performed for the radio wave. A sampling means 10 detects the receiving level of the receiving means 2 and samples the receiving level of the specified frequency in synchoronization with the inverse diffusion control. A memory means 14 stores the specified number of the sampling data of the sampling means 10 in time series. A counting means 15 obtains a counted value in the specified time when the difference becomes the specified threshold value or more by comparing the sampling data in the memory means 14 in time series. A converting means 19 obtains the relative moving speed with the other station, which transmits the radio wave, based on the counted value of the counting means 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moving speed detecting device in a frequency hopping system, and more specifically to a relative moving speed between two stations performing spread spectrum communication by a frequency hopping (FH) system. The present invention relates to a moving speed detecting device in a frequency hopping system that detects the moving speed based on the.

[0002] In a mobile communication system, a mobile station is used for priority control of handover to a mobile station moving at a high speed, switching control of a synchronous / delayed detection system according to stop / movement of the mobile station, and other various service controls. The relative moving speed of is an important parameter. Currently 3 channel TD
Although the MA method is adopted, what is promising in the future is a so-called spread spectrum communication method using code (direct) spreading or frequency hopping. Therefore, it is necessary to detect the moving speed even in the FH method.

[0003]

2. Description of the Related Art FIG. 6 is a diagram for explaining conventional digital mobile communication according to the FH system, in which 100 is a base station according to the FH system, 200 is a mobile station according to the FH system, 1 is an antenna, 3 is a radio frequency. Receiving unit (RFA), 4 is a mixer, 5 is a bandpass filter (BPF), 6 is an intermediate frequency amplifying unit (IFA), 7 is a hopping frequency (HF) synthesizer, 8 is a frequency hopping (FH) control unit, and 9 is This is a demodulation unit using the PSK method.

[0004] For example 800MHz _Z ～810MH the band of _Z hopping frequencies f ₁ ~f _N (where the figure is set to f _N = f ₅ for simplicity of explanation) is divided into. Base station 10
At 0, for example, 1-symbol information to be transmitted to the mobile station 200 is code-spread by a predetermined pseudo-random sequence (5 sequences in this example), and a hopping frequency (for example, f ₃ , f ₅ , f ₁ , Each symbol information is transmitted by repeating f ₄ , f ₂ ). Note that 1/0 of the symbol information is PSK modulated.

In the mobile station 200, the receiving section 3 has an antenna 1
The received wave RF of is amplified and input to the mixer 4. On the other hand, F
In the H control unit 8, the hopping frequency control signal HFC based on the same pseudo random sequence as the above is synchronized with the base station 100.
D, which causes the HF synthesizer 7 to generate a local oscillation signal L _HF having a corresponding frequency. The mixer 4 sequentially heterodyne-detects the received signal RF with the local oscillation signal L _HF , and the band pass filter 5 obtains an intermediate frequency signal IF having a constant frequency. The signal IF is amplified by the intermediate frequency amplifying section 6 and further PSK detected by the demodulating section 9 to obtain a demodulated baseband signal BBS corresponding to 1/0 of each transmission symbol.

In the land mobile communication system, the propagation path through which such a transmission wave propagates is a multiple wave propagation path because it is reflected, diffracted, scattered, etc. by the topography and buildings around the mobile station. A random standing wave electromagnetic field distribution is formed. When the mobile station travels in this, the envelope R of the received wave varies independently of the Rayleigh distribution and the phase θ follows a uniform distribution.

P (R, θ) = (R / 2πb ₀ ) exp (−R ² / 2b ₀ ) (1) where b ₀ is the average received power. However, in the FH method, the frequencies of the entire hopping band do not drop at the same time even under such a fading environment, so that a kind of frequency diversity effect is obtained.

By the way, the applicant of the present invention has proposed a moving speed detecting device in a mobile communication system capable of independently detecting the relative moving speed v of a mobile station from the received wave without referring to the speed information of the moving body itself. Already proposed (PCT /
JP93 / 01714). According to the first principle, the speed v of the mobile station is directly obtained by measuring the number of branch switching times N _BC of space selection diversity in a predetermined time.

That is, when a mobile station travels at a velocity v in a standing wave electromagnetic field distribution of wavelength λ (constant), the Doppler frequency f _D representing the rate of fluctuation of Rayleigh fading is f _D = v / There is a relationship of λ (2). On the other hand, when the time correlation of the fading received wave is obtained, the time interval τ at which the autocorrelation is 0 (that is, the first-order Bessel function is 0) is expressed as τ = 2.4 / 2πf _D (3) To be done. That is, the spatially independent reception levels R ₁ and R ₂ of the two branches are independent from each other, and each takes an independent value for each τ. Therefore, the number of times R ₁ > R ₂ (that is, the number of times of branch switching in one direction) N _BC in 1 second is N _BC = 1 / 2τ = 2πf _D / (2 × 2.4) = 1.3 ( v / λ) (4) Therefore, if the number of branch switching times N _BC is counted,
The velocity v is obtained from v = (N _BC /1.3)λ (5). The specification also shows the following empirical formula, v≈ (N _BC /2.6) ^1.2 λ (6).

Further, according to the second principle, the speed v of the mobile station is the number N _{3 dB} of times when the amount of change of the envelope R per unit minute time T _s in a predetermined time becomes equal to or more than a predetermined threshold value (for example, 3 dB). Directly obtained from measurement. That is, the probability density function of the time derivative R ′ of the typical Rayleigh envelope R is p (R ′) = {1 / √ (2πb ₂ )} exp (−R ′ ² / 2b ₂ ) (7) It is given a Gaussian distribution with a mean value of zero. Then, the standard deviation sigma (i.e., √b ₂₎ is represented by _{σ = 2πf D √ (b 0} /2) (8), the Doppler frequency f _D (i.e., velocity v) is the proportional.

FIG. 7 is a diagram for explaining the previously proposed speed detection principle (2). In FIG. 7A, when f _D is high, in FIG. 7B, when f _D is low, respectively. The probability density function of the time differential coefficient R'is shown. In addition, (A) of FIG.
7B illustrates the relationship between FIGS. 7A and 7B on the time axis. According to the figure, the variance of the time derivative R'is as large as a high f _D, smaller the low f _D. Therefore, f _D can be estimated by detecting some information indicating the degree of dispersion of the time differential coefficient R ′, and thus the velocity v can be estimated.

Specifically, as shown in FIGS. 8A and 8B, one second is divided into M sections by an appropriate minute time T _s . The probabilities P ₁ and P ₂ of the shaded areas in (A) and (B) of FIG. 7 have a reception level R of 3 dB during the minute time T _s.
The probabilities of increasing or decreasing are shown respectively. If the mobile station does not accelerate or decelerate rapidly, in the range of about 1 second,
It can be assumed that the probabilities P ₁ and P ₂ are substantially constant in any minute section T _s . Therefore, the number of times N _3dB the reception level R in one second is increased and reduced by more than 3dB is given by _{N 3dB = M (P 1 +} P 2) = f s (P 1 + P 2) (9). However, f _s is the sampling frequency (1 /
T _s ).

Therefore, when substituting specific probability density functions p (R) and p (R ') into the probabilities P ₁ and P ₂ of the equation (9) for transformation, N _3dB = (f _s / 2 ) {1-1 / √ _{[1 + 2 (2πf D / f} s) 2 ]} the relationship (10) is obtained. Therefore, f _D is obtained by counting N _{3 dB,} and the velocity v can be detected if f _D is obtained. In addition,
Since the equation (10) does not include the received average power b ₀ , it is not necessary to obtain b _0, and the device becomes simple.

[0014] (C) in FIG. 7 is f _s = 400H _Z (i.e.,
Dosler frequency f _D when T _s = 2.5 ms)
And a number of times N _3dB are graphs, and a solid line shows a theoretical value by the equation (10) and a dotted line shows a result by another computer simulation. From the graph, it can be seen that the Doppler frequency f _D (that is, the speed v) is approximately proportional to the number of times N _{3 dB} .

[0015]

However, the above-mentioned first principle requires the configuration of selective diversity, and is not suitable for the FH system which does not require the configuration of selective diversity. Further, in the FH method, the frequency of the received wave changes randomly in a short time, and the influence of fading is independent for each frequency. Therefore, even when the reception levels (each sampling data) are viewed in time series, there is no correlation due to fading between adjacent reception levels. That is, even if the increase / decrease of the reception level is checked in time series as in the second principle, the fading information cannot be extracted. Therefore, the second principle is also incompatible with the FH method.

Thus, conventionally, there has been no moving speed detecting device suitable for the FH system. An object of the present invention is to provide a moving speed detecting device in a frequency hopping system capable of efficiently detecting a relative moving speed between two stations performing spread spectrum communication by a frequency hopping system based on the received wave with a simple configuration. It is in.

[0017]

The above-mentioned problems can be solved by the structure shown in FIG. That is, the moving speed detecting device in the frequency hopping system of the present invention (1) receives a radio wave spectrum-spread by the frequency hopping system, detects the reception means for despreading the spectrum, and the reception level of the reception means. Sampling means for sampling a reception level of a predetermined frequency in synchronization with the despreading control, storage means for storing a predetermined number of sampling data of the sampling means in time series, and comparing sampling data of the storage means in time series. According to the above, a counting means for obtaining a count value in a predetermined time when the difference is equal to or more than a predetermined threshold, and a converting means for obtaining a relative moving speed with another station that transmits radio waves based on the count value of the counting means are provided. is there.

Further, the moving speed detecting device in the frequency hopping system of the present invention (2) receives the radio wave spectrum-spread by the frequency hopping system, and detects the reception level of the reception means for despreading the spectrum of the radio wave. In addition, sampling means for sampling a reception level of a predetermined frequency in synchronization with the despreading control, storage means for storing a predetermined number of sampling data of the sampling means in time series, sampling data of the storage means and a predetermined section thereof. Counting means for obtaining a count value at a predetermined time of the number of times the sampling data intersects the moving average level by comparing with the moving average level;
And a conversion means for obtaining a relative moving speed with respect to another station that transmits a radio wave based on the count value of the counting means.

[0019]

In the present invention (1), the receiving means 2 receives the radio wave spectrum-spread by the frequency hopping method from the antenna 1 and despreads the spectrum. The sampling means 10 detects the reception level of the reception means 2 (for example, the envelope level R of the intermediate frequency signal IF) and is synchronized with the above-mentioned despreading control and has a predetermined frequency (for example, all hopping frequencies f _{1 to} f _N ). Sample the received level at any particular frequency f _i ). The storage means 14 stores a predetermined number (at least two) of sampling data SD ₁ of the sampling means 10 in time series. The counting means 15 compares the sampling data SD ₂ (that is, the sampling data at the present time point and the sampling data at the previous time point) in the storage means 14 in time series, and when the difference is a predetermined threshold value (for example, 3 dB) or more, a predetermined time (for example, 1 dB). Count value N in seconds)
_{Calculate 3dB} . Then, the converting means 19 obtains the relative moving speed v with respect to the other station that transmits the radio wave, for example, according to the above equation (10) based on the count value N _3dB of the counting means 15.

By the way, the equation (10) is the average received power b ₀
Each sampling data SD is not included
_The number of level crossings corresponding to the Doppler frequency f _D (that is, the speed v) can also be detected by comparing ₂ with the amount corresponding to the received average power b ₀ in a relatively short period (for example, the received average level √b ₀ ). . Number of level crossings N in this case
_b0 is represented by N _b0 = f _D √π · e ^−1/2 ≈f _D (11).

Therefore, the counting means 15 of the present invention (2) is
Sampling data SD of storage means 14₂And its designated ward
Moving average level √b₀By comparing with
When the sampling data crosses the moving average level
Count value N for a predetermined number of times (for example, 1 second)_b0Seeking
It Then, the conversion means 19 determines the count value N of the counting means 15. _b0
Other stations that transmit radio waves according to equation (11) based on
The relative moving speed v of

According to the present invention (1) and (2), since only sampling data of an arbitrary specific frequency f _{i out} of all hopping frequencies is used, the time series of each sampling data is fading with respect to the frequency f _i . Has a strong correlation with the effect of. Therefore, it is possible to efficiently detect the relative moving speed between two stations that perform spread spectrum communication by the frequency hopping method based on the received wave with a simple configuration.

Further, preferably, the counting means 15 is configured to obtain the count value based on the average value of the sampling data of the plurality of frequencies having the frequency correlation with each other in the storage means 14. That is, a plurality of frequencies (for example, f _i-1 , f _i , f _{i + 1,} etc.) that are adjacent to each other on the frequency axis have strong correlation with each other with respect to fading on the time axis, and level fluctuations of the same degree. Have. Therefore, if the count value is calculated based on the average value of each sampling data of a plurality of frequencies, the reliability of the detection speed is improved.

Also preferably, the counting means 15 is a storage means.
14 sampling data of multiple frequencies uncorrelated to each other
The count value is calculated based on the
Is each movement obtained respectively based on each count value of the counting means 15.
It is configured to determine the average value of speed. That is, Zhou
Multiple frequencies that are uncorrelated with each other on the wavenumber axis (for example,
F with frequency difference Ω_i, F_j, F_kEtc.) on the time axis
Are independently affected by fading. However,
Each frequency f_i, F_j, F_kFor each of the
Number N _i, N_j, N_kEach reflect the same velocity v
It Therefore, each count value N of the counting means 15_i, N_j, N_k
Each moving speed v obtained respectively based on_i, V_j, V_kNodaira
If it is configured to obtain the average value v, the reliability of the detection speed will be improved.
improves.

Further, preferably, the counting means 15 is configured to obtain the respective count values based on the average value of the sampling data of the plurality of frequencies having the respective frequency correlations with respect to the plurality of frequencies having no correlation with each other in the storage means 14. There is. This is a combination of the above, and the reliability of the detection speed is further improved.

[0026]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that the same reference numerals indicate the same or corresponding parts throughout the drawings. FIG. 2 is a block diagram of the moving speed detecting device of the embodiment, showing an example of application to a digital mobile communication system by the FH method.

In the figure, 1 is an antenna, 3 is a receiving means, 3 is a radio frequency receiver (RFA), 4 is a mixer, and 5 is a receiver.
Is a band pass filter (BPF), 6 is an intermediate frequency amplification unit (IFA), 7 is a hopping frequency (HF) synthesizer, 8 is a frequency hopping (FH) control unit, and 9 is PSK.
A demodulation unit according to the method, 10 is a sampling unit, 11 is a detection unit (DET) for a reception level R (for example, reception electric field strength RSSI), 12 is an A / D conversion unit (A / D), 13 is a comparison unit (CMP), 14 is a dual port RAM (DPR
AM), 15 (further 15 ₂ , 15 ₃ ) are counting means, 16
Is an arithmetic unit, 17 is a comparator (CMP), 18 is a counter (CTR), and 19 is a conversion means.

The received wave RF by the FH method is amplified by the receiving section 3 and input to the mixer 4. On the other hand, the FH control unit 8 generates the hopping frequency control signal HFCD by the same pseudo-random sequence in synchronization with the hopping sequence of the transmitting station, which causes the HF synthesizer 7 to generate the local oscillation signal L _HF of the corresponding frequency. . The mixer 4 sequentially heterodyne-detects the received signal RF with the local oscillation signal L _HF , and the BPF 5 obtains an intermediate frequency signal IF having a constant frequency. The signal IF is amplified by the intermediate frequency amplifying section 6 and further PSK detected by the demodulating section 9 to obtain a demodulated baseband signal BBS corresponding to 1/0 of each transmission symbol. The demodulated baseband signal BBS is used by the main body (not shown).

In the sampling means 10, the detector 1
1 is the reception level R (that is, the signal I from the intermediate frequency signal IF).
The envelope signal R of F is detected, and the A / D conversion unit 12 detects FH
Timing synchronized with the spectrum despreading control of the control unit 8
The signal of the reception level R is A / D converted into TS. This A /
D conversion is hopping all frequencies f₁~ F_NGo about
Is also good. However, in a first preferred aspect of the invention,
Any specific frequency f _iA / D change only the reception level R of
Replace. That is, the comparison unit 13 controls the series of hopping frequencies.
Control signal HFCD and preset frequency setting signal f_iWhen
Are compared and only when a match is obtained, the A / D converter
Energize twelve. Therefore, the minimum required sampling data
Data SD₁Occurs, which saves DPRAM 14 described later.
It

The DPRAM 14 stores each sampling data SD ₁ in time series by the address signal AD ₁ from which the address from the sampling means 10 is updated in the sequential mode. However, the address signal AD ₁ returns to 0 when it reaches a predetermined maximum value of 2 or more. Counting means 1
In 5, the arithmetic unit 16 reads out the sampling data SD ₂ the current and previous time from DPRAM14 by controlling the address signal AD _2. It should be noted that the sampling data at the previous time point is actually read out at the previous time point, so that it is not read out at this time point.

By the way, it is preferable that the interval at each time point in this example corresponds to the sampling interval T _s (for example, 2.5 ms) in FIG. This is because if the hopping cycle T _{FH in} FIG. 6 (that is, the interval at which the frequency f _i appears) matches the sampling interval T _{s in} FIG. 8, the conversion table in FIG. 7C can be used as it is. Of course, when the hopping cycle T _FH is faster than this, it is only necessary to thin out an appropriate one from among the plurality of sampling data SD ₂ or use these by averaging them. If the hopping cycle T _FH is slow, the system may be designed by _increasing the sampling interval T _s in FIG. However, if the sampling interval T _s is too long, the correlation is lost in the preceding and following times, and it becomes difficult to estimate the Doppler frequency f _D. Therefore, the system design considering the frequency band to be used and the expected maximum moving speed of the mobile station ( Hopping period, etc.) is required.

Next, the arithmetic unit 16 determines the current and previous time points.
Pulling data SD₂Of the difference by comparing
Absolute value | R_t´ | is output. Comparator 17 is the difference
｜ R _t'| And a predetermined threshold R_tTH'(For example, 3 dB)
By comparing | R_t´ ｜ ≧ R_tTHIf ', then HIG
Outputs H level. The counter 18 is the comparator 17
The count is activated by the HIGH level of the output of
Clock signal CK generated in synchronization with each inspection time
Count up.

The counter 18 is energized only while the count energizing signal CE from the outside is HIGH level (for example, 1 second). Therefore, the output of the counter 18 is enveloped during the minute time T _s. When the level of the line R changes by 3 dB or more, the _count value N _{3 dB} for 1 second is obtained. The count value N _3dB of the counter 18 is the count energizing signal C
It is latched in the conversion means 19 at the falling edge of E. Then, the conversion means 19 obtains the speed v from the _count value N _{3 dB} by the conversion principle based on the above equation (10).

It should be noted that such a conversion means 19 has a count value N.
It may be formed by a ROM which reads data of the corresponding speed v with _{3 dB} as an address input. Also, DPRA
The part including the M14, the counting means 15 and the converting means 19 may be realized by a dedicated digital signal processor (DSP) or a part of the DSP that realizes other functions of the main body. Furthermore, especially in this example, since it is only necessary to use the sampling data at the present time point and the previous time point, the expensive DP
A latch circuit or the like may be used instead of using the RAM 14.

FIG. 3 is a timing chart of the speed detecting apparatus of the embodiment. In FIG. 3A, when f _D is high, and in FIG. 3B, when f _D is low, the respective reception levels R are shown. The mode of fluctuation is shown. As in FIG. 8, the arrow indicates the minute time T _s.
The difference in the reception level R is shown for each of the cases, and the circles superimposed on the arrows show the case where the difference in the reception level R exceeds 3 dB.

Here, the envelope R shown by the dotted line in FIG. 3 is a virtual one about the frequency f _i . That is, the period T _s
The sampling data f _i1 , f _i2, etc. for the frequency f _i actually exist at each sampling time point, but since symbol information is sent by another frequency in the intermediate section, as shown by the dotted line. A continuous envelope R
Does not really exist. However, even if the use of the frequency f _i is intermittent (periodic) as shown, the effect of Rayleigh fading on the frequency f _i appears as shown according to the velocity v. Therefore, the speed can be detected by using these sampling data f _i1 and f _i2 .

FIG. 4 is a diagram for explaining various other embodiments of the counting means 15 of FIG. By the way, the frequency correlation ρ (Ω) of Rayleigh fading that is typical for such a land mobile communication system is Ω is the frequency difference, l ₀ is the shortest propagation path length, Δl is the spread of the propagation path length, and c is the speed of light. Then, ρ (Ω) = 1 / (1 + j2πΩ (Δl / c) · expj2π (l ₀ / c) (12) That is, when the frequency difference Ω is small, the correlation approaches 1, and the frequency difference Ω is Correlation is 0 at (c / Δl)
Approach. For example, if Δl = 200 m, the correlation is almost 0.
The frequency difference Omega made to be _{Ω = c / Δl = 1.5MH Z} .

Therefore, the counting means 15 of the second preferred embodiment of the present invention is configured to obtain the count value based on the average value of the sampling data of a plurality of frequencies of the DPRAM 14 which have frequency correlation with each other. The operation will be specifically described below. In (A) in FIG. 4, hopping all frequencies f ₁ ~f _N (e.g. 800MH _Z ~810
If any specific frequency of MH _Z ) is f _i , the frequencies f _i−1 , f _{i + 1 and the} like adjacent thereto have a strong correlation with the frequency f _i . On the other hand, in FIG. 4B, since the use of these frequencies f _i , f _i-1 , and f _{i + 1} complies with the FH method, when viewed on the time axis t, they are sufficiently spaced from each other. Appears.

Therefore, in FIG. 2, the comparison part of this example is
13 is the frequency setting signal f_i-1, F _i, F_{i + 1}Given by
The comparison unit 13 controls the series of hopping frequencies.
Signal HFCD matches any of these set frequencies
It is configured to energize the A / D conversion unit 12 every time.
It Therefore, the frequency f_i, F_i-1,
f_{i + 1}Each sampling data SD₁Is written in chronological order
I will.

[0040] In the counting means 15, calculating unit 16 the moment of the frequency f _i from DPRAM14 by controlling the address signal AD _2, reads the f _i-1, f _{i +} the sampling data SD ₂ of _1, the average of these Find the value.
Since the average value at the previous time point has been calculated at the previous time point, it is not necessary to calculate it again. Next, the calculation unit 16 outputs the absolute value | R _t ′ | of the difference by comparing the respective average values at the present time point and the previous time point. For the subsequent operation, see FIG.
Is the same as that described above.

Particularly in the high-speed FH method, the time at a specific frequency f _i becomes very short, so the frequency f _i
If only the sampling data of is used, there is a concern that the reliability of the detection speed will decrease. However, the detection error of the speed v can be minimized by sampling the reception levels R of a plurality of frequencies having a correlation with each other as in this example and obtaining the count value based on the average value thereof.

Further, the counting means 15 of the third preferred embodiment of the present invention obtains the respective count values based on the sampling data of the DPRAM 14 having a plurality of frequencies which are uncorrelated with each other, and the converting means 19 causes the counting means 15 to measure the respective count values. It is configured to obtain an average value of each moving speed obtained based on a numerical value. That is, in FIG. 4C, there is no correlation between the specific frequency f _i and the frequencies f _j , f _k, etc. having a sufficient frequency difference Ω. However, the effect of fading depending on the speed v is that each frequency f _i ,
Appear independently and equally with respect to f _j and f _k .

Then, referring again to FIG. 2, comparison of this example
The frequency setting signal f_i, F _j, F_k(Not shown)
Is given, the comparison unit 13 determines that a series of hopping
The wave number control signal HFCD is set to one of these set frequencies.
It is configured to activate the A / D conversion unit 12 each time there is a match.
Have been. Therefore, the frequency f_i, F
_j, F_kEach sampling data SD₁Is written in chronological order
Get caught.

Further, in this example, for simplification of description, the counting means 15 is equivalent to the counting means 15 ₂ , 1
It is assumed that 5 ₃ are provided in parallel. The counting means 15 performs the same processing as the first embodiment described with reference to FIG. 2 on the frequency f _{i, and} outputs the count value N _{3d Bi} . The counting means 15 ₂ performs the same processing as the counting means 15 for the frequency f _j and the counting means 15 ₃ for the frequency f _k , _{respectively,} and outputs the _count values N _3dBj and N _3dBk .

Then, the conversion means 19 uses the above equation (10).
Based on the conversion principle based on_{3d Bi}, N_{3 dBj}, N_{3 dBk}
To speed v_i, V_j, V_kAsk for. Note that this speed v
_i, V_j, V_kIn each process of obtaining_i= F_Diλ_i, V
_j= F_Djλ_j, V_k= F_Dkλ _kThe relationship is adopted
Needless to say. Therefore, usually v_i≒ v_J≒ v_Kof
The result is obtained. Then the conversion means 19_i, V_j, V
_kThe average value v of is calculated and output. Therefore, this third state
The detection error of the speed v can be minimized by the above.

Furthermore, according to the fourth preferred embodiment of the present invention,
Counting means 15 (15₂, 15₃) Is the DPRAM 14
There is frequency correlation for multiple uncorrelated frequencies.
Based on the average value of the sampling data of each multiple frequency
It is configured to individually obtain the count value. Figure again
In (C) of 4, the specific frequency f_iAnd enough for this
F with different frequency difference Ω_j, F_kEtc. are correlated with each other
There is no. On the other hand, these frequencies f_i, F _j, F_kTo each
Adjacent frequencies (f_i-1, F_{i + 1}), (F_J-1,
f_{j + 1}), (F _k-1, F_{k + 1}) Is the frequency f_i, F_j,
f_kAnd each have a strong correlation. Therefore, the frequency f_i,
f_j, F_kSpeed v based on the average value of each group of_i,
v_j, V _kFor each of them, and the obtained speed v_i,
v_j, V_kIf it is configured to obtain the average value v of
The detection error of v can be further reduced. In addition, this fourth state
Such a configuration is a combination of the configurations of the above second and third aspects.
This can be easily achieved.

FIG. 5 is a block diagram of the counting means of another embodiment. In this embodiment, the sampling data of the DPRAM 14 is compared with the moving average level in a predetermined section so that the sampling data intersects the moving average level. The case where the count value of the number of times in a predetermined time is obtained is shown. That is, the arithmetic unit 16 of this embodiment reads the current sampling data SD ₂ from the DPRAM 14 by controlling the address signal AD ₂ , and outputs the sampling data R _t . In addition, the calculation unit 16 calculates the moving average value √
b ₀ is obtained, and this is output at the same time as the sampling data R _t . The comparator 17 compares the current sampling data R _t with the moving average value √b ₀ to obtain R _t.
When ≧ √b ₀ , the HIGH level is output. In other cases, LOW level is output. The counter 18 counts up when the output of the comparator 17 rises. The counter 18 is energized only while the count energizing signal CE is at the HIGH level (for example, 1 second). Therefore, when the sampling data exceeds the moving average level at the output of the counter 18 (from the bottom to the top) ( The number of level crossings N _{b0 in} one direction) is obtained. And
In this case, the conversion means 19 obtains the speed v from the _count value N _b0 by the conversion principle based on the above equation (11).

Needless to say, the second to fourth embodiments described with reference to FIG. 4 can be applied to the embodiment of FIG. Further, it can be seen that the moving speed detecting device according to the present invention can be applied to both a mobile station and a base station considering the symmetry of the land propagation path in the mobile communication system. Although a plurality of preferred embodiments of the present invention have been described above, it is needless to say that various changes in configuration and combination can be made without departing from the spirit of the present invention.

[0049]

As described above, since the moving speed detecting device in the frequency hopping system of the present invention has the above-mentioned configuration, the relative moving speed between the two stations performing the spread spectrum communication by the frequency hopping system is determined by the received wave. Based on the above, it is possible to detect efficiently with a simple configuration.

[Brief description of drawings]

FIG. 1 is a principle configuration diagram of the present invention.

FIG. 2 is a block diagram of a moving speed detection device according to an embodiment.

FIG. 3 is a timing chart of the speed detection device according to the embodiment.

FIG. 4 is a diagram illustrating another embodiment of the counting means.

FIG. 5 is a block diagram of a counting means of another embodiment.

FIG. 6 is a diagram for explaining digital mobile communication according to a conventional FH method.

FIG. 7 is a diagram for explaining the proposed speed detection principle (2).

FIG. 8 is a timing chart of the proposed speed detection principle (2).

[Explanation of symbols]

 1 Antenna 2 Receiving Means 10 Sampling Means 14 Storage Means 15 Counting Means 19 Converting Means

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Claims (5)

[Claims] 1. A reception means for receiving a spectrum-spread radio wave by a frequency hopping method and despreading the spectrum, and a reception level of the reception means and detecting a reception level of a predetermined frequency in synchronization with the despreading control. Sampling means for sampling, a storage means for storing a predetermined number of sampling data of the sampling means in time series, and a predetermined time when the difference becomes equal to or more than a predetermined threshold value by comparing the sampling data of the storage means in time series. 2. A moving speed detecting device in a frequency hopping system, comprising: counting means for obtaining a count value in 1); and conversion means for obtaining a relative moving speed with another station that transmits radio waves based on the count value of the counting means. 2. A reception means for receiving a spectrum-spread radio wave by a frequency hopping method and despreading the spectrum, and detecting a reception level of the reception means and synchronizing with the despreading control, a reception level of a predetermined frequency. Sampling means for sampling, a storage means for storing a predetermined number of sampling data of the sampling means in time series, and the sampling data of the storage means is compared with the moving average level in the predetermined section to obtain the moving average of the sampling data. Frequency hopping, comprising counting means for obtaining a count value of the number of times of crossing the level in a predetermined time, and conversion means for obtaining a relative moving speed with another station that transmits radio waves based on the count value of the counting means. Speed detection device in the system. 3. The frequency according to claim 1, wherein the counting means is configured to obtain a count value based on an average value of sampling data of a plurality of frequencies having frequency correlation with each other in the storage means. Moving speed detection device in hopping system. 4. The counting means obtains a count value based on each sampling data of a plurality of frequencies having no correlation with each other in the storage means, and the converting means obtains each moving speed obtained based on each count value of the counting means. The moving speed detecting device in the frequency hopping system according to claim 1 or 2, wherein the moving speed detecting device is configured to obtain an average value. 5. The counting means is configured to individually obtain a count value based on an average value of sampling data of a plurality of frequencies having a frequency correlation with respect to a plurality of uncorrelated frequencies of the storage means. The moving speed detecting device in the frequency hopping system according to claim 4.