JP3230952B2 - Multipath delay spread measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multipath delay spread measuring apparatus used for designing a service area of digital mobile communication.

[0002]

2. Description of the Related Art Mobile communication such as a portable telephone is realized by wireless communication between a base station and a terminal. In actually performing such mobile communication, it is necessary to determine the service area of each base station.

The reason that these conditions are different in each service area is that a transmission signal is reflected by a shield or a reflector of a building or a house, and is transmitted to a receiving side as a multiplex wave via a multipath. That is because

However, in the conventional analog system,
Even when the transmission signal is a multiplex wave, the deterioration of the transmission quality does not cause much problem, so that the effective area (service area) design of the base station by measuring the electric field strength of the transmission signal has been relatively easy.

[0005] However, in recent years, mobile communication has been improved due to efficiency of frequency utilization, digitization of source data, and the like.
The transition to digital systems is progressing rapidly. When such a digital method is used, a delayed wave (reflected wave) transmitted from a transmitting side to a receiving side with respect to a direct wave (fundamental wave) transmitted without passing through a shield is delayed from a direct wave by a reflector or the like. The permissible conditions for the effect of waves) become severe.

In digital communication, if the opening of the so-called eye pattern is narrowed, the bit error rate when demodulating into digital data is increased and the transmission quality is deteriorated. For example, the delay of the reflected wave depends on the period of the transmission speed. 30
%, The bit error rate exceeds the allowable value.
It is said. Also, the intensity ratio of the delayed wave to the direct wave,
The bit error occurrence rate changes depending on the phase difference.

Therefore, in digital mobile communication, it is necessary to accurately measure the delay time, intensity ratio, phase difference, and the like of a delayed wave with respect to a direct wave, and to determine a service area, a transmission speed, and the like using these results. Can be.

In making this measurement, it is conceivable to use a modulated wave with a single pulse having a large transmission power, but in practice, it is difficult to realize this due to regulations of the Radio Law. Therefore, in such an apparatus for measuring multipath delay waves, a spread spectrum method is used which can reduce the intensity of a single frequency component by spreading the radio wave intensity of a transmission signal in the frequency direction.

FIG. 7 is a diagram for explaining spread spectrum and despreading of a transmission signal. First, in order to generate a spread spectrum signal, an RF signal having a certain frequency fr and a certain strength is spread using a signal over a wide frequency band, specifically, a pseudo random code signal (PN signal). Let it.

On the other hand, when the spread spectrum signal thus created is despread on the receiving side with the PN signal of the same code string used for spreading, an RF signal of frequency fr is reproduced.

Since this spread spectrum signal is a low-intensity signal over a wide frequency band, if it is used as a transmission wave, it is unlikely to be an obstacle to other signals in the same space, and the spread spectrum signal is spread over a wide frequency band. From the signal
Since the F signal is reproduced, it is hardly affected by other signals or thermal noise.

The PN signal is a signal in which the same pseudo-random code sequence is repeatedly output at a constant period. Therefore, in a device for measuring a multipath delay wave, when performing despreading, the code rate of the PN signal on the receiving side is slightly changed by changing the code rate of the PN signal on the transmitting side slightly. Each time a certain number of repetitions are performed, the two PN signals are synchronized, and the RF signal is extracted as a correlation coefficient between the two PN signals.

The number of repetitions of the pseudo-random code sequence in this case is called a K factor. Also, despreading is performed with PN signals having slightly different code rates, and for each K factor,
A method that enables an RF signal to be extracted as a correlation coefficient of a PN signal is called a sliding correlation method.

FIG. 8 is an explanatory diagram of the sliding correlation. In FIG. 8, the transmitting PN signal and the receiving P
The code rate is slightly different from that of the N signal. Therefore, the code string of the reception PN signal is slightly shifted (sliding) with respect to the transmission PN signal.

Here, considering the correlation between the two PN signals, the correlation coefficient when the phases are not synchronized is small. However, as shown in FIG. 8, since the beginning of the pseudo-random code sequence eventually coincides due to the sliding of the receiving-side PN signal, the correlation coefficient becomes maximum at this point, and a triangular wave having this point as the vertex becomes a correlation waveform. It is formed.

For example, if the PN signal code rate on the transmitting side is 30.
01Mbps, and the PN signal code rate on the receiving side is 30M
bps, the factor K = 30 / (30.01-3
0) = 3000, and the above-mentioned correlation waveform is obtained every 3000 times of the code string.

The above description is a correlation waveform of only a direct wave when an RF signal, which is also a propagation wave of a spread spectrum signal, is directly transmitted from a transmission unit to a reception unit. On the other hand, when a delayed wave is present, the delayed wave is transmitted with a time delay with respect to the direct wave, so that the beginning of the PN signal code train is delayed by the delay time.

Here, if the difference between the code rates of the PN signals on the transmitting and receiving sides is sufficiently small, that is, if the K factor is sufficiently large, the code sequence of the reflected wave which is the same as the code sequence from which the correlation waveform is obtained in the direct wave is obtained. , The code sequence of the receiving side PN after the delay time coincides with the start position thereof. Therefore, at this point delayed by the delay time from the direct wave, a correlation waveform of the delayed wave is obtained.

The time resolution for detecting the delay time is the case where the delayed wave correlation waveform is detected in the code sequence next to the direct wave correlation waveform. = 1/30 Mbps = 33 ns.
This is 10 m when converted into a distance using the propagation speed of radio waves (300 m / μs). Therefore, when it is desired to increase the delay resolution, the code speed of the PN signal should be increased. However, the code rate of the PN signal in the method of measuring a delayed wave as described above depends on the R
Limited by the frequency of the F or IF signal.

The reason is that, in this case, BPSK modulation is applied to the RF or IF signal by the code string of the PN signal. FIG. 9 is a diagram showing BPSK modulation.

As shown in FIG. 9, the PN
When the sign changes between "1" and "0", the phase of the RF signal is inverted and becomes a modulated signal. Therefore, when producing such a modulated signal, it is understood that the frequency of the RF (or IF) signal must be 3 to 5 times higher than the code rate of the PN signal.

An apparatus for measuring a multipath delay wave, that is, a multipath delay spread measuring apparatus is constructed by using the above-described techniques such as spread spectrum, sliding correlation, and BPSK modulation. FIG. 2 is a configuration diagram illustrating a receiving unit of the path delay spread measuring device.

In FIG. 10, the RF means that the RF signal of about 2 GHz shown in FIGS.
This figure shows a reception signal RF obtained by receiving a transmitted signal which is spread by a PN signal of 0.01 Mbps and received by an antenna 59.

In the receiving section of the multipath delay spread measuring apparatus, the received signal RF and the local oscillation signal LO, which are spread in spectrum, are input to the mixer 51 and converted into a 140 MHz intermediate frequency signal IFa.

On the other hand, the 30 Mbps PN signal output from the PN signal generator 60 and the 140 MHz intermediate frequency signal IFb are BPSK-modulated in the mixer 52 and output as the intermediate frequency signal IFc.

The intermediate frequency signal IFc is further supplied to the phase shifter 5
At 3, it is decomposed into an in-phase component and a quadrature component, and input to the mixer 54 and the mixer 55, respectively. On the other hand, the intermediate frequency signal IFa from the received signal RF is also
Are input to the mixer 55, and the mixers 54 and 55 perform spectrum despreading, and at the same time, extract a correlation waveform.

Outputs from the mixers 54 and 55 via the low-pass filters 56 and 57 are an in-phase component correlation waveform I and a quadrature component correlation waveform Q, respectively. These I and Q correlation waveforms are input to a calculator 58. . In the arithmetic unit 58, the amplitude absolute value E (= SQRT (I ² + Q
² )) The logarithm operation value is calculated and extracted as amplitude information logE.

Here, when the received signal R includes a delayed wave such as a reflected wave, each output is as shown in FIG. FIG. 11 is an explanatory diagram showing each correlation waveform extracted from the conventional multipath delay spread measuring device and calculation of phase information.

FIG. 11A shows an in-phase component correlation waveform I, a quadrature component correlation waveform Q, and an amplitude absolute value E of a correlation waveform when a direct wave, a first delay wave, and a second delay wave are included. Is shown. Here, I1, Q1 and E1 are each correlation waveform of the direct wave, I2, Q2 and E2 are each correlation waveform of the first delay wave,
I3, Q3, and E3 are correlation waveforms of the second delayed wave.

The phase information (phase angle θ) of each correlation waveform can be obtained from the I and Q correlation waveforms. FIG.
(B) shows the phase angle θ of each correlation waveform on the I and Q planes.
Is shown. That is, the phase angle θ is calculated by taking the arc tangent of the I / Q ratio.

[0031]

According to the conventional multipath delay spread measuring apparatus described above, FIG.
The delay time can be calculated from the output result of (a), and the relative intensity ratio between the delayed wave and the delayed wave can also be calculated.

However, in the digital mobile communication, in order to prevent the occurrence of bit errors as described above,
Various conditions must be set with an accuracy higher than that of analog mobile communication, and for that purpose, more accurate measurement results are required.

For example, in digital mobile communication, FIG.
As shown in (a), T is a method of transmitting and receiving a plurality of communication channels in one carrier frequency in a time-division manner.
In many cases, DMA communication is performed.

In this method, when a strong reflected wave (delayed wave) is generated, the fundamental wave (direct wave) is affected as shown in FIG. 12B (the hatched portion of the fundamental wave in the figure). Is the part interfered by the reflected wave), and the communication is interrupted.

Therefore, how much multiplexing occurs in a certain area is checked in advance, and the absolute intensity value of the delayed wave is not the relative intensity ratio to the direct wave but an accurate absolute intensity value. It is necessary to perform measurement at a position on a proper time axis.

However, in the conventional multipath delay spread measuring apparatus shown in FIG. 10, for example, the amplitude information logE cannot be used as the absolute reception level because of the temperature characteristics and output characteristics of the analog elements constituting the circuit. . That is, these outputs need to be calibrated, and the absolute intensity value of the detected correlation waveform cannot be measured accurately under the current condition.

In addition, in the apparatus shown in FIG. 10, in particular, in the two mixers 54 and 55 used for the reverse diffusion, the output drifts due to the difference in the temperature characteristic of the forward voltage of the diode inside the mixer, and the output drifts due to the temperature change. There is also a problem that a DC drift of the IQ signal occurs and the absolute value levels of the amplitude information and the phase information output become inaccurate.

The present invention has been made in view of such circumstances, and is intended to provide an apparatus for measuring the transmission state of a signal transmission system transmitted via a multipath using spread spectrum, and to provide a direct wave of a transmission signal. It is another object of the present invention to provide a multipath delay spread measuring device capable of outputting an accurate absolute value of each reception level of a delay wave at the time position.

[0039]

According to a first aspect of the present invention, there is provided an apparatus for measuring a delay wave by multipath of a radio wave propagation path in digital communication. Spread spectrum R modulated by
A signal receiving unit for receiving the F signal, a PN signal generating unit for generating a receiving PN signal in the same sequence as the PN code, and a receiving PN
A mixer for mixing a signal and a spread spectrum RF signal received by a signal receiving unit, despreading by sliding correlation, and extracting a correlation waveform signal, and an amplitude information calculating means for outputting an amplitude information signal by performing an operation on the correlation waveform signal When,
Temperature measuring means for measuring the temperature in the receiving unit main body of the measuring device including at least the mixer and the amplitude information calculating means, and the absolute value of the reception level in the signal receiving unit corresponding to the temperature and the amplitude information signal in the receiving unit main body A calibration data storage unit for storing the temperature and amplitude information signals in the receiving unit body, and a signal reception unit based on the input data and the calibration data read from the calibration data storage unit. And a calibration processing unit for calculating and outputting the absolute value of the reception level in the multipath delay spread measurement apparatus.

According to a second aspect of the present invention, there is provided an apparatus for measuring a delay wave caused by multipath of a radio wave propagation path in digital mobile communication, wherein a spread spectrum RF signal obtained by modulating a first RF signal with a PN code is used. A signal receiving unit for receiving, and a PN for generating a receiving-side PN signal in the same series as the PN code
A signal generating unit, a first mixer that mixes the spread spectrum RF signal received by the signal receiving unit and the receiving-side PN signal, and despreads by sliding correlation, and a second mixer that outputs a second signal based on the output of the first mixer. A band-pass filter for extracting an RF signal, a first signal generator for generating a local oscillation signal, and a second mixer for mixing the second RF signal and the local oscillation signal and outputting a first intermediate frequency signal A DC component removing unit that removes a DC component of the first intermediate frequency signal, a logarithmic amplifier that outputs an amplitude information signal and a limiter signal from an output of the DC component removing unit, and a first intermediate frequency signal. A second signal generator for generating a second intermediate frequency signal having the same frequency;
A phase detector that outputs phase information of a second RF signal from the limiter signal and the second intermediate frequency signal, a temperature measuring unit that measures a temperature in a receiving unit main body of a measuring device including at least a logarithmic amplifier, and a receiving unit A calibration data storage unit that stores the absolute value of the reception level in the signal receiving unit corresponding to the temperature and amplitude information signal in the main body as calibration data, and a temperature and amplitude information signal in the receiving unit body are input. A multipath delay spread measurement apparatus comprising: a calibration processing unit that calculates an absolute value of a reception level in a signal receiving unit based on input data and calibration data read from a calibration data storage unit and outputs the calculated absolute value.

[0041]

Accordingly, in the multipath delay spread measuring apparatus according to the first aspect of the present invention, the signal receiving section receives the spread spectrum RF signal obtained by modulating the RF signal with the PN code.

Next, the PN signal generating section generates a receiving PN signal in the same series as the PN code. Further, the signal including the PN signal on the receiving side and the spread spectrum RF signal received by the signal receiving unit are mixed by the mixer and despread by sliding correlation to extract a correlation waveform signal.

Further, an amplitude information signal is output by an operation on the correlation waveform signal by the amplitude information calculating means. The amplitude information calculating means may be, for example, a log amplifier, or, for example, a calculator for calculating from in-phase and quadrature correlation information.

On the other hand, the temperature in the receiving section main body of the measuring device including at least the mixer and the amplitude information calculating means is measured by the temperature measuring means. Further, the absolute value of the reception level in the signal receiving section corresponding to the temperature and the amplitude information signal in the receiving section main body is stored as calibration data in the calibration data storage section.

The absolute value of the reception level in the signal receiving section is calculated by the calibration processing section based on the temperature and amplitude information signal in the receiving section main body and the calibration data read from the calibration data storage section. Is output.

In the multipath delay spread measuring apparatus according to the second aspect of the present invention, the signal receiving section receives the spread spectrum RF signal obtained by modulating the first RF signal with the PN code.

The PN signal generator generates a PN signal on the receiving side that is the same as the PN code. And the first
, The spread-spectrum RF signal received by the signal receiving unit and the receiving-side PN signal are mixed, and despread by sliding correlation.

Further, a second RF signal is output from the output of the first mixer by a band-pass filter (pass band filter).
The signal is extracted. On the other hand, a local oscillation signal is generated by the first signal generation unit.

Next, the second RF signal is supplied to the second mixer.
The signal and the local oscillation signal are mixed, and a first intermediate frequency signal is output. Further, the DC component of the first intermediate frequency signal is removed by the DC component removing unit.

The logarithmic amplifier outputs an amplitude information signal and a limiter signal from the output of the DC component removing unit. On the other hand, the second signal generating section generates a second intermediate frequency signal having the same frequency as the first intermediate frequency signal.

Next, the phase detector outputs phase information of the second RF signal from the limiter signal and the second intermediate frequency signal. On the other hand, the temperature in the receiving section main body of the measuring device including at least the logarithmic amplifier is measured by the temperature measuring means.

In the calibration data storage unit, the absolute value of the reception level in the signal receiving unit corresponding to the temperature and the amplitude information signal in the receiving unit body is stored as calibration data. Then, the absolute value of the reception level in the signal receiving unit is calculated and output by the calibration processing unit based on the temperature and amplitude information signal in the receiving unit main body and the calibration data read from the calibration data storage unit. .

[0053]

Embodiments of the present invention will be described below. (First Embodiment) FIG. 1 is a block diagram showing a multipath delay spread measuring apparatus according to a first embodiment of the present invention.

This multipath delay spread measuring device comprises a transmitting section 10 and a receiving section 20. In the transmission unit 10 , for example, a 10 MHz reference signal Ref
Is output from an oscillator 11 composed of a rubidium atomic oscillator, and the reference signal Ref is a carrier signal SG of 2.2 GHz.
1 is input to a signal generator 12 for generating a 1 and a signal generator 13 . For example, 1 output from the signal generator 13
The signal SG2 of 50.05 MHz is supplied to the PN signal generator 14.
9 with a code rate of 150.05 Mbps
It is output as a stage M series PN signal PN1.

Then, the carrier signal SG1 and the PN signal P
N1 is spread spectrum in mixer 15 and BPSK
The modulated transmission signal RF is output from the transmission antenna 17.

On the other hand, the receiving section 20 includes a receiving antenna 21
, An oscillator 22, a first signal generator 23, a PN signal generator 24, a first mixer 25, a band-pass filter 26, a second signal generator 27, and a second mixer 28
, A band-pass filter 29, a DC component removing unit 30,
Logarithmic amplifier 31, third signal generator 32, phase detector 33, A / D converter 41, temperature sensor 42, calibration data storage unit 43, calibration data processing unit 44, data display unit 45.

Also, the transmitting unit 10 and the receiving unit 20 have the configuration shown in FIG.
Is provided with a measurement terminal and a switch (not shown) for acquiring each calibration data described later. The receiving antenna 21
The transmission signal is multiplexed by a shield, a reflector, or the like on the way, and the transmission signal transmitted through the multipath is received as a reception signal RF.

The oscillator 22 comprises a rubidium atomic oscillator and outputs a 10 MHz reference signal Ref. The first signal generator 23 outputs a signal SG3 of 150 MHz based on the reference signal Ref output from the oscillator 22.

The PN signal generator 24 has a code rate of 150 based on the signal SG3 output from the first signal generator 23.
An Mbps PN signal PN2 is output. Here, this P
The N signal PN2 is the PN used for the spread spectrum in the transmitter 10 except that the code rate is slightly lower.
It is the same as the signal PN1 and has the same code string.

The first mixer 25 mixes the received signal RF received by the antenna 21 with the PN signal PN2 output from the PN signal generator 24, despreads the spectrum by sliding correlation, and filters the bandpass filter 26. Then, a correlation waveform RF1 is output. At this time, the K factor is K = 150 / (150.05-150) = 300
0.

The second signal generator 27 outputs, for example, 2189. based on the reference signal Ref output from the oscillator 22.
A local oscillation signal LO of 3 MHz is output. The second mixer 28 mixes the correlation waveform RF1 output from the first mixer 25 and passed through the band-pass filter 26 with the local oscillation signal LO output from the second signal generator 27,
For example, it outputs a first intermediate frequency signal IF1 of 10.7 MHz. This enables handling with a logarithmic amplifier or the like.

The band-pass filter 29 band-limits the output value of the second mixer 28 and outputs it as a 10.7 MHz first intermediate frequency signal IF1. DC component removing unit 30
Is composed of a capacitor 30a, removes the DC component of the first intermediate frequency signal IF1, and outputs the signal. Therefore, even if a DC drift has occurred up to this point, the DC component is removed from the output value of the DC component removing unit 30.

The logarithmic amplifier 31 performs envelope detection on the first intermediate frequency signal IF1 output from the DC component removing unit 30, performs logarithmic conversion on the detected correlation waveform, and outputs the result as amplitude information logE.

The logarithmic amplifier 31 is provided with a limiter output section 31a. The limiter output unit 31a
The input first intermediate frequency signal IF1 is output as a limiter output signal lim having a constant amplitude. This limiter output signal lim is converted into a wave of constant amplitude in the correlation detection range regardless of the envelope shape in a portion where the correlation waveform is detected, and becomes a noise of constant amplitude in a portion where the correlation waveform is not detected. .

The third signal generator 32 outputs a 10.7 MHz second intermediate frequency signal IF2 based on the reference signal Ref output from the oscillator 22. Phase detector 3
Reference numeral 3 denotes a 90 ° phase shifter 34, an in-phase mixer 35, a quadrature-phase mixer 36, and a calculator 37.

The 90 ° phase shifter 34 is connected to the third signal generator 3
2 is decomposed into an in-phase component and a quadrature component, and the in-phase intermediate frequency signal I
F0 ° and the quadrature intermediate frequency signal IF90 ° are output.

The in-phase mixer 35 cooperates with a low-pass filter (not shown) provided behind the same-phase mixer 35, and outputs the limiter output signal lim output from the limiter output unit 31a and the 90 ° phase shifter 34. In-phase intermediate frequency signal I
The average value of the product of F0 ° is calculated, and in-phase information cos θ on the correlation waveform is output.

The quadrature-phase mixer 36 cooperates with a low-pass filter (not shown) provided behind the quadrature-phase mixer 36 to output a limiter output signal lim output from the limiter output unit 31a.
And the quadrature intermediate frequency signal IF 90 ° output from the 90 ° phase shifter 34 to calculate the average value of the product, and output quadrature phase information sin θ regarding the correlation waveform.

The arithmetic unit 37 outputs the in-phase information cos θ output from the in-phase mixer 35 and the quadrature-phase mixer 3
The phase information θ is calculated from the arc tangent of the ratio to the quadrature phase information sin θ output from 6 and output.

The A / D converter 41 converts the amplitude information logE output from the logarithmic amplifier 31 into a digital quantity.
The temperature sensor 42 measures and outputs the internal temperature of the receiving unit 20. The output of the temperature sensor 42 is provided so that the temperature of the logarithmic amplifier 31 is reflected in particular.

The calibration data storage unit 43 is composed of an EEPROM and stores the data of the reception level of the reception signal RF with respect to the output of the amplitude information logE shown in FIG. FIG. 2 is a graph showing the absolute reception level (dBm) of the reception signal RF with respect to the amplitude information logE voltage value (V).

The data shown in FIG. 2 shows the absolute reception level (dB) of the reception signal RF with respect to the amplitude information logE voltage value (V) from the logarithmic amplifier 31 at each temperature in the reception unit 20.
m), and what is actually stored in the calibration data storage unit 43 is each measurement point on the graph.

The calibration data is measured as described below. FIG. 3 is a diagram illustrating a connection configuration between the transmission unit 10, the reception unit 20, and each measurement device during calibration data measurement.

In FIG. 3, the output of the mixer 15 is input to the attenuator 46 from the measuring terminal P1. In the attenuator 46, the transmission signal RF from the mixer 15 is adjusted to a required level and then output. The switch SW2 is connected to the output terminal of the attenuator 46.
The other end is connected to the measuring terminal P3 of the receiving unit 20, and the other end is connected to the wattmeter 47.

The transmission signal RF adjusted to the required level and output from the attenuator 46 is connected to the power meter 47 by the switch SW2, and its signal output is measured as the reception level (dBm) of the reception signal RF. Then, the temperature setting described later is performed, the switch SW2 is connected to the measuring terminal P3 of the receiving unit 20, and the signal output is changed to the received signal RF.
Is input to the receiving unit 20 as the receiving level of

On the other hand, the PN signal generator 14 in the transmitting section 10
Is output via the measuring terminal P2, and this output signal is input to the receiving unit 20 via the signal line 1 and the measuring terminal P4. A switch SW1 for switching between the PN signal PN1 from the measuring terminal P4 and the PN signal PN2 from the PN signal generator 24 and inputting the PN signal PN2 to the first mixer 25 is provided inside the receiving unit 20. .

When measuring the calibration data, the measuring terminals P2 and
A signal line 1 is provided between the measurement terminals P4, and a switch SW
1 is switched so that the PN signal PN1 from the measurement terminal P4 is input to the first mixer 25.

That is, if a normal signal is input to obtain the calibration data of the receiving unit 20, no output can be obtained.
Only when the above-described configuration is provided, calibration data measurement can be performed.

According to each signal input, the logarithmic amplifier 31 outputs the amplitude information logE voltage value (V). At this time, the receiving unit 20 must be set to the measured temperature.

That is, the temperature inside the receiving unit 20 is adjusted by a temperature heating / cooling unit (not shown). The output of the temperature sensor 42 is supplied to the receiving unit 20 via the measuring terminal P5.
It is input to the temperature display 49 connected outside.

When the temperature in the receiving section 20 indicated by the temperature display device 49 reaches the temperature at which the calibration data is obtained, the power meter 47
, Ie, the absolute reception level (dB) of the reception signal RF.
m) is measured. Then, the switch SW2 is switched, and the amplitude information logE voltage value (V) is read from the logarithmic amplifier 31 by the voltmeter 48 connected to the outside of the receiving unit 20 via the measuring terminal P6.

Hereinafter, the calibration condition shown in FIG. 2 is measured by changing the temperature condition and the output condition in the same procedure. The data stored in the calibration data storage unit 43 is the calibration data point under each condition obtained in this manner. In this calibration measurement, the PN signal PN1 input to the first mixer 25 is transmitted by the transmission unit. At 10, the transmission signal RF
Signal PN1 used to spread the spectrum of
Since the parameters such as the code rate and the phase necessary for extracting the correlation waveform at the time of despreading match, the correlation waveform can be reliably extracted, and the level calibration measurement can be reliably performed.

In FIG. 1, the calibration data processing unit 44 has amplitude information logE output from the A / D converter 41.
And the internal temperature of the receiver 20 measured by the temperature sensor 42.

The calibration data processing unit 44 reads out the measured calibration data from the calibration data storage unit 43, and calculates the absolute value level of the received signal RF based on the amplitude information logE, the internal temperature of the receiver 20, and the calibration data. . Also,
The calibration data processing unit 44 receives the input amplitude information log
E, When the internal temperature of the receiver 20 does not match the calibration data points, linear interpolation is performed between the calibration data points to calculate the absolute value level of the reception signal RF.

The data display unit 45 is provided with the calibration data processing unit 4
The absolute reception level of the reception signal RF calculated in step 4 is displayed for each of the direct wave and each delay wave in the amplitude information logE. Further, for the direct wave indicating the absolute reception level and each delayed wave, the intensity ratio between the direct wave and the delayed wave, the delay time, and the phase information θ output from the arithmetic unit 37,
Displays the phase difference, etc.

The amplitude information calculating means according to claim 1 is constituted by a logarithmic amplifier 31, and the temperature measuring means is constituted by a temperature sensor 42. Further, the first signal generator according to claim 2 is constituted by, for example, a second signal generator 27, and the second signal generator is constituted by, for example, a third signal generator 32. ing.

Next, the operation of the multipath delay spread measuring apparatus according to the present embodiment having the above configuration will be described. First, in the transmission unit 10, the carrier signal S
The G1 and the PN signal PN1 are BPSK-modulated, for example, a spread spectrum signal having a center frequency of 2200 MHz and output as a transmission signal RF.

Next, the transmission signal RF is multiplexed by reflection or the like during signal propagation, and is received as a reception signal RF by the receiving unit 20 via a multipath. Therefore, the received signal RF includes a direct wave whose output from the transmitting unit 10 is directly received and a delayed wave such as a reflected wave which is reflected on the way and is received after being delayed from the direct wave.

FIG. 4 shows an operation in which the received signal RF (RF input signal) is output as a log E waveform as amplitude information.
This will be described with reference to (a) and (b). FIG. 4A is an explanatory diagram showing a process until the reception signal RF is converted into the first intermediate frequency IF1.

First, the received signal RF (RF input signal) is
The signal is a spread spectrum signal having a center frequency of 2200 MHz.
, Despread and extract the correlation waveform RF1. In normal despreading, that is, the PN signals PN1 and PN
If 2 is the same, the signal is demodulated over the entire time range, but in the case of the present embodiment, the sliding waveform obtained by slightly changing the code rate of both PN signals is used. It consists of correlation values for both code strings.

The correlation waveform RF1 extracted at this time is shown in FIG. In this example, the direct wave D
W and a delayed wave RW delayed therefrom are shown. Next, in FIG. 4A, the correlation waveform RF1 that has passed through the band-pass filter 26 is a signal of 2200 MHz and cannot be handled by the logarithmic amplifier 31 as it is, so that it is output from the second signal generator 27. Down-converted by the local oscillation signal LO. As a result, the correlation waveform becomes a first intermediate frequency signal IF1 having a frequency of 10.7 MHz.

FIG. 4B shows the first intermediate frequency signal IF1 at this time. Then, the DC component of the first intermediate frequency signal IF1 is removed by the capacitor 30a of the DC component removing unit 30, and the logarithmic amplifier 31 outputs the first intermediate frequency signal IF1 as a logE waveform having amplitude information as shown in FIG. .

The amplitude information logE is supplied to the A / D converter 4
A / D conversion is performed at 1 and input to the calibration processing unit 44.
The amplitude information logE converted into the digital amount is converted into an absolute reception level in the calibration processing unit 44 based on the calibration data read from the calibration data storage unit 43. If the temperature condition and the logE output voltage condition at this time match the conditions of the calibration data points stored in the calibration data storage unit 43, the conversion can be performed as it is, but in fact, these conditions do match. Often not.

If they do not match, interpolation is performed using the preceding and succeeding calibration data points. FIG. 5 is a diagram illustrating interpolation using calibration data points. As shown in FIG. 5, the internal temperature of the receiving unit 20 is 55 ° C., and the calibration data points are spaced at 10 ° C. intervals.
That is, when the data has only 50 ° C. and 60 ° C., for example, the calibration data corresponding to the amplitude information logE = 3.55 V is calculated by performing linear interpolation as shown in the equation (1).

Calibration data (55 ° C.) = (53.6-53.1) / 10 (55-50) +53.1 (1) = 53.35 When the logE output voltage is 3.55 V, the reception level is 53.35 dBm as it is. And it is sufficient.

However, since the calibration data points are at 0.05 V intervals for the log E output voltage,
When the gE output voltage takes a value between 3.55 V and 3.60 V, the temperature is set to 55 ° C. in the same manner as calculated by the equation (1).
3.60V calibration data at is calculated. And
Based on the 3.55 V calibration data at 55 ° C. and the 3.60 V calibration data at 55 ° C., linear interpolation similar to the equation (1) is performed to calculate the reception level for the logE output voltage.

In this way, the amplitude information logE is converted into a reception level as an absolute level displayed in a decibel and input to the data display section 45. On the other hand, the first intermediate frequency signal IF <b> 1 is converted into a limiter output lim by a limiter output unit 31 a in the logarithmic amplifier 31 and input to the phase detector 33.

The second intermediate frequency signal IF2 output from the third signal generator is decomposed by the 90 ° phase shifter 34 into an in-phase intermediate frequency signal IF0 ° and a quadrature intermediate frequency signal IF90 °. .

Then, the in-phase mixer 35 and the quadrature-phase mixer 36 calculate the average value of the products of the limiter output lim and the in-phase intermediate frequency signal IF 0 °, and the limiter output lim and the quadrature intermediate frequency signal IF 90 °, respectively.
In-phase phase information cos θ and quadrature phase information sin θ are output from in-phase mixer 35 and quadrature-phase mixer 36, respectively.

Further, the computing unit 37 calculates the phase angle θ from the combination of the in-phase information cos θ and the quadrature information sin θ. That is, θ = tan ⁻¹ (sin θ /
cos θ). Further, the in-phase waveform output I is represented by I =
The quadrature waveform output Q
Can be calculated by Q = Ecos θ.

The phase angle θ is stored in the data display unit 4
5 and in the data display section,
Using the reception level for the gE output voltage, the direct wave D
The delay time, intensity ratio, phase difference, and the like between W and the delayed wave RW are calculated and displayed.

Next, the calculation of the delay time, the intensity ratio, and the phase difference between the direct wave DW and the delayed wave RW will be described with reference to FIG. In FIG. 4B, the direct wave DW is detected at time t1, and subsequently, the delayed wave RW is detected at time t2.

Here, the delay time of the delayed wave RW with respect to the direct wave DW is calculated from t2−t1. Also, the direct wave D
The intensity ratio between W and the delayed wave RW is calculated by (absolute reception level corresponding to log E2) / (absolute reception level corresponding to log E1). Further, the direct wave DW and the delayed wave RW
The phase difference from 1 is calculated as θ2−θ1.

Since the intensity ratio at this time is calculated based on the absolute reception level, it is not a relative value but an absolute value. Then, the data display unit 45 displays and outputs the delay time, the intensity ratio, and the phase difference between the direct wave DW and the delayed wave RW.

The data display unit 45 is configured to accept a display instruction input from the outside. For example, the operator can specify a specific delay wave R displayed on the data display unit 45 by the operator.
When W 'is designated, the delay time, intensity ratio, and phase difference between the delayed wave RW' and the direct wave DW are calculated and displayed.

Further, it is possible to set and input the calculation display conditions in advance in the data display section 45, and to automatically display each information for the delay wave exceeding the set intensity ratio condition and the delay time condition. You can also.

As described above, in the multipath delay spread measuring apparatus according to the present embodiment, the spectrum is despread by the first mixer 25, the correlated waveform output is converted into the amplitude information logE by the logarithmic amplifier 31, and further received. Since the temperature inside the unit 20 is measured and the logE output is calibrated with the calibration data including the temperature characteristic, the apparatus for measuring the transmission state of the signal transmission system transmitted through the multipath using the spread spectrum is used. Accordingly, it is possible to output an accurate absolute value of each reception level of the direct wave and the delay wave of the transmission signal at the position on the time axis.

Therefore, it is possible to set various conditions for communication such as determination of a service area with high certainty, and to prevent bit errors from occurring in digital mobile communication in advance.

Further, as described above, the multipath delay spread measuring apparatus according to the present embodiment performs despreading by the first mixer 25, does not divide the correlation waveform output into in-phase components, and outputs a DC component. The removal unit 30 uses the first and second mixers 25 and 28 to change D due to a temperature change.
After removing the influence of the C drift, the logarithmic amplifier 31 outputs the amplitude information logE.
The influence of the temperature change of the log E output can be removed, and the direct wave DW, the delayed wave RW, and the intensity ratio can be calculated with higher accuracy.

Therefore, unlike the conventional apparatus, the minimum reception level does not deteriorate, and the measurement dynamic range can be increased. Further, as described above, the multipath delay spread measuring apparatus according to the present embodiment mixes the PN signal PN2 in the first mixer, that is, the first mixer 25, and extracts the correlation waveform from the BPSK-modulated received signal RF. With this configuration, when the delay resolution is changed, it is not necessary to change the design of the entire circuit of the receiving unit 20, the first signal generator 23 is changed, and the code rate of the PN signal PN2 from the PN signal generator 24 is changed. , The delay resolution can be easily changed.

In the present embodiment, the use of the present invention for the design of a service area of mobile communication has been described in mind. However, the use of the present invention is not limited to this. It can also be used to develop simulation models for service area design. Further, according to the present invention, it is possible to provide a measuring device having a high delay resolution and capable of calculating a high-accuracy intensity ratio, so that it can be used for grasping and measuring propagation delay characteristics of an indoor wireless LAN system in a building or an underground shopping mall. Can be used.

In this embodiment, the limiter output section 31a is part of the function of the logarithmic amplifier 31 (log amplifier). However, the configuration of the present invention is not limited to this.
The limiter output section 31a may be configured separately from the logarithmic amplifier 31, for example, in a discrete manner. (Second Embodiment) FIG. 6 is a block diagram showing a multipath delay spread measuring apparatus according to a second embodiment of the present invention, and the same parts as those of the conventional apparatus shown in FIG. Detailed description is omitted.

The receiving section of the multipath delay spread measuring apparatus shown in FIG. 6 is the same as the multipath delay spread measuring apparatus shown in FIG. 10 except for the temperature sensor 42, the calibration data storage section 43, the calibration processing section 44, and the data display section 45. It is configured and operates similarly to the receiving section of the delay spread measuring device. That is, the output from the arithmetic unit 58 is the amplitude information logE converted for digital use.

On the other hand, the temperature sensor 42, the calibration data storage unit 43, the calibration processing unit 44, and the data display unit 45
It is configured and operates in the same manner as the first embodiment, calibrates the amplitude information logE output from the arithmetic unit 58, and converts it into an absolute reception level.

The calculation section calculates the correlation angle θ from the in-phase component correlation waveform I and the quadrature component correlation waveform Q, and inputs the correlation angle θ to the data display section 45. The display of this section is shown in FIG.
Has been omitted.

The amplitude information calculating means according to claim 1 is constituted by a logarithmic amplifier 31, and the temperature measuring means is constituted by a temperature sensor. As described above, the multipath delay spread measuring apparatus according to the present embodiment performs spectrum despreading by the mixers 54 and 55, converts the in-phase and quadrature-phase correlation waveform outputs into the amplitude information logE by the calculator 58, and Since the temperature inside the receiving unit 20 is measured and the logE output is calibrated with the calibration data including the temperature characteristic, the transmission state of the signal transmission system transmitted via the multipath is measured using spread spectrum. In this case, it is possible to output an accurate absolute value of each reception level of the direct wave and the delay wave of the transmission signal at the position on the time axis.

Therefore, it is possible to set various conditions for communication such as determination of a service area with high certainty, and to prevent bit errors from occurring in digital mobile communication in advance.

This embodiment can be easily realized by modifying a conventional multipath delay spread measuring apparatus. The present invention is not limited to the above embodiments, but can be variously modified without departing from the gist thereof.

[0119]

As described above in detail, according to the present invention, the amplitude information logE is calibrated by the calibration data including the temperature characteristic, so that the transmission state of the signal transmission system transmitted via the multipath is changed. In an apparatus for measuring using spread spectrum, it is possible to provide a multipath delay spread measuring apparatus capable of outputting an accurate absolute value of each reception level of a direct wave and a delayed wave of a transmission signal at that time position.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a multipath delay spread measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a graph showing an absolute reception level of a reception signal with respect to an amplitude information voltage value in the multipath delay spread measurement apparatus of the embodiment.

FIG. 3 is a diagram illustrating a connection configuration between a transmission unit, a reception unit, and each measurement device when measuring calibration data in the multipath delay spread measurement apparatus according to the embodiment.

FIG. 4 is an explanatory diagram showing a process until amplitude information is extracted from a received signal in the multipath delay spread measuring apparatus of the embodiment.

FIG. 5 is an explanatory diagram of interpolation using calibration data points in the multipath delay spread measurement device of the embodiment.

FIG. 6 is a configuration diagram showing a multipath delay spread measuring apparatus according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram of spectrum spreading and despreading of a transmission signal.

FIG. 8 is an explanatory diagram of a sliding correlation.

FIG. 9 is an explanatory diagram of BPSK modulation.

FIG. 10 is a configuration diagram showing a receiving unit of a conventional multipath delay spread measuring device.

FIG. 11 is an explanatory diagram showing correlation waveforms extracted from a conventional multipath delay spread measurement device and phase information calculation.

FIG. 12 is an explanatory diagram of interference caused by TDMA communication and a delayed wave.

[Explanation of symbols]

10: transmission unit, 20: reception unit, 21: reception antenna, 2
2 oscillator, 23 first signal generator, 24 PN signal generator, 25 first mixer, 26 bandpass filter, 27 second signal generator, 28 second mixer, 2
9 bandpass filter, 30 DC removing unit, 31
Logarithmic amplifier, 32: third signal generator, 33: phase detector, 34: 90 ° phase shifter, 35: in-phase mixer, 36
.., Quadrature phase mixer, 41, A / D converter, 42, temperature sensor, 43, calibration data storage unit, 44, calibration data processing unit, 45, data display unit.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-9-8767 (JP, A) JP-A-4-242332 (JP, A) JP-A-1-154640 (JP, A) JP-A-58-1983 34370 (JP, A) JP-A-6-148246 (JP, A) JP-A-2-174324 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 1 / 69-1 / 713 H04J 13/00-13/06

Claims (2)

(57) [Claims] An apparatus for measuring a delay wave by multipath of a radio wave propagation path in digital mobile communication, comprising: a signal receiving unit (21, 59) for receiving a spread spectrum RF signal obtained by modulating an RF signal with a PN code; A PN that generates a receiving-side PN signal in the same series as the PN code
A signal generator (24, 60); a mixer (25, 60) that mixes the reception-side PN signal and the spread spectrum RF signal received by the signal receiver, performs despreading by sliding correlation, and extracts a correlation waveform signal.
54, 55); amplitude information calculating means (31, 58) for outputting an amplitude information signal by calculation on the correlation waveform signal; and a receiving unit main body of the measuring apparatus including at least the mixer and the amplitude information calculating means. A temperature measuring means (42) for measuring the temperature of the receiver, and a calibration data storage unit for storing, as calibration data, an absolute value of a reception level in the signal receiving unit corresponding to the temperature in the receiving unit body and the amplitude information signal. 43), a temperature in the receiving unit main body and the amplitude information signal are input, and a reception level of the signal receiving unit in the signal receiving unit is determined based on the input data and the calibration data read from the calibration data storage unit. A multipath delay spread measuring device, comprising: a calibration processing unit (44) for calculating and outputting an absolute value. 2. An apparatus for measuring a delay wave due to multipath of a radio wave propagation path in digital mobile communication, comprising: a signal receiving unit (21) for receiving a spread spectrum RF signal obtained by modulating a first RF signal with a PN code; A PN that generates a receiving PN signal in the same series as the PN code.
A signal generating unit (24); a first mixer (25) for mixing the spread spectrum RF signal received by the signal receiving unit and the receiving-side PN signal and despreading by sliding correlation; A band-pass filter (26) for extracting a second RF signal from an output of the mixer; a first signal generator (27) for generating a local oscillation signal; and a second RF signal and the local oscillation signal. A second mixer (28) for mixing and outputting a first intermediate frequency signal
A DC component removing unit (30) for removing a DC component of the first intermediate frequency signal; a logarithmic amplifier (31) for outputting an amplitude information signal and a limiter signal from an output of the DC component removing unit; A second signal generator (32) for generating a second intermediate frequency signal having the same frequency as the first intermediate frequency signal; and a phase of the second RF signal from the limiter signal and the second intermediate frequency signal. Phase detector that outputs information (3
3), a temperature measuring means (42) for measuring a temperature in a receiving unit main body of the measuring device including at least the logarithmic amplifier, and the signal reception corresponding to the temperature in the receiving unit main unit and the amplitude information signal. A calibration data storage unit (43) for storing the absolute value of the reception level in the unit as calibration data; a temperature in the receiving unit main body and the amplitude information signal; and input data of the input data and the calibration data storage unit. A multipath delay spread measuring device, comprising: a calibration processing unit (44) that calculates an absolute value of a reception level in the signal receiving unit based on the read calibration data and outputs the calculated absolute value.