JPH0621864A - Radio environment measuring device - Google Patents

Abstract

PURPOSE:To easily acquire inspection data when the environment for radio wave propagation is inspected. CONSTITUTION:A transmitter system 12 at a radio equipment station 1 has a dispersive delay line DDL, a receiver system 13 has a limit amplifier LIM and the DDL, a repeater 2 is provided with the LIM, the radio station 1 generates the same signal as a radar radio wave and applies linear frequency modulation and spactrum diffusion processing to form an expanded pulse signal, the signal is sent to the repeater 2 as a pulse signal, the repeater 2 implements frequency conversion of a received radio wave by spectrum inverter and relayed and sent to the radio station 1, the radio station 1 uses the same local oscillator as the repeater 2 to convert the frequency and a reception pulse is compressed by a converse pulse compression radar function to that at the time of transmission to concentrate reflected energy spread in terms of frequency and timewise and the radio wave propagation of various propagation paths is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave environment measuring apparatus for measuring characteristics of a radio wave propagation path. In recent years, mobile phones have been remarkably developed in the field of mobile radio, but with the spread thereof and the complexity of the system, in the radio wave propagation between radio devices in the usage environment, especially from direct waves between radio devices and structures. The important issue is how reflected waves and other extraneous radio waves propagate.

In the installation of fixed stations for mobile radios, there is always a demand for investigation of propagation paths of radio waves, investigation of radio wave usage conditions, and the like. In particular, it is important to set up a radio wave environment in which a mobile phone or the like is not disconnected. The purpose of the present invention is to investigate the environment of radio wave propagation in such an urban area, easily enable the acquisition of survey data on various emitted radio waves and their arrival, and display them in an easy-to-understand manner. An object of the present invention is to provide a radio environment measuring device for use in installing a transmitting station or improving an existing station.

[0003]

2. Description of the Related Art Conventionally, when radio wave propagation is investigated by a radio wave environment measuring device, radio waves are emitted from a fixed station, which is a radio base station, through an omnidirectional antenna, and the radio waves are received by a repeater, and the It was done in a one-way radio path that measures the distance between and the reception level. On the other hand, in urban areas, high-rise buildings are reflected objects of radio waves, so when there are many reflected objects of these structures, the repeater side either receives the direct wave from the fixed station or the reflected wave from the reflected object. It is very difficult to identify whether or not other external waves have been received, and thus there is a problem that it is difficult to measure the radio wave environment.

In order to deal with such a problem, conventionally,
When measuring in a one-way radio path, pseudo noise with a large autocorrelation, that is, PN (pseudo n
(Oize) code is used to modulate the carrier wave and then transmitted. On the repeater side, the direct wave or the reflected wave is discriminated based on the point where the autocorrelation becomes maximum, and the modulation speed is increased to about 10 MHz. A method has been proposed in which the reflection points can be decomposed.

[0005]

In the conventional radio environment measuring apparatus as described above, there is a problem that measurement is difficult due to interference due to multipath from a reflecting object, and a radio station at a measuring point becomes large. I have a problem to do. Furthermore, in order to improve the distance resolution (distance resolution to the object),
It is necessary to shorten the range cell, which is the minimum resolution distance, in a short time, which means that the modulation speed is increased. Therefore, the required band of the radio wave is widened.

However, the increase in the required bandwidth of the required radio wave has been a problem due to restrictions on the use of the radio wave (a radio wave having an excessively wide band is difficult to obtain a license from the viewpoint of radio wave administration). Therefore, the modulation speed cannot be increased, and thus it is difficult to improve the range resolution. On the other hand, the repeater side normally receives an electric wave from a fixed station by using an omnidirectional antenna, so that it is impossible to measure the direction. In addition, when the azimuth measurement is performed using the directional antenna, there is a high possibility that the side lobe reception may be mistaken for the main lobe reception direction, and thus the azimuth measurement is difficult.

Further, the radio wave environment measuring device needs to be a device of a system capable of easily propagating the radio wave and reducing the influence of the interference wave when propagating in the air. An object of the present invention is to provide a radio wave environment measuring device that improves the distance resolution and can also accurately perform azimuth measurement.

[0008]

The present invention relates to a radio wave environment measuring apparatus for measuring a radio wave propagation environment between a radio station which is a measuring point and a repeater which is a mobile radio.
Dispersive delay line D for transmitter system 12
Having a DL and a linear frequency modulated pulse source 2-1;
The receiver system 13 has a limit amplifier LIM and a dispersive delay line, and further has a frequency converter and a limit amplifier on the repeater side, and uses a reciprocal radio path instead of a one-way radio path. On the radio station side, the same signal as the radar radio wave is generated, frequency conversion is performed by linear frequency modulation and a local oscillator, spectrum spreading is performed, and an extended pulse signal is transmitted to the repeater side, and on the repeater side 2, Spectrum inversion is performed by frequency conversion of the received radio wave, and relay retransmission is performed to the wireless station side, frequency conversion is performed at the wireless station side with the same local oscillator as the repeater side, and a linear frequency modulation wave opposite to that at the time of transmission As a result, the pulse compression radar function compresses the received pulse to concentrate the reflected energy in frequency and time, For the reflected wave by wave path difference from the station side, the delay time for each of from the time of its launch, characterized in that to perform the radio wave propagation measurements for various propagation paths.

[0009]

According to the present invention, not only a unidirectional path but also a radio wave propagation between two points for measuring radio wave propagation makes the physical distance between two points to be measured equal to each other. The propagation distance is extended to increase the propagation time to improve the distance resolution, and the change in the signal is markedly measured. In addition, directional processing is performed by sidelobe reception, and because radar-based pulse compression technology is used, the radio wave energy that propagates is diffused both in terms of frequency and time, and strong measurements are made against interference waves. It is possible to provide a measuring device capable of performing the above.

That is, in order to make the receiving direction of the antenna accurate, suppression processing by a side lobe, which will be described later, is performed on the radio station side to measure the direction. Further, the suppression of the interference wave has the problem of the conventional problem, except for the case where the propagation frequency is widened to widen the spectrum in the propagation like the spread spectrum communication and the signal frequency can be separated relatively with little interference to the propagating signal. As one countermeasure, when the interference wave is strong, the interference wave is limited by a limit amplifier or the like to suppress the interference wave energy and reduce the influence mixed in the air propagation path. Then, in a state where there is little influence, re-transmission is performed using a repeater, the influence of strong interference waves is also suppressed on the receiving side via a limit amplifier, and the signal is transmitted using a dispersive delay line (dispersive delay line). By concentrating the energy of the wave in time, line spectrum, that is, by dispersing and spreading the concentrated interference wave using the dispersive delay line in reverse, by reducing the influence of the interference wave, Perform operations to improve range resolution.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is an explanatory diagram of radio wave propagation between a wireless station as a measuring point and a mobile wireless station (repeater). As shown, there is a direct wave between the radio station and the repeater, and a reflected wave if there is a construct in between. As shown in FIG. 1, it is roughly divided into a radio station 1 having a transmitter / receiver and a repeater 2 serving as a mobile radio, which are installed in respective propagation sections of radio waves, and various propagation paths, that is, a direct wave and a reflected wave. The measurement is performed again by the transmitter / receiver at the measurement point received through the propagation path consisting of and.

FIG. 2 is an explanatory diagram of the relationship between the radio wave propagation distance (round-trip elapsed time) and the received correlation output of the wireless station 1. As shown in the figure, it can be seen that the received correlation output indicating the strength of the received signal becomes weaker as the radio wave propagation distance increases, that is, as the elapsed time elapses. This example represents the "A scope" in radar. In this way, the correlation output of the received signal with respect to the transmission signal changes according to the elapsed time (distance) from the transmission time, and it is generally the shortest propagating wave that causes the received correlation output to increase first. Is the round-trip propagation distance R ₀ of the direct wave between the wireless station and the repeater at that time (distance R ₀ ). After that, the distances R ₁ and R
_Although there is an increase in the received correlation output in Fig. ₂ , both are due to the reflected wave, and it is clear that the reflected wave has a longer propagation distance. By using this received correlation output, not only the propagation distance of the direct wave between the wireless station, which is the measurement point, and the repeater can be measured, but also the reflection point in the structure or the like can be measured.

FIG. 3 is a basic configuration diagram of the radio wave environment measuring apparatus of the present invention. In the figure, 11 is an antenna system unit, 12 is a transmitter system unit, 13 is a receiver system unit, 14 is a local transmission system unit, 15 is a signal processing system unit, and 16 is a control display system unit. Make up 1. On the other hand, the repeater 2 includes an antenna / transmission / reception shared system unit 21, a transmitter system unit 22, a receiver system unit 2
3. The frequency conversion system unit 24.

In the present invention, it is assumed that the frequency of the radio wave emitted by the own station and the time / phase of the modulation code are accurately known as in the radar device. Regarding the range resolution, in the present invention, as in the principle of the radar, since the propagation is a round-trip path, the velocity is 150 m, which is equivalent to half the speed of light.
/ Μs, and therefore the time is doubled, so that the distance resolution can be improved as compared with the one-way route.

Further, in the present invention, a so-called pulse compression / radar system is adopted, and in accordance with this pulse compression / radar system, the signal being propagated is apparently a long transmission pulse and spread on the frequency axis. After reception, the received pulse is compressed to a pulse width of several to several tens of times from the transmitted pulse to measure the distance. Note that this long-time pulse allows a large amount of energy (power × time) to be sent even if the peak power is constant. Furthermore, FM
Like a chirp pulse, the spectrum can be spread in frequency and transmitted without increasing the energy per unit frequency.

That is, according to this pulse compression / radar system, not only the radio waves are emitted, but the propagation energy is diffused both in terms of time and frequency, and the energy is dispersed within the permissible frequency band and distributed in the air. Propagate radio waves. Normal interference waves often have a line spectrum where energy is converged on the frequency axis, and such interference waves are received and limiting is performed during amplification in the receiver system to reduce unnecessary radio wave energy that has more intensity than necessary. Then, the energy is converted to an intermediate frequency and the received energy diffused by the dispersive delay line is converged, and at the same time, the energy of the line spectrum interference wave is diffused.

In the present invention, both the radio station and the repeater on the measurement point side use omnidirectional antennas, the radio wave propagation path is arbitrarily selected regardless of the directivity between them, and the data is transmitted while moving. However, when acquiring detailed data, both the wireless station and the repeater are measured by the directional antenna. FIG. 4 is a block diagram of an embodiment of an antenna system, a transmitter system, a receiver system, a local oscillator system and a distance measuring system on the radio station side of the radio wave environment measuring apparatus according to the present invention, and FIG. It is an example block diagram.
As shown in FIG. 4, the antenna of the transceiver on the radio station side, which is the measurement point, is a directional antenna (ANT2) and an omnidirectional antenna (A
NT1), except the side lobe reception, to detect by looking at the direction of the true arrival radio wave, in the direction detection, when the electric field strength of the radio wave received by the omnidirectional antenna is stronger than the directional antenna, It is determined that the directional antenna is receiving side lobes, and conversely, when the directional antenna is receiving more strongly, it is determined that the main lobe is receiving the two lobes and the side lobe suppression. (SLS) The judgment is made by forming the logic of the processing system. As described above, at the measurement point, the directional antenna and the omnidirectional antenna are used, and the function of suppressing the sidelobe reception in the directional antenna (sidelobe suppressing function, that is, SLS function) is provided, and The signal from the beam is received to prevent misrecognition of azimuth measurement.

On the other hand, the repeater-side antenna (ANT
As for 2), the omnidirectional antenna and the directional antenna (parabola) can be exchanged as needed during measurement. The repeater 2 creates a measured radio wave state in an actual use environment simply by simulating the use state like a mobile phone that moves with time. Unwanted strong line-spectrum interference waves mixed in the course of propagation are subjected to limiting to suppress energy, and then transmitted again after frequency conversion for spectrum inversion.

In FIG. 4, an antenna system 1 includes an omnidirectional antenna (ANT1) 1-1, a directional antenna (ANT2) 1-2, and directional couplers (DC) 1-3,1-6. , Received wave detector (DET) 1-4,
Sidelobe suppression processor (SLS) 1-5 and changeover switch (SW)
1-7 and circulator (CIR) 1-8. The transmitter system 2 is a high stability oscillator synthesizer 2-1, a directional coupler (DC) 2-2, a pulse switch (SW) 2-3, and a dispersive delay line (DDL) 2-4. And the filter (F
L) 2-5, mixer 2-6, filter (FL) 2-7, and amplifier
2-8 and modulator 2-9. In the present invention, the description has been made especially by providing the dispersive delay line (DDL) 2-4, but a similar effect can be obtained by a pulsed RF super oscillator capable of generating an FM chirp pulse signal equivalent to its output signal. can get.

The receiver system 3 is a limit amplifier (LIM) 3-1.
, Filter (FL) 3-2, Mixer 3-3, Dispersive Delay Line (DDL) 3-4, Filter (FL) 3-5
, Directional coupler (DC) 3-6, amplifier 3-7, received wave detector (DET) 3-8, amplifiers 3-9, 3-10, and π / 2 phase shifter (3
-11), phase detector (PD) 3-12, 3-13, and AD conversion circuit 3-
It consists of 14,3-15. In the present invention, in particular, the limit amplifier (LIM) 3-1 and the dispersive delay line are
It is characterized by having (DDL) 3-4.

The local oscillator system includes a local oscillator 4-1 and a directional coupler.
4-2, amplifiers 4-3 and 4-5, and filter 4-4. Although not shown in detail, the signal processing system 5 includes a normal moving target display (MTI) radar signal processing unit. The display system 7 is composed of a system controller (PG) 7-1 equipped with a pulse generator, a display controller 7-2 for displaying by direction / distance, and a display (DPL) 7-3.

In FIG. 5, the repeater 8 is an omnidirectional antenna (ANT3) 8-1, a circulator (CIR) 8-2, a filter (FL) 8-3, an amplifier 8-4, and a limit amplifier. (LI
M) 8-5, filter (FL) 8-6, mixer 8-7, shift oscillator 8-8, filter (FL) 8-9, amplifier 8-
10 and a filter (FL) 8-11. In the present invention,
In particular, it is characterized in that it has a limit amplifier (LIM) 8-5.

FIGS. 6A to 6H are explanatory views of the pulse compression / radar system by the linear frequency modulation system used in the present invention. First, in (a), in the transmitter system, the transmission source as shown in FIG. 4 is a stable oscillator (synthesizer or the like), and a signal from this is transmitted to the pulse switch 2-.
3 makes impulse.

Then, as shown in (b), a high-frequency pulse that can be regarded as an impulse has a wide spectrum in the vicinity of its carrier frequency, so that it can be tolerated, and a spectrum having a substantially flat amplitude in the required band ( Diffusion). (C) shows the characteristic of the dispersive delay line 2-4 (or 3-4), and shows the characteristic that the input spectrum increases the delay amount with frequency. Therefore, a signal having a high input frequency component has a large delay.

As shown in (d), the output of the dispersive delay line has a characteristic that the frequency increases with time, and such a signal is filtered by the filter 2-5.
To the required band by (g) up converter 2-6
Up to the carrier frequency by (g) filter
After selecting by 2-7, transmit amplification is performed by amplifier 2-8,
Finally, it is emitted from the antenna of the wireless station.

As shown in (e), contrary to (d), in order to obtain the characteristic that the frequency decreases with time, the radio wave from the above-mentioned radio station is received by the repeater side, and (g) the local oscillator of the radio station. Position it on the opposite side with the frequency fL of 4-1 as the center. (G) Shift spectrum at shift local 8-8 on the repeater side. Then, the signal received at the radio station side is passed through the reception filter 3-2 to the local oscillator.
The local frequency fL from 4-1 is mixed (down-converted) by the mixer 3-3 and dropped to the baseband of the original frequency band as shown in (g). In this way, the signal converted to the original frequency becomes the spectrum of (g), which is the original baseband spectrum (g) inverted, and has a signal waveform like (e). When this is passed through the dispersive delay line 3-4 shown in (f), the higher the frequency component is, the more the delay amount is given, and the longer pulse width T is compressed and the pulse is compressed as shown in (h). The width is 1 / Δf and the amplitude is √ (T · Δf). For example, if T = 10 μs and Δf = 10 MHz, it becomes as high as 10 times. In (h), the vertical axis is the one-amplitude envelope, and the horizontal axis is the time.

Since the short pulse is received at the original frequency in this manner, the amplitude is detected by the reception detector 3-8 (see FIG. 4) to obtain the reception timing, and the round trip is made with the time of emission. I know the time required for. That is, the distance to the reflection point can be known, and what kind of reflection will be performed can also be understood. The operation of the configurations of FIGS. 4 and 5 will be described below.

The radio wave emitted from the radio station reaches the repeater 8 having a frequency conversion / amplifier whose amplitude component does not saturate under the measurement conditions, where the received wave is amplified and the limiting function of the amplifier exceeds the required amplitude. Limited by 8-5. The received signal thus obtained is a stable crystal oscillator 8-8
Frequency mixing 8-7 is performed with the local oscillation signal oscillated by to shift the frequency and shift it to the opposite side around the local oscillation frequency of the transceiver. Then, the received wave shifted to the opposite side is transmitted again (see FIG. 6 (g)).

Then, it returns to the radio station side through the same route. The radio waves received at the measurement point use the round-trip route at a distance and time twice as long as the one-way route. Also, the signal received at the wireless station side is phase-detected with the original transmitter signal, and the output of the amplifier 3-10 has a 90-degree phase difference in order to avoid phase blindness with the phase detector.
Phase detection 1-4 is performed for each signal. Signal A and Signal B
Phase detection output is, (A · B · SIN ( θ a - θ b)) becomes. Since the phase detection circuit synthesizes the frequency with a mixer circuit having a non-linear circuit and takes it out, one of these circuits generates phase blind (θ _a − θ _b = 0) where the phase detection output disappears due to the reflected distance. However, in that phase blind, the receiver function is completely lost.

As a circuit for eliminating the phase blind, two phase reference signals having a phase difference of 90 degrees are prepared and mixed with the same received signal to obtain two phase detection outputs, that is, different by 90 degrees. I video signal (A ・ B ・ SIN (θ _a − θ _b )) and Q video signal (A
・ B · COS (θ _a − θ _b )) is obtained. The output is A /
It is D-converted and input to the radar signal processing circuit. In the radar signal processing circuit, for example, the I and Q video signals are squared by the high-speed multiplier circuit, and the two signals are combined (summed) into the power signal (A / B) ² to obtain the signal A. The signal that is not related to the two phases (θ _a , θ _b ) of the signal B is used, and the subsequent fast Fourier transform (FFT)
Performs processing on the frequency axis with. (That is, the signal without phase blind is used, and the power spectrum is processed by the FFT filter bank for processing). Since the FFT can perform signal processing even on a signal containing a Doppler frequency when the other party is moving (effectively separating the output with a filter bank by the FFT to obtain its output), it can be used with a moving vehicle (person). Data can be acquired even in the meantime.

In the present invention, since bidirectional measurement is performed,
Since it is possible to use a round-trip path like a radar, it becomes a radio wave passage path with improved distance resolution, and it is possible to easily clarify what kind of propagation characteristics it has. In addition, since the energy spectrum of the propagating radio wave is dispersed (spread), the energy spectrum per unit is weak, so the limit amplifier is not subject to amplitude limitation. On the other hand, the interference wave
In many cases, the spectrum converges in frequency to form a line spectrum, and these interference waves are amplitude-limited, equivalently weaken the energy relatively, and further, due to the dispersive delay line inside the receiver. , The dispersed signal wave is converged, but the line-spread interference wave is spread in the opposite direction and is not affected by the interference wave. Therefore, the influence of unnecessary interference waves can be reduced and the passage route of radio waves can be investigated and measured.

Further, since a crystal oscillator with high stability is provided as a frequency oscillation source on both the measurement side and the repeater side, the phase of the incoming radio wave obtained by reciprocating is compared with the phase at the oscillation source and the distance is accurately measured. It will also be possible to make measurements and process signals with Doppler effects. In addition, the antenna system can also suppress reception from the side lobes of directional antennas, know the direction of incoming radio waves, and in particular, it is possible to remove radio waves in undesired directions, so interference between received signals It is possible to measure less.

Since both the radio station side and the repeater side process the Doppler frequency even when they move, it is possible to measure the radio wave environment under such conditions, and the actual use of the radio wave environment is possible. It can be measured as in the situation. With the above-described configuration, the environment measurement of the measurement system is suitable for automatic data measurement and can be applied to many portable wireless devices and mobile phones.

[0034]

As described above, according to the present invention,
It is possible to improve the distance resolution and measure and acquire data, and also improve the azimuth resolution. Moreover, the influence of the interference wave can be reduced and the radio wave propagation environment of the communication path can be investigated. Moreover, since a stable crystal oscillator is built in as a phase reference, measurement can be done systematically and automatically at the point of emission of radio waves in a short time.
It can be measured very easily. It is also possible to measure while moving.

As described above, since it is possible to remove the radio wave from the azimuth which is unnecessary for the radio wave environment measurement, and since the spectrum is spread and the radio wave is propagated, the radio wave environment measuring apparatus that is strong against the interference radio wave is supplied. Therefore, it can greatly contribute to the future environment measurement of radio waves of portable wireless devices and the like.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of radio wave propagation between a wireless station and a mobile wireless station.

FIG. 2 is an explanatory diagram of a relationship between a radio wave propagation distance and a received correlation output.

FIG. 3 is a basic configuration diagram of a radio wave environment measuring apparatus of the present invention.

FIG. 4 is a configuration diagram of an embodiment of an antenna system, a transmitter system, a receiver system, a local oscillator system, and a distance measurement system of the present invention.

FIG. 5 is a configuration diagram of an embodiment of a repeater side of the present invention.

FIG. 6 is an explanatory diagram of a pulse compression / radar system used in the present invention.

[Explanation of symbols]

 1 ... Wireless station 2 ... Repeater 11 ... Antenna system 12 ... Transmitter system 13 ... Receiver system 14 ... Local oscillator system 15 ... Signal processing system 16 ... Control display system 21 ... Antenna / transmission / reception shared system 22 ... Transmitter system 23 ... Receiver system 24 ... Frequency conversion system

Claims (2)

[Claims] 1. A radio wave environment measuring apparatus for measuring a radio wave propagation environment between a radio station as a measuring point and a repeater as a mobile radio, wherein a transmitter system (12) on the radio station side (1) is dispersive. -Has a delay line (DDL) and a linear frequency modulation pulse generator (2-1), and has a limit amplifier (LIM) and a dispersive delay line (DDL) in the receiver system (13) , And the repeater side (2)
Is equipped with a frequency converter and limit amplifier (LIM). On the radio station side, the same signal as the radar wave is generated, linear frequency modulation and frequency conversion are performed by the local oscillator, and spread spectrum is performed and expanded. It makes a pulse signal and transmits it to the repeater side, the repeater side performs spectrum inversion by frequency conversion of the received radio wave, and relays and retransmits to the wireless station side, and the wireless station side performs frequency conversion with the same local oscillator as the repeater side. The received pulse is compressed by the pulse compression radar function as a linear frequency-modulated wave opposite to that at the time of transmission, and the reflected energy diffused in frequency and time is concentrated, and the radio path difference from the radio station side is concentrated. It is characterized in that the radio wave propagation of various propagation paths is measured for each delay time from the time when the reflected wave is emitted. Radio environment measurement device. 2. The radio environment measuring apparatus according to claim 1, wherein the receiver system and the limit amplifier on the repeater side have a function of suppressing the intensity of strong interference waves mixed in the radio propagation path.