JP2002051025A - Broadcast radio wave relay reception/ re-transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system where a broadcast radio wave receiver I relay-receives an analog broadcast radio wave such as a medium AM radio wave, a VHF-FM radio wave, and a VHF/UHF-TV radio wave, converts the obtained electric signal into an optical signal, uses an optical fiber 4 to transmit the optical signal for a distance of several kilometers at maximum, and a broadcast radio wave re-transmitter II converts the optical signal into an electric signal again and re-transmits the electric signal. SOLUTION: In the system of this invention, the broadcast radio wave receiver I relay- receives various broadcast radio waves altogether, simultaneously amplifies them altogether over a broadband, applies electrooptic conversion to the amplified radio waves, and transmits the optical signals through the optical fiber altogether to the broadcast radio wave re- transmitter II at the same time. The broadcast radio wave re-transmitter II applies photoelectric conversion to the optical signals transmitted altogether at the same time through the optical fiber, obtains the electric signals, amplifies them again altogether at the same time and re-transmits the electric signals. In the system of this invention, the broadcast radio wave receiver is connected to one set of the broadcast radio wave re-transmitter II or over through the one optical fiber 4 or more. Since the system configuration is simplified, the system is characterized in ease of system extension.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for receiving and retransmitting a broadcast wave charged wave, and more particularly to a plurality of medium wave AM broadcast waves.
VHF / UHF FM radio broadcast wave or VHF / U
The present invention relates to a broadcast radio relay reception / retransmission system that collectively receives HF TV broadcast waves and retransmits them in a radio wave blocked area such as a tunnel.

[0002]

2. Description of the Related Art Conventionally, various systems have been proposed as relay receiving / retransmitting apparatuses for radio waves in the AM broadcast wave band in the medium wave or in the FM radio or TV broadcast wave band in the VHF / UHF. For example, a radio wave of a specific medium-wave broadcast wave band or a VHF / UHF broadcast wave band is selected and received,
High-frequency amplification, frequency conversion, detection, low-frequency amplification or video amplification, transmission by cable, low-frequency amplification or video amplification, modulation, frequency conversion or multiplication again, high-frequency amplification and retransmission System. When receiving and retransmitting a plurality of signal radio waves with this type of apparatus, a receiving side channel device including high frequency amplification means, frequency conversion means, detection means, low frequency amplification means or video amplification means, and a low frequency amplification means Alternatively, a system including a retransmitting channel device including video amplifying means, modulating means, frequency converting means or multiplying means, and high frequency amplifying means, and a wire cable connecting a receiving channel to the retransmitting channel for each signal radio wave. Is configured. Therefore, for example, when receiving and retransmitting 10 channels or 10 signal radio waves, it is necessary to install 10 types of reception and retransmission channel devices in parallel.

Since the frequency of a received radio wave differs for each signal radio wave, it is necessary to prepare a device having a different frequency specification for each signal radio wave in each channel device. Also,
When a receiving antenna and a re-transmitting antenna are shared by each channel, branching and combining networks are installed at the receiving end and the transmitting end, respectively.

[0004] As a modification of the first conventional system, an intermediate frequency signal obtained by frequency conversion of a receiving side channel is synthesized between signal radio waves, transmitted by one wire cable, and then transmitted again. And a second conventional system for passing the signal through a retransmission side channel. In this system, since the intermediate frequency signal is transmitted instead of the original signal, signal radio waves of many channels can be transmitted simultaneously and collectively. However, because we use wire cables,
When transmission is performed without compensation, the transmission frequency band, the upper limit of the transmission frequency, the transmission distance, and the like are limited.

In the third conventional system, a receiving-side channel device selects and receives a specific medium-wave broadcast wave band or a VHF / UHF broadcast wave band, and further amplifies the signal wave of the selected specific channel. Then, the signal is transmitted to the retransmission-side channel device via a wire cable, and the retransmission-side channel device amplifies and retransmits the signal wave of the selected specific channel. In order to receive and retransmit a plurality of signal radio waves in the third conventional system, it is most common to provide the reception side channel device, the wire cable, and the retransmission side channel device in a number corresponding to the number of channels. It is a method. By doing so, it is possible to avoid problems specific to high frequencies, such as interference and cross modulation.

However, when the length of the wire cable is long, it is necessary to prepare the number of wire cables corresponding to the number of channels, so that there is a problem that facility costs increase. Therefore, in such a case, a signal synthesizing circuit means is provided at a stage subsequent to the plurality of receiving-side channel devices, and after synthesizing a plurality of received signal radio waves, transmitting the radio waves to a wire cable, further branching again, and thereafter, Is supplied to each of the retransmission-side channel devices. In this method, multiple signals are transmitted only within the cable,
It is considered that the problem of non-linearity can be avoided, and the problem of cross-modulation can generally be sufficiently eliminated.

[0007] However, the problem of ground current noise due to the installed potential difference between the transmitting and receiving sides remains in the wire cable. In particular, in the third conventional system for transmitting a high-frequency signal by a cable, it is extremely difficult to completely remove the influence of the ground current noise. The solution to this problem is a system that employs optical fibers instead of wire cables.

A fourth conventional system is a system for connecting a receiving channel device and a retransmitting channel device with an optical fiber cable. In the fourth conventional system,
The receiving-side channel device is configured to include high-frequency amplification means with a frequency selection function for selecting and amplifying only a specific signal radio wave, and electro-optical conversion means for converting the high-frequency amplified signal radio wave to an optical signal. I have. On the other hand, the retransmission-side channel device includes a photoelectric conversion unit for converting the optical signal into a signal radio wave, and a high-frequency amplification unit with a frequency selection function.

In order to receive and retransmit a plurality of signal radio waves in this type of conventional system, the receiving side channel device requires:
A plurality of high frequency amplifying means each having a signal frequency selecting bandpass filter are provided. Different high frequency amplifying means selectively amplify different signal radio waves individually, combine them, and combine them. After being converted into a signal, it is transmitted through an optical fiber. The optical signal transmitted by the optical fiber is converted into a signal radio wave by a photoelectric conversion means, the plurality of signal radio waves are demultiplexed / branched, and each signal radio wave is selectively amplified by a plurality of high-frequency amplification means and combined again. Wave and retransmit. The purpose of optical cable transmission is to prevent sneaking from the receiving cable, and to prevent beat interference in the area.

Therefore, in one example of the fourth conventional system, a band-pass filter as a tuning circuit is provided in the high-frequency amplifying means as described above, and a broadcast wave of one specific wave or a plurality of frequencies is transmitted to the tuning circuit. And converts it into an optical signal, which is transmitted to the transmission side channel device via an optical fiber. In the embodiment described above, in addition to the above description, the high-frequency signal from the receiving antenna is directly converted into an optical signal and supplied to the receiving-side channel device. However, when the preamplifier is arranged near the receiving antenna, the noise figure (NF) of the preamplifier can be made sufficiently small, which is generally better than an electronic circuit that performs direct light-to-light conversion. Since a high signal-to-noise ratio (SNR) can be easily obtained, it is not advisable to transmit the received radio wave directly to the optical fiber, but the optical fiber may be transmitted after obtaining a sufficient S / N with a preamplifier.

With respect to the prior art broadcast wave receiving / retransmitting apparatus, the flow of signal waves from reception to retransmission has been mainly described for the first to fourth conventional systems. Next, the transmission circuit means of the signal radio wave will be described briefly.

The transmission circuit means has a method of obtaining a predetermined power by the analog power amplifier circuit means and a method of amplifying the power by the pulse amplifier circuit means as employed in a normal analog broadcast radio wave transmitter. And a method of obtaining analog power by a low-pass filter. In the retransmission method that selectively amplifies only one selected signal wave,
Both the former and the latter are possible, but it is generally considered difficult to employ the former only in the retransmission system in which a plurality of signal radio waves are simultaneously amplified and output in power.

[0013]

The first to fourth prior art systems each include a receiving channel device and a retransmitting channel device for each signal radio channel or frequency, and a plurality of signal radio frequencies. In the case of receiving and retransmitting, a system needs to be configured by providing a plurality of receiving side channel devices and a plurality of retransmitting side channel devices in a number corresponding to the number of signal radio waves of a plurality of frequencies. For this reason, the system configuration becomes complicated, performance degradation is likely to occur, it is difficult to receive and retransmit other than broadcast waves of a preset channel or frequency, and further, cost efficiency and maintainability are reduced, There is a problem that the reliability of the system is reduced.

An object of the present invention is to eliminate the above-mentioned problems of the first to fourth conventional systems, so that the system configuration is simplified, the performance is hardly deteriorated, the versatility of the system can be improved, and the system can be improved. It is an object of the present invention to provide a broadcast wave relay reception / retransmission system configured so that the reliability, cost efficiency, maintainability, and the like of the broadcast wave are not reduced.

[0015]

In order to achieve the above object, a broadcast wave relay receiving / retransmitting system according to the present invention comprising a broadband modulation / demodulation system capable of collective reception and retransmission is provided. Receiving simultaneously and collectively extracting a plurality of analog high-frequency signal voltages included in the plurality of broadcast waves, and a broadcast wave receiving unit for collectively outputting the plurality of analog high-frequency signal voltages, and collectively output from the broadcast wave receiving unit. First broadband amplification means for collectively linearly amplifying the plurality of analog high-frequency signal voltages and outputting the plurality of analog high-frequency signal voltages collectively, and the plurality of analog high-frequency signals collectively output from the first broadband amplification means. And a light-to-light conversion means for converting the signal voltage into a corresponding analog light intensity signal at a time and outputting the analog light intensity signal. A broadcast radio wave receiving device for repeating reception and outputting an analog signal light proportional to each intensity of the plurality of broadcast radio waves, and the analog light intensity signal transmitted from the electro-optical conversion means via a transmission line using an optical fiber And a corresponding plurality of analog high-frequency signal currents, or photoelectric conversion means for converting and outputting a plurality of analog high-frequency signal voltages, and the plurality of signal currents output from the photoelectric conversion means, or a plurality of A second broadband amplifying means for amplifying the signal voltages collectively and outputting a plurality of signal voltages collectively; and a plurality of signal voltages collectively output from the second broadband amplifying means. High-frequency power amplifying means for driving and outputting broadband analog high-frequency power, and re-outputting the output power of the high-frequency power amplifying means collectively as a plurality of signal radio waves. Radio wave retransmitting means for transmitting, receiving a wide range of analog optical signals proportional to the respective intensities of the plurality of broadcast radio waves received collectively, a plurality of broadcast radio waves proportional to the analog optical signal One or a plurality of broadcast wave retransmitting devices for simultaneous batch relay and retransmission, and a broadband connection between the broadcast wave receiving device and the broadcast wave retransmitting device, from the broadcast wave receiving device To the broadcast radio wave retransmitting device, one or more optical fibers as a transmission path for collectively transmitting the analog optical signals having respective intensities proportional to the plurality of collectively received broadcast radio waves, It is provided and comprised.

In the broadcast wave relay receiving / retransmitting system, the broadcast wave receiving means included in the broadcast wave receiving device includes an antenna for receiving a plurality of broadcast waves, and a band of the antenna for the plurality of broadcast waves. A band filter for suppressing a band other than the band including the plurality of broadcast waves while maintaining a wide band so that a signal wave can be received can be provided.

In the above-mentioned broadcast wave relay receiving / retransmitting system, the broadcast wave receiving means included in the broadcast wave receiving apparatus includes: an antenna for receiving a plurality of broadcast waves; And a broadband filter including a passive filter for varying the sensitivity of each of the plurality of broadcast waves while maintaining a wide band so that the signal waves can be received.

In the above-mentioned broadcast radio wave relay receiving / retransmitting system, the electro-optical conversion means included in the broadcast radio wave reception apparatus can obtain light emission power proportional to the output voltage of the first broadband amplification means. A light emitting diode driving means for performing analog luminance modulation, and a light emitting diode driven by the driving means to obtain a controlled light emission power, and included in the broadcast radio wave retransmission device The photoelectric conversion unit receives the analog optical signal transmitted from the electro-optical conversion unit via the optical fiber, and converts the signal into a signal current or a signal voltage, and a signal obtained from the photodiode. Is converted from high impedance to low impedance and sent to the second broadband amplifier. It can be configured by including the order of impedance conversion means.

In the above-mentioned broadcast wave relay receiving / retransmitting system, the electro-optical conversion means included in the broadcast wave receiving device can obtain a light emission power proportional to the output voltage of the first broadband amplifying means. A laser diode driving unit for performing analog brightness modulation, and a laser diode driven by the driving unit to obtain a controlled emission power, and
The photoelectric change unit included in the broadcast radio wave retransmitting device receives the analog optical signal transmitted from the electric light change unit via the optical fiber, and converts the signal current or a signal voltage to a photodiode. And impedance converting means for converting the impedance of the signal obtained from the photodiode from high impedance to low impedance and sending it to the second broadband amplifying means.

In the above-mentioned broadcast radio wave relay receiving / retransmitting system, the electro-optical conversion means included in the broadcast radio wave receiving device includes a light emitting diode or a laser diode for outputting a constant optical power; On / off control of the constant light power to change the effective analog intensity so as to be proportional to the output voltage of the amplification means,
An external light modulation means for applying luminance modulation can be provided.

In the above-mentioned broadcast wave relay receiving / retransmitting system, the external light modulating means may be an A / O mode type analog light modulating means comprising an A / O mode light modulator main body and a driving part thereof. it can. In the above-mentioned broadcast wave relay receiving / retransmitting system, the broadcast wave receiving device is a receiving device for receiving a broadcast wave in a medium wave AM broadcast wave band, and the broadcast wave retransmitting device is a medium wave AM. A retransmission device for retransmitting a broadcast wave in a broadcast wave band can be provided. In the above-mentioned broadcast wave relay receiving / retransmitting system, the broadcast wave receiving device is a VH
F-FM radio, VHF-TV, or UHF-TV
A receiving device for receiving broadcast waves in a broadcast wave band,
Further, the broadcast radio wave retransmitting device can be a retransmitting device for retransmitting a broadcast radio wave in a VHF-FM radio, VHF-TV, or UHF-TV broadcast wave band. In the above-mentioned broadcast wave relay reception / retransmission system, the external light modulation means included in the light-to-light conversion means of the broadcast wave reception apparatus is an analog modulation device utilizing a phenomenon other than the A / O mode type analog light modulation means. A light emitting diode or a laser diode. In the above-mentioned broadcast radio wave relay receiving / retransmitting system, the external light modulating means included in the electro-optical conversion means of the broadcast radio wave receiving apparatus is a Mach-Zehnder type optical modulating means comprising a Mach-Zehnder type optical modulator main body and a driving unit thereof. The light emitting means may be a laser diode.

[0022]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a first embodiment of a relay reception / retransmission system for a medium-wave AM broadcast wave according to the present invention. In FIG. 1, 1 is a radio wave receiving means, 2 is a first broadband amplifying means, 3 is an electro-optical conversion means, 4 is an optical fiber, 5 is a photoelectric conversion means, 6 is a second broadband amplifying means, and 7 is a high frequency power amplifier. Means 8 is a radio wave retransmitting means comprising a transmitting antenna and a second matching circuit.

The radio wave receiving means 1 comprises a receiving antenna 11 and a first matching circuit 12, and is 525 kHz to 1635 kHz included in a medium wave AM broadcast wave band to be retransmitted.
1 to capture the incident radio waves in the range of
To be sent. The receiving antenna 11 is configured in a wide band so as to cover the entire broadcast wave band, and has a flat response characteristic or is adjusted so as to obtain a desired response characteristic. On the other hand, the first matching circuit 12
Is for impedance matching between the receiving antenna 11 and the input section of the first broadband amplifying means 2, and the received voltage induced in the receiving antenna 11 has a good signal-to-noise ratio (SNR). Thus, the first broadband amplification means 2 can be inputted. Therefore, when the signal-to-noise ratio is good, the first matching circuit 12
May not be provided with particular awareness. Further, the first matching circuit 12 is an active filter that individually varies the sensitivity of a signal radio wave among a plurality of broadcast radio waves and outputs the variance.
It may be a wideband filter including a passive filter.

The first broadband amplifying means 2 amplifies the received signal voltage induced in the receiving antenna 1 and converts
This is to make the size that can be input to the. The first broadband amplifying unit 2 is configured to receive and amplify a medium-wave AM broadcast wave from 525 kHz to 1 kHz.
It consists of an integrated circuit for obtaining a flat characteristic or a desired response characteristic at 635 kHz, or a transistor broadband amplifier.
It has a voltage gain of B and an operating range of 1.0 Vrms or more. An integrated circuit, a transistor broadband amplifier, or the like often has a bandwidth exceeding the reception bandwidth of the broadcast wave.

Therefore, the gain other than the above band is set to 30 to 40.
It is preferable that the effective signal-to-noise ratio in the electro-optical conversion means 3 or a subsequent stage is improved by lowering by at least dB. For this reason, a band-pass filter having a wide band for passing only the band can be inserted into the input side or the output side of the integrated circuit or the transistor wide-band amplifier. This type of bandpass filter
The configuration and the operation concept are completely different from those of the band pass filter for selecting and passing one specific wave or one of a plurality of signal radio waves used in the prior art. For example, the bandpass filters that can be used in the present invention are typically four-terminal broadband networks, whereas those in the prior art are typically single-tuned or double-tuned.

The light-to-light conversion means 3 has a structure in which the amplitude of a current flowing through a light emitting diode is normally analog-modulated by a transistor circuit. FIG. 2 is a circuit configuration diagram showing one embodiment of the electro-optical conversion means 3. In FIG. 2, 3
1, 32, and 35 are resistors, 33 is a light emitting diode, 34 is a transistor, 36 is a voltage source + Vcc line, 37 is a common potential GND line, and 38 is an input terminal. The input terminal 38 is connected to the voltage source Vcc and the resistors 31, 3
2, at a potential determined by the transistor 34 and the resistor 35.

Since the potential at the input terminal 38 is substantially equal to the potential at both ends of the resistor 35, a current proportional to the potential at the input terminal 38 flows through the resistor 35. For this reason, a good linear relationship is maintained between the potential of the input terminal 38 and the current of the resistor 35.

Therefore, the collector current of the transistor 34 is proportional to the potential of the input terminal 38,
The current of 3 is equal to the collector current of transistor 34.
The light emitting power of the light emitting diode 33 is
And a good linear relationship is maintained between the potential of the input terminal 38 and the emission power. Since a good linear relationship is maintained between the input and output of the first broadband amplifying unit 2, the relationship between the signal voltage induced in the radio wave receiving unit 1 and the emission power of the electro-optical conversion unit 3 is a good linear relationship. Kept in a relationship.

The light emission power of the light-to-light conversion means 3 is coupled so that it can be efficiently input to the optical fiber 4. Optical fiber 4 can typically be a single mode fiber or a multimode fiber. In the case of a single mode fiber, the light emitting diode 33 needs to be an edge emitting type. However, in the case of multimode fiber,
The light emitting diode 33 can be of a surface emitting type, but may be of an edge emitting type. In any case, in the case of the present embodiment, any device having a frequency response characteristic capable of covering the response in the medium-wave AM broadcast wave band may be used.

FIG. 3 shows a circuit configuration of one embodiment of the photoelectric conversion means 5. In FIG. 3, 51 is a pin photodiode, 52, 53, 55 and 56 are resistors, respectively, and 54 is a gallium arsenide field effect transistor (GaAs-FE).
T) or a high frequency amplifying device such as a femto (FEMT), 57 is a capacitor for bypassing a high frequency voltage at both ends of a resistor 56, and 58 is a broadband amplifier for further amplifying the output voltage of the high frequency amplifying device 54. , An integrated circuit or a transistor amplifier. 590 is a power supply + Vcc line, and 591 is a GND line. 592 is an output terminal.

The photodiode 51 is reverse-biased through a resistor 52, and has a power supply + Vcc line 5 at both ends.
From 90, a DC voltage Vcc is applied. Optical fiber 4
When the signal light power is applied to the photodiode 51 via the photodiode 51, an optical signal current proportional to the signal power is generated in the photodiode 51. This optical signal current causes the resistor 5
A signal voltage is generated at both ends of the circuit 2, and this signal current or signal voltage is amplified by the high-frequency amplification device 54.

The output voltage of the high-frequency amplification device 54 is generated at both ends of the resistor 53, and this voltage is amplified by the wide band amplifier 58 and output to the output terminal 592. The broadband amplifier 58 is mainly for performing impedance conversion. Resistors 55 and 56 and capacitor 57
As a result, a bias circuit of the high-frequency amplification device 54 is formed, and its operating point is determined by the resistors 55 and 56.

The second broadband amplification means 6 broadly amplifies the output voltage of the photoelectric conversion means 5, and may have a voltage gain of 30 to 50 dB as an example. In the present embodiment, the second broadband amplifying means 6 has a uniform frequency response characteristic over the entire medium-wave AM broadcast wave band, has a good linearity with a distortion factor of -30 dB or less, and generally has It can have a low output impedance. The high-frequency power amplifying means 7 can amplify the output of the second wide-band amplifying means 6 in a wide band, and obtain a predetermined high-frequency power with good linearity.

In the embodiment of the medium wave AM wave receiving / retransmitting apparatus shown in FIG.
A medium-wave AM signal voltage of 80 dBμV is induced and input to the first broadband amplifier 2. First broadband amplification means 2
Is amplified with a gain of 10 dB to 40 dB. The signal voltage amplified to a maximum of 107 dBμV is input to the electro-optical conversion means 3 and converted into an equivalent optical signal. The electro-optical conversion means 3 has a voltage gain of -6 dB to 0 dB. As described above, it is configured by the broadband amplifier including the transistor 34 and the light emitting diode 33.

First broadband amplification means 2 and light-to-light conversion means 3
The receiving-side channel constituted by the above is composed of an amplification / conversion circuit by resistance / capacitor coupling having a flat frequency response characteristic in the medium wave AM broadcast wave band. Therefore, neither a filter nor a tuning resonance circuit for tuning to a specific signal radio wave is provided. This is a major feature of the configuration of the present invention. FIG.
5 is a graph showing an example of a frequency response characteristic of a signal path from an input terminal of the first broadband amplifying unit 2 to an emitter resistor 35 of a driving transistor 34 of the light emitting diode 33 of the electro-optical conversion unit 3. 525 kHz or less, and 16
In a frequency band of 35 kHz or more, if noise occurs due to the response of the system, there is a possibility that the noise causes cross modulation. For this reason, the receiving channel usually contains
Although a noise removal filter is inserted, this filter has a different configuration and operation from the tuning circuit.
The decrease in response below 525 kHz and below 1635 kHz is due to the insertion of this filter.

When the output of the radio wave receiving means 1 is input to the first broadband amplifier 2, if the impedance relationship between the two is not maintained well, reflection or the like occurs between the two, deteriorating the quality of the received signal. For this reason, the output of the antenna 11 in the radio wave receiving means 1 is set to a 0-∞ impedance matching method, a wideband matching is performed while considering the relationship between the noise figure and the input power, and the output impedance of the matching circuit 12 is adjusted. 0-50 / 0-75Ω system, and
One method is to match the input impedance of the first broadband amplifying means 2 to 50Ω or 75Ω.

In the radio wave receiving means 1, the impedance of the receiving antenna is not always 50Ω or 75Ω, but a matching circuit 12 is provided so that reflection or the like does not occur in the receiving band. In general, the input stage of the low-noise amplification of the matching circuit 12 has a capacitive impedance, and the input resistance at low frequencies is often several hundred kΩ to 1 MΩ. It is assumed that such an input stage is generally adjusted so that the noise figure is several dB or less, typically 8 dB or less.

On the other hand, the optical signal transmitted from the light emitting diode 33 of the electro-optical conversion means 3 shown in FIG.
m having a center near 1300 nm or 1500 nm and having energy distributed at a wavelength near the center wavelength, and is usually coupled to a glass-based single mode fiber or multimode fiber. . When the light signal power of the light emitting diode 33 is large,
0 dBm of energy, but the power input to the fiber is typically -10 dBm to -15 dBm.
Often becomes. Even in this case, it is possible to transmit a distance of 2 to 3 km or more, and in many cases, to a distance of 10 km or more using a glass optical fiber.

The light emitting diode 33 in FIG. 2 can be replaced with a laser diode having the same wavelength band as the light emitting diode. In this case, when return light is incident on the laser diode, the operation of the laser diode is disturbed by the return light, and noise may be generated. Therefore, in this case, it is necessary to insert an optical isolator or an optical attenuator between the laser diode and the optical fiber. Further, the connection needs to be performed so that the return light from the optical fiber connector for connecting the optical fiber is -60 dB or less. With the simplest circuit configuration, analog light intensity modulation similar to that of a light emitting diode can be performed.
In a medium-wave band AM radio wave reception / retransmission system using a normal analog modulation method, distortion or cross-modulation does not pose a problem as long as it is 1 to 2% or less. There is no problem if noise due to the fractionation of the wavelength of the optical signal is -50 dB or less.

When an analog modulation method is applied to an optical signal obtained by using a laser diode, an external light modulation method can be employed in addition to the direct modulation method.
FIG. 5 is a block diagram showing an embodiment of the electro-optical conversion means 3 using the external modulation method. In FIG. 5, reference numeral 301 denotes a laser diode, 302 denotes an A / O mode light intensity modulator, 303 denotes a high-frequency bias power supply, 304 denotes a modulation signal driving unit, and 305 denotes a modulation signal input terminal. The A / O mode light intensity modulator 302 is driven by a high frequency bias power supply of about 100 MHz, and vibrates in an acoustic mode.
A / O mode light intensity modulator 302 in which incident light is oscillating
When the light emission output of the laser diode 301 is input so that the incident light is reflected in a flag, the reflected light and the refracted light are intensity-modulated according to the vibration. Modulation signal driver 30
Numeral 4 is for supplying drive power to the high-frequency bias power supply 303, and the drive power can be obtained by superimposing DC power and modulated AM signal power.
A modulation signal input terminal 305 applies a medium-wave band AM signal to the modulation signal driver 304 as a modulation signal.

When the high-frequency output power from the high-frequency bias power supply 303 on which the medium-wave band AM signal is superimposed is applied to the A / O mode modulator 302, the optical output intensity-modulated according to the medium-wave band AM signal becomes A / O. O-mode light intensity modulator 3
02. This optical output is input to the optical fiber 4 and is again converted into an electric signal by the photoelectric conversion means 5.
Further, it is sent to the second broadband amplification means 6.

The optical signal arriving at the photoelectric conversion means 5 by the optical fiber 4 shown in FIG. 1 is converted into an electric signal by a pin photodiode 51 constituting the photoelectric conversion means 5. Since the optical signal current induced in the pin photodiode 51 by the optical input is typically on the order of 1 μA or less, the current is amplified by a low-impedance low-noise amplifier or the high-impedance input type. The voltage is amplified by a low noise amplifier.

In the former case, a low-noise npn transistor is used. The low-noise npn transistor is a transistor having a low collector current, for example, a high current amplification factor of 10 μA to 100 μA, and has a small 1 / f noise and shot noise. The design policy of this type of amplifier is based on the idea of efficiently using the photocurrent of a pin photodiode as the base current of a transistor and performing current amplification at a high amplification factor.

On the other hand, in the latter case, it is necessary to convert the voltage signal into a voltage signal using an input stage constituted by a high impedance input type low noise amplifier. A gallium arsenide field effect transistor (GaAs-FET) or a junction field effect transistor (J-FET) can be given as a high impedance input type low noise amplifier.

The output of the photoelectric conversion means 5 is sent to the second broadband amplifying means 6, where the signal is amplified to a power level of 100 mVrms to 1 Vrms. The high frequency power amplifying means 7 is 1
When an input signal voltage of 00 mVrms or more is input, 1
The high-frequency power of 00 mW or more is supplied to the load resistance of 50Ω, that is, the broadband antenna 8. The signal voltage response characteristic of the retransmission side channel from the optical signal input terminal of the photoelectric conversion means 5 to the output terminal of the second broadband amplifying means 6 is 525 kHz to 1635 in the same manner as the characteristic shown in FIG.
It must be flat within the range that covers the medium-wave AM broadcast wave band of kHz. However, outside the band, the noise characteristics must be improved by reducing the response by a filter or the like. As a result, it is possible to prevent noise and parasitic transmission outside the band from falling into the band due to cross modulation or the like.

The second broadband amplifying means 6 has good linearity between the input and the output, and the harmonic distortion at the output terminal is equal to 0.1.
It is desirable that it is 1% or less. Since the high-frequency power amplifying means 7 is driven by the output of the second broadband amplifying means 6, the high-frequency power amplifying means 7 has a single-ended MOS field effect transistor (MOS-FE) as described above.
T) A high frequency class A power amplifier or a bias voltage applied to use a MOS field effect transistor (MOS-FET) array connected to a half bridge or a full bridge for class A power amplification. .

The MOS field effect transistor (MOS)
-FET) high frequency narrow band power amplifiers are typically of the amplifier type tuned to a single carrier.
However, by using a band-pass filter that covers the entire medium-wave AM broadcast wave band instead of the tuning circuit as a load, the MOS field-effect transistor (MOS-FE) can be used.
The high-frequency power amplifier according to T) can be used as a broadband amplifier. The equivalent resistance of the tuning circuit when tuning is 10
Since it can be set to kΩ to 100 kΩ, a large power gain of 30 dB or more can be obtained very easily in one stage in the narrow band power amplifier. However, when a band-pass filter is used as a load, the characteristic impedance of the band-pass filter is selected to be 50Ω or 75Ω,
Alternatively, the gain is limited because it is often selected to be 300Ω. For example, when 300Ω is selected, good band-pass characteristics can be obtained in the entire medium-wave AM broadcast wave band, and 20 dB
Power gain. One radio wave receiving means 1
Are connected to one radio wave retransmitting means 8. At this time, the MOS field effect transistor (M
An output terminal of the high-frequency power amplifying means 7 using an OS-FET is connected to one of the radio wave retransmitting means 8. However, when connecting a radio signal received by one radio receiver 1 to a number of radio retransmitters 8, the connection method shown in FIG. 6 can be adopted.

In FIG. 6, 1 is a signal radio wave receiving means, 2
-1 is a first broadband amplifying means, 202 is an analog branching means, 3-1 to 3-2 and 3-n are first, second, and n-th light-to-light conversion means, respectively. 3, 4-1, 4-2, and 4-n are first, second, and n-th optical fibers, respectively, having the same configuration as the optical fiber 4 in FIG. 5-1, 5-2,5
-N are first, second, and n-th photoelectric conversion units, respectively, having the same configuration as the photoelectric conversion unit of FIG. The first, second, and n-th represent the first, second, and n-th channels, respectively.

The first broadband amplifier 2-1 has basically the same configuration and performance as the first broadband amplifier 2 shown in FIG. An analog branching means 202 is inserted at the output side. The branch circuit employs a low impedance output circuit so that a large number of loads can be connected.

FIG. 7 is a circuit diagram showing an embodiment of the circuit configuration of the analog branching means 202 inserted on the output side of the first broadband amplifying means 2-1 shown in FIG. In FIG. 7, 2
Reference numerals 12-1, 212-2, and 212-n denote series resistors for preventing regulated vibration, respectively.
2-n is a buffer transistor, respectively 232-1,
232-2 and 232-n are emitter resistors, respectively. For example, transistor 2 through resistor 212-1
The radio signal voltage input to the base side of 22-1 appears at its emitter, is output from both ends of the resistor 232-1 to the electro-optical conversion means 3-1 and is input to the optical fiber 4-1. Similarly, the radio signal voltage appearing on the other channels is also input to the corresponding optical fiber via the corresponding electro-optical conversion means. The radio signal extracted for each channel by each photoelectric conversion means connected to the other end of each optical fiber is retransmitted through a retransmission system provided for each channel.

Further, in the case where a plurality of retransmitting devices are satisfied and the optical power is sufficiently large,
A plurality of photoelectric conversion units can be connected to one electro-optical conversion unit. FIG. 8 is a block diagram showing an embodiment in which a plurality of photoelectric conversion units are connected to one electro-optical conversion unit.

In FIG. 8, 411-11, 411-1
2, 411-13 are optical fibers, 412-1, respectively.
411-2, 412-n are first, second, and n-th optical branching means, respectively, 411-1, 411-2, and 411-n.
n is an optical fiber for supplying a radio signal to the first, second, and n-th channels, respectively;
-N are first, second, and n-th photoelectric conversion means, respectively, which form the front end portion of the retransmission system of the first, second, and n-th channels.

Light branching means 412-1, 412-2, 41
2-n is for splitting the input optical power and transmitting it in two directions. The optical power input from the electro-optical conversion unit 3 via the optical fiber 411-11 is split by the first optical splitting unit 412-1 and a part is split by the optical fiber 411-1 to the first photoelectric conversion unit 5-1-1. 1 and the rest is sent to the second optical branching means 412-2 by the optical fiber 411-12. The optical fiber 41
The optical power transmitted from 1-1 to the photoelectric conversion means 5-1 is 50%, 30%, 10% of the optical output power of the electro-optical conversion means 3.
% Or 1%. In this case, the branching ratio of the optical branching unit is set to a value designed in advance. Hereinafter, branching can be performed in the same manner.

In the above description, the embodiments in the medium wave AM broadcast wave band have been described. However, the broadcast wave of the present invention is not limited to the above, and the VHF-FM radio broadcast wave,
Even in the case of VHF-TV or UHF-TV broadcast wave radio waves, specific examples of the system do not exceed the scope of the present invention. In this case, broadband amplification means, light-to-light conversion means,
The basic configuration of the photoelectric conversion unit and the high-frequency power amplifying unit is the same, and the operating range and the specific configuration are such that an operation of relaying and retransmitting the corresponding broadcast wave in the frequency band and retransmitting can be performed. Needless to say, the operation is premised.

Further, in the embodiment of the present invention, in the described medium-wave AM broadcast radio wave relay receiving / retransmitting system, the light-to-light conversion means includes direct current modulation of a light emitting diode,
Alternatively, a combination of a laser diode and an A / O mode modulator is used, but a direct current modulation of a light emitting diode or a combination with another modulator, or a combination of a laser diode and a Mach-Zehnde (Mach-Zehnde).
r) It can be a modulator or a combination with an equivalent EO mode modulator. Further, in the analog modulation method, the output of the modulation transistor can be equivalently changed in an analog manner by on / off control of the modulation transistor.

[0056]

According to the prior art, since the receiving channel device and the transmitting channel device are provided for each channel of the signal radio wave, there is a problem that the system is complicated and the performance is liable to be deteriorated. On the other hand, in the system according to the present invention, a plurality of broadcast wave radio waves are collectively received in a wide band,
This is a system that retransmits after transmitting by optical fiber. Therefore, the system configuration is simplified, the performance is hardly deteriorated, the versatility of the system can be improved, and the reliability, maintainability and the like of the system are not reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of a broadcast wave relay reception / retransmission system according to the present invention.

FIG. 2 is a circuit diagram showing an embodiment of an electro-optical conversion means used in the relay reception / retransmission system of the broadcast radio wave according to the present invention.

FIG. 3 is a circuit diagram showing an embodiment of a photoelectric conversion unit used in the relay reception / retransmission system of the broadcast wave according to the present invention.

FIG. 4 shows a frequency response characteristic of a signal path from an input terminal of a first broadband amplifying means to an emitter resistance of a driving transistor of a light emitting diode of an electro-optical conversion means in the relay reception / retransmission system of the broadcast radio wave according to the present invention. It is a graph shown.

FIG. 5 is a block diagram showing an embodiment of an electro-optical conversion means using an external modulation method.

FIG. 6 is a circuit diagram showing an embodiment of a circuit configuration of an analog branching unit inserted on the output side of the first broadband amplifying unit.

FIG. 7 is a circuit diagram showing an embodiment of a circuit configuration of an analog branching unit inserted on the output side of the first broadband amplifying unit shown in FIG. 6;

FIG. 8 is a block diagram showing a modified example of the broadcast radio wave relay reception / retransmission system according to the present invention in which a plurality of photoelectric conversion units are connected to an electro-optical conversion unit.

[Explanation of symbols]

 I Broadcast Radio Reception Device II Broadcast Radio Retransmission Device 1 Receiving Antenna (Radio Receiving Means) 2 First Broadband Amplifying Means 3 Electric Light Conversion Means 4 Optical Fiber 5 Photoelectric Conversion Means 6 Second Broadband Amplifying Means 7 High Frequency Power Amplifying Means 8 Transmission antenna (radio wave retransmission means)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) // H03F 3/08 F term (reference) 5C056 FA05 HA01 HA04 5J092 AA04 AA56 CA51 CA58 HA01 HA25 HA44 SA13 TA01 TA02 UL01 UL07 UR14 5K002 AA05 CA02 CA13 FA01 GA07 5K072 AA19 AA29 BB03 BB04 BB14 BB25 BB27 DD15 GG01 GG12 GG13

Claims (11)

[Claims] 1. Broadcast radio wave receiving means for receiving a plurality of broadcast radio waves simultaneously and collectively in a wide band, extracting a plurality of analog high-frequency signal voltages included in the plurality of broadcast radio waves, and outputting them collectively, A first broadband amplifying section for collectively and linearly amplifying the plurality of analog high-frequency signal voltages collectively output from the broadcast radio wave receiving section and collectively outputting the plurality of analog high-frequency signal voltages; Electro-optical conversion means for converting the plurality of analog high-frequency signal voltages output collectively into a corresponding analog optical intensity signal and outputting the same, and collectively transmitting the plurality of broadcast radio waves over a wide band. Simultaneously relay-received, a broadcast radio wave receiving device for outputting an analog signal light proportional to each intensity of the plurality of broadcast radio waves, and a transmission path using an optical fiber from the electro-optical conversion means. A plurality of analog high-frequency signal currents or a plurality of analog high-frequency signal voltages corresponding to the analog light intensity signal transmitted and output, and a plurality of analog high-frequency signal voltages. A second broadband amplifying means for collectively linearly amplifying the plurality of signal currents or a plurality of signal voltages and outputting a plurality of signal voltages collectively; Driven in accordance with the plurality of signal voltages output as a high-frequency power amplifying means for outputting broadband analog high-frequency power, and for retransmitting the output power of the high-frequency power amplifying means collectively as a plurality of signal radio waves. Radio wave retransmitting means, comprising: receiving, over a wide band, an analog optical signal proportional to each of the intensities of the plurality of broadcast radio waves received collectively; One or more broadcast radio retransmitters for simultaneously relaying and retransmitting a plurality of broadcast radio waves at the same time in proportion to the optical signal, and a broadband between the broadcast radio receiver and the broadcast radio retransmitter. Connected to the broadcast radio wave receiving device to the broadcast radio wave retransmitting device, as a transmission path for collectively transmitting the analog optical signals of respective intensities proportional to the plurality of collectively received broadcast radio waves. A broadcast radio relay reception / retransmission system, comprising: at least one optical fiber; 2. The broadcast wave relay receiving / retransmitting system according to claim 1, wherein the broadcast wave receiving means included in the broadcast wave receiving device includes: an antenna for receiving a plurality of broadcast waves; And a band filter for suppressing a band other than the band including the plurality of broadcast radio waves while maintaining the band of the plurality of signal radio waves in a wide band so as to be able to receive the plurality of signal radio waves. Transmission system. 3. The broadcast wave relay receiving / retransmitting system according to claim 1, wherein the broadcast wave receiving means included in the broadcast wave receiving device includes: an antenna for receiving a plurality of broadcast waves; An active filter for varying the sensitivity or a wide band filter including a passive filter for each of the plurality of broadcast waves while maintaining the band of the plurality of broadcast waves so as to receive the plurality of signal waves. A broadcast wave relay reception / retransmission system characterized by the following. 4. The broadcast radio wave relay receiving / retransmitting system according to claim 1, wherein the light-to-light conversion means included in the broadcast radio wave reception device outputs light emission power proportional to an output voltage of the first broadband amplification means. Light emitting diode driving means for performing analog luminance modulation so as to obtain the light emitting diode, and a light emitting diode driven by the driving means for obtaining a controlled light emitting power; and The photoelectric conversion unit included in the retransmission device receives the analog optical signal transmitted from the electro-optical conversion unit via the optical fiber, and converts the signal into a signal current or a signal voltage. From the high impedance to the low impedance, and transmits the signal to the second broadband amplifying means. Airwaves relay-receiving and re-transmitting system characterized by being configured to comprise an impedance conversion means for output. 5. The broadcast radio wave relay receiving / retransmitting system according to claim 1, wherein the light-to-light conversion unit included in the broadcast radio wave reception device comprises:
A laser diode driving unit for performing analog luminance modulation so as to obtain an emission power proportional to an output voltage of the first broadband amplifying unit, and a laser diode driving unit driven by the driving unit to obtain a controlled emission power. Comprising the laser diode, and, the photoelectric change means included in the broadcast radio wave retransmission device receives the analog optical signal transmitted via the optical fiber from the electric light change means, A photodiode for converting a signal current or a signal voltage, and an impedance conversion unit for converting the impedance of a signal obtained from the photodiode from a high impedance to a low impedance and sending the impedance to the second broadband amplifying unit. A broadcast wave relay reception / retransmission system characterized by comprising: 6. The broadcast radio wave relay receiving / retransmitting system according to claim 1, wherein the electro-optical conversion means included in the broadcast radio wave reception device includes a light emitting diode or a laser diode for outputting a constant optical power; External light modulating means for turning on and off the constant optical power so as to be in proportion to the output voltage of the first broadband amplifying means, thereby effectively changing the analog intensity, and applying luminance modulation. A broadcast radio relay receiving / retransmitting system, characterized in that: 7. An analog optical modulator according to claim 6, wherein said external optical modulator comprises an A / O mode optical modulator main body and a drive section thereof. A broadcast radio relay reception / retransmission system, characterized in that: 8. The broadcast wave relay receiving / retransmitting system according to claim 1, wherein the broadcast wave receiving device is a receiving device for receiving a broadcast wave in a medium wave AM broadcast wave band, and wherein the broadcast wave is received. The radio wave retransmitting device is a retransmitting device for retransmitting a broadcast wave in the medium-wave AM broadcast wave band. 9. The broadcast wave relay receiving / retransmitting system according to claim 1, wherein the broadcast wave receiving device is a VHF-FM radio, a VHF
A receiving device for receiving a broadcast wave in a TV or UHF-TV broadcast wave band, and the broadcast wave retransmitting device is a receiver for a VHF-FM radio, a VHF-TV, or a UHF-TV broadcast wave band. It is a retransmission device for retransmitting broadcast waves.
Retransmission system. 10. The broadcast wave relay reception / retransmission system according to claim 6, wherein the external light modulation means included in the electro-optic conversion means of the broadcast wave reception device is the A / O mode type analog light modulation means. An analog modulation means utilizing a phenomenon other than the above, wherein the light-to-light conversion means is a light emitting diode or a laser diode. 11. The broadcast radio relay receiving and receiving device according to claim 10,
In the retransmission system, the external light modulation means included in the light-to-light conversion means of the broadcast radio wave reception device is a Mach-Zehnder light modulation means including a Mach-Zehnder light modulator main body and a driving unit thereof, and the light-emitting means is a laser. A broadcast radio relay reception / retransmission system, which is a diode.