JPH0773247B2 - Optical transmission system for antenna feeding - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal for transmitting / receiving via a wireless line when a transmitting / receiving terminal device for modulating / demodulating a baseband signal and a transmitting / receiving antenna are separated (hereinafter referred to as an antenna feeding signal). That is, an optical transmission system for feeding an antenna for transmitting the signal using an optical fiber cable.

[0002]

2. Description of the Related Art An optical transmission system for transmitting a signal for feeding an antenna in a microwave band or a millimeter wave band depending on the strength of an optical signal transmitted in an optical fiber cable makes use of the characteristic of low loss transmission by the optical fiber cable. As a transmission means instead of the conventional electric signal transmission using a coaxial line, attention is being paid to increase the applicable frequency. In this optical transmission system for feeding an antenna, a direct modulation and direct detection method using an electric / optical conversion element such as a laser diode module and an optical / electric conversion element such as an optical fiber cable and a photodiode module is used. Among these components, generally, the upper limit of the frequency that can drive the laser diode in the laser diode module (hereinafter, referred to as the maximum drive frequency) is relatively low, and therefore, for antenna power feeding applicable to this optical transmission system. The upper frequency limit of the signal is limited by the maximum drive frequency of this laser diode.

FIG. 3 shows an optical transmission system for feeding a conventional antenna (for example, R.R.Kunas (R.
R. Kunath) et al. “Optical High Frequency Distribution Link for MMIC Phased Array Antennas (Optica)
l RF Distribution Links f
or MMIC Phased Array Anten
NAS, ”IEEE, Antenna and Propagation Society (Antennas and Pro)
Pagation Society), 87CH243
5-6, Vol. 1, AP11-2, pp426-43
0, June 15-19, 1987, or AS
DARIYOSH et al. "High-speed analog fiber optical link for satellite communication (High-Spe
ed Analog Fiber Optic Lin
ks for Satellite Communic
ation) "SPIE '88, Boston, September 1988).

As shown in FIG. 3, in the transmitting terminal device 100, a carrier signal generator 51, an intermediate frequency signal generator 61, an FM modulator 62, and a baseband signal generator 6 are provided.
3 and laser diodes 52 and 64. On the other hand, in the transmitting device 200 provided in the vicinity of the transmitting antenna 70 separated from the transmitting terminal device 100 by a predetermined distance, the photodiodes 53 and 65 and the amplifiers 54 and 66 are provided.
, Band pass filters (BPF) 55 and 68, a mixer 67, and a power amplifier 69. Here, the transmitting terminal device 100 and the transmitting device 200 are connected via two optical fiber cables 71 and 72.

Carrier wave signal generator 5 of transmitting terminal device 100
1 generates a carrier wave signal having a frequency fc higher than the highest drive frequency of the laser diode 52, for example, 2 GHz and outputs the carrier wave signal to the laser diode 52, and uses the nonlinear electric-optical conversion characteristic of the laser diode 52 by this carrier wave signal. Intensity modulation is performed so that a harmonic component is generated.
Therefore, the optical signal intensity-modulated by the laser diode 52 contains not only the fundamental wave component of the frequency fc of the carrier signal but also harmonic components of frequencies 2fc, 3fc, ..., Nfc ,. Here, n is a natural number. The optical signal is transmitted via the optical fiber cable 71 to the transmitting device 200.
Is transmitted to the photodiode 53.

Further, the intermediate frequency signal generator 61 is lower than the maximum driving frequency of the laser diode 64, for example, 1
An intermediate frequency signal having a frequency fi of GHz is generated and output to the FM modulator 62. The FM modulator 62 FM-modulates the intermediate frequency signal with a baseband signal including the information signal output from the baseband signal generator 63, and, for example, fi ±
An FM signal whose frequency is shifted in the range of Δfs is output to the laser diode 64, and the intensity modulation is performed by the FM signal in the linear electric-optical conversion characteristic region of the laser diode 64. Therefore, the optical signal intensity-modulated in the laser diode 64 includes only the FM signal that is frequency-shifted within the range of fi ± Δfs. The optical signal is transmitted to the photodiode 65 of the transmitter 200 via the optical fiber cable 72.

The photodiode 53 of the transmitter 200
Photoelectrically converts the received optical signal into an electric signal containing a fundamental wave component of the frequency fc of the carrier wave signal and harmonic components of frequencies 2fc, 3fc, ..., Nfc ,. Output to the pass filter 55. The band pass filter 55 filters only the signal of the harmonic component of the frequency nfc, and then outputs the filtered signal to the main signal input terminal of the mixer 67. On the other hand, the photodiode 65
Photoelectrically converts the received optical signal into the FM signal,
The signal is output to the local oscillation signal input terminal of the mixer 67 via the amplifier 66. The mixer 67 mixes and multiplies the input signals, and outputs the resulting signal to the power amplifier 69 via the band pass filter 68 that passes only the center frequency nfc + fi and the frequency components in the vicinity thereof. The power amplifier 69 amplifies the input FM signal that is frequency-shifted within the range of (nfc + fi) ± Δfs, and then outputs the amplified FM signal as a transmission signal to the transmission antenna 70 and a reception antenna (not shown) of the receiving station. Sent to. Here, the carrier frequency of the transmission signal is nfi + fi, and the maximum frequency shift of the transmission signal is 2Δfs.

In the optical transmission system for feeding antennas configured as described above, the harmonic component of the carrier signal is generated by using the nonlinear electrical-optical conversion characteristic of the laser diode 52, and the harmonic component is generated by the optical fiber. Cable 71
To the transmitting device 200 via the optical fiber cable 72 while transmitting the FM signal obtained by FM-modulating the intermediate frequency signal with the baseband signal to the transmitting device 200 via the optical fiber cable 72.
In the transmission device 200, the transmitted FM signal is used as a local oscillation signal to frequency-convert one frequency of the harmonic component to a higher frequency, and the frequency-converted signal is used as a transmission signal.

[0009]

However, in the above-mentioned conventional optical transmission system for feeding an antenna, the number of
In order to transmit a transmission signal to one transmission antenna, it is necessary to provide two pairs of a pair of laser diode and photodiode connected through an optical fiber cable, and a carrier signal generator 51 and a mixer 67. Since it is necessary to provide the bandpass filters 55 and 68, the number of parts constituting the system increases, and the system configuration becomes complicated.

The object of the present invention is to solve the above problems and to reduce the number of constituent parts as compared with the conventional example and to simplify the structure.
An object of the present invention is to provide an optical transmission system for antenna feeding, which is inexpensive to manufacture.

[0011]

According to a first aspect of the present invention, there is provided an antenna power feeding optical transmission system comprising: a transmitting terminal station device; and a transmitting device provided at a predetermined distance from the transmitting terminal station device. An optical transmission system for feeding an antenna, comprising: the transmitting terminal device and an optical transmission line connecting the transmitting device, wherein the transmitting terminal device modulates a carrier signal with an information signal to generate a modulated signal. A modulation means for outputting and a non-linear electric-optical conversion characteristic, and the modulated signal output from the modulating means is converted into a fundamental wave component and at least one harmonic by using the non-linear electric-optical conversion characteristic. An electrical / optical conversion means for performing electrical / optical conversion so as to generate a wave component and outputting an optical signal containing the modulated signal to the optical transmission line, wherein the transmitter is configured to convert the electrical / optical conversion means to the optical signal. Via transmission line Optical-electrical conversion means for optical-electrically converting the transmitted optical signal to output a fundamental wave component and at least one harmonic component of the modulated signal, and the modulated signal output from the optical-electrical conversion means 1 of the fundamental wave component and at least one harmonic component of
It is characterized by comprising: filtering means for filtering one harmonic component; and transmitting means for wirelessly transmitting one predetermined harmonic component of the modulated signal filtered by the filtering means. .

According to a second aspect of the present invention, there is provided an optical transmission system for feeding power to an antenna, wherein a transmitter / receiver terminal device, a transmitter / receiver device provided at a predetermined distance from the transmitter / receiver terminal device, and the transmitter / receiver terminal. An optical transmission system for antenna feeding, comprising: a first and a second optical transmission line for connecting a station device and the transmitter / receiver, wherein the transmitter / receiver terminal device modulates a carrier signal with a first information signal. And a non-linear electric-optical conversion characteristic, and a first modulation signal output from the above-mentioned modulating means by using the non-linear electric-optical conversion characteristic. A first electrical device that performs an electrical / optical conversion to generate a fundamental wave component and at least one harmonic component of the first modulated signal and outputs an optical signal including the first modulated signal to a first optical transmission line. .Equipped with optical conversion means, The receiving device optically-electrically converts the optical signal transmitted from the first electrical / optical converting means via the first optical transmission line to perform the fundamental wave component of the first modulated signal and at least one Of the first optical / electrical converting means for outputting a harmonic component, and the fundamental wave component and at least one harmonic component of the first modulated signal output from the first optical / electrical converting means, in advance, Filtering means for filtering a harmonic component having the same fixed frequency component or two harmonic component having different predetermined frequency components, and the first filter filtered by the filtering means. Transmitting means for wirelessly transmitting a harmonic component that is the same predetermined frequency component of the modulated signal or one of two harmonic components that are different predetermined frequency components, and a partner station. At the second Receiving means for wirelessly receiving a transmission signal modulated by an information signal and wirelessly transmitted and outputting a reception signal, and the same predetermined frequency of the first modulated signal filtered by the filtering means. Reproducing means for reproducing the carrier wave signal of the harmonic component in response to the other harmonic component of the two harmonic components which are the different harmonic components or the predetermined different frequency components, and the reproducing means. The carrier wave signal reproduced by the above is used as a local oscillation signal to convert the received signal received by the receiving means into a predetermined intermediate frequency signal, and an intermediate frequency signal output from the frequency converting means. A second electrical-optical conversion means for optically converting and outputting an optical signal including the intermediate frequency signal to the second optical transmission line, wherein the transmitting / receiving terminal station device further comprises:
Second optical / electrical converting means for optically / electrically converting the optical signal transmitted from the second electric / optical converting means via the second optical transmission line to output the intermediate frequency signal; Demodulation means for demodulating the intermediate frequency signal output from the second optical / electrical conversion means and outputting the second information signal.

[0013]

In the optical transmission system for feeding an antenna according to claim 1, the modulating means of the transmitting terminal station device modulates the carrier signal with the information signal and outputs the modulated signal, and then the electrical / optical converting means. , Has non-linear electrical-optical conversion characteristics,
The modulated signal output from the modulation means is converted into an electric wave by using the non-linear electric-optical conversion characteristic so that a fundamental wave component and at least one harmonic component of the modulated signal are generated, and the modulated signal is included. The optical signal is output to the optical transmission line. On the other hand, the optical-electrical converting means of the transmitting device performs optical-electrical conversion of the optical signal transmitted from the electric-optical converting means via the optical transmission line, and at least one of the fundamental wave component of the modulated signal and After outputting the harmonic component, the filtering means outputs one predetermined harmonic component of the fundamental wave component and at least one harmonic component of the modulated signal output from the optical-electrical converting means. Filter. Then, the transmitting means wirelessly transmits one predetermined harmonic component of the modulated signal filtered by the filtering means. The antenna-feeding optical transmission system according to claim 1 configured as described above is realized with a simpler configuration than the configuration of the system of the conventional example shown in FIG. 3, so the manufacturing cost is significantly reduced. can do.

Further, in the optical transmission system for feeding antenna according to the present invention, the modulating means of the transmitting / receiving terminal station device modulates the carrier signal with the first information signal and outputs the first modulated signal. The first electro-optical conversion means uses the non-linear electro-optical conversion characteristic of the first modulated signal output from the modulation means to generate a fundamental wave component of the first modulated signal and at least one Electrical / optical conversion is performed so that a harmonic component is generated, and an optical signal including the first modulated signal is output to the first optical transmission line. On the other hand, the first electric / optical converting means of the transmitting / receiving device converts the optical signal transmitted from the first electric / optical converting means through the first optical transmission line into an electric signal, and converts the optical signal into an electric signal. After outputting the fundamental wave component of the first modulated signal and at least one harmonic component, the filtering means outputs the fundamental wave component of the first modulated signal and the fundamental wave component of the first modulated signal output from the first optical-electrical converting means. Of at least one harmonic component, a harmonic component having the same predetermined frequency component or two harmonic components having different predetermined frequency components are filtered. Then, the transmitting means is the harmonic component that is the same predetermined frequency component of the first modulated signal that has been filtered by the filtering means, or the predetermined different frequency component of the first modulated signal. One of the two harmonic components is wirelessly transmitted. Further, the receiving means is the second station in the partner station.
Of the information signal to be wirelessly transmitted and wirelessly receive the transmission signal to output a reception signal, while the reproduction means outputs the reception signal, the predetermined modulation signal of the first modulation signal filtered by the filtering means. Harmonic components which are the same frequency component or different frequency components which are predetermined from each other.
In response to the other harmonic component of the one harmonic component, the carrier signal of the above harmonic component is reproduced. Then, the frequency conversion means uses the carrier signal reproduced by the reproduction means as a local oscillation signal to convert the reception signal received by the reception means into a predetermined intermediate frequency signal,
The second electro-optical converting means electro-optically converts the intermediate frequency signal output from the frequency converting means and outputs an optical signal including the intermediate frequency signal to the second optical transmission line. On the other hand, the second optical / electrical converting means of the transmitting / receiving terminal station device performs optical / electrical conversion of the optical signal transmitted from the second electric / optical converting means via the second optical transmission line. After outputting the intermediate frequency signal, the demodulating means demodulates the intermediate frequency signal output from the second optical-electrical converting means and outputs the second information signal. In the optical power feeding system for antenna power feeding according to claim 2, which is configured as described above, the optical power feeding system for antenna power feeding for transmission signals is simpler than the configuration of the conventional system shown in FIG. In addition to the above, it is possible to realize an optical transmission system for feeding an antenna for received signals with a simple configuration.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings.

<First Embodiment> FIG. 1 is a block diagram of an antenna feeding optical transmission system according to a first embodiment of the present invention.

The optical transmission system for feeding antennas according to the first embodiment includes a transmitting terminal station device 101 and a transmitting terminal station device 10.
A transmission antenna 9 provided at a predetermined distance from
And a transmission terminal station device 1 provided near the
01 and a single optical fiber cable 10 for connecting the transmitter 201, the harmonic component of the FM signal obtained by FM-modulating a carrier signal with a baseband signal is used to determine the nonlinear electrical-optical conversion characteristics of the laser diode 4. Generated and used to transmit the harmonic component to the transmitting device 201 via the optical fiber cable 10 to generate one FM of the high frequency component.
The signal is transmitted from the transmission antenna 9 as a transmission signal.

As shown in FIG. 1, the transmitting terminal apparatus 101 includes a carrier signal generator 1, an FM modulator 2, a baseband signal generator 3, and a laser diode 4. On the other hand, in the transmission device 201 provided near the transmission antenna 9, the photodiode 5 and the amplifier 6 are provided.
A band pass filter (BPF) 7 and a power amplifier 8. Here, the transmitting terminal device 101 and the transmitting device 201 are connected via one optical fiber cable 10.

Carrier signal generator 1 of transmitting terminal device 101
Is higher than the maximum driving frequency of the laser diode 4,
For example, a carrier signal having a frequency fc of 15 GHz is generated and output to the FM modulator 2. The FM modulator 2 FM-modulates the carrier signal with a baseband signal including an information signal output from the baseband signal generator 3, and, for example, fc ±
An FM signal that is frequency-shifted in the range of Δfs is output to the laser diode 4, and the carrier wave signal is used to perform intensity modulation using the nonlinear electrical-optical conversion characteristic of the laser diode 4 to generate a harmonic component. The diode 4 outputs the intensity-modulated optical signal. This optical signal has an FM frequency-shifted in the range of frequency fc ± Δfs.
In addition to the fundamental wave component of the signal, frequency 2 (fc ± Δfs),
3 (fc ± Δfs), ..., N (fc ± Δfs), ... Includes harmonic components of the FM signal that are frequency-shifted in the range. Here, n is a natural number. The optical signal is transmitted to the photodiode 5 of the transmitter 201 via the optical fiber cable 10.

On the other hand, the photodiode 5 of the transmitter 201 photoelectrically converts the received optical signal into an electric signal containing the fundamental wave component and the harmonic wave component of the FM signal, and then, through the amplifier 6, the center frequency is changed. It is nfc and is output to the band pass filter 7 that passes the center frequency nfc and the frequency components in the vicinity thereof. The band pass filter 7 has a frequency n
After filtering only the component of the FM signal whose frequency is shifted in the range of (fc ± Δfs), it is output to the power amplifier 8. After amplifying the filtered FM signal, the power amplifier 8 outputs the amplified FM signal as a transmission signal to the transmission antenna 9 and transmits it to the reception antenna (not shown) of the reception station.

Here, if n is 3, the carrier frequency of the transmission signal transmitted from the transmission antenna 9 is 45.
GHz, and the maximum frequency shift of the transmission signal is 6Δfs. In this case, in order to make the maximum frequency deviation of the transmission signal the maximum frequency deviation of the conventional example, the modulation index of the FM modulator 2 needs to be 1/3 of that of the conventional example. Therefore,
In the antenna-feeding optical transmission system according to the first embodiment, since the harmonic component is used as the transmission signal as described above, even if the modulation index of the FM modulator 2 is small, a large frequency deviation occurs. There is an advantage that can be obtained.

In the optical transmission system for feeding antennas of the first embodiment configured as described above, the harmonic component of the FM signal obtained by FM-modulating the carrier signal by the baseband signal is used to generate the nonlinear electric power of the laser diode 4. Generated by using optical conversion characteristics, and generate the harmonic component concerned by the optical fiber cable 1
0 is transmitted to the transmitting device 201, and one FM signal of the high frequency component is transmitted from the transmitting antenna 9 as a transmitting signal. Therefore, the optical transmission system for antenna feeding can be realized with a simpler structure than that of the system of the conventional example shown in FIG. 3, and the manufacturing cost can be significantly reduced. The antenna feeding optical transmission system of the first embodiment is particularly useful for an antenna such as an array antenna that needs to optically transmit a large number of high frequency signals.

<Second Embodiment> FIG. 2 is a block diagram of an antenna feeding optical transmission system according to a second embodiment of the present invention.

In the optical transmission system for feeding antenna according to the second embodiment, a transmitting / receiving terminal device 102 having the functions of a transmitting terminal device 101 and a receiving terminal device, and a transmitting / receiving terminal device 10 are provided.
2 a transmission antenna 9 provided at a predetermined distance from
And a transmitting device 200 provided near the receiving antenna 30.
And a transmitting / receiving device 202 having the function of a receiving device, and two optical fiber cables 10 and 11 connecting the transmitting / receiving terminal device 102 and the transmitting / receiving device 202. The first embodiment shown in FIG. Each circuit 2 for comparing and transmitting the information signal of the received signal received by the receiving antenna 30
It is characterized by further including 0, 22, 23, 31 to 37 and the optical fiber cable 11. Note that FIG.
In FIG. 1, the same components as those in FIG. 1 are designated by the same reference numerals.

As shown in FIG. 2, the transmitting / receiving terminal device 102
1, a carrier signal generator 1, an FM modulator 2, a baseband signal generator 3, a laser diode 4, a photodiode 36, and an FM demodulator 37 are provided. On the other hand, in the transmitter / receiver 202 provided near the transmitting antenna 9 and the receiving antenna 30, the photodiode 5, the amplifiers 6 and 32, the distributor 20, the band pass filters (BPF) 21, 22, 31 and 34, A power amplifier 8, a carrier recovery circuit 23, a mixer 33, and a laser diode 35 are provided. Here, the transmission / reception terminal device 102 and the transmission / reception device 202 are connected via two optical fiber cables 10 and 11.

The carrier signal generator 1 of the transmitter / receiver terminal device 102 generates a carrier signal having a frequency fc higher than the maximum driving frequency of the laser diode 4, for example, 5 GHz, and outputs the carrier signal to the FM modulator 2. The FM modulator 2 FM-modulates the carrier signal with a baseband signal including the information signal output from the baseband signal generator 3, and outputs the modulated signal, for example, fc.
An FM signal that is frequency-shifted in the range of ± Δfs is output to the laser diode 4, and the carrier wave signal is used to perform intensity modulation so that a harmonic component is generated by using the nonlinear electrical-optical conversion characteristic of the laser diode 4, The laser diode 4 outputs the intensity-modulated optical signal. Similar to the first embodiment, this optical signal includes not only the fundamental wave component of the FM signal that is frequency-shifted in the range of frequency fc ± Δfs, but also frequencies 2 (fc ± Δfs), 3 (fc ± Δfs), …, N
The harmonic component of the FM signal that is frequency-shifted in the range of (fc ± Δfs), (n + 1) (fc ± Δfs), ... Here, n is a natural number. The optical signal is transmitted to the photodiode 5 of the transmission / reception device 202 via the optical fiber cable 10.

On the other hand, the photodiode 5 of the transmitter 201 photoelectrically converts the received optical signal into an electric signal containing the fundamental wave component and the higher harmonic wave component of the FM signal, and then supplies it to the distributor 20 via the amplifier 6. Output. The distributor 20 divides the input FM signal into two, and divides one FM signal after distribution into
The center frequency is (n + 1) fc, and the center frequency (n
+1) A band which outputs to the band pass filter 21 which passes the frequency component of fc and its vicinity, and which passes the other FM signal after distribution with the center frequency of nfc and the frequency component of the said center frequency nfc and its vicinity. Output to the pass filter 22. The bandpass filter 21 filters only the component of the FM signal that is frequency-shifted in the range of frequency (n + 1) (fc ± Δfs), and then outputs it to the power amplifier 8. After amplifying the filtered FM signal, the power amplifier 8 outputs the amplified FM signal as a transmission signal to the transmission antenna 9 and transmits it to the reception antenna (not shown) of the partner station. Further, the bandpass filter 22 has a frequency n
After filtering only the component of the FM signal that is frequency-shifted in the range of (fc ± Δfs), it is output to the carrier wave regenerating circuit 23 configured by, for example, a PLL circuit. The carrier wave reproduction circuit 23
The carrier component of the input FM signal is reproduced and the frequency nf
The unmodulated carrier wave of c is output to the local oscillation signal input terminal of the mixer 33 as a local oscillation signal.

Here, if n is 2, the carrier frequency of the transmission signal transmitted from the transmission antenna 9 is 15
GHz, the maximum frequency shift of the transmission signal is 6Δfs, and the carrier frequency reproduced by the carrier reproducing circuit 23 is 10 GHz. In this case, in order to make the maximum frequency deviation of the transmission signal the maximum frequency deviation of the conventional example, the modulation index of the FM modulator 2 needs to be 1/3 of that of the conventional example. Therefore, in the antenna-feeding optical transmission system of the second embodiment, since the harmonic component is used as the transmission signal as described above, even if the modulation index of the FM modulator 2 is small, a large frequency is generated. The advantage is that a shift can be obtained.

The reception antenna 30 receives the transmission signal transmitted from the transmission antenna (not shown) of the partner station, and the received transmission signal (hereinafter referred to as the reception signal) has a center frequency of nfc '. Yes Bandpass filter 31 that passes the center frequency nfc ′ and the frequency components in the vicinity thereof
And is output to the mixer 33 as a main signal via the amplifier 32. Here, the transmission signal is a signal transmitted from a transmission antenna after a predetermined carrier signal is FM-modulated by a baseband signal including an information signal in the partner station. The band pass filter 31 has a frequency n (fc ′).
After filtering only the component of the FM signal whose frequency shifts in the range of ± Δfs ′), it is output to the main signal input terminal of the mixer 33 via the amplifier 32.

The mixer 33 mixes the input signals and multiplies them, and the resulting signal is a band pass filter 34 that passes only the center frequency fi and the frequency components in the vicinity thereof.
The received signal output to the laser diode 35 via the filter, that is, filtered by the bandpass filter 31, is frequency-converted into a frequency band of the intermediate frequency fi by the frequency converter including the mixer 33 and the bandpass filter 34. Here, the band-pass filter 34 filters only the FM signal whose frequency shifts in the range of frequency fi ± Δfs and outputs it to the laser diode 35, and the intermediate frequency fi of the intermediate frequency signal is higher than the highest drive frequency of the laser diode 35. Is also set low. Further, since the bandpass filter 34 of the present embodiment is configured to filter only the frequency component of the difference between the signals input to the mixer 33, each input / output of the mixer 33 and the bandpass filter 34. The relationship between the frequencies of the signals is represented by the following "Equation 1".

[0031]

[Equation 1]

Therefore, the intermediate frequency fi of the intermediate frequency signal and its frequency shift Δfs ″ are expressed by the following “Equation 2” and “Equation 3”, respectively.

[0033]

[Equation 2]

[0034]

[Equation 3]

Next, in the laser diode 35,
Intensity modulation is performed within the range of the linear electric-optical conversion characteristics of the laser diode 35 by the FM signal of the received signal whose frequency is shifted within the range of the frequency fi ± Δfs ″, and the laser diode 35 is subjected to the above intensity modulation. Output an optical signal. This optical signal contains only the fundamental wave component of the FM signal that is frequency-shifted within the range of frequency fi ± Δfs ″. The optical signal is transmitted to the photodiode 36 of the transmission / reception terminal device 102 via the optical fiber cable 11.

On the other hand, the photodiode 36 of the transmitter / receiver terminal device 102 photoelectrically converts the received optical signal into an electric signal containing the fundamental wave component of the FM signal, and then the FM demodulator 3
Output to 7. The FM demodulator 37 FM demodulates a baseband signal from the input electric signal and outputs the baseband signal.

In the optical transmission system for feeding antennas according to the second embodiment having the above-described structure, the nonlinear characteristic of the laser diode 4 is used as the harmonic component of the FM signal obtained by FM-modulating the carrier signal with the baseband signal. Generated by
The harmonic component is transmitted to the transmission / reception device 202 via the optical fiber cable 10, and one FM signal of the high frequency component is transmitted from the transmission antenna 9 as a transmission signal, and from another FM signal of the high frequency component. After the carrier wave is regenerated and the received signal received by the receiving antenna 30 is frequency-converted using the regenerated carrier wave as a local oscillation signal, an intermediate frequency signal including an information signal of the received signal is generated,
A baseband signal is demodulated by transmitting to the transmitting / receiving terminal device 102 by an optical transmission system including the laser diode 35, the optical fiber cable 11, and the photodiode 36, and performing FM demodulation of the transmitted intermediate frequency signal by the FM demodulator 37. To be done. Therefore, the optical transmission system for transmitting power to the antenna for transmitting signals is realized with a simple configuration as compared with the configuration of the conventional system shown in FIG. 3, and the optical transmission system for transmitting power to antenna for receiving signals is simple. There is an advantage that can be realized in. The antenna feeding optical transmission system of the second embodiment is particularly useful for an antenna such as an array antenna that needs to optically transmit a large number of high frequency signals.

<Other Embodiments> In the above embodiments, F
Although the M modulator 2 is used, the present invention is not limited to this, and the F modulator
A modulator of another modulation method such as an SK modulator may be used.

In the second embodiment described above, the harmonic components of the FM signal filtered by the bandpass filter 21 and the harmonic components of the FM signal filtered by the bandpass filter 22 are different from each other, The present invention is not limited to this, and the same harmonic component may be used. In this case, for example, the distributor 20 is provided after the band pass filter 21 or 22.
Is provided, the FM signal output from the band-pass filter 21 or 22 is divided into two, one FM signal after distribution is output to the power amplifier 8, and the other FM signal after distribution is output to the carrier recovery circuit 23. You may do it.

[0040]

As described in detail above, in the optical transmission system for feeding an antenna according to claim 1 of the present invention,
In the transmitting terminal device, a carrier signal is modulated with an information signal to output a modulated signal, and the modulated signal is converted into a fundamental wave component and at least one harmonic component by using a nonlinear electrical-optical conversion characteristic. The optical signal including the modulated signal is output to the optical transmission line by performing the electrical-optical conversion so that the optical signal transmitted through the optical transmission line is converted into the optical signal by the transmitting device. A fundamental wave component and at least one harmonic component of the modulation signal are output, and one predetermined harmonic component of the fundamental wave component and at least one harmonic component of the output modulation signal is filtered. , A predetermined one of the filtered modulated signals
Radio transmission of two harmonic components. Therefore, the optical transmission system for transmission signals is realized with a simpler structure than that of the system of the conventional example shown in FIG. 3, so that there is an advantage that the manufacturing cost can be significantly reduced.

Further, in the optical transmission system for feeding antenna according to claim 2 of the present invention, in the transmitting and receiving terminal station device, the carrier signal is modulated with the first information signal to obtain the first signal.
Is output, and the first modulated signal is subjected to electrical-optical conversion by using a non-linear electrical-optical conversion characteristic so that a fundamental wave component and at least one harmonic component of the first modulated signal are generated. To output an optical signal including the first modulated signal to the first optical transmission line, while the transmitter / receiver performs optical-electric conversion of the optical signal transmitted via the first optical transmission line. The fundamental wave component and at least one higher harmonic wave component of the first modulated signal are output, and the output first signal
Of the fundamental wave component and the at least one higher harmonic wave component of the modulated signal of 1., the higher harmonic wave component of the same predetermined frequency component or the predetermined different frequency components of 2
Two harmonic components are filtered, and two harmonic components of the same predetermined frequency component of the filtered first modulated signal or two predetermined different frequency components of the first modulated signal are filtered. One of the harmonic components of the component is wirelessly transmitted, and the other station wirelessly receives the transmission signal which is modulated by the second information signal and wirelessly transmitted, and outputs a reception signal, and the filtered first signal is output. Of one of the modulated components in response to the harmonic component of the same predetermined frequency component or the other harmonic component of the two harmonic components that are different predetermined frequency components. The carrier signal is reproduced, the reproduced carrier signal is used as a local oscillation signal, the received signal received by the receiving means is converted into a predetermined intermediate frequency signal, and the output intermediate frequency signal is converted into an electric signal. The converted optical signal including the intermediate frequency signal is output to the second optical transmission line, and the optical signal transmitted through the second optical transmission line is transmitted to the second optical transmission line by the optical transmitter / receiver terminal device. The intermediate frequency signal is electrically converted to output the intermediate frequency signal, the output intermediate frequency signal is demodulated, and the second information signal is output. Therefore, the optical transmission system for transmitting power to the antenna for transmitting signals is realized with a simple configuration as compared with the configuration of the conventional system shown in FIG. 3, and the optical transmission system for transmitting power to antenna for receiving signals is simple. There is an advantage that can be realized in.

[Brief description of drawings]

FIG. 1 is a block diagram of an antenna transmission optical transmission system that is a first embodiment according to the present invention.

FIG. 2 is a block diagram of an optical power transmission system for feeding an antenna according to a second embodiment of the present invention.

FIG. 3 is a block diagram of a conventional antenna-feeding optical transmission system.

[Explanation of symbols]

1 ... Carrier signal generator, 2 ... FM modulator, 3 ... Baseband signal generator, 4,35 ... Laser diode, 5,36 ... Photodiode, 6,32 ... Amplifier, 7,21,22,31,34 … Band pass filter (BP
F), 8 ... Power amplifier, 9 ... Transmission antenna, 10, 11 ... Optical fiber cable, 20 ... Distributor, 23 ... Carrier regeneration circuit, 30 ... Reception antenna, 33 ... Mixer, 37 ... FM demodulator, 101 ... Transmitting terminal station device, 201 ... Transmitting device, 102 ... Transmitting / receiving terminal device, 202 ... Transmitting / receiving device.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-181504 (JP, A) JP-A-55-8197 (JP, A)

Claims (2)

[Claims] 1. A transmission terminal station apparatus, a transmission apparatus provided at a predetermined distance from the transmission terminal station apparatus, and an optical transmission line connecting the transmission terminal station apparatus and the transmission apparatus. An optical transmission system for antenna feeding, wherein the transmitting terminal device has a modulation unit that modulates a carrier signal with an information signal and outputs a modulation signal, and has a non-linear electric-optical conversion characteristic. The output modulation signal is subjected to electrical / optical conversion by using the non-linear electrical / optical conversion characteristic so that a fundamental wave component and at least one harmonic component of the modulation signal are generated, and an optical signal including the modulation signal is converted into the optical signal. The transmitting device is provided with an electrical / optical converting means for outputting to an optical transmission line, and the transmitting device optically / electrically converts an optical signal transmitted from the electrical / optical converting means via the optical transmission line to convert the modulated signal Basic wave component and small And an optical / electrical converting means for outputting one harmonic component, and one predetermined harmonic of the fundamental wave component and at least one harmonic component of the modulated signal output from the optical / electrical converting means. An antenna power supply, comprising: a filtering means for filtering a component; and a transmitting means for wirelessly transmitting one predetermined harmonic component of the modulated signal filtered by the filtering means. Optical transmission system. 2. A transmission / reception terminal station device, a transmission / reception device provided at a predetermined distance from the transmission / reception terminal station device, and first and second optical lines connecting the transmission / reception terminal device and the transmission / reception device. An optical transmission system for feeding an antenna, comprising: a transmission line, wherein the transmission / reception terminal device modulates a carrier signal with a first information signal and outputs a first modulated signal; A first modulated signal having an optical conversion characteristic, the fundamental wave component and at least one higher harmonic wave component of the first modulated signal being generated by using the non-linear electric-optical conversion characteristic A first electro-optical converting means for electro-optically converting so as to generate and outputting an optical signal including the first modulated signal to the first optical transmission line, From the electrical / optical conversion means to the first optical transmission line And optical and electrical converts the transmitted optical signal via the first
First optical / electrical converting means for outputting a fundamental wave component and at least one harmonic component of the modulated signal of, and a fundamental wave component of the first modulated signal output from the first optical / electrical converting means. And a filtering means for filtering a harmonic component having the same predetermined frequency component or two harmonic components having different predetermined frequency components among at least one harmonic component, One of the harmonic components of the same predetermined frequency component or the two harmonic components of the predetermined different frequency components of the first modulated signal filtered by the wave means. Transmitting means for wirelessly transmitting the component, receiving means for wirelessly receiving a transmission signal which is modulated by the second information signal and wirelessly transmitted at the partner station, and outputs a reception signal, and the filtering means for filtering. In response to the harmonic component of the same predetermined frequency component or the other harmonic component of the two predetermined different frequency components of the modulated first modulated signal. And a reproducing means for reproducing the carrier wave signal of the harmonic component and a carrier wave signal reproduced by the reproducing means as a local oscillation signal to convert the received signal received by the receiving means into a predetermined intermediate frequency signal. The frequency conversion means and the intermediate frequency signal output from the frequency conversion means are electrically / optically converted to generate an optical signal including the intermediate frequency signal as the second signal.
Second electric / optical conversion means for outputting to the optical transmission line of the above, and the transmission / reception terminal device is further transmitted from the second electric / optical conversion means via the second optical transmission line. Second optical-electrical converting means for converting the optical signal into an electric signal and outputting the intermediate-frequency signal, and the second optical-electrical converting means for demodulating the intermediate-frequency signal outputted from the second optical-electrical converting means. And a demodulation means for outputting the information signal of 1.