JP2008160343A - Optical transmission method, optical transmission device, and optical transmission system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical transmission method, an optical transmission device, and an optical transmission system which are capable of flexibly multiplexing electric signals in an electric level or an optical level and of extending services toward the future. <P>SOLUTION: The optical transmission device edits and synthesizes input electric signals in the electric level so that frequency bands don't overlap, and uses one or more different wavelength light sources to modulate the intensity of an edited and synthesized signal and synthesizes modulation results in the optical level and transmits a synthesis result. A subscriber device receives an optical signal by an optical conversion element and separates the obtained edited and synthesized signal by a filter to obtain the input electric signals. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention combines an optical level multiplexing and an optical level multiplexing after optical modulation to form an optical multiplexed signal from a plurality of high frequency electrical signals and transmit the optical multiplexed signal, The present invention relates to an optical transmission device that realizes an optical transmission method and an optical transmission system that realizes the optical transmission method.

  In recent years, in addition to conventional VHF / UHF band analog TV broadcasts, various TV broadcast services for broadcasting high-frequency radio signals such as BS broadcasts, CS broadcasts, and digital terrestrial broadcasts have become available in individual houses or apartment houses. Yes. These broadcast services are used when receiving and viewing broadcast high-frequency radio signals individually as direct waves with an antenna, and distributing broadcast high-frequency radio signals as optical signals through cables such as optical fibers, for example. There is a case of the CATV format for receiving and viewing on the Internet.

  In the case of the CATV format using the latter optical fiber, an intermediate frequency obtained by converting a high-frequency radio signal for broadcasting from the station to the subscriber's home at the radio frequency or, if the radio frequency is too high, the low-frequency side. Then, the optical signal is transmitted as an optically modulated signal. At the subscriber's home, the transmitted optical signal is photoelectrically converted into a radio frequency electrical signal again and input to a tuner terminal corresponding to the high frequency radio signal of the broadcast, so that the television can be viewed.

  Further, it is conceivable that radio frequency communication radio signals such as mobile phone signals, radio LAN signals, WiMAX signals, and GPS signals are multiplexed and transmitted on an optical fiber for the purpose of widening the service.

  For example, in Patent Document 1, as a technique for multiplexing and transmitting an amplitude-modulated signal obtained by frequency-multiplexing a high-frequency radio signal for broadcasting and a high-frequency radio signal for communication, the amplitude-modulated signals are collectively FM-modulated, An optical transmission device that multiplexes with a communication radio frequency radio signal and transmits the optical signal is described. Since the optical transmission device of Patent Document 1 performs FM modulation of frequency-multiplexed amplitude-modulated video signals at once, cross-modulation is reduced, and an FM modulator corresponding to the number of channels is not required, so a low-cost system is constructed. It is described that it can be done.

  Patent Document 2 describes a system that converts a plurality of broadcast radio frequency radio signals into optical signals having different wavelengths, optically multiplexes them, and transmits them using a single fiber. It is described that the system of patent document 2 can suppress the complexity of the wiring form in a house and can improve workability.

  Furthermore, in Patent Document 3, as a conventional technique for multiplexing and transmitting a plurality of broadcast high-frequency radio signals, a CS broadcast signal and a terrestrial digital broadcast signal are received by a station and demodulated to generate a baseband signal. Then, a technique for digitally time-division-multiplexing each type of baseband signal and optically transmitting it to a subscriber is described.

Patent 3339031 JP 2006-074138 A Patent 3660174

  In such an optical transmission system that multiplex-transmits a radio frequency radio signal for broadcasting and a radio frequency radio signal for communication, how to multiplex at the electrical level depends on the signal level of the radio frequency radio signal, the frequency band used for the radio frequency radio signal, and It is necessary to consider the maximum degree of modulation of the high-frequency wireless signal into the optical signal. In addition, it is necessary to consider the dynamic range of the optical modulator / demodulator and the fiber dispersion characteristics in the optical transmission path as to how to multiplex at the optical level. That is, whether to multiplex at the electrical level or at the optical level depends on the radio frequency radio signal to be multiplexed, so by selecting a combination of multiplexing at the electrical level or multiplexing at the optical level, the radio frequency radio signal Transmission quality and transmission cost can be optimized.

  However, recently, new radio frequency services such as digital terrestrial broadcasting, WiMAX, wireless LAN, GPS services, and new entry of mobile phones have been added, and wireless signal transmission using optical fibers to expand the service area. The situation is increasingly being used.

  However, the optical transmission device disclosed in Patent Document 1 includes a plurality of types of high-frequency radio signals for broadcasting and a plurality of types of high-frequency radio signals for communication, such as terrestrial digital broadcasting, CS broadcasting, and BS broadcasting. Is transmitted through an optical fiber, it is not a structure that performs multiplexing at the electrical level or multiplexing at the optical level according to the characteristics of the high-frequency radio signal itself, and it is difficult to expand the service.

  Further, the system disclosed in Patent Document 2 has a structure that requires an optical modulation element and an optical reception element for each high-frequency radio signal, and if the service is expanded, the optical modulation element and the optical reception element must be added. There is a difficulty that the cost of the circuit portion increases.

  Further, the technique disclosed in Patent Document 3 has a structure that requires a demodulator that demodulates a high-frequency radio signal for broadcasting on the station side. If the service is expanded, the demodulator must be added and the cost on the station side is increased. Will increase. Furthermore, since the transmission rate of time-division multiplexed signals increases as the number of broadcasting schemes for which services are expanded and multiplexed increases, the subscriber side device must cope with the increase in transmission rate, and the cost of the subscriber side device is increased. There is also a difficulty that increases.

  In other words, since the techniques disclosed in Patent Document 1 to Patent Document 3 are intended to solve problems associated with multiplexing individually, there is a problem that it is difficult to expand future services structurally.

  Therefore, in order to solve such a conventional problem, the present invention can flexibly perform multiplexing of electric signals at the electric level or the optical level, and enables an optical transmission method and an optical transmission capable of expanding services in the future. It is an object to provide a transmission device and an optical transmission system.

  In order to achieve the above object, an optical transmission method according to the first invention of the present application is an optical transmission device that edits and synthesizes input electrical signals at an electrical level so that frequency bands do not overlap, By modulating the intensity using different wavelength light sources, combining and transmitting them at the optical level, receiving the optical signal with the optical conversion element at the subscriber unit, and separating the resulting edited combined signal with a filter The input electric signal was obtained.

  Specifically, according to the first invention of the present application, when the optical transmission apparatus has at least frequency band duplication occurring in n input electrical signals (n is an integer of 1 or more), the frequency band A frequency rearrangement step of converting at least one frequency band among the overlapping input electrical signals into a frequency band unused by another input electrical signal to generate n frequency adjusted electrical signals, and the frequency rearrangement step Thereafter, the optical transmission device passes the n frequency adjustment electric signals generated in the frequency rearrangement step as they are, or out of the n frequency adjustment electric signals generated in the frequency rearrangement step. A signal combining step of combining at least two and generating m (m is an integer of 1 ≦ m ≦ n) editing combined electric signals, and after the signal combining step, the optical transmitting apparatus The m edited combined electric signals generated in step are intensity-modulated with light of any one of p wavelengths (p is an integer of 1 ≦ p ≦ m), and m combined optical signals are generated. An optical transmission step of multiplexing the m combined optical signals to generate one transmission optical signal and outputting it to an optical transmission line; and after the optical transmission step, a subscriber unit transmits the optical transmission A light receiving step of receiving the transmitted optical signal propagated through the path and photoelectrically converting it to generate a received electrical signal; and after the light receiving step, the subscriber unit filters the received electrical signal generated in the light receiving step with a filter. An electric signal converting step for converting into m received electric signals, and after the electric signal converting step, a subscriber unit converts n output electric signals from the m received electric signals converted in the electric signal converting step. Separation that separates signals And management step, an optical transmission method comprising.

  The optical transmission method performs optical modulation without demodulating an input electrical signal and outputs an optical signal. Therefore, no demodulator is required, and there is no need to increase the number of demodulators even if the service is expanded.

  In the frequency rearrangement step, the frequency band of the input electrical signal can be converted and frequency shifted. Also, the electrical signal can be multiplexed for each group of electrical signals that can be multiplexed in the signal synthesis step. Therefore, even if the frequency bands of each input electrical signal overlap and cannot be synthesized as they are, or even if the frequency bands of each input electrical signal are separated and cannot be synthesized as they are, the frequency rearrangement It is possible to perform flexible multiplexing at the electrical level by shifting the frequency of the input electrical signal in steps and synthesizing the electrical signals after the frequency rearrangement step in the signal synthesis step.

  After the signal synthesis step, the electrical signals multiplexed for each group are converted into optical signals in the optical transmission step, and multiplexed at the optical level.

  Therefore, the optical transmission method does not increase the optical conversion elements of the optical transmission device and the optical reception elements of the subscriber device, and the optical transmission even if the number of input electrical signals is increased by expanding the service. It is possible to respond flexibly without increasing the load on the road.

  Therefore, the first invention of the present application can provide an optical transmission method that can flexibly multiplex electric signals at an electric level or an optical level and can expand future services.

  In order to achieve the above object, an optical transmission apparatus according to the second invention of the present application edits and synthesizes input frequency bands of input electric signals so as not to overlap, and modulates intensity using one or more different wavelength light sources. Thus, a synthesized light signal is output.

  Specifically, according to the second invention of the present application, when at least frequency band overlap occurs in n input electric signals (n is an integer of 1 or more), input electric power having overlapping frequency bands is generated. A frequency rearrangement unit that converts at least one frequency band of the signals into a frequency band that is not used by another input electric signal and outputs n frequency adjustment electric signals; and the n number of frequency rearrangements from the frequency rearrangement unit The frequency adjustment electrical signals are passed as they are, or at least two of the n frequency adjustment electrical signals from the frequency rearrangement unit are synthesized, and m (m is an integer satisfying 1 ≦ m ≦ n). An electric signal combining unit that outputs an electric signal, and the m edit combined electric signals from the signal combining unit are set to any one of p wavelengths (p is an integer of 1 ≦ p ≦ m). Modulated with light to change to m composite optical signals Electrical to - the optical conversion unit, the electro - an optical transmitter having a light transmitting section that the m-number of combined optical signals from the light conversion unit and outputs as a transmission optical signal.

  The optical transmitter performs optical modulation without demodulating an input electrical signal and outputs an optical signal. Therefore, no demodulator is required, and there is no need to increase the number of demodulators even if the service is expanded.

  The frequency rearrangement unit can shift the frequency by converting the frequency band of the input electrical signal. Further, the electrical signal synthesis unit can perform multiplexing for each group of electrical signals that can be multiplexed. Therefore, even if the frequency bands of each input electrical signal overlap and cannot be synthesized as they are, or even if the frequency bands of each input electrical signal are separated and cannot be synthesized as they are, the frequency rearrangement When the unit shifts the frequency of the input electrical signal and the electrical signal synthesis unit synthesizes the frequency adjustment electrical signal from the frequency rearrangement unit, flexible multiplexing at the electrical level becomes possible.

  Furthermore, if the electro-optical conversion unit converts the edited combined electric signal from the electric signal combining unit into a combined optical signal, and the optical transmission unit multiplexes the combined optical signal, multiplexing at the optical level is performed.

  Therefore, even if the number of input electric signals to be input is increased due to the expansion of service, the optical transmission device does not increase the number of optical conversion elements of the optical transmission device and the optical reception element of the subscriber unit, and can perform optical transmission. It is possible to respond flexibly without increasing the load on the road.

  Therefore, the second invention of the present application can provide an optical transmission apparatus that can flexibly multiplex electric signals at an electric level or an optical level and can expand future services.

  It is preferable that the optical transmission device further includes a frequency modulation unit that frequency-modulates the edited combined electric signal from the signal combining unit and outputs the modulated electric signal to the electro-optical conversion unit.

  The frequency modulation unit can make the envelope signal of the input signal to the electro-optical conversion unit constant by performing frequency modulation on the edited combined electric signal. Therefore, it is possible to increase the degree of modulation of each electric signal that has been limited by the dynamic range of the electro-optical conversion element, and to simultaneously realize distortion reduction and SN ratio improvement due to nonlinearity of the electro-optical conversion element. .

  Accordingly, the second invention of the present application is an optical transmission device that can multiplex electrical signals flexibly at the electrical level or optical level, and can expand future services, and output optical signals with low distortion and high SN ratio. Can be provided.

  In the third invention of the present application, when at least frequency band overlap occurs in n input electrical signals (n is an integer of 1 or more), at least one of the input electrical signals having overlapping frequency bands is present. A frequency rearrangement unit that converts one frequency band into a frequency band that is not used by another input electric signal and outputs n frequency adjustment electric signals; and the n frequency adjustment electric signals from the frequency rearrangement unit Is modulated with light of any one of q wavelengths (q is an integer of 1 ≦ q ≦ n) and converted into n wavelength adjusted optical signals, and the n wavelength adjusted optical signals are Or combining the at least two of the n wavelength-adjusted optical signals and outputting m (m is an integer of 1 ≦ m ≦ n) and outputting the combined optical signal, The m combined optical signals from the combining unit are output as transmission optical signals. A light transmitting unit for an optical transmission apparatus having a.

  The optical transmission device according to the third aspect of the present invention converts the frequency adjustment electrical signal from the frequency rearrangement unit into an optical signal, and then converts the optical signal synthesis unit at an optical level for each group of optical signals that can be multiplexed by the optical signal synthesis unit. Multiplexing is performed. Therefore, the optical transmission device according to the third invention of the present application performs multiplexing at the optical level, which is performed by the optical transmission device of the second invention of the present application at the optical level. Even if the number of optical signals increases, it can be grouped into a group of optical signals that can be multiplexed.

  The optical transmission device includes the frequency rearrangement unit and the optical signal synthesis unit, so that the load on the optical transmission line increases even if the number of input electrical signals to be input is increased due to service expansion. It can respond flexibly without making it.

  Therefore, the third invention of the present application can provide an optical transmission device that can flexibly multiplex electrical signals at the optical level and can expand future services.

  If the number of input electrical signals increases due to the expansion of services, the number of electro-optic conversion elements that convert frequency-adjusted electrical signals from the frequency rearrangement unit into optical signals increases. The required linearity and broadband characteristics are alleviated by the electro-optical conversion element of the electro-optical conversion unit according to the second aspect of the present invention. Therefore, an inexpensive electro-optical conversion element can be used, and the overall cost can be reduced.

  In order to achieve the above object, an optical transmission system according to a fourth invention of the present application is an optical transmission system in which an optical transmission device according to the second invention of the present application or the third invention of the present application multiplexes an input electric signal and optically modulates it Then, the subscriber device receives the transmission optical signal and converts it into an edited combined electrical signal, and separates the edited combined electrical signal.

  Specifically, in the fourth invention of the present application, the optical transmission apparatus according to the second invention of the present application or the third invention of the present application is combined with the transmission optical signal from the optical transmission apparatus, and the transmission optical signal is propagated. An optical transmission line that receives the transmitted optical signal coupled from the optical transmission line and converts it to m received electrical signals, and the m received electrical signals converted by the light receiving unit are n And a subscriber unit having a separation processing unit that performs separation processing into individual output electrical signals.

  Since the optical transmission system includes the optical transmission device of the second invention of the present application or the third invention of the present application, the same effects as those described in the optical transmission device of the second invention of the present application and the third invention of the present application are obtained. be able to.

  Therefore, the fourth invention of the present application can provide an optical transmission system that can flexibly multiplex electric signals at an electric level or an optical level and can expand future services.

  In the optical transmission system, the optical transmitter of the optical transmitter includes an optical combiner that multiplexes the m combined optical signals to form one transmitted optical signal, and the light receiver of the subscriber unit Preferably includes one photoelectric element that receives the transmission optical signal coupled from the optical transmission path, and a filter that separates an electrical signal output from the photoelectric element into the m reception electrical signals.

  Further, in the optical transmission system, the optical transmission path includes a plurality of optical fibers that propagate the transmission optical signal coupled from the optical transmission apparatus for each transmission optical signal, and a subscriber apparatus side of the optical fiber. An optical combining unit that multiplexes the transmission optical signal at an end and outputs the optical signal as one optical signal, and the light receiving unit of the subscriber unit receives one of the transmission optical signals coupled from the optical transmission line. It is preferable to include a photoelectric element and a filter that separates an electrical signal output from the photoelectric element into the m received electrical signals.

  The optical transmission unit or the optical transmission line includes the optical multiplexing circuit, so that the combined optical signal from the electro-optical conversion unit is multiplexed at the optical level and combined into one transmission optical signal to the subscriber unit. Output. In the light receiving unit of the subscriber unit, the multiplexed transmission optical signals are collectively converted into optical signals by one photoelectric element, and after the conversion, the received electric signals are separated by frequency band by a filter at an electric level. Thus, the number of expensive photoelectric elements can be reduced.

  Therefore, the fourth invention of the present application can provide an optical transmission system that can flexibly multiplex electrical signals at the electrical level or optical level, enable future service expansion, and reduce the cost of the subscriber unit. .

  The optical transmission line of the optical transmission system that multiplexes the combined optical signals and outputs the combined transmission optical signals to the optical transmission line is separated for each wavelength band. An optical wavelength separation filter, an optical amplifier that amplifies each optical signal separated for each wavelength band by the optical wavelength separation filter, and an optical combining unit that multiplexes the optical signals amplified by the optical amplifier, It is preferable to have a relay station that relays the transmitted optical signal.

  Further, the optical transmission line of the optical transmission system that multiplexes the transmission optical signals propagated through the optical transmission line and outputs the multiplexed optical signals to the subscriber unit is a light that amplifies the optical signal for each optical fiber. It is preferable to further include an amplifier.

  Since the transmission optical signal is amplified by the optical amplifier in the optical transmission line, the transmission optical signal can be propagated even at a long distance. Therefore, the fourth invention of the present application provides an optical transmission system that can flexibly perform multiplexing at the electrical level or optical level, enable future service expansion, and transmit optical signals to remote subscriber units. Can be provided.

  According to the present invention, it is possible to provide an optical transmission method, an optical transmission apparatus, and an optical transmission system that can flexibly perform multiplexing at an electrical level or an optical level and can expand services in the future.

  Embodiments of the present invention will be described with reference to the accompanying drawings. The embodiment described below is an example of the configuration of the present invention, and the present invention is not limited to the following embodiment.

(Embodiment 1)
In the present embodiment, the optical transmission device according to the second invention of the present application, the transmission optical signal from the optical transmission device are combined, the optical transmission line that propagates the transmission optical signal, and the optical transmission line are combined. A light receiving unit that receives the transmitted optical signal and converts it to m received electrical signals, and a separation processing unit that separates the m received electrical signals converted by the light receiving unit into n output electrical signals. An optical transmission system according to a fourth invention of the present application.

  The optical transmission apparatus according to the second invention of the present application provided in the optical transmission system according to the present embodiment is such that at least frequency band overlap occurs in the input n input electric signals (n is an integer of 1 or more). A frequency rearrangement unit that converts at least one frequency band of input electric signals having overlapping frequency bands into a frequency band that is not used by another input electric signal and outputs n frequency adjustment electric signals; and The n frequency adjustment electric signals from the rearrangement unit are passed as they are, or at least two of the n frequency adjustment electric signals from the frequency rearrangement unit are combined, and m (m is 1 ≦ m ≦ n (integer of n) electrical signal synthesizer for outputting edit synthesized electrical signal; and m (m is an integer of 1 ≦ p ≦ m) wavelengths of the m edited synthesized electrical signals from the signal synthesizer. Any of the wavelengths of light Light having an electrical-optical conversion unit that modulates the intensity into m composite optical signals, and an optical transmission unit that outputs the m composite optical signals from the electrical-optical conversion unit as transmission optical signals It is a transmission device.

  FIG. 1 is a block diagram showing an optical transmission system 500 which is an embodiment of an optical transmission system according to the fourth invention. The optical transmission system 500 includes an optical transmission device 1, an optical transmission line 5, and a subscriber device 6. In FIG. 1, the arrows indicate the flow of signals. The input electrical signal 200, the frequency adjustment electrical signal 201, the edit combined electrical signal 202, the combined optical signal 203, the transmitted optical signal 205, the received electrical signal 207, and the output electrical signal, respectively. Signal 208.

  The input electric signal 200 is obtained by receiving a high-frequency radio signal by an antenna (not shown) and converting it into an electric signal. The number of input electric signals 200 is generated as many as the number of high-frequency radio signals to be received (this embodiment will be described assuming that there are n input electric signals 200). Examples of high-frequency radio signals include terrestrial digital broadcast signals, BS digital broadcast signals, and mobile phone signals.

  The optical transmission device 1 includes a frequency rearrangement unit 27, an electric signal synthesis unit 28, an electro-optical conversion unit 3, and an optical transmission unit 4. The frequency rearrangement unit 27 and the electrical signal synthesis unit 28 are included in the signal editing synthesis unit 2. The subscriber device 6 includes a light receiving unit 7 and a separation processing unit 8.

  When at least frequency band overlap occurs in the n input electric signals 200, the frequency rearrangement unit 27 uses at least one frequency band of the input electric signals 200 having overlapping frequency bands as another input electric signal. 200 converts to an unused frequency band and outputs n frequency adjustment electric signals 201. Here, “at least” means “if necessary”, and means that frequency band conversion is performed when frequency band duplication occurs at least in the input electrical signal 200. That is, the frequency rearrangement unit 27 confirms the frequency band of the n input electric signals 200, and if there is an input electric signal 200 that needs to be frequency shifted, the frequency of the input electric signal 200 is shifted, and the frequency adjustment electric signal 201 is detected. Is a circuit that outputs. The frequency rearrangement unit 27 does not perform frequency shift on the input electric signal 200 that does not require frequency shift, and outputs it as the frequency adjustment electric signal 201 while maintaining the frequency band of the input electric signal 200.

  For example, when two of the input electric signals 200 have overlapping frequency bands, the frequency rearrangement unit 27 performs a frequency shift so that one of them does not overlap with the frequency band of the other input electric signal 200. Let The same applies when frequency band overlap occurs in three or more signals.

  Further, the frequency rearrangement unit 27 may shift the frequency of the input electrical signal 200 even if the input electrical signal 200 has no overlapping frequency band. This is because there is a case where multiplexing of the electric signal synthesizing unit 28, which will be described later, can be efficiently performed when the frequency is shifted.

  The electrical signal synthesizer 28 is a circuit that performs multiplexing at the electrical level, passes the n frequency adjusted electrical signals 201 as they are, or synthesizes at least two of the n frequency adjusted electrical signals 201 and m The edit synthesized electric signals 202 (m is an integer satisfying 1 ≦ m ≦ n) are output. Specifically, the electrical signal synthesis unit 28 selects and synthesizes a plurality of signals that can be multiplexed from the input frequency adjustment electrical signal 201, and outputs the synthesized signal as an edited synthesized electrical signal 202. When there are a plurality of groups of signals that can be multiplexed in the frequency-adjusted electrical signal 201, the electrical signal synthesis unit 28 can perform synthesis for each group. On the other hand, the electric signal combining unit 28 does not synthesize a signal that cannot be multiplexed among the input frequency adjustment electric signal 201 and outputs it as an edited combined electric signal 202. In the case of m = n, there is no signal that can be multiplexed, and the frequency adjusted electric signal 201 is output as it is as the edit synthesized electric signal 202. In the case of m <n, two or more frequency adjustment electric signals 201 are combined and output as an edited combined electric signal 202.

  FIG. 2 shows a first embodiment of the signal editing / synthesizing unit 2. In the signal editing / synthesizing unit 2, the frequency adjustment electric signal 201 output from the frequency rearrangement unit 27 is connected to the electric signal combining unit 28. The signal editing / synthesizing unit 2 in FIG. 2 can output a maximum of four outputs in any combination with respect to four inputs. The input electric signal 200 is first input to the frequency rearrangement unit 27, converted in frequency band so that the frequency bands of the electric signals to be combined do not overlap, and output to the electric signal combining unit 28. Reference numerals 11 to 26 of the electric signal synthesizer 28 are 2-input and 2-output signal synthesis switches all having the same configuration. FIG. 3 shows the configuration and state of the signal synthesis switch 11. The signal synthesis switch 11 has two states. FIG. 3A is a diagram of state 1 in which the signal on the signal line 31 is connected to the signal line 32 and the signal on the signal line 33 is connected to the signal line 34. FIG. 3B is a diagram of state 2 in which the signal on the signal line 31 is connected to the signal line 32 and the signal on the signal line 33 is connected to the signal line 32. That is, in FIG. 3B, a signal obtained by combining the signal on the signal line 31 and the signal on the signal line 33 is obtained on the signal line 32. By setting the states of the signal synthesis switches 11 to 26 in FIG. 2 by the operation of the signal synthesis switch shown in FIG. 3, an edit synthesis electrical signal 202 in which the frequency adjustment electrical signal 201 is multiplexed is output.

  In the present embodiment, the configuration of the signal editing / synthesizing unit having four inputs and a maximum of four outputs is shown. However, it is apparent that the present invention includes a configuration for an arbitrary number of inputs.

  FIG. 4 is a diagram for explaining the operation of the first embodiment of the signal editing / synthesizing unit 2 of FIG. The input electric signal 200 input to the signal editing / synthesizing unit 2 includes four electric signals (electric signal 40, electric signal 41, electric signal 42, and electric signal 43). In the figure, four electric signals are displayed in a graph. The horizontal axis of the graph indicates the frequency, and the vertical axis indicates the signal intensity. Since the electric signal 42 of the electric signal 40 to the electric signal 43 overlaps with the electric signal 41 in the frequency band, in this example, another electric signal (electric signal 40, electric signal 41, electric signal) is generated in the frequency rearrangement unit 27. 43) The frequency of the electric signal 42 is shifted so as not to overlap with the frequency band 43). By shifting the frequency in this way, the electrical signal 42 can be combined and added with other electrical signals. After the frequency shift of the electric signal 42, the electric signal 43 does not overlap with other electric signals in frequency, but the input level is small and the amplitude is small, so that the single electric signal is not synthesized with the other electric signals. Will be output.

  Therefore, the signal synthesis switch 11, the signal synthesis switch 15, the signal synthesis switch 19, and the signal synthesis switch 24 of the electrical signal synthesis unit 28 are set to state 2, and the other signal synthesis switches are set to state 1. By setting the signal combining switch as described above, the three input electric signals of the electric signal 40, the electric signal 41, and the electric signal 42 are combined and output to the signal line 71. The electric signal 43 is output to the signal line 70 as it is. In FIG. 4, the switch in which the signal synthesis switch is shown in white is in state 1 in FIG. 3, and the switch in which the signal synthesis switch is shown in black is in state 2 in FIG.

  FIG. 5 shows another configuration example of the electrical signal synthesis unit 28. The signal synthesis switch 51 to the signal synthesis switch 53 are the same as the signal synthesis switch having two inputs and two outputs shown in FIG.

  The signal combining switch 51 receives the first electric signal and the second electric signal, one of the output signals is input as the editing combined electric signal 202 of the signal editing combining unit 2, and the other is input to the signal combining switch 52. . The signal synthesis switch 52 receives the third electrical signal and one of the outputs from the signal synthesis switch 51. One of the output electrical signals is the edit synthesis electrical signal 202 of the signal editing synthesis unit 2, and the other is the signal synthesis switch. 53. One of the fourth electrical signal and the output from the signal synthesis switch 52 is input to the signal synthesis switch 53, and the two outputs become the edit synthesis electrical signal 202 of the signal editing synthesis unit 2.

  Next, the operation of the electric signal synthesis unit 28 in FIG. 5 will be described. As described with reference to FIG. 4, four electric signals (electric signal 44, electric signal 45, electric signal 46, and electric signal 47) are also input from the frequency rearrangement unit 27 to the electric signal synthesis unit 28 in FIG. The electric signal 44 to the electric signal 47 are changed from the first electric signal to the fourth electric signal, respectively. In FIG. 5, the frequency band of the electrical signal 46 is shifted, and any electrical signal does not overlap with the frequency bands of other electrical signals. Similar to FIG. 4, the electrical signal 44 to the electrical signal 47 are graphically displayed.

  The electrical signal 44 and the electrical signal 45 are input to the signal synthesis switch 51 in the state 2 having the internal connection state indicated by the dotted line in the figure, and are synthesized and added to be output to the signal synthesis switch 52. Since the signal synthesis switch 52 is in the state 1 having an internal state indicated by a dotted line in the figure, a synthesized addition signal of the input electric signal 44 and the electric signal 45 is output to the signal line 54 and the electric signal 46 is signal synthesized. Output to the switch 53. Since the signal synthesis switch 53 is in state 1 having an internal state indicated by a dotted line in the figure, the electrical signal 46 input from the signal synthesis switch 52 is applied to the signal line 55, and the input electrical signal 47 is applied to the signal line 56. Each is output. Although the frequency band distributions of the four electric signals input to the electric signal synthesizing unit 28 in FIG. 5 and the electric signal synthesizing unit 28 in FIG. 4 are the same, the edited synthesized electric signals 202 having different patterns are output.

In the present embodiment, the electric signal combining unit 28 is configured by three signal combining switches, but in general, (n−1) signal combining switches are used for any n input electric signals. well, it is possible to configure the electric signal combining unit 28 as compared with the ^two n of the embodiment of FIG. 2, with a small number of signal combining switch.

  As described above, in the embodiment of FIG. 5, the electrical signal synthesis unit 28 can be realized with a small number of signal synthesis switches. However, it is necessary to input the electric signal to be combined to the adjacent position.

  FIG. 6 shows another embodiment of the signal editing / synthesizing unit 2. In FIG. 6, the same reference numerals as those described in FIGS. 1 to 4 denote the same components. The difference from the signal editing / synthesizing unit 2 in FIG. 2 is that the signal editing / synthesizing unit 2 in FIG. 6 further includes a frequency modulation unit 61. The frequency modulation unit 61 outputs an electric signal obtained by frequency-modulating each input electric signal. For example, a frequency modulator using an optical heterodyne method can be used as the frequency modulation unit 61 (for example, Shibata et al. “Optical video distribution system using FM batch conversion method”, IEICE Transactions B vol. 83-B No7 pp 948-959 July 2000). By using a frequency modulator using the optical heterodyne method, it is possible to obtain a wideband frequency modulation signal having a large modulation degree.

  FIG. 7 is a diagram for explaining the operation of the signal editing / synthesizing unit 2 of FIG. In FIG. 7, the same reference numerals as those used in FIGS. 1 to 6 denote the same or the same signals. However, in FIG. 7, it is assumed that the signal strength of the electrical signal 43 is equal to the signal strength of other electrical signals. As described with reference to FIG. 4, the frequency rearrangement unit 27 shifts the frequency of the electric signal 42. The signal synthesis switch 11, the signal synthesis switch 15, the signal synthesis switch 20, and the signal synthesis switch 24 of the electric signal synthesis unit 28 in FIG. 7 are in state 2, and the other signal synthesis switches are in state 1. By setting the signal synthesis switch in this way, the electrical signal 40 and the electrical signal 41 are synthesized and added and output to the signal line 71, and the electrical signal 42 and the electrical signal 43 are synthesized and added and outputted to the signal line 70. . The electric signals of the signal line 70 and the signal line 71 are input to the frequency modulation unit 61 and subjected to frequency modulation to obtain an electric signal 62 and an electric signal 63, respectively. As described above, when the signal editing / synthesizing unit 2 of FIG. 6 is used, the electric signal 62 and the electric signal 63 become the editing / combining electric signal 202. In FIG. 7, the electric signal 62 and the electric signal 63 are also displayed in a graph.

  In this way, the signal editing / synthesizing unit 2 can multiplex at the electrical level even if the frequency bands of the input electrical signal 200 overlap.

  The electro-optical conversion unit 3 inputs m (m is an integer of 1 ≦ m ≦ n) input composite editing electric signals 202 out of p (p is an integer of 1 ≦ p ≦ m) wavelengths. The intensity is modulated with light of any wavelength and converted into m composite optical signals 203. When p = 1, the light of the same wavelength is intensity-modulated, and when p = m, the light having a different wavelength is intensity-modulated for each editing / combining electric signal 202. An example of the electro-optical converter 3 is an optical circuit in which p laser diodes and an external modulator are combined. The electro-optical conversion unit 3 converts the intensity of the light from the laser diode with an external modulator and converts the edited combined electric signal 202 into the combined optical signal 203.

  The optical transmission unit 4 outputs m combined optical signals 203 as transmission optical signals 205 to the outside of the optical transmission device 1. The optical sending unit 4 outputs a single optical signal by multiplexing m optical signals 203 as they are as transmission optical signals 205 and multiplexing the optical signals 203 at an optical level such as optical wavelength multiplexing and optical coupling. In some cases, the transmitted optical signal 205 may be output. The optical transmitter 4 of the first embodiment is the latter case, and includes an optical combiner that multiplexes m combined optical signals 203 to form one transmitted optical signal 205.

  An example of the optical transmission line 5 is an optical fiber. In the case of Embodiment 1, the number of optical fibers is one.

  The light receiving unit 7 receives the transmission light signal 205 and converts it to m reception electric signals 207. FIG. 8 is an example showing one configuration of the light receiving unit 7 in the case of the first embodiment. The light receiving unit 7 includes a photoelectric element 80 such as a PD and a filter group 81. The filter group 81 can separate each electric signal when the frequency bands of the electric signals obtained by modulating the optical signals do not overlap. The light receiving unit 7 converts the input optical signal into an electrical signal by the photoelectric element 80, and the electrical signal is separated into m received electrical signals 207 by the filter group 81 and output.

  When the optical transmission line 5 is a plurality of optical fibers and the transmission optical signal 205 is m optical signals that are not multiplexed at the optical level, the light receiving unit 7 includes the same number of photoelectric elements as the number of optical fibers. . The light receiving unit 7 receives the optical signal propagated through each optical fiber by the corresponding photoelectric element, and outputs m received electrical signals 207.

  The separation processing unit 8 separates m received electrical signals 207 into n output electrical signals 208. In the case of the embodiment of the signal editing / synthesizing unit shown in FIG. 6, the separation processing unit 8 needs an FM demodulation function for demodulating the frequency-modulated signal at the input part.

  The optical transmission system 500 in FIG. 1 has frequency band overlap when the optical transmission apparatus has at least frequency band overlap in n input (n is an integer of 1 or more) input electrical signals. A frequency rearrangement step of converting at least one frequency band of the input electric signal into a frequency band that is not used by another input electric signal to generate n frequency adjustment electric signals; and after the frequency rearrangement step, An optical transmission device passes the n frequency adjustment electric signals generated in the frequency rearrangement step as they are, or at least two of the n frequency adjustment electric signals generated in the frequency rearrangement step And m (m is an integer satisfying 1 ≦ m ≦ n) to generate an edit combined electric signal, and after the signal combining step, the optical transmission apparatus The m edited combined electric signals generated in step are intensity-modulated with light of any one of p wavelengths (p is an integer of 1 ≦ p ≦ m), and m combined optical signals are generated. An optical transmission step of multiplexing the m combined optical signals to generate one transmission optical signal and outputting it to an optical transmission line; and after the optical transmission step, a subscriber unit transmits the optical transmission A light receiving step of receiving the transmitted optical signal propagated through the path and photoelectrically converting it to generate a received electrical signal; and after the light receiving step, the subscriber unit filters the received electrical signal generated in the light receiving step with a filter. An electric signal converting step for converting into m received electric signals, and after the electric signal converting step, a subscriber unit converts n output electric signals from the m received electric signals converted in the electric signal converting step. Separation that separates signals And management step, in the optical transmission method comprising, delivery to subscribers high-frequency radio signals to be inputted.

  The n input electric signals 200 are input to the signal editing / synthesizing unit 2 of the transmission unit 1. The frequency band of the input electric signal 200 is converted by the frequency rearrangement unit 27 of the signal editing / synthesizing unit 2 (frequency rearrangement step). It is converted to a signal that does not overlap in frequency with m (m ≦ n) and output (signal synthesis step). Here, when m is smaller than n, the electrical level is multiplexed and two or more electrical signals are combined into one electrical signal. Further, the m electrical transmission signals are converted into optical signals by the electrical-optical conversion unit 3 and transmitted from the optical transmission unit 4 to the optical transmission line 5 (optical transmission step). In the case of the first embodiment, the optical transmission step transmits an optical signal on one fiber by wavelength multiplexing. However, there are cases in which individual optical signals are transmitted on individual optical fibers.

  An optical signal from the optical transmission line 5 enters the subscriber unit 6 and is received by the light receiving unit 7 by one light receiving element (light receiving step), and after reception, is converted into m received electric signals by the filter (electrical). Signal conversion step). The m received electrical signals are subjected to signal frequency conversion and separation processing by the filter by the separation processing unit 8 (separation processing step), and n output electrical signals are output.

  In the optical transmission system 500, even if the number of input electric signals 200 increases, the signal editing / synthesizing unit 2 multiplexes the electric levels, so that the number of editing / combining electric signals 202 can be reduced. Thereafter, in the optical transmission system 500, the edited combined electric signal 202 is converted into the combined optical signal 203 by the electro-optical converting unit 3, and the optical transmission unit 4 performs optical level multiplexing. Therefore, the optical transmission system 500 can flexibly multiplex electric signals at an electric level or an optical level, and can expand services in the future.

(Embodiment 2)
When the distance of the optical transmission path 5 in the optical transmission system 500 of FIG. 1 is long, the optical transmission path is an optical wavelength separation filter that separates the transmission optical signal coupled from the optical transmission apparatus for each wavelength band, the optical An optical amplifier that amplifies each optical signal separated for each wavelength band by a wavelength separation filter, and an optical combining unit that multiplexes the optical signals amplified by the optical amplifier, and relays the combined transmission optical signal You may have a station.

  FIG. 10 is a diagram illustrating a configuration example of the optical transmission path 5 in the optical transmission system 500 according to the second embodiment, and illustrates only the electro-optical conversion unit 3, the light transmission unit 4, the optical transmission path 5, and the light receiving unit 7. Others are omitted. 10, the same reference numerals as those used in FIGS. 1 to 8 denote the same components and the same signals. The difference between the optical transmission line 5 in FIG. 10 and the optical transmission line 5 in FIG. 1 is that the optical transmission line 5 in FIG. 10 has a relay unit 92 that relays the transmission optical signal 205.

  In the electro-optical conversion unit 3, the m optical signals are subjected to light intensity modulation by the electro-optical conversion elements 82 to 84 having different wavelengths λ 1 to λ m, and the combined optical signal 203 is transmitted to the light combining unit 87 of the light transmission unit 4. Wavelength multiplexing is then performed and output to a single optical fiber.

  The relay unit 92 of the optical transmission line 5 amplifies the input transmission optical signal 205. For example, the input transmission optical signal 205 is separated into a long wavelength band optical signal and a short wavelength band optical signal by the wavelength separation unit 88. As an example, the separated optical signal is a 1.3 μm band short wavelength optical signal and a 1.5 μm band long wavelength optical signal. The optical signal in the short wavelength band and the optical signal in the long wavelength band are amplified by the individual optical amplifier 89 and the optical amplifier 90, and the output optical signal is wavelength-multiplexed by the optical combining unit 91. The number of relay units 92 is determined according to the distance between the optical transmission device 1 and the subscriber device 6. The transmission optical signal 205 reaches the subscriber device 6 via the relay unit 92. Therefore, the subscriber device 6 receives the transmission optical signal 205 and outputs the output electrical signal 208 as described in the first embodiment.

  Therefore, the optical transmission system 500 of the second embodiment can obtain the same effects as the optical transmission system 500 of the first embodiment.

(Embodiment 3)
In the optical transmission system 500 of FIG. 1, when the optical transmission unit 4 does not include an optical combining unit and outputs the combined optical signal 203 as it is to the optical transmission line 5 as the transmission optical signal 205, the optical transmission line is the optical transmission device. A plurality of optical fibers that propagate the transmission optical signals combined for each transmission optical signal, and the transmission optical signals are multiplexed on the end of the optical fiber on the subscriber unit side and output as one optical signal A light combining unit, wherein the light receiving unit of the subscriber unit receives one of the photoelectric elements that receive the transmission optical signal coupled from the optical transmission path and the m signals received from the photoelectric elements. A filter that separates into electrical signals may be included.

  FIG. 9 is a diagram illustrating a configuration example of the optical transmission path 5 in the optical transmission system 500 according to the third embodiment, and illustrates only the electro-optical conversion unit 3, the light transmission unit 4, the optical transmission path 5, and the light receiving unit 7. Others are omitted. 9, the same reference numerals as those used in FIGS. 1 to 8 denote the same components and the same signals. 9 is different from the optical transmission line 5 in FIG. 1 in that the optical transmission line 5 in FIG. 9 includes a plurality of optical fibers and an optical combining unit 86 for multiplexing the transmission optical signal 205. It is. The light combining unit 86 is in the vicinity of the junction between the optical transmission line 5 and the subscriber unit 6.

  When the distance of the optical transmission line 5 is long, the optical transmission line may further include an optical amplifier that amplifies an optical signal for each optical fiber.

  In the electro-optical conversion unit 3, the m optical signals are subjected to light intensity modulation by the electro-optical conversion elements 82 to 84 having different wavelengths λ1 to λm. Each is coupled to a fiber.

  The transmission optical signal 205 coupled to each optical fiber is amplified and transmitted by the optical amplifier 85 according to the transmission distance in the optical transmission line 5. The transmission optical signal 205 is received by one photoelectric element in the light receiving unit 7 of the subscriber device 6, and is multiplexed by the light combining unit 86 of the optical transmission path 5. The multiplexed optical signal is received by the light receiving unit 7. Therefore, the subscriber device 6 receives the transmission optical signal 205 and outputs the output electrical signal 208 as described in the first embodiment. Therefore, the optical transmission system 500 of the third embodiment can obtain the same effects as the optical transmission system 500 of the first embodiment.

(Embodiment 4)
The optical transmission device included in the optical transmission system according to the fourth invention of the present application has a frequency band when at least frequency band overlap occurs in n input electrical signals (n is an integer of 1 or more). A frequency rearrangement unit that converts at least one frequency band among the overlapping input electric signals into a frequency band that is not used by another input electric signal and outputs n frequency adjustment electric signals, and the frequency rearrangement unit The n frequency-adjusted electric signals from the light are intensity-modulated with light of any one of q wavelengths (q is an integer of 1 ≦ q ≦ n) and converted into n wavelength-adjusted optical signals. The n wavelength adjustment optical signals are passed as they are, or at least two of the n wavelength adjustment optical signals are combined, and m (m is an integer of 1 ≦ m ≦ n) combined optical signals. An optical signal combining unit to output, and a signal from the signal combining unit An optical transmitting section for outputting m number of the combined light signal as a transmitted optical signal may be an optical transmission apparatus having a.

  The present embodiment is another example of the optical transmission system according to the fourth invention of the present application. FIG. 11 is a block diagram showing the optical transmission system 510 of this embodiment. In FIG. 11, the same reference numerals as those used in FIGS. 1 to 10 denote the same components and the same signals. The difference between the optical transmission system 510 and the optical transmission system 500 of FIG. 1 is that the optical transmission apparatus 101 is not the optical transmission apparatus 1.

  The difference between the optical transmitter 101 and the optical transmitter 1 of FIG. 1 is that the signal editing / synthesizing unit 2 is the signal editing / synthesizing unit 102 and does not have the electro-optical converting unit 3.

  FIG. 12 shows an embodiment of the signal editing / synthesizing unit 102. The difference between the signal editing / synthesizing unit 102 and the signal editing / synthesizing unit 2 in FIG. 2 is that an electrical-to-optical conversion unit 121 is provided for each output of the frequency rearrangement unit 27 in the subsequent stage of the frequency rearrangement unit 27. An optical signal synthesis unit 128 is provided as an alternative to the signal synthesis unit 28.

  The electro-optical conversion unit 121 modulates the intensity of the n frequency-adjusted electric signals 201 with light of any one of q wavelengths (q is an integer of 1 ≦ q ≦ n), and outputs n frequency-adjusted electric signals 201. It converts into the wavelength adjustment optical signal 301. As the electro-optical converter 121, the optical circuit described in the electro-optical converter 3 can be exemplified.

  The optical signal combining unit 128 passes the n wavelength adjustment optical signals 301 as they are or combines at least two of the n wavelength adjustment optical signals 301, and m (m is an integer of 1 ≦ m ≦ n). The combined optical signal 203 is output. The optical signal synthesizer 128 synthesizes an optical signal that can be multiplexed from the wavelength-adjusted optical signal 301 as in the electrical signal synthesizer 28 described with reference to FIGS. Therefore, the signal editing / synthesizing unit 102 can multiplex the optical signals into groups that can be multiplexed even if the number of input electrical signals that are input by expanding the service increases, and the number of combined optical signals 203 can be reduced. .

  The combined optical signal 203 from the signal editing / combining unit 102 is output to the optical transmission line 5 as the transmission optical signal 205 via the optical transmission unit 4. The subscriber device 6 receives the transmission optical signal 205 and outputs the output electrical signal 208 as described in the first embodiment.

  Therefore, the optical transmission system 510 can flexibly multiplex electrical signals at the optical level, and enables future service expansion.

  Although the number of electro-optical conversion elements to be used is increased by optically modulating the frequency-adjusted electric signal 201 by the individual electro-optical conversion unit 121, the linearity and broadband characteristics required for the electro-optical conversion unit 121 are increased. Is relaxed from the electro-optic conversion element of the electro-optic conversion unit 3 that performs electro-optic conversion after multiplexing at the electrical level. Therefore, an inexpensive electro-optical conversion element can be used, and the overall cost can be reduced.

  The optical transmission method according to the present invention can be used not only for distributing an optical signal multiplexed using an optical waveguide such as an optical fiber but also as a radio signal for multiplexing a plurality of electrical signals.

It is a figure which shows the structural example of the optical transmission system which concerns on one Embodiment of this invention. It is a figure which shows 1st Example of a signal edit synthetic | combination part. It is a figure which shows the structure and state of an electric signal synthetic | combination switch. It is a figure which shows the operation example of 1st Example of a signal edit synthetic | combination part. It is a figure which shows another structural example and operation example of an electric signal synthetic | combination part. It is a figure which shows 2nd Example of a signal edit synthetic | combination part. It is a figure which shows the operation example of 2nd Example of a signal edit synthetic | combination part. It is a figure which shows one Example of a light-receiving part. It is a figure which shows one structural example of an optical transmission line. It is a figure which shows another structural example of an optical transmission line. It is a figure which shows the structural example of the optical transmission system which concerns on other embodiment of this invention. It is a figure which shows 3rd Example of a signal edit synthetic | combination part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 Optical transmission apparatus 2,102 Signal edit combining part 3,121 Electrical-optical conversion part 4 Optical transmission part 5 Optical transmission line 6 Subscriber apparatus 7 Light receiving part 8 Separation processing parts 11-26, 51, 52, 53 Signal Synthesis switches 111 to 126 Optical switch 27 Frequency rearrangement unit 28 Electrical signal synthesis unit 128 Optical signal synthesis units 31 to 34, 54, 55, 56, 70, 71 Signal lines 40 to 47, 62, 63 Electrical signal 61 Frequency modulation unit 80 Photoelectric element 81 Filter group 82, 83, 84 Electro-optical conversion elements 85, 89, 90 Optical amplifiers 86, 87, 91 Optical synthesis unit 88 Wavelength separation unit 92 Relay unit 200 Input electrical signal 201 Frequency adjustment electrical signal 202 Editing / synthesis electrical signal 203 Combined Optical Signal 205 Transmitted Optical Signal 207 Received Electrical Signal 208 Output Electrical Signal 301 Wavelength Adjustment Optical Signal 500, 510 Optical Transmission System

Claims (9)

When at least frequency band duplication occurs in the input electric signals of n (n is an integer of 1 or more), at least one frequency among the input electric signals having overlapping frequency bands is received by the optical transmission device. A frequency rearrangement step of converting the band to a frequency band that is not used by other input electric signals to generate n frequency-adjusted electric signals;
After the frequency rearrangement step, the optical transmission device passes the n frequency adjustment electrical signals generated in the frequency rearrangement step as they are, or the n frequencies generated in the frequency rearrangement step. A signal synthesis step of synthesizing at least two of the adjusted electrical signals and generating m (m is an integer of 1 ≦ m ≦ n) edit synthesis electrical signals;
After the signal synthesizing step, the optical transmission device is one of p (p is an integer of 1 ≦ p ≦ m) wavelengths of the m edited synthesized electric signals generated in the signal synthesizing step. An optical transmission step of modulating the intensity with light having a wavelength of m to convert it into m composite optical signals, multiplexing the m composite optical signals to generate one transmission optical signal, and outputting it to the optical transmission line;
After the light transmission step, the subscriber unit receives the transmission optical signal propagated through the optical transmission line, photoelectrically converts it to generate a received electrical signal, and
After the light receiving step, the subscriber device converts the received electrical signal generated in the light receiving step into m received electrical signals by a filter; and
After the electrical signal conversion step, the subscriber device performs a separation process from the m received electrical signals converted in the electrical signal conversion step to n output electrical signals;
An optical transmission method comprising: When at least frequency band overlap occurs in n input electrical signals (n is an integer equal to or greater than 1), at least one frequency band of the input electrical signals having overlapping frequency bands is input to another input signal. A frequency rearrangement unit that converts an electrical signal into an unused frequency band and outputs n frequency-adjusted electrical signals;
The n frequency adjustment electrical signals from the frequency rearrangement unit are passed as they are, or at least two of the n frequency adjustment electrical signals from the frequency rearrangement unit are combined, and m (m is 1 An electrical signal synthesis unit that outputs an edit synthesis electrical signal of ≦ m ≦ n),
The m synthesized synthesized electric signals from the signal synthesizing unit are intensity-modulated with light of any one of p wavelengths (p is an integer of 1 ≦ p ≦ m), and m synthesized lights. An electro-optical converter that converts the signal into a signal;
A light transmission unit that outputs the m combined optical signals from the electro-optical conversion unit as a transmission optical signal;
An optical transmitter having   The optical transmission device according to claim 2, further comprising a frequency modulation unit that modulates the frequency of each of the edited combined electric signals from the signal combining unit and outputs the modulated electric signals to the electro-optical conversion unit. When at least frequency band overlap occurs in n input electrical signals (n is an integer equal to or greater than 1), at least one frequency band of the input electrical signals having overlapping frequency bands is input to another input signal. A frequency rearrangement unit that converts an electrical signal into an unused frequency band and outputs n frequency-adjusted electrical signals;
The n frequency-adjusted electric signals from the frequency rearrangement unit are intensity-modulated with light of any one of q wavelengths (q is an integer of 1 ≦ q ≦ n), and n wavelengths Convert to an adjusted optical signal, pass the n wavelength adjusted optical signals as they are, or synthesize at least two of the n wavelength adjusted optical signals, m (m is an integer of 1 ≦ m ≦ n) An optical signal combining unit that outputs a combined optical signal of
An optical transmission unit that outputs the m combined optical signals from the signal combining unit as transmission optical signals;
An optical transmitter having An optical transmission device according to any one of claims 2 to 4,
An optical transmission path through which the transmission optical signal from the optical transmission device is combined and propagates the transmission optical signal;
A light receiving unit that receives the transmission optical signal coupled from the optical transmission path and converts it into m received electrical signals, and the m received electrical signals converted by the light receiving unit into n output electrical signals. A subscriber unit having a separation processing unit for separation processing;
An optical transmission system comprising: The optical transmitter of the optical transmitter includes an optical combiner that multiplexes the m combined optical signals to form one of the transmitted optical signals,
The light receiving unit of the subscriber unit separates one photoelectric element that receives the transmission optical signal coupled from the optical transmission path and an electric signal output from the photoelectric element into the m reception electric signals. The optical transmission system according to claim 5, further comprising a filter.   The optical transmission line amplifies the optical wavelength separation filter that separates the transmission optical signal coupled from the optical transmission device for each wavelength band, and the optical signals separated for each wavelength band by the optical wavelength separation filter. The optical transmission system according to claim 6, further comprising an optical amplifier and an optical combining unit that multiplexes the optical signal amplified by the optical amplifier, and a relay station that relays the combined transmission optical signal. The optical transmission path includes a plurality of optical fibers that propagate the transmission optical signal coupled from the optical transmission apparatus for each transmission optical signal, and the transmission optical signal at an end of the optical fiber on the subscriber unit side. Including a light combining unit that multiplexes and outputs as one optical signal,
The light receiving unit of the subscriber unit separates one photoelectric element that receives the transmission optical signal coupled from the optical transmission path and an electric signal output from the photoelectric element into the m reception electric signals. The optical transmission system according to claim 5, further comprising a filter.   The optical transmission system according to claim 8, wherein the optical transmission path further includes an optical amplifier that amplifies an optical signal for each of the optical fibers.

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