JP2005026770A - Transmission apparatus mounted on moving object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transmission apparatus mounted on a moving object which can efficiently use a space inside the moving body and has efficient countermeasures against electromagnetic disturvance. <P>SOLUTION: In the transmission apparatus 100 mounted on the moving object, signals of communication services such as a GPS signal 120, a VICS signal 124 and a ETC signal 128 are transmitted directly using radio frequencies or after converted to an intermediate frequency through a single-core optical cable 104, and optical beacon signals 130, 134 are frequency-modulated to be frequency-multiplexed, are converted into optical signals to be optical-multiplexed, and are transmitted by the cable 104, between an end edge side apparatus 106 provided on the end edge side of a communication service apparatus and a main body apparatus 108 provided on the main body. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mobile unit-mounted transmission device, and more particularly to a vehicle-mounted transmission device that is mounted on a vehicle such as an automobile and transmits a signal between an edge portion of an antenna of a vehicle-mounted communication device and a main body connected thereto. Is.
[0002]
[Prior art]
As is well known, for example, land transportation vehicles such as automobiles tend to be equipped with various communication devices using a gigahertz (GHz) frequency band. These in-vehicle communication devices include, for example, a global positioning system (GPS), an intelligent road traffic system (ITS), and a road traffic information communication system in addition to existing broadcasting devices such as AM broadcasting, FM broadcasting, and analog television broadcasting. (VICS) and in-vehicle communication devices of various communication systems such as terrestrial digital television broadcasting are included.
[0003]
[Problems to be solved by the invention]
Since these in-vehicle communication devices are generally mobile bodies, they naturally require an edge portion such as an antenna. Connection lines are laid separately for each communication system in order to transmit signals between these edge portions and the in-vehicle device main body. Therefore, as the number of in-vehicle devices increases, the number of signal transmission cables increases. , Complicated in a narrow interior space. Also, the importance of electromagnetic interference (EMI) countermeasures increases.
[0004]
However, since each communication system has been independently developed, it often uses a unique method such as a frequency band or a modulation method. Therefore, it is not easy to reduce the number of in-vehicle transmission cables by integrating the transmission lines of each communication system.
[0005]
An object of the present invention is to provide a mobile unit-mounted transmission device that eliminates the above-described drawbacks of the prior art, can efficiently use the space inside the mobile unit, and is effective in preventing electromagnetic interference.
[0006]
[Means for Solving the Problems]
The mobile-mounted transmission device according to the present invention provides a GPS signal between an edge side device arranged near the edge side of a communication service device and a body side device arranged near the body side. The signal of the first communication service such as the VICS signal and the ETC signal is directly converted into the radio frequency or the intermediate frequency, and the signal of the second communication service such as the optical beacon signal is frequency-modulated to convert them. Frequency-multiplexed, converted into an optical signal, wavelength-multiplexed, and transmitted by a single-core optical cable 104.
[0007]
A mobile unit-mounted transmission device according to the present invention includes an edge side device disposed near an edge side of a communication service device, a body side device disposed near a body side, and an edge side. The device and the main unit side device are connected to each other with an optical transmission line, and the edge side device converts the first communication service signal such as a radio frequency GPS signal, VICS signal and ETC signal directly or to an intermediate frequency. The second communication service signal such as an optical beacon signal is frequency-modulated, frequency-multiplexed and converted into an optical signal, and the optical transmission line transmits the optical signal from the edge side device to the main unit. Transmit to the side device.
[0008]
According to the present invention, the main unit side device converts the optical signal received from the optical transmission path into an electrical signal, and the signal of the first communication service is frequency-separated with respect to the converted electrical signal, and the second The communication service signal may be demodulated.
[0009]
Further, according to the present invention, the edge side device includes a wavelength multiplexing circuit that wavelength-multiplexes the optical signal prior to transmission to the transmission line, and the main unit side device wavelength-separates the optical signal received from the transmission line. A separation circuit may be included.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of a mobile unit-mounted transmission device according to the present invention will be described in detail with reference to the accompanying drawings. Referring to FIGS. 1 and 2, the illustrated embodiment is an in-vehicle transmission device 100 mounted on a vehicle such as an automobile, and includes four types of communication systems, namely, a global positioning system (GPS), an intelligent road traffic system ( Integrated ITS), road traffic information communication system (VICS), and optical beacon system, which is an edge that integrates an antenna and a light projecting / receiving unit that communicate with external devices such as communication satellites and ground stations A single optical cable 104 connects the antenna 102 and the main body (not shown) of the communication system that is remote from the antenna 102 in the vehicle. As shown in the drawing, the in-vehicle transmission device 100 of the embodiment as a whole has an edge side device 106 disposed between the integrated antenna unit 102 and one end 104 a of the optical cable 104, and the other end of the optical cable 104. And a main body side device 108 disposed between the end 104b and the main body.
[0011]
Referring to FIG. 1, the integrated antenna unit 102 is basically a physically integrated unit including a GPS antenna 110, a VICS antenna 112, an ETC antenna 114, and an optical beacon light projecting / receiving unit 116. is there. The GPS antenna 110 is connected to the input 120 of the GPS unit 118 of the edge side device 106. Further, the VICS antenna 112 is connected to the input 124 of the VICS unit 122 of the edge side device 106, and the ETC antenna 114 is similarly connected to the input / output 128 of the ETC unit 126 of the edge side device 106. Has been. In the light beacon light projecting / receiving unit 116, the projector input 132 is connected to the input of the optical beacon unit 132 of the edge side device 106, and the light receiver output 134 is connected to the input of the optical beacon unit 132. In the following description, signals are indicated by the reference numerals of the connecting lines that appear.
[0012]
The GPS unit 118 down-converts the GPS signal arriving at the input 120 to a predetermined intermediate frequency IF1, and automatically gain-controls (AGC) the signal to a predetermined level, and this is output from the output 136 to one input of the multiplexer 138. It is the conversion circuit given to. The current GPS signal has a frequency of about 1.5 GHz and a bandwidth of about 1 MHz. In this embodiment, the intermediate frequency IF1 is 5 MHz. This is because the influence of the group delay time characteristic is great, so that the lowest possible frequency is selected to compensate for the delay. Hereinafter, in the description of the embodiments, a number of numerical values are described. However, these numerical values are for description of the embodiments and should not be construed as limiting the present invention.
[0013]
The VICS unit 122 down-converts the VICS signal arriving at the input 124 to another predetermined intermediate frequency IF2, automatically controls the gain to the predetermined level described above, and outputs it from the output 140 to the other of the multiplexer 138. It is a conversion circuit given to one input. The current VICS signal has a frequency of about 2.5 GHz and a bandwidth of 0.85 MHz. In this embodiment, the intermediate frequency IF2 is 10.8 MHz, and the GMSK modulation bandwidth is 64 kHz or less. In this embodiment, the GPS unit 118 and the VICS unit 122 may be structurally the same as described later.
[0014]
Further, the ETC unit 126 up-converts an ETC output signal 144 supplied from a duplexer 142 (to be described later) and drives the antenna 114 through the input / output 128, and receives an ETC signal arriving from the antenna 114 at the input / output 128. This is a conversion circuit that down-converts to another predetermined intermediate frequency IF3, performs automatic gain control to a predetermined level, and supplies this to the other input of the multiplexer 138 from its output 146. The current ETC signal differs between upstream and downstream, but has a frequency of about 5.8 GHz and a bandwidth of 8 MHz. In the present embodiment, the intermediate frequency IF3 is a double conversion in which 26 MHz is employed, the first stage uses an intermediate frequency of 40 MHz with a bandwidth of 4 MHz, and the second stage uses 26 MHz. This is to comply with the output spectrum standard of ETC output, and such double conversion is advantageous as a measure against unnecessary radiation. Moreover, the circuit element which can be obtained cheaply can be utilized by performing double conversion. Of course, the present invention is not limited to this double conversion.
[0015]
Further, the optical beacon unit 132 performs pulse amplitude modulation (PAM) on the frequency-modulated (FM) optical beacon output signal 148 supplied from the duplexer 142, drives the light emitter / receiver 116 through the output 130, and A conversion circuit that converts the PAM-modulated optical beacon input signal 134 arriving from the light emitter / receiver 116 into an FM signal at a predetermined carrier frequency IF4 and applies this to the remaining input of the multiplexer 138 from its output 150. is there. In this embodiment, the optical beacon signal has a bit rate of 64 kbps for the transmission signal and 1024 kbps for the reception signal. In this embodiment, the carrier frequency IF4 is 16.384 MHz, and the bandwidth is 1 MHz or less. Such a frequency avoids distortion drop.
[0016]
The multiplexer 138 superimposes signals arriving from the GPS unit 118, the VICS unit 122, the ETC unit 126, and the optical beacon unit 132 on its four inputs 136, 140, 146, and 150, that is, frequency multiplexing (FDM). , A signal synthesis circuit that outputs the output 152 to an electrical / optical (E / O) converter 154. The E / O converter 154 is a photoelectric conversion circuit that includes, for example, a semiconductor laser, converts an electrical signal input to its input 152 into a corresponding optical signal, and outputs the latter from its output 156. Of course, a light emitting diode or VCSEL (Vertical Cavity Surface Emitting Laser) may be used instead of the semiconductor laser. The output 156 is connected to the input of a wavelength division multiplexing (WDM) circuit 158.
[0017]
The WDM circuit 158 has an input / output end 104 a connected to one end of the single-core optical fiber 104, wavelength-multiplexes an optical signal input to the input 156, and sends it to the optical fiber 104. This is a wavelength division multiplexing optical transmission circuit that receives and demultiplexes an optical signal transmitted from the end side and outputs it from its output 160. The output 160 is connected to the input of an optical / electrical (O / E) converter 162. In this embodiment, a single-core glass fiber is advantageously applied to the optical fiber 104 in terms of securing the transmission procedure in this embodiment, but of course, a plastic fiber may be used, and the latter is advantageous in terms of economy. is there. Thus, in the present embodiment, the edge side device 106 and the main body side device 108 are connected by the single-core optical fiber 104. As a result, the optical fiber cable 104 can be easily routed even in a narrow interior space.
[0018]
The O / E converter 162 is a photoelectric conversion circuit that includes, for example, a photodiode, converts an optical signal input to the input 160 into a corresponding electrical signal, and outputs the electrical signal to the input 164 of the duplexer 142. . The demultiplexer 142 is a signal demultiplexing circuit that demultiplexes the signal frequency-multiplexed to the input 164, outputs the ETC output signal 144 to the ETC unit 126, and outputs the optical beacon output signal 148 to the optical beacon unit 132.
[0019]
Now, the other end 104 b of the optical fiber 104 is connected to another WDM circuit 170 in the main unit 108. Referring to FIG. 2, the WDM circuit 170 of the main unit side device 108 receives and demultiplexes the optical signal transmitted from one end side of the optical fiber 104 at the input / output end 104 b, and outputs the O / E from the output 172. This is a wavelength multiplexing / demultiplexing circuit that outputs this to the input of the converter 174 and wavelength-multiplexes an optical signal arriving at the input 176 from an E / O converter 178 described later and sends it to the optical fiber 104.
[0020]
The O / E converter 174 is a photoelectric conversion circuit that converts an optical signal input to the input 172 into a corresponding electrical signal and outputs the electrical signal to the input 182 of the duplexer 180. The duplexer 180 separates the frequency-multiplexed signal at the input 182, the GPS output signal 184 to the GPS unit 186, the VICS output signal 188 to the VICS unit 190, the ETC output signal 192 to the ETC unit 194, The optical beacon output signal 196 is a signal separation circuit that outputs to the optical beacon unit 198.
[0021]
The E / O converter 178 converts the electrical signal input from the multiplexer 200 into its input 198 into a corresponding optical signal, and outputs this from the output 176 toward the input of the WDM circuit 170. Circuit. The multiplexer 200 is a signal synthesizing circuit that frequency-multiplexes the two inputs 202 and 204 and outputs the result from the output 198 to the E / O converter 178.
[0022]
In the main unit 108, the GPS unit 186 is a conversion circuit that up-converts the GPS signal arriving at the input 184 at the intermediate frequency IF2 and outputs the result from the output 206. It also has an output terminal 208 that outputs the GPS signal 184 input from the duplexer 180 to the input 184 at its intermediate frequency.
[0023]
The VICS unit 190 is a conversion circuit that up-converts the VICS signal arriving at the input 188 at the intermediate frequency IF2 and outputs it from its output 210. This circuit also has an output terminal 212 for outputting the VICS signal 188 input from the duplexer 180 to the input 188 at its intermediate frequency.
[0024]
Further, the ETC unit 194 is a conversion circuit that up-converts the ETC signal arriving from the duplexer 180 at the input 128 at the intermediate frequency IF3 and outputs the up-converted signal from the output 214. The ETC unit 194 also has an output terminal 216 that outputs the ETC signal input to the input 192 without changing the intermediate frequency. Further, the ETC unit 194 has a function of outputting the ETC output signal supplied to the input terminal 218 from the output 202 to the multiplexer 200. In the present embodiment, the GPS unit 186, the VICS unit 190, and the ETC unit 194 may be structurally the same as described later.
[0025]
The optical beacon unit 198 converts the FM modulated optical beacon input signal 196 supplied from the duplexer 180 into a PAM signal at the carrier frequency IF4, and outputs the PAM signal to the beacon output terminal 220. The PAM optical beacon output signal inputted to 222 is FM-modulated at the carrier frequency IF4, and this is given to the input of the multiplexer 200 from its output 204.
[0026]
In summary, in this embodiment, when transmitting through the optical cable 104, the optical beacon signal is converted into an FM signal by the edge side device 106, returned to the PAM signal by the main body side device 108, and the reverse direction is the same. Further, the GPS signal and the VICS signal are converted into an intermediate frequency signal by the edge side device 106, and returned to the radio frequency signal by the main body side device 108. The same applies to the ETC signal in both transmission and reception directions. Furthermore, the optical cable 104 is wavelength-multiplexed in both transmission and reception directions, thereby enabling the use of a single-core optical fiber cable.
[0027]
In the present embodiment, the intermediate frequency is selected to have the above-mentioned value in consideration of the ratio band corresponding to the transmission procedure of each signal and the interference wave in the usage environment. Of course, the present invention is not limited to such numerical values. In consideration of the economics of circuit elements that are available at present, particularly digital circuit elements of analog / digital conversion circuits that are connected to the intermediate frequency output, for the utilization apparatus connected to the subsequent stage of the present apparatus, the above-described intermediate frequency IF1, IF2 and IF3 are set to the lowest possible frequency suitable for intermediate frequency processing, preferably about 30 MHz or less. The same applies to the carrier frequency IF4.
[0028]
In consideration of severe environmental conditions such as in-vehicle temperature and electromagnetic waves, selection of the intermediate frequency is important. In particular, in the case of the present embodiment, when a large number of IF signals of 2 to 4 waves are multiplexed, a filter characteristic capable of sufficiently securing the reception image sensitivity of the signal and sufficiently removing the local frequency and the image frequency of IF transmission. This is realized by a filter element that can be obtained at low cost.
[0029]
As for the image frequency, when frequency multiplexing is performed, each signal is arranged in an attenuation region of 40 dB or more, and each image frequency is set to a frequency that does not interfere with each other. If there is an interference wave in the image frequency band of the down conversion, the desired wave is included in the same band as the interference wave. As can be seen from FIG. 8, for example, in the example of a GPS signal having a frequency of 1575.42 MHz ((A) in the same figure), when the local frequency is 1566.42 MHz, the intermediate frequency 7 MHz is included in the Inmarsat band 7.42 MHz to 41.42 MHz. (FIG. (B)). Filtering such a signal at the RF stage or providing a sufficient image suppression mixer leads to a complicated configuration. Therefore, for example, when the local frequency is 1570.42 MHz, the intermediate frequency 5 MHz can avoid the Inmarsat band of 11.42 MHz to 45.42 MHz ((C) in the figure).
[0030]
It is also important to avoid signal distortion by eliminating proximity interference due to interference waves such as cellular phones and MCA systems. For example, it is not preferable to use a cellular phone band of 1429 MHz to 1559 MHz. Therefore, the GPS intermediate frequency 73.21 MHz to 8.21 MHz cannot be used.
[0031]
Furthermore, it is advantageous to consider up to, for example, third-order distortion so that intermodulation distortion is not affected during combined transmission in WDM optical transmission. That is, the distortion component of the signal of a certain communication service is prevented from dropping into the main band of the signal of another communication service. In the case of the present embodiment, in particular, the C / N (carrier-to-noise ratio) characteristics of the photoelectric conversion unit are also taken into consideration, and the band is 30 MHz or less.
[0032]
An optical beacon signal is a signal that cannot be transmitted as it is but cannot be transmitted to the outside. Therefore, when transmitting over the optical cable 104, the received data and the transmitted data are converted into an optical signal with a unique signal form and frequency. Yes. However, since the original optical beacon signal is a PAM signal, the amplitude value changes drastically, that is, the frequency spectrum is distributed over a wide range. If this is converted to an intermediate frequency as it is and transmitted, a GPS signal, VICS signal, ETC, etc. May adversely affect other signals such as signals. Therefore, in this embodiment, the PAM optical beacon signal received by the edge side device is converted into an FM signal, converted to an intermediate frequency and frequency-multiplexed with other signals, and the main body side device converts this to the PAM signal. It has returned to. The transmission signal is operated in the reverse manner. As a result, transmission at a level 10 dB or more lower than other signals becomes possible, and the adverse effect of the optical beacon signal in the optical multiplexing unit, transmission unit, and optical separation unit of the transmission apparatus can be minimized.
[0033]
In this embodiment, the edge side device 106 and the main body side device 108 are integrally formed as an LSI (Large Scale Integration) integrated circuit. Elements of the edge side device 106 other than the IF processing units 234 and 268 may be incorporated into the integrated antenna unit 102.
[0034]
In the present embodiment, as described above, the GPS unit 118 and the VICS unit 122 of the edge side device 106 may have the same structure. As shown in FIG. 3 using the GPS unit 118 as an example, the GPS unit 118 basically includes a down converter 230 having a GPS signal input 120 connected to the input, and an output 232 of the down converter 230 and a GPS unit output 136. An intermediate frequency (IF) processing circuit 234 connected therebetween is included. The down converter 230 includes a band-pass filter (BPF) 236 that passes the signal band of the GPS signal 120, an amplifier 238, a local oscillation circuit (LO OSC) 240 that oscillates the intermediate frequency IF1 to the output 241, and a combination that combines the two. A circuit 242 is connected as shown, and is a frequency conversion circuit that down-converts the GPS input signal arriving at the input 120 to the above-described intermediate frequency IF1. Its output 232 is connected to an intermediate frequency bandpass filter (IFBPF) 244.
[0035]
The IF band pass filter 244 is a filter that passes the output band of the synthesis circuit 242, and a variable gain amplifier 246 and an automatic gain control (AGC) circuit 248 are connected to the output thereof as shown in the figure to form an AGC loop. ing. The IF processing circuit 234 is formed by the IF band pass filter 244, the variable gain amplifier 246, and the AGC circuit 246.
[0036]
The VICS unit 122 has substantially the same configuration as the GPS unit 118, and the intermediate frequency IF2 and its bandwidth are different from the intermediate frequency IF1 of the GPS unit 118 and its bandwidth as described above.
[0037]
As can be seen from FIG. 4, the ETC unit 126 basically includes a down converter 230 having the same configuration as the GPS unit 118, and an IF processing circuit 234 connected between the latter output 232 and the ETC unit output 146. including. The ETC unit 126 further includes an up-converter 250 having an input connected to the ETC unit input 144, which is a frequency conversion circuit that up-converts the ETC output signal 144 arriving at an intermediate frequency and outputs it to its output 252. .
[0038]
The down converter 230 of the ETC unit 126 may have the same configuration as that of the GPS unit 118, but the local oscillation circuit 240 has another output 254 in addition to the intermediate frequency output 241, and the intermediate frequency IF3 and its output as described above. The bandwidth is different from the intermediate frequency IF1 of the GPS unit 118 and its bandwidth.
[0039]
The up-converter 250 of the ETC unit 126 includes a combining circuit 256 in which one input is connected to the input 144 and the other input is connected to the other output 254 of the local oscillation circuit 240, and an amplifier connected thereto as shown in the figure. 258 and a band pass filter 260. The connection line 158 to the ETC antenna 114 is connected to the switch (SW) 262, the other terminal 264 of the switch 262 is connected to the input of the band pass filter 236, and the other terminal 252 is connected to the output of the other band pass filter 260. It is connected. The switch 262 is a selection circuit that selectively connects the connection line 158 with the ETC antenna 114 to either the input 264 of one band pass filter 236 or the output 252 of the other band pass filter 260.
[0040]
As shown in FIG. 5, the optical beacon unit 132 converts the optical beacon output signal 148 supplied from the duplexer 142 into a PAM signal and outputs the PAM signal to the output 130, and the projector / receiver 116. An FM modulation circuit 268 that is FM modulated with an incoming PAM optical beacon input signal connected to the input 134 from the output signal 140 with a predetermined carrier frequency IF4 and outputs the result to the multiplexer 138, and a local oscillation circuit 270. Including. The local oscillation circuit 270 is an oscillation circuit that self-oscillates the carrier frequency IF4 and outputs it to its two outputs 272 and 274.
[0041]
More specifically, the signal conversion circuit 266 includes a combining circuit 276 in which one input is connected to the optical beacon unit input 148 and the other input is connected to one oscillation output 272 of the local oscillation circuit 270. The band-pass filter 278, the frequency / voltage (F / V) conversion circuit 282, and the amplifier 258 are connected in this manner. On the other hand, the FM modulation circuit 268 includes an amplifier 284 having an input connected to the light emitter / receiver output 134, a voltage / frequency (V / F) conversion circuit 286, a synthesis circuit 288, a band-pass filter 290, and another amplifier 292. Are connected and configured. In the synthesis circuit 288, one input is connected to the output 294 of the V / F conversion circuit, that is, the frequency modulation circuit 286, and the other input is connected to the other output 274 of the local oscillation circuit 270. The input of the pass filter 290 is connected.
[0042]
The V / F conversion circuit 336 is a voltage / frequency conversion circuit that has a discrimination characteristic, receives a baseband PAM signal, and outputs an FM signal whose frequency is modulated accordingly. The F / V conversion circuit 280 is a frequency / voltage conversion circuit that has frequency discrimination characteristics and outputs a baseband signal having an amplitude corresponding to the frequency signal as a PAM signal when the FM signal is input.
[0043]
By the way, in the main unit side device 108, in this embodiment, as described above, the GPS unit 186, the VICS unit 190, and the ETC unit 194 may have the same structure. As illustrated in the GPS unit 186 of the main unit 108 in FIG. 6, the GPS unit 186 basically has the up-converter 300 whose input is connected to the output 184 of the duplexer 180 and the same output 184 as an intermediate frequency. And an amplifier 302 that outputs the output 208 as it is. The duplexer output 184 is connected to the input of the amplifier 302 and one input of the multiplexing circuit 304, and the other input 306 of the multiplexing circuit 304 is connected to the output of the local oscillation circuit 308. The output 310 of the synthesis circuit 304 is connected to a band-pass filter 312 and an amplifier 314 that pass the band of the GPS signal as shown in the figure. The output of amplifier 314 forms GPS unit output 206.
[0044]
In the present embodiment, the GPS unit 186, the VICS unit 190, and the ETC unit 194 are configured to have both a circuit 300 that upconverts an intermediate frequency and outputs it as a radio frequency, and a circuit 302 that outputs the intermediate frequency as it is. ing. Of course, the GPS unit 186, the VICS unit 190, and / or the ETC unit 194 may not necessarily include both of these circuits, and may be configured to output only a radio frequency or an intermediate frequency.
[0045]
The VICS unit 190 has substantially the same configuration as the GPS unit 186, and the intermediate frequency IF2 and its bandwidth are different from the intermediate frequency IF1 of the GPS unit 186 and its bandwidth as described above.
[0046]
The ETC unit 194 basically includes the configuration shown in FIG. 6, but as described above with reference to FIG. 2, the ETC output signal supplied to the input terminal 218 is sent from the output 202 to the multiplexer 200. It also has a through circuit (not shown) that outputs the intermediate frequency. Further, the intermediate frequency IF2 of the VICS unit 190 and its bandwidth are different from the intermediate frequency IF1 of the GPS unit 186 and its bandwidth as described above.
[0047]
As shown in FIG. 7, the optical beacon unit 198 demodulates the FM optical beacon input signal 196 supplied from the duplexer 180 into a PAM signal and outputs it to the output terminal 220, and an input terminal. A PAM optical beacon output signal provided from 222 is FM-modulated at a carrier frequency IF4 and output from the output 204 to the multiplexer 200, and a local oscillation circuit 320 is included. The local oscillation circuit 320 is a self-excited oscillation circuit that oscillates the carrier frequency IF4 and outputs it to its two outputs 322 and 324.
[0048]
More specifically, the FM demodulation circuit 316 includes a combining circuit 326 having one input connected to the duplexer output 196 and the other input connected to one output 322 of the local oscillation circuit 320, as shown in FIG. A band-pass filter 328, an F / V conversion circuit 330, and an amplifier 322 connected to each other. On the other hand, the FM modulation circuit 318 includes an amplifier 334 having an input connected to the input terminal 222, a V / F conversion circuit 336, a synthesis circuit 338, and a band pass filter 340 as shown in the figure. The synthesis circuit 338 has one input connected to the output 342 of the V / F conversion circuit 336, the other input connected to the other output 324 of the local oscillation circuit 320, and the synthesis output 344 of the bandpass filter 340. Connected to the input.
[0049]
In this embodiment, GPS signals, VICS signals, and ETC signals are converted to intermediate frequencies and transmitted to an optical fiber. However, these signals may be directly frequency-multiplexed and transmitted in the radio frequency (RF) band without being converted to an intermediate frequency.
[0050]
Although the mobile body mounted transmission apparatus of the embodiment is an example applied to a vehicle, the present invention is not limited to such a specific embodiment, and is not limited to a land transportation mobile body, but a ship. The present invention is also advantageously applied to marine or air transportation vehicles such as aircraft and aircraft.
[0051]
【The invention's effect】
As described above, according to the mobile unit-mounted transmission device according to the present invention, signals of a plurality of communication services are directly converted into radio frequencies or converted into intermediate frequencies between the main body and the edge of the communication service device. Frequency-multiplexed, converted to an optical signal, and transmitted over an optical cable. Accordingly, it is possible to efficiently use the space inside the moving body without receiving or giving electromagnetic interference to other devices.
[Brief description of the drawings]
FIG. 1 is a schematic functional block diagram showing an embodiment of a mobile unit-mounted transmission device according to the present invention on the edge side of an in-vehicle communication device.
FIG. 2 is a schematic functional block diagram similar to FIG. 1, showing an embodiment of a mobile unit-mounted transmission device according to the present invention on the main body side of the in-vehicle communication device.
3 is a schematic functional block diagram showing a configuration example of a GPS unit or a VICS unit in the embodiment shown in FIG.
4 is a schematic functional block diagram similar to FIG. 3, showing a configuration example of an ETC unit in the embodiment shown in FIG. 1;
5 is a schematic functional block diagram similar to FIG. 3, showing a configuration example of an optical beacon unit in the embodiment shown in FIG.
6 is a schematic functional block diagram showing a configuration example of a GPS unit, a VICS unit or an ETC unit in the embodiment shown in FIG.
7 is a schematic functional block diagram similar to FIG. 6, showing a configuration example of an optical beacon unit in the embodiment shown in FIG. 2;
FIG. 8 is a frequency band diagram for explaining selection of an intermediate frequency for the GPS signal in the embodiment.
[Explanation of symbols]
100 On-vehicle transmission device
104 Optical cable
106 Edge side device
108 Main unit side device
118, 186 GPS section
122, 190 VICS Department
126, 194 ETC Department
132, 198 Optical beacon section
138, 200 multiplexer
142, 180 duplexer
154, 178 Electrical / optical converter
162,174 Optical / electrical converter
158, 170 Wavelength multiplexing circuit

Claims (11)

An edge side device disposed near the edge side of the communication service device, a body side device disposed near the body side, and the edge side device and the body side device are connected to each other. Including an optical transmission line,
The edge side device converts a signal of the first communication service such as a radio frequency GPS signal, a VICS signal and an ETC signal directly or into an intermediate frequency, and also converts the signal of the second communication service such as an optical beacon signal. The signals are frequency modulated, frequency multiplexed, and converted to optical signals,
The optical transmission path transmits the optical signal from the edge side device to the main body side device. 2. The transmission device according to claim 1, wherein the main unit side device converts an optical signal received from the optical transmission path into an electrical signal, and the signal of the first communication service is a frequency of the converted electrical signal. A mobile unit-mounted transmission device, wherein the second communication service signal is separated and demodulated. The transmission apparatus according to claim 2,
The main unit side device converts the signal of the first communication service directly or into an intermediate frequency, and frequency-modulates the signal of the second communication service such as an optical beacon signal, frequency-multiplexes them, Convert it into a signal
The optical transmission line transmits the optical signal from the main body side device to the edge side device,
The edge side device converts an optical signal received from the optical transmission path into an electric signal, and the signal of the first communication service is frequency-separated from the converted electric signal, and the second communication service A mobile unit-mounted transmission device characterized in that a signal is demodulated. The transmission apparatus according to claim 1, wherein the edge-side apparatus includes a wavelength multiplexing circuit that wavelength-multiplexes the optical signal prior to transmission to the transmission path. The transmission apparatus according to claim 2,
The edge side device includes a wavelength multiplexing circuit that wavelength-multiplexes the optical signal prior to transmission to the transmission line,
The mobile unit-mounted transmission device, wherein the main unit side device includes a wavelength separation circuit for wavelength-separating an optical signal received from the transmission path. The transmission apparatus according to claim 2,
The main unit side device includes a wavelength multiplexing circuit that wavelength-multiplexes the optical signal prior to transmission to the transmission line,
The mobile unit-mounted transmission device, wherein the edge side device includes a wavelength separation circuit for wavelength-separating an optical signal received from the transmission path. 7. The transmission apparatus according to claim 3, wherein the optical transmission path includes a single-core optical fiber cable. The transmission apparatus according to claim 1, wherein the intermediate frequency is a low frequency suitable for processing the intermediate frequency of the signals of the first and second communication services. The transmission apparatus according to claim 1, wherein the low frequency does not exceed about 30 MHz. 3. The transmission apparatus according to claim 2, wherein the main unit side device includes output means for outputting the frequency separated signal at an intermediate frequency. 3. The transmission apparatus according to claim 2, wherein the main unit side device includes output means for outputting the frequency separated signal at a radio frequency.

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