JP6363450B2 - Communication device - Google Patents

Description

  The present invention relates to a communication device, and more particularly to a communication device that distributes a local oscillation signal to a plurality of frequency converters.

  A communication device that distributes a local oscillation signal to a plurality of frequency converters generates a plurality of local oscillation signals that are used when modulating or demodulating a radio signal, for example, as disclosed in Japanese Patent Application Laid-Open No. 2002-198844. A radio signal is modulated by frequency-converting the input signal using the generator, the synthesis unit that mutually vector-combines the local oscillation signals generated by each generation unit, and the local oscillation signal that is vector-synthesized by the synthesis unit Or a plurality of converters for demodulation.

  In a satellite-mounted communication device, a local oscillator and a distributor are used to supply local oscillation signals from a plurality of frequency converters from a single local oscillator, thereby reducing the number of local oscillators. Further, by using a centralized power source that supplies power to a local oscillator, a distributor, and a frequency converter from a single power source, the efficiency of the power source can be increased, and miniaturization and weight reduction are realized. Further, in order to cope with various specifications, a frequency converter, a local oscillator, and a power source are stored in a single casing. For example, as disclosed in Non-Patent Document 1, a plurality of frequency converters and distributors are used. Is generally used as a centralized frequency converter in a single housing, and a local oscillator and a centralized power supply are housed in a separate housing.

JP 2002-198844 A

Ka band communication received banks with centralized LO and power supply (19th Ka and Broadband Communications, Navigation and Earth Observation Conference)

  In recent years, in order to mount a large number of channels in a communication apparatus, a plurality of local oscillators having different oscillation frequencies are mounted. With the mounting of a plurality of local oscillators, various housings are required if the local oscillator and the centralized power source are housed in one housing. In addition, various distributors having different breakdowns of the number of communication channels using each local oscillator are required, and the centralized frequency converter also requires various housings. In a satellite-mounted communication device, when changing the housing of each unit, an evaluation model (EQM: Engineering Qualification Model) is produced, and enormous evaluation is required to verify that quality requirements are satisfied. .

  An object of the present invention is to provide a communication device that can add a local oscillator having a different oscillation frequency and change the breakdown of the number of communication channels using each local oscillator without changing the structure of the casing of each unit. And

The communication apparatus of the present invention includes a centralized local oscillator having a local oscillator, a local oscillation signal distributor that branches a signal input from the centralized local oscillator into two or more, and a plurality of frequency converters that input the branched signal. A centralized power supply for supplying power to the local oscillation signal distributor, frequency converter and centralized local oscillator;
The centralized local oscillator, local oscillation signal distributor, frequency converter, and centralized power supply unit each have an independent casing.

  According to the present invention, it is possible to add a concentrated local oscillator having a different oscillation frequency and change the breakdown of the number of communication channels without changing the structure of the casing of each unit.

FIG. 1 is a block diagram showing the configuration of the first embodiment. FIG. 2 is a diagram showing an example of the configuration of the local oscillation signal distributor of FIG. FIG. 3 is a block diagram showing the configuration of the second embodiment. FIG. 4 is a diagram showing a first example of the configuration of the local oscillation signal distributor of FIG. FIG. 5 is a diagram showing a second example of the configuration of the local oscillation signal distributor of FIG. FIG. 6 is a diagram showing a third example of the configuration of the local oscillation signal distributor of FIG. FIG. 7 is a block diagram showing the configuration of the third embodiment. FIG. 8 is a diagram showing an example of the configuration of the local oscillation signal distributor of FIG. FIG. 9 is a block diagram illustrating a configuration of the fourth embodiment. FIG. 10 is a diagram illustrating an example of the configuration of the local oscillation signal distributor of FIG.

  FIG. 1 is a block diagram showing the configuration of the first embodiment of the communication apparatus of the present invention.

  As shown in FIG. 1, the communication device 1 according to the first embodiment inputs a centralized local oscillator 10 having a local oscillator 11, a local oscillation signal distributor 21, and a signal branched by the local oscillation signal distributor 21. And a centralized power converter 30 that supplies power to the centralized local oscillator 10 and the centralized frequency converter 20. Further, in the first embodiment of the communication device of the present invention, as shown in FIG. 1, the local oscillator 11, the local oscillation signal distributor 21, the frequency converter 22, and the centralized power supply unit 30 are respectively independently a casing 41, 42, 43, 44. As shown in FIG. 2, the local oscillation signal distributor 21 includes a distribution signal output terminal 211, a local oscillation signal input terminal 212, and a substrate 213. The substrate 213 is configured so that the microstrip branch circuit 215, which is half of the frequency converter, has N columns (N in this embodiment) if the number of columns corresponding to the number of the frequency converters 22, that is, the number of frequency converters is N to the Nth power. = 3, so that it can be mounted in 3 rows).

As shown in FIG. 1, the housing 43 of the frequency converter 22 may be configured to have a plurality of, for example, two frequency converters 22 mounted therein. In the first embodiment, the local oscillator 11 This is an example in which one unit and eight frequency converters 22 are mounted.

  The local oscillator 11 generates a local oscillation signal used when modulating or demodulating a radio signal. The local oscillation signal distributor 21 receives the local oscillation signal from the local oscillator 11, and the local oscillation signal distributor 21 converts the local oscillation signal into a plurality of signals, for example, as shown in FIG. Branch to one signal. The signal branched by the local oscillation signal distributor 21 is input to the frequency converter 22. The frequency converter 22 uses the local oscillation signal input from the local oscillation signal distributor 21 to convert the frequency of the high-frequency modulation signal received by the communication device into an intermediate frequency, and so on. ).

  Although not shown in FIG. 1, the local oscillator 11 of the centralized local oscillator 10, the local oscillation signal distributor 21, and the centralized power supply unit 30 are also provided in the chassis 41, 42, 44 in redundant configurations, for example, two each. An oscillator, a signal distributor, and a power source may be mounted.

  FIG. 2 is a block diagram showing an example of the configuration of the local oscillation signal distributor 21 of FIG. As shown in FIG. 2, the local oscillation signal distributor 21 includes a housing 42, a distribution signal output terminal 211, a local oscillation signal input terminal 212, and a substrate 213.

  The example of FIG. 2 is an example in which local oscillation signals are output to eight frequency converters 22, and eight distribution signal output terminals 211 are provided on one side surface of the casing 42. The example shown in FIG. 2 is an example in which the local oscillator 11 has a redundant configuration and two local oscillators 11 are mounted, and faces one side of the housing 42, for example, the distribution signal output terminal 211. Two local oscillation signal input terminals 212 are provided on the side for inputting signals from the two local oscillators 11. The distribution signal output terminal 211 and the local oscillation signal input terminal 212 are fixed to the housing 42 with screws. Although not shown in FIG. 2, a mounting portion for fixing two or more, for example, eight oscillation signal input terminals 212 is provided on the side surface of the housing 42 on which two oscillation signal input terminals 212 are provided. The position where the oscillation signal input terminal 212 is attached can be changed without changing the housing.

  From the distribution signal output terminal 211 and the local oscillation signal input terminal 212, conductor pins for passing electrical signals protrude, and the distribution signal output terminal 211 and the local oscillation signal input terminal are soldered to the substrate 213. 212 is electrically connected to the circuit on the substrate.

  One hybrid coupler 214 is mounted on the substrate 213 at a region close to the local oscillation signal input terminal 212 when mounted on the housing, for example, at an end of the substrate 213. The hybrid coupler 214 is connected to the two local oscillation signal input terminals 212 and receives signals input to the two local oscillation signal input terminals 212.

  In addition, two microstrip branch circuits 216 are mounted on the substrate 213 in parallel to the end of the substrate 213 in a region near the two output terminals of the hybrid coupler 214. Each of the microstrip branch circuits 216 branches the signal output from the hybrid coupler 214 into two.

  Further, when mounting the board on the housing, the two signals output from the microstrip branch circuit 216 are arranged in parallel with the area close to the distribution signal output terminal 211, for example, the end opposite to the end of the board 213. In order to branch respectively, half of the frequency converters, that is, four microstrip branch circuits 215 are mounted on the substrate 213 in one row. The microstrip branch circuit 215 is connected to each of the two distribution signal output terminals 211, and a local oscillation signal branched from the distribution signal output terminal 211 is output. The hybrid coupler 214 and the microstrip branch circuit 215 can be approximately the same size. The microstrip branch circuit 216 is slightly different in size from the microstrip branch circuit 215, but is not limited in electrical performance, and is only required to be changed to be laid out internally.

  In this way, the substrate 213 is divided into half the number of columns corresponding to the number of the frequency converters 22, that is, the number of the frequency converters is half the microstrip branch circuit 215 of the frequency converters. In the embodiment, since N = 3, the size can be mounted in 3 rows). As a result, a layout in which local oscillation signals from one local oscillator are distributed to the number of frequency converters mounted on the communication device in the substrate 213 is possible.

  Next, the configuration of the second embodiment, which is an example in which two local oscillators and eight frequency converters 22 are mounted, will be described. FIG. 3 is a block diagram showing the configuration of the second embodiment.

  As shown in FIG. 3, in the communication device 2, the centralized local oscillator 10 includes two local oscillators 11 and 12, and the local oscillation signal distributor 24 provided in the centralized frequency conversion unit 23 includes the local oscillator 11. 1 and 12 is different from the configuration of FIG. 1 in that the local oscillation signals from 12 and 12 are branched into a predetermined number without changing the frequency, and the local oscillation signals are output as a total of 8 signals.

  The local oscillators 11 and 12 independently generate local oscillation signals having different frequencies.

  As shown in FIG. 3, the two local oscillators 11 and 12 of the concentrated local oscillator 10 each have a housing 41. As in the first embodiment, the housing 43 of the frequency converter 22 may be configured to mount a plurality of, for example, two frequency converters 22 therein. Further, the local oscillators 11 and 12 of the centralized local oscillator 10, the local oscillation signal distributor 24, and the centralized power supply unit 30 are also provided in the casings 41, 43, and 44 in redundant configurations, for example, two oscillators, signal distributors, A power supply may be configured to be implemented.

  FIG. 4 is a diagram showing a configuration of a first example of the configuration of the local oscillation signal distributor 24 of FIG. The first example is an example in which the local oscillation signals of the local oscillators 11 and 12 are each branched into four and output to the frequency converter.

  FIG. 5 is a diagram showing a configuration of a second example of the configuration of the local oscillation signal distributor 24 of FIG. The second example is an example in which one local oscillation signal of the local oscillators 11 and 12 is branched into five and the local oscillation signal of the other local oscillator is branched into three and output to the frequency converter.

  FIG. 6 is a diagram showing a configuration of a third example of the configuration of the local oscillation signal distributor 24 of FIG. The third example is an example in which one local oscillation signal of the local oscillators 11 and 12 is branched into six, and the local oscillation signal of the other local oscillator is branched into two and output to the frequency converter.

  4, 5, and 6, each of the local oscillators 11 and 12 has a redundant configuration including two oscillators as in the example illustrated in FIG. 2, and one side of the housing 42, for example, a distributed signal A total of four local oscillation signal input terminals 212 including two terminals corresponding to the local oscillator 11 and two terminals corresponding to the local oscillator 13 are provided on the side facing the output terminal 211.

  4, 5, and 6, the substrates 241, 242, and 243 are mounted on a region close to the local oscillation signal input terminal 212, for example, at the ends of the substrates 241, 242, and 243 when mounted on the housing. Two hybrid couplers 214 are mounted corresponding to the local oscillators 11 and 12. Each hybrid coupler 214 is connected to two local oscillation signal input terminals 212 corresponding to the local oscillators 11 and 12 and receives local oscillation signals.

  In the example of FIG. 4, two microstrip branch circuits 216 are mounted side by side on the substrate in parallel to the end of the substrate 241 in a region near the output terminal of the hybrid coupler 214. Each of the microstrip branch circuits 216 branches the signal output from one terminal of the hybrid coupler 214 into two. Similarly to the example of FIG. 2, when the substrate 241 is mounted on the housing 42, a region near the distribution signal output terminal 211, for example, parallel to the end opposite to the end of the substrate 241, Half, that is, four microstrip branch circuits 215 are mounted on the substrate 243 in a line. The output terminals of the microstrip branch circuit 215 are connected to the two distribution signal output terminals 211, respectively. In this way, the four distribution signal output terminals 211 branch the local oscillation signal of the local oscillator 11 and output it to the frequency converter, and the other four distribution signal output terminals 211 branch the local oscillation signal of the local oscillator 13. And output to the frequency converter.

  Next, in the example of FIG. 5, the microstrip branch circuit 216 branches the signal output from one terminal of one hybrid coupler 214 into two. Similarly to the example of FIG. 2, when the substrate 242 is mounted on the housing 42, three microstrips are arranged in parallel to the region close to the distribution signal output terminal 211, for example, the end opposite to the end of the substrate 242. Branch circuits 215 are mounted on the substrate 242 in a line. Of these, the two microstrip branch circuits 215 branch the two outputs of the microstrip branch circuit 216, respectively, and output them to the distribution signal output terminal 211. Of the output terminals of the hybrid coupler 214, a terminal not connected to the microstrip branch circuit 216 is connected to the distribution signal output terminal 211. One output terminal of the other hybrid coupler 214 is connected to the distribution signal output terminal 211. The other output of the other hybrid coupler 214 is branched by the microstrip branch circuit 215 and output from the distribution signal output terminal 211. In this manner, the local oscillation signal of either the local oscillator 11 or 13 is branched from the five distribution signal output terminals 211 and output to the frequency converter, and the other three distribution signal output terminals 211 receive the local signal. The other local oscillation signal of the oscillator 11 or 13 is branched and output to the frequency converter.

  Further, in the example of FIG. 6, the microstrip branch circuit 216 branches one output of one hybrid coupler 214 into two. Similarly to the example of FIG. 2, when the substrate 243 is mounted on the housing, three microstrip branches are parallel to the region near the distribution signal output terminal 211, for example, the end opposite to the end of the substrate 243. The circuits 215 are mounted in a line on the substrate 243. Of these, the two microstrip branch circuits 215 branch the two outputs of the microstrip branch circuit 216, respectively, and output them to the distribution signal output terminal 211. The remaining two microstrip branch circuits 215 branch the other output of one hybrid coupler 214 and output it to the distribution signal output terminal 211. The output terminal of the other hybrid coupler 214 is connected to the distribution signal output terminal 211, respectively. In this way, the local oscillation signal of either one of the local oscillators 11 or 12 is branched from the six distribution signal output terminals 211 and output to the frequency converter, and the other two distribution signal output terminals 211 receive the local signal. The other local oscillation signal of the oscillator 11 or 12 is branched and output to the frequency converter.

  Also in this embodiment, the substrates 242, 243, 244, half the microstrip branch circuit 215 of the frequency converter, and the number of columns corresponding to the number of frequency converters 22, that is, the number of frequency converters is N to the second power. If so, the size is such that it can be mounted in N columns (3 columns since N = 3 in this embodiment). As a result, local oscillation signals from two local oscillators can be mounted on the communication device in various ratios such as 4 and 4 units, 5 and 3 units, or 6 and 2 units. Can be laid out for distribution to frequency converters. Therefore, it is possible to deal with various models in which the number of local oscillators is two without changing the housing of each unit in the communication device by replacing the substrate.

  Next, a configuration when three local oscillators are mounted on the centralized local oscillator 10 will be described. In FIG. 7, three local oscillators are mounted on the centralized local oscillator 10, four frequency converters are connected to the first local oscillator, two frequency converters are connected to the second local oscillator, It is a block diagram which shows the structure of 3rd Embodiment by which two frequency converters are connected to the local oscillator.

  As shown in FIG. 7, the communication device 3 includes a centralized local oscillator 10 having three local oscillators 11, 12, and 13. The local oscillation signals from the oscillators 11, 12 and 13 are different from the configurations of FIGS. 1 and 3 in that the local oscillation signals are branched into a predetermined number without changing the frequency and the local oscillation signals are output as a total of eight signals.

  The local oscillators 11, 12, and 13 generate local oscillation signals having different frequencies independently of each other.

  As shown in FIG. 7, the three local oscillators 11, 12, and 13 of the concentrated local oscillator 10 each have a housing 41. Similar to the first and second embodiments, the housing 43 of the frequency converter 22 may be configured to have a plurality of, for example, two frequency converters 22 mounted therein, and further the local part of the centralized local oscillator 10. The oscillators 11, 12, 13, the local oscillation signal distributor 26, and the centralized power supply unit 30 may also be configured to be mounted on the casings 41, 42, 44 in redundant configurations, for example, two each.

  FIG. 8 is a diagram showing a configuration of the local oscillation signal distributor 26 of FIG. In this embodiment, the local oscillation signal of any one of the local oscillators 11, 12, and 13 is branched into four, and the local oscillation signals of the other two local oscillators are branched into two and output to the frequency converter. This is an example.

  In the example of FIG. 8, each of the local oscillators 11, 12, and 13 has a redundant configuration including two oscillators as in the example shown in FIG. For this reason, on one side of the housing 42, for example, on the side facing the distribution signal output terminal 211, two corresponding to the local oscillator 11, two corresponding to the local oscillator 12, and two corresponding to the local oscillator 12 are provided. A total of six local oscillation signal input terminals 212 are provided.

  In the example of FIG. 8, three hybrids corresponding to the local oscillators 11, 12, and 13 are provided on the substrate 261 in the region close to the local oscillation signal input terminal 212 when mounted on the housing 42, for example, at the end of the substrate 261. Couplers 214 are mounted in a line. Each hybrid coupler 214 is connected to three local oscillation signal input terminals 212 corresponding to the local oscillators 11, 12, and 13, and receives local oscillation signals. Further, one microstrip branch circuit 216 is mounted on the substrate in a region close to the output terminal of one hybrid coupler 214. The microstrip branch circuit 216 branches two signals output from one of the output terminals of one hybrid coupler 214 into two. Similarly to the example of FIG. 2, when the substrate 261 is mounted on the housing 42, four microstrips are parallel to the region close to the distribution signal output terminal 211, for example, the end opposite to the end of the substrate 261. Branch circuits 215 are mounted in a line on the substrate 252. The two microstrip branch circuits 215 branch the two outputs of the microstrip branch circuit 216, respectively, and output them to the distribution signal output terminal 211. The output terminals of the remaining two hybrid couplers 214 are connected to the distribution signal output terminal 211, respectively. In this way, the local oscillation signal of any one of the local oscillators 11, 12, and 13 is branched into four, and the local oscillation signals of the other two local oscillators are branched into two and output to the frequency converter. .

  Also in the present embodiment, the substrate 261 is arranged in the number of columns corresponding to the number of the frequency converters 22, that is, if the number of frequency converters is half the microstrip branch circuit 215 of the frequency converters, that is, N columns. (In this embodiment, since N = 3, it is a size that can be mounted in three rows). As a result, the substrate 261 can be laid out so that the local oscillation signals from the three local oscillators are distributed to the frequency converters mounted on the communication device. Therefore, it is possible to deal with a model in which the number of local oscillators is three without changing the housing of each unit in the communication device by replacing the substrate.

  Next, a configuration when four local oscillators are mounted on the centralized local oscillator 10 will be described. In FIG. 9, four local oscillators are mounted on the centralized local oscillator 10, two frequency converters are connected to the first local oscillator, two frequency converters are connected to the second local oscillator, It is a block diagram which shows the structure of 4th Embodiment by which two frequency converters are connected to a local oscillator, and two frequency converters are connected to the 4th local oscillator.

  As shown in FIG. 9, in the communication device 4, the centralized local oscillator 10 includes four local oscillators 11, 12, 13, and 14, and the local oscillation signal distributor 28 provided in the centralized frequency converter 27 is 1, 3, and 7 in that the local oscillation signals from the local oscillators 11, 12, 13, and 14 are branched without changing the frequency and the local oscillation signals are output to a total of eight signals. Different.

  The local oscillators 11, 12, 13, and 14 each independently generate local oscillation signals having different frequencies.

  As shown in FIG. 9, the four local oscillators 11, 12, 13, and 14 of the concentrated local oscillator 10 each have a housing 41. As in the first and second embodiments, the housing 43 of the frequency converter 22 may be configured to have a plurality of, for example, two frequency converters 22 mounted therein, and may further include a centralized local oscillator 10 and a local part. The oscillation signal distributor 28 and the centralized power supply unit 30 may also be configured such that an oscillator, a signal distributor, and a power supply are mounted on the casings 41, 42, and 44, for example, two each in a redundant configuration.

  FIG. 10 is a diagram showing a configuration of the local oscillation signal distributor 28 of FIG. This embodiment is an example in which the local oscillation signals of the local oscillators 11, 12, 13, and 14 are branched into two and output to the frequency converter.

  In the example of FIG. 10, each of the local oscillators 11, 12, 13, and 14 has a redundant configuration including two oscillators as in the example shown in FIG. A total of eight local oscillation signal input terminals 212, two corresponding to the local oscillators 11, 12, 13, and 14, are provided on the side facing the 211.

  In the example of FIG. 10, when mounted on the substrate 281, the region close to the local oscillation signal input terminal 212, for example, the end of the substrate 281 has 4 corresponding to the local oscillators 11, 12, 13, and 14. Two hybrid couplers 214 are mounted in a line. Each hybrid coupler 214 is connected to four local oscillation signal input terminals 212 corresponding to the local oscillators 11, 12, 13, and 14, respectively, and receives local oscillation signals. The two output terminals of each hybrid coupler 214 are connected to the distribution signal output terminal 211, respectively. In this way, the local oscillation signals of the local oscillators 11, 12, 13, and 14 are branched into two and output to the frequency converter.

  Also in the present embodiment, the substrate 281 is divided into half the number of columns corresponding to the number of frequency converters 22, that is, half the number of frequency converters, that is, half the number of frequency converters. (In this embodiment, since N = 3, it is a size that can be mounted in three rows). As a result, the substrate 281 can be laid out so that the local oscillation signals from the four local oscillators are distributed to the frequency converters mounted on the communication device. Therefore, it is possible to deal with a model in which the number of local oscillators is four without changing the housing of each unit in the communication apparatus.

  While the present invention has been described with reference to the embodiments, the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  For example, in the above-described embodiment, the local oscillators 11, 12, 13, and 14 have been described as having a redundant configuration including two oscillators. However, each of the local oscillators is not a redundant configuration but a single local oscillator. Also good.

  In addition, the local oscillation signal distributor has been described as a configuration in which the oscillation signals output from the two oscillators from each local oscillator are input to the hybrid coupler, but one signal is input from each local oscillator. It may be done. In that case, a micro split branch circuit may be provided instead of the hybrid coupler.

  As in the above embodiment, the local oscillation signal distributor receives the oscillation signals output from the two oscillators from each local oscillator and inputs them to the hybrid coupler, thereby performing switching control. In addition, there is an effect that the communication apparatus can be used continuously even if one of the two oscillators fails.

  Further, when the number of frequency converters 22 is less than eight in the configuration of the above embodiment, the distribution signal output terminal 211 may be removed and a cover may be attached so as to be shielded from the outside. By adopting such a configuration, it is possible to cope with specifications with few frequency converters 22 without changing the housing.

1, 2, 3, 4 Communication device 10 Centralized local oscillator 11, 12, 13, 14 Local oscillator 20, 23, 25, 27 Centralized frequency converter 21, 24, 26, 28 Local oscillation signal distributor 211 Distributed signal output terminal 212 Local oscillation signal input terminal 213, 241, 242, 243, 261, 281 Substrate 214 Hybrid coupler 215, 216 Microstrip branch circuit 22 Frequency converter 30 Centralized power supply 41, 42, 43, 44 Case

Claims (5)

A centralized local oscillator having a local oscillator;
A local oscillation signal distributor for branching a signal input from the centralized local oscillator into two or more;
A plurality of frequency converters for inputting the branched signals;
A centralized power supply for supplying power to the local oscillation signal distributor, the frequency converter and the centralized local oscillator;
The centralized local oscillator, the local oscillation signal distributor, the frequency converter, and the centralized power supply unit each have an independent casing. The local oscillation signal distributor is:
A microstrip branch circuit having a microstrip line that branches an input signal into two or more signals;
2. The communication apparatus according to claim 1, further comprising: a substrate having a size capable of mounting half of the microstrip branching circuits of the centralized local oscillator in a number of columns corresponding to the number of the centralized local oscillators. . The centralized local oscillator has a plurality of local oscillators that generate the same frequency,
The communication apparatus according to claim 1, wherein the local oscillation signal distributor includes a hybrid coupler to which signals generated by a plurality of local oscillators are input from the centralized local oscillator.   The communication apparatus according to claim 1, wherein a housing of the frequency converter accommodates a plurality of the frequency converters.   5. The housing of the local oscillation signal distributor includes an input terminal for inputting a signal from the centralized local oscillator and a fixing part for removably fixing a cover to be attached when the input terminal is removed. The communication apparatus in any one of.

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