Satellite communication equipment for mobile object

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a mobile satellite communication device used in a mobile satellite communication system, and more particularly to a mobile satellite communication device that enables the use of satellite communication indoors.

【0002】

[Conventional technology]

A conventional mobile satellite communication device will be described with reference to FIG. 5, which shows a system diagram of a mobile satellite communication system.

【0003】

This system consists of a base station 1, a plurality of mobile satellite communication devices 40-1 to 40-3 (hereinafter abbreviated as devices for the sake of simplicity), and satellite 2.

【0004】

The devices 40-1 to 40-3 are mobile satellite communication devices having the same configuration, and are devices that can be easily carried. Among them, for example, the device 40-1 is used outdoors and shows a configuration in which it is connected to the base station 1 via the satellite 2. In this case, even if the device 40-1 is moved to a mountainous area, a building, or the like, communication is possible within a range in which the device can see the satellite 2.

【0005】

In addition, device 40-2 shows the case where it is installed in a building such as a building. In this case, communication is possible because the signal is slightly attenuated at a position where the satellite can be seen, for example, near the window 21 provided in the building.

【0006】

On the other hand, since the device 40-3 is used in a place away from the window 21 inside the building, the satellite 2 cannot be seen through, and the transmission / reception signal for satellite communication cannot be transmitted.

【0007】

In order to communicate with this device 40-3, it is necessary to move to a place such as a window where radio waves reach, such as device 40-2.

【0008】

Documents describing the mobile satellite communication system described above include PTC'93 Proceedings, p.835 to p.840, and "INMARSAT-M.PORTABLE MES".

【0009】

[Problems to be Solved by the Invention]

As described above, in the conventional mobile satellite communication system, communication becomes impossible when there is an obstacle between the mobile satellite communication device and the satellite.

【0010】

In particular, in a building such as a building, communication can be performed only in a limited place such as near a window, and even if it can be moved as a terminal device for mobile satellite communication, it can be used with a high degree of freedom. It had a problem that made it impossible.

【0011】

An object of the present invention is to provide a mobile satellite communication device capable of freely using satellite communication even in a mobile satellite communication terminal device installed in a building where satellites cannot be seen. is there.

【0012】

[Means for solving problems]

The present invention is a mobile satellite communication device capable of moving indoors and outdoors via a satellite to transmit and receive. Indoors, a first antenna for a terrestrial wireless line is attached to a mobile unit and externally connected by a terrestrial wireless line. An indoor device that transmits / receives a signal connected to the above and a relay device that attaches the first antenna and the second antenna for the satellite line and converts the terrestrial wireless line into the satellite line are used outdoors. A second antenna for the satellite line is attached to the mobile unit to use an outdoor device for transmitting and receiving signals connected to the outside by the satellite line, and further, the first, which is attached to the mobile unit. It has a feature that both the indoor device and the outdoor device can be configured by exchanging the second antenna.

【0013】

BEST MODE FOR CARRYING OUT THE INVENTION

Next, the mobile satellite communication device of the present invention will be described with reference to the drawings.

【0014】

FIG. 1 shows a system diagram of a mobile satellite communication system using the mobile satellite communication device of the present invention.

【0015】

In this figure, the mobile satellite communication device of the present invention mainly connects directly to a subscriber terminal and transmits the signal using the satellite line 11 or the terrestrial wireless line 12, and the mobile devices 3 and 4 and the satellite line. It can be divided into two types: a relay device 10 that converts transmission / reception signals between 11 and the terrestrial wireless line 12.

【0016】

Further, the mobile device has a removable antenna portion and a common configuration other than that, and is divided into two devices according to the type of antenna. That is, there are two types of devices: a mobile device 3 equipped with a satellite communication antenna (hereinafter referred to as an outdoor device) and a mobile device 4 equipped with a terrestrial wireless line antenna (hereinafter referred to as an indoor device). is there.

【0017】

The reason for dividing into the outdoor device 3 and the indoor device 4 in this way is as follows.

【0018】

The frequency band used for transmitting and receiving to and from the satellite 2 is usually a microwave band or a quasi-microwave band, and a high frequency is used. As for the modulation / demodulation method, QPSK (4-phase phase shift keying) or OQPSK (offset QPSK), which can efficiently use the radio band and enable low C / N (carrier power to noise ratio) operation, is selected.

【0019】

On the other hand, the distance between the terrestrial wireless line between the relay device 10 and the indoor device 4 is very close, and the frequency used is below the VHF band so that the directivity is as wide as possible and it can be used even outside the line of sight. A relatively low frequency band is used. Therefore, as the modulation / demodulation method, for example, the FSK method or the FM modulation method can be used.

【0020】

In this way, in order to use two lines having different uses, the outdoor device 3 and the indoor device 4 are divided.

【0021】

Here, the terrestrial wireless line 12 is a line used exclusively for indoor communication, and refers to a wireless line that enables non-line-of-sight communication using a relatively low frequency (for example, a frequency in the VHF band).

【0022】

The mobile satellite communication system shown in FIG. 1 is configured by using the above mobile satellite communication device.

【0023】

That is, in the building 22 shown in FIG. 1, the relay device 10 is installed in a place where the satellite 2 can be seen, for example, in the vicinity of the window 21.

【0024】

The relay device 10 includes an antenna (A) 5 for transmitting and receiving to and from the satellite 2, an antenna (B) 6 for transmitting and receiving to and from the indoor device 4 via a terrestrial wireless line, and an antenna (A) 5 and an antenna (B) 6. the reception signal signal varying between constructed from the conversion unit 9 for conversion.

【0025】

The antenna (A) 5 and the antenna (B) 6 have a structure that can be mechanically attached to and detached from the conversion unit 9. Further, in the building 22, an indoor device 4 equipped with a detachable antenna (B) 6 so that transmission / reception can be performed by the relay device 10 and the terrestrial wireless line 12 is installed.

【0026】

On the other hand, an outdoor device 3 to which a detachable antenna (A) 5 is attached so that the satellite 2 and the satellite line 11 can transmit and receive is installed outdoors.

【0027】

Next, the specific operation of these mobile satellite devices will be described.

【0028】

First, the relay device 10 will be described below.

【0029】

In the present invention, in order to use satellite communication indoors, the relay device 10 is provided at a position where the satellite 2 can be seen.

【0030】

The relay device 10 has two antennas, an antenna for satellite communication (A) 5 and an antenna for terrestrial radio (B) 6.

【0031】

This device uses these two antennas, for example, when receiving a received signal from satellite 2, the antenna (A) 5 receives the satellite line 11 directly through the window 21, and the converter 9 signals to the ground line 12. After conversion, it is transmitted to the indoor device 4 using the antenna (B) 6.

【0032】

As a result, even if the indoor device 4 is installed in a place where the satellite 2 cannot be seen at all, it is possible to transmit and receive to and from the satellite 2 via the relay device 10.

【0033】

Next, a specific configuration of the indoor device 4 will be described.

【0034】

The indoor device 4 is composed of an antenna (B) 6 for the terrestrial wireless line 12, an interface 13, an RF (A) 7, an RF (B) 8, and a common portion 15. Here, the interface 13 has a function of selecting the RF corresponding to the antenna provided between the antenna and the two types of RFs (A) and (B) and automatically connected according to the type of the antenna. ing. Here, the antenna and the interface 13 have a structure that can be mechanically removed by using a high-frequency connector. Then, the interface 13 determines whether the connected antenna is the terrestrial radio antenna (B) 6 or the satellite communication antenna (A) 5, and selects the corresponding RF.

【0035】

That is, in the indoor device 4, RF (B) 8 for transmitting and receiving signals of the terrestrial wireless line is selected and input / output to the common unit 15.

【0036】

Next, the common unit 15 has two types of modulation / demodulation functions, a baseband processing function, and the like. When a signal that determines the type of antenna from the interface 13 is input to the common unit 15, the modulation / demodulation method for terrestrial lines (referred to as modulation / demodulation method (B)) or the modulation / demodulation method for satellite communication (modulation / demodulation method (A)) Select either).

【0037】

That is, the common unit 15 selects the modulation / demodulation method (B) in response to the detection signal indicating that the antenna (B) 6 for the indoor device 4 is connected at the interface 13.

【0038】

As a result, when a voice or data signal or the like is transmitted from the indoor device 4 to the base station 1, the modulation signal by the modulation / demodulation method (B) is first output by the common unit 15. Next, the modulated signal is converted to the carrier frequency (B) by RF (B) 8 and then transmitted to the relay device 10 by the antenna (B) 6 via the interface 13.

【0039】

The relay device 10 receives the transmission signal having the carrier frequency (B) modulated by the modulation / demodulation method (B) at the antenna (B) 6.

【0040】

When the conversion unit 9 receives the signal from the indoor device 4, the conversion unit 9 sets the carrier frequency (B) to the carrier frequency (A), which is the carrier wave for satellite communication, and the modulation / demodulation method (B) to the modulation / demodulation method (B), which is the modulation / demodulation method for satellite communication. Convert to A) respectively.

【0041】

The output signal of the conversion unit 9 is transmitted to the satellite 2 by the satellite line 11 by the carrier frequency (A) and the modulation / demodulation method (A) by the antenna (A) 5 which is a satellite communication antenna.

【0042】

On the contrary, when the indoor device 4 receives the modulation signal, the relay device 10 receives the modulation signal by the modulation / demodulation method (A) at the carrier frequency (A) from the satellite 2. The signal received by the relay device 10 is converted into a signal of the carrier frequency (B) and the modulation / demodulation method (B) for the ground line, and transmitted to the indoor device 4.

【0043】

The indoor device 4 receives the signal from the relay device 10 and outputs the received signal.

【0044】

Next, a case where the mobile satellite communication device of the present invention is used as the outdoor device 3 will be described.

【0045】

An antenna (A) 5 for satellite communication is attached to the antenna of the outdoor device 3 so that the satellite communication line can be used.

【0046】

As described above, except for the antenna, the mobile device has the same configuration regardless of whether it is an outdoor device or an indoor device.

【0047】

The interface unit 13 of the outdoor device 3 detects that the satellite communication antenna (A) 5 is attached. Then, the RF (A) 7 is controlled so as to generate the carrier frequency (A) for satellite communication, and the common unit 15 is controlled so as to be the modulation / demodulation method (A) for satellite communication.

【0048】

As a result, the outdoor device 3 can transmit and receive via the satellite communication line.

【0049】

In the configuration described above, the modulation / demodulation method of this device is different between the wireless line and the satellite line.

【0050】

However, in order to simplify the device configuration, the device configuration is not limited to this, and the modulation / demodulation method may be the same for the wireless line and the satellite line.

【0051】

Next, a specific configuration of the mobile satellite communication device of the present invention will be described in detail.

【0052】

2 (a) to 2 (d) are views showing exchange units constituting the mobile satellite communication device of the present invention.

【0053】

Here, FIG. 2A is a diagram showing a replacement unit (referred to as a mobile unit) 16 used to form a mobile device. Here, the moving unit 16 is connected to the antenna (A) 5 or the antenna (B) 6 shown in FIGS. 2 (c) and 2 (d) by using a coaxial connector. Here, the interface unit 13 of the mobile unit 16 has RF (A) 7 or RF (B) 8 and common unit 15 depending on the type of antenna to be connected (antenna (A) 5 or antenna (B) 6). It has a function to select the modulation method and the like.

【0054】

As a method of detecting the type of antenna, for example, separate connectors are provided in advance for attaching the antenna (A) 5 and the antenna (B) 6 to the interface 13. Then, the impedance of the connector can be detected by the interface 13 to know whether or not the antenna is connected.

【0055】

As another method, in order to improve economy and miniaturization, the mounting connector of the interface 13 is the same for both antennas, and only one of the antennas is provided with a DC loop formed in the signal line of the interface 13. There are methods such as detecting the current.

【0056】

Further, RF (A) 7 is a high frequency circuit unit for a satellite communication line, and has a function of amplifying a high frequency signal and a frequency conversion function.

【0057】

Similarly, RF (B) 8 is a high-frequency circuit section for terrestrial wireless lines, and while high-frequency signals for satellite communication lines usually require a high-power amplification function on the transmitting side and a low-noise amplification function on the receiving side. , The terrestrial wireless line does not require these, so it is prepared independently for the terrestrial wireless line.

【0058】

The common unit 15 performs modulation / demodulation processing of the intermediate frequency band signal frequency-converted by RF (A) 7 or RF (B) 8 or baseband signal processing, and transmits / receives a transmission / reception signal to the outside of the apparatus. Is an interface.

【0059】

FIG. 3 is a diagram showing the configuration of the mobile unit 16.

【0060】

In this figure, the interface 13 is connected to the antenna A (5) or the antenna B (6) via the coaxial connector 133.

【0061】

The antenna detection circuit 132 is a detection circuit for the type of antenna, and controls the high frequency switch 131 by the detection output thereof. This high frequency switch can be easily configured using a pin diode switch.

【0062】

The RF (A) 7 is frequency-converted to an intermediate frequency band by the mixer 73 after the received signal input via the duplexer 71 is amplified by the low noise amplifier 72.

【0063】

Here, RX SYNTH (A) 75 is a synthesizer for frequency conversion. The received signal in this intermediate frequency band is demodulated by DEM (A) 153 to obtain a baseband signal.

【0064】

On the transmitting side, on the other hand, the baseband signal is modulated by MOD (A) 154, amplified by the intermediate frequency band amplifier 79, frequency-converted by TX SYNTH (A) 78 and mixer 77, and then high frequency. It is amplified by the power amplifier 76 and input to the duplexer 71.

【0065】

The transmitted signal is output from the output end force 133 through the RF SW131.

【0066】

Since RF (B) 8 has the same configuration, detailed description will be omitted.

【0067】

The common unit 15 includes a modulation / demodulation circuit MOD (A) 154 and DEM (A) 153 for satellite communication and a modulation / demodulation circuit MOD (B) 152 and DEM (B) 151 for terrestrial radio.

【0068】

Further, the control circuit 134 of the interface 13 controls the baseband switch (BB SW) 156 based on the detection output of the antenna detection circuit 132, and switches between satellite communication and terrestrial radio.

【0069】

Next, the conversion unit 9 shown in FIG. 2B has a frequency conversion function between the satellite communication line and the terrestrial radio line used in the relay device 10.

【0070】

The conversion unit 9 has a structure in which the antenna (A) 5 and the antenna (B) 6 used for the mobile device are attached, and the antenna is shared as the whole mobile satellite communication device to improve economy. There is.

【0071】

Figures 2 (c) and 2 (d) are antennas (A) 5 and antennas (B) 6, respectively, which are independent transmitting and receiving antennas. Both are connected to the interface 13 or the conversion unit 9 using the coaxial connector for transmission / reception signals.

【0072】

FIG. 3 is a diagram showing a configuration when transmitting and receiving from indoors to a satellite using the mobile satellite communication device.

【0073】

In this figure, the relay device 10 has an antenna (A) 5 and an antenna (B) 6 attached to a conversion unit 9.

【0074】

Further, the indoor device 4 is a mobile unit 16 to which an antenna (B) 6 is attached.

【0075】

As described above, signals can be transmitted / received between the indoor device 4 and the relay device 10 using the terrestrial wireless line 12, and can be transmitted / received between the relay device 10 and the satellite 2 using the satellite line 11.

【0076】

As a result, when performing satellite communication freely in the building, the mobile unit 16 and the antenna (B) 6 are combined to form the indoor device 4, and the converter 9, the antenna (A) 5, and the antenna (B) 6 are combined. And can be combined to form a relay device.

【0077】

On the other hand, when performing satellite communication outdoors, the outdoor device 3 can be configured by combining the mobile unit 16 and the antenna A (5).

【0078】

Therefore, by preparing at least one mobile unit 16, one antenna (A) 5, two antennas (B) 6, and one converter 9, satellite communication can be easily performed in any usage environment. Available.

【0079】

In the embodiment described above, the outdoor device 3 is not used only outdoors, and it goes without saying that the outdoor device 3 can directly transmit and receive via the satellite in a place where the satellite can be seen indoors, such as the relay device 10.

【0080】

Similarly, the indoor device 4 is not used only indoors, and it goes without saying that the indoor device 4 can transmit and receive using a terrestrial wireless line outdoors.

【0081】

Further, it is naturally possible to use both the indoor device 4 and the relay device 10 outdoors to perform satellite communication.

【0082】

[Effect of the invention]

As described above, the present invention can use satellite communication in various indoor and outdoor environments by using a compatible antenna for satellite communication and an antenna for terrestrial wireless line, and has sufficient potential as a mobile device. It has an effect that can be exerted.

[Simple explanation of drawings]

[Figure 1]

It is a figure which shows the system diagram of the mobile satellite communication system using the mobile satellite communication apparatus of this invention.

[Figure 2]

(a) to (d) are diagrams showing replacement units which are the basic elements of the present invention, respectively.

[Fig. 3]

It is a figure which shows the specific structure of the mobile unit 16.

[Fig. 4]

It is a figure which showed the structure when the basic elements shown in FIG. 2 are combined and communication is performed indoors.

[Fig. 5]

It is a figure which shows the system diagram of the conventional mobile satellite communication system.

[Explanation of symbols]

1 base station 2 satellites 3 Mobile satellite communication device (outdoor device) 4 Mobile satellite communication device (indoor device) 5 Antenna (A) 6 Antenna (B) 7 RF (A) 8 RF (B) 9 Conversion unit 10 Relay device 11 satellite line 12 terrestrial wireless line 13 interface 15 common part 16 mobile unit 21 windows 22 buildings 71,81 Duplexer 72,82 Low noise amplifier 73,83 Mixer 74,84 Receive amplifier 75,85 Receive synthesizer 76,86 High Frequency Power Amplifier 77,87 Mixer 78,88 Send Synthesizer 79,89 transmit amplifier 131 RF switch 132 Antenna detection circuit 133 Coaxial connector 134 Control circuit 151 Demodulator (B) 152 Modulator (B) 153 Demodulator (A) 154 Modulator (A) 156 Baseband switch