JPS6281820A - Distress communication method by geostationary satellite - Google Patents

Abstract

PURPOSE:To detect a distressed position by utilizing a geostationary satellite by obtaining information of said position from a reception power level of a distress signal radio wave at each multi-beam antenna even when no distressed position information is sent from a transmitter of a wrecked ship. CONSTITUTION:When a wrecked ship exists in a beam irradiation area of an antenna beam 13-i and when a distress signal from a transmitter of the wrecked ship is found out, the distress signal radio wave is caught by the antenna beam 13-i, the signal passes through a feed horn 17-i, received and detected by a receiver 18-i and converted into a reception power level signal and inputted to a signal processing circuit 19. The signal processing circuit 19 applies A/D conversion signal to each reception power level signal and sends the result to an earth station 9 in a signal format corresponding to each antenna beam. Since the sending point of the distress signal exists in the beam irradia tion area of the antenna beam having the maximum reception power level, the earth station finds out the distressed position.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention utilizes artificial satellites to enable people in distress to transmit distress signals and inform rescue agencies of their location in the event that a ship or aircraft is in distress. This relates to a distress communication method.

[Conventional technology]

The method of using geostationary satellites to communicate distress of ships, etc. can provide a very wide antenna coverage, and can immediately report distress without the waiting time for a satellite as in the single-orbiting satellite system.

FIG. 4 shows a principle diagram of a conventional distress communication method using a geostationary satellite. In addition, in FIG. 4, the case of a ship will be explained as an example.

In Figure 4, (1) is the Earth, (2) is the ship in distress, and (3 is
) is a distress transmitter, (41 is a radio wave of a distress signal transmitted from this distress transmitter (3), (5) is a geostationary satellite located in the geostationary satellite orbit of the earth + 11 above, and (6) is this geostationary satellite. An antenna installed on the ship that captures the radio waves (4) of the above-mentioned distress signal.

(7) is the beam of this antenna (61) which has a wide beam width to widen the beam irradiation area 2, such as the global beam, (8) is its beam irradiation area, (
9) is the earth station, 雛 is the antenna for communication with the earth station, a1
+ indicates a downlink signal radio wave from the geostationary satellite (5) to the earth station.

The conventional distress communication method using a geostationary satellite is configured as described above, and since antenna coverage can be widened by stabilizing the geostationary satellite (5), antenna f61U is used to widen the beam width to greatly expand the beam irradiation area (8). It has an antenna beam (7) similar to the digit global beam. When a ship is in distress, information such as the identification code of the 11Jlii ship (2), the time of the shipwreck, and the position of the ship is sent to the distress transmitter (3).
) to 2! ! Transmit on poor signal radio waves (4).

When the distress transmitter (3) is within the beam irradiation area 18),
The geostationary satellite (5) is connected to the antenna beam (7) of the antenna (6).
1 receives the distress signal radio wave (4) and sends it to the geostationary satellite (5).
) repeater performs frequency conversion and multiplication to antenna α1.
It is then retransmitted to the earth station (9) using the downlink signal radio wave ALL.

The ground station (9) demodulates and decodes the received downlink signal, and then communicates the obtained distress location information to the rescue organization and sends it to rescue ships and aircraft a! and others will head to the scene of the disaster.

[Problem that the invention seeks to solve]

In the conventional distress communication method using geostationary satellites as described above,
Transmissions from the distress transmitter (3) within the beam irradiation area (81) can be monitored at all times, but 2 SOS signals without location information do not know where within the satellite's antenna coverage the signal was sent from, which can cause distress. It is necessary to transmit a distress signal containing the position information of the ship (2) from the distress transmitter (3).For this reason, the distress transmitter (3) must have a built-in positioning device, or.

Distress transmitter (3) always transmits the position determined from the ship's navigation equipment.
This has the disadvantage that the device needs to be inputted in advance, making the device complicated. In addition, for this reason, it has the disadvantage that it cannot be used to pierce distress transmitters that only transmit SOS signals, which are currently widely used in aircraft and small ships.

The present invention has been made in order to solve these drawbacks, and aims to provide a distress communication method that allows the location of a distress situation to be known by using a geostationary satellite without transmitting distress location information from a distress transmitter. Objective 0 [Means for solving the problems] A distress communication method using a geostationary satellite according to the present invention.

Instead of the conventional global beam antenna, a multi-beam antenna is mounted on a geostationary satellite that covers the entire predetermined antenna coverage area with multiple antenna beams that are spatially fixed and have sufficiently narrow beam damage.

Information on the distress position can be obtained from information on the received power level of the distress signal radio waves for each antenna beam.

[Effect]

A geostationary satellite is in a geostationary satellite orbit above the earth's equatorial plane (altitude 3
It is located at an altitude of 6,000 km) and revolves in the same direction at the same period as the Earth's rotation, so when viewed from the ground, it appears to be stationary at a single point in the sky.

Therefore, since the relative positional relationship between the ground and the geostationary satellite remains constant, if the direction of the beam of the antenna mounted on the geostationary satellite is always directed to a specific direction on the earth,
The antenna beam will be spatially fixed.

On the other hand, if the beam width of the antenna beam is narrowed, the area of the beam irradiation area becomes smaller and the antenna gain becomes higher.

For example, in an aperture antenna, the beam width can be narrowed by increasing the aperture size of the antenna or by increasing the operating frequency.

An antenna with a sufficiently narrow beam width is generally called a pencil beam. A pencil beam has a high gain inside the beam, but the gain drops sharply outside the beam. A given antenna coverage is covered by multiple pencil beams, each with a different direction.

The antenna coverage area is subdivided in units of beam irradiation area of each antenna beam. Now, when a distress signal is transmitted from a distress transmitter within the irradiation area of one antenna beam with a multi-beam antenna using multiple pencil beams, that antenna beam receives a high received power level, but the other antenna beams receive a high received power level. The received power level becomes very small. Therefore, by monitoring the received power level for the distress signal radio waves for each antenna beam, it can be determined that the distress signal transmission point is within the antenna beam irradiation area where the received power level is maximum.

In addition, in this invention, by using a geostationary satellite, a wide antenna coverage can be obtained and immediacy can be maintained, as in the conventional system.

〔Example〕

Figure WL1 is a principle diagram of a 417m communication method using a geostationary satellite according to the present invention. In the figure, 11+, +5
1°(9), α(1, QB are the same as those shown in FIG. 4).

αa is the antenna beam of the multi-beam anti-f, a3U multi-beam antenna α mounted on the geostationary satellite (5), and 1 is a plurality of narrow antenna beams such as a pencil beam (141 is each of the above antennas) The beam irradiation area of the beam α3 on the earth's surface, a9, indicates the entire antenna coverage of the multi-beam antenna α2.

FIG. 2 is a block diagram showing an embodiment of a distress communication device mounted on a geostationary satellite (5). In the figure, H
, Ql) are the same as those shown in FIG. 1.aOc The reflection m and αη of the multi-beam antenna (7) are the feed horns of the multi-beam antenna αa.

Each feed horn αη has a one-to-one correspondence with the antenna beam αa shown in FIG. The correspondence relationship is indicated by a subscript. Nishiki is a receiver connected to the output end of the feed horn + IT), which receives and detects the distress signal radio wave and outputs a received power level signal.

(11 is a signal processing circuit that converts the output of the received power level signal corresponding to each antenna beam into an appropriate signal format for transmission to the ground, and (a) is a transmitter that transmits the output signal after signal processing to the ground. It is.

In the distress communication method using a geostationary satellite configured as described above, a predetermined antenna coverage is subdivided into beam irradiation areas of a plurality of antenna beams having sufficiently narrow beam widths.

FIG. 3 is an explanatory diagram of the operation of the embodiment of the present invention. As shown in the figure, if there is a ship in distress (21) within the beam irradiation area (14-1) of the antenna beam (13-1), and a distress signal is transmitted from the distress transmitter (3), the distress signal radio wave will be transmitted. (4) is captured by antenna beam (13-i),
Pass through the feed horn (17-1) and connect to the receiver (18-i).
), and the detection output indicating the reception level is converted into a reception power level signal and input to the signal processing circuit α1.

Is the detection output of the receivers other than the receiver (18-1) at a noise level because the distress signal is not received because the transmission point of the distress signal is outside the beam irradiation area of those antenna beams?

Alternatively, even if it is received using an adjacent antenna beam, the reception level will be extremely low. The signal processing circuit a9 performs analog/digital conversion on each received power level signal from the receivers (18-1) to (18-N).

The signal is processed to indicate information on the received power level corresponding to each antenna beam, converted into an appropriate signal format, and output. The output signal of the signal processing circuit is transmitted to the transmitter (
(a) and is transmitted from the antenna α1 to the earth station (9). The downlink signal radio wave αB received by the earth station (91) is demodulated and decoded to obtain information on the received power level for each antenna beam.Beam irradiation of the antenna beam (13-1) with the highest received power level Since there is a distress signal transmission point within the area (14-1), information on the distress location can be obtained.

In the above embodiment, a multi-beam antenna with a two-reflector antenna was shown, but the present invention can also be applied to other types of multi-beam antennas such as a lens antenna.

Incidentally, in the above explanation, the present invention was described in the case of attaching a piece to a ship in distress, but it goes without saying that it can also be used for distress communication in the event of a distress on an aircraft or on land.

〔Effect of the invention〕

As explained above, this invention includes a multi-beam antenna mounted on a geostationary satellite that covers a predetermined antenna coverage with multiple antenna beams with sufficiently narrow beam widths, and information on the received power level of distress signal radio waves in each antenna beam. Depending on the direction in which the distress signal is transmitted to the earth station, if the distress signal radio waves are transmitted by a simple distress transmitter, the location information of the distress point can be easily known without having to transmit the distress location information from the victim's side. It has the effect of being able to

[Brief explanation of drawings]

FIG. 1 is a principle diagram of a distress communication method using a geostationary satellite showing an embodiment of the present invention, and FIG. 2 is a block diagram of the configuration of a distress communication device mounted on a geostationary satellite showing an embodiment of the present invention.
FIG. 3 is an explanatory diagram of the operation of the present invention, and FIG. 4 is a principle diagram of a conventional distress communication method using a geostationary satellite. In the figure, (1) is the Earth, (3) is the distress transmitter, and (4)
) is the distress signal radio wave, (5) is the geostationary satellite, (9) is the earth station, Ql is the antenna of the earth station communication piece, 01) is the downlink signal radio wave, σ2 is the multi-beam antenna, and αj is the antenna beam of the multi-beam antenna. , α4 is the beam irradiation area, (
l is the antenna coverage, αη is the feedhorn, a
gta receiver, α9 is a signal processing circuit, and ■ is a transmitter. Nafu・9 The same group numbers in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] A multi-beam antenna is mounted on a geostationary satellite located in a geostationary satellite orbit of the earth, and has a plurality of antenna beams at the same frequency corresponding to a plurality of output terminals, each in a different direction and having a sufficiently narrow beam width, and Distress transmitted from a distress transmitter that covers a predetermined antenna coverage by each beam irradiation area on the earth's surface of a plurality of spatially fixed antenna beams of a multi-beam antenna, and is within the predetermined antenna coverage. The signal radio waves are received by the above multi-beam antenna, information on the received power level of the distress signal radio waves for each antenna beam is transmitted from the geostationary satellite to the earth station, and the received power level of the distress signal radio waves corresponding to each antenna beam is determined on the ground. A distress communication method using a geostationary satellite characterized by obtaining location information of a distress point from level information.