JP3180396B2 - Antenna adjustment method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for adjusting an antenna of a receiving apparatus for receiving a transmission signal by wireless communication.

[0002]

2. Description of the Related Art As a receiving apparatus for receiving a transmission signal by wireless communication, for example, a communication satellite (CS) is used.
There is a receiving device that receives a transmission signal from a satellite, for example, using a so-called parabolic antenna.

Here, satellite communication (satellite communicati)
On) means that satellites orbiting the earth have a relay function and communicate at multiple points on the earth. As satellites, there are satellites that orbit in synchronization with the rotation of the earth (24-hour cycle) and others. Of the former, an orbit about 35790 km above the equator is called a geostationary satellite because it appears relatively stationary from the earth, and that orbit is called a geosynchronous orbit.

[0004] The above satellite communication is different from other communication means.
With a single pass through a repeater at a height of about 36000 km, communication can be made anywhere between locations where satellites can be seen. From this, for example, wide area communication is possible, it is hard to be affected by ground disaster, flexible line setting is possible, construction and maintenance are easy, and transmission is possible regardless of the distance between earth stations. Constant quality and cost,
It is characterized by a delay of about 0.25 s per way.

[0005] The ground station for the satellite communication is a radio station installed on the earth for setting up a radio communication line via the satellite, and an antenna for transmitting / receiving radio waves to / from the satellite, a transmitting device, and a receiving device. It comprises a modem and a demodulator, a multiple access device, a carrier terminal device, and the like for efficiently communicating the device and information on radio waves. The type of ground station depends on the purpose of the communication,
Depending on the type of information, number of lines, etc., large to small fixed stations,
A portable station, a mobile station, and the like are realized.

The types of antennas for the ground station include axisymmetric antennas generally used, offset antennas for lower sidelobes, torus antennas for accessing multiple satellites without moving the main reflector, and offset spherical antennas. At small earth stations, elliptical beam antennas and the like aiming at reducing radio interference with adjacent satellites have been developed and put to practical use.

Incidentally, in recent years, so-called broadcast satellites (broadcast satellites) have been proposed.
It is considered that the communication satellite (CS) is used instead of the casting satellite (BS) to transmit a television broadcast signal, or to transmit, for example, an audio signal (digital audio data) of only audio or other data. .

Here, in the case of performing a television broadcast or an audio broadcast using the communication satellite (CS), the television broadcast signal is, for example, the broadcast satellite (BS).
It is a format of the so-called BS standard system using
The audio broadcast signal is, for example, MSK (Minimum) after convolutionally encoding (for example, a total of 12 Mbps) six PCM audio data of 2 Mbps corresponding to the so-called B mode of the satellite broadcast (total of 12 Mbps).
(Shift Keying) is modulated and sent.

The satellite broadcasting (BS) is generally a broadcasting performed using an artificial satellite launched in a geostationary satellite orbit about 36,000 km above the equator. It is understood that broadcast signals from broadcast satellites are received by simple receiving equipment (particularly equipment having a small antenna).

The video signal of the television broadcast signal in the satellite broadcasting is currently in the NTSC system, the maximum frequency is 4.5 MHz, the modulation system is FM modulation, the video frequency shift is 17 MHz _PP , and the energy spread signal is used. The frequency deviation of the main carrier is 600 kHz _PP and the main carrier frequency bandwidth is 27 MHz. The audio signal of the television broadcast signal in the satellite broadcast is a PCM signal.
Is a PCM subcarrier system in which a subcarrier of 5.727272 MHz is PSK-modulated with a digital signal according to the above. Further, the B mode has only two channels, and has a sound signal bandwidth of 20 kHz, which is wider than that of the A mode to enable wideband sound transmission.

[0011]

However, the above satellite communication generally has the following disadvantages, for example.

That is, the propagation path of the satellite communication is composed of the troposphere, the ionosphere and the outer space, and so-called fading which is a problem in the terrestrial radio communication system is small, but it is 10 GHz.
Above the z band, the attenuation of radio waves due to rainfall becomes significant. The attenuation of radio waves due to the rain is caused by absorption and scattering by raindrops, and this is generally called rain attenuation. In addition, noise (rain noise) is generated in addition to absorption and attenuation of radio waves due to rainfall. When the wavelength of the radio wave is sufficiently long compared to the diameter of the raindrop, the above-mentioned rain attenuation is almost entirely caused by “absorption”, but the ratio of “scattering” gradually increases as the frequency increases.

In satellite communications, in order to launch as many satellites as possible into a geosynchronous satellite orbit, it is necessary to reduce the interval between satellite orbits. Currently, the satellite orbit interval is 6/4
3 ° to 5 ° in the GHz band, 14/11 (or 12) GHz
It is 2 ° to 4 ° in the band, and tends to become narrower. As a result, for example, when the satellites use the same frequency band, they interfere with each other.

[0014] From the above, in the case of a system using a small antenna arranged in a general home, such as a broadcast using the communication satellite (CS), good reception can be achieved with the small antenna. In order to perform the above, the installation direction of the small antenna is very important. For example, when the direction of the antenna is not optimal, the reception condition deteriorates due to the rain attenuation, and the satellite is easily affected by adjacent satellites.

Here, as a conventional method for setting the direction of the antenna to an optimum one, for example, a method in which the antenna is pointed in a direction with the best reception state while observing the state of the received signal, That is, for example, in the case of audio broadcasting, a method is considered in which the antenna is pointed in the direction of the best reception state while listening to the audio.

Normally, however, high-performance error correction is performed on the above-mentioned received signal, so that even if the direction of the antenna is degraded and the reception state is deteriorated, it can be obtained as a normal received signal within a certain range. Therefore, in the case of the above method, it is difficult to determine how much the reception state has actually deteriorated (how much the antenna direction is deviated from the optimal direction). In addition, in the case of the above method, for example, if the error is out of the error correction threshold (correctable limit), the reception quality rapidly deteriorates. For this reason, it is difficult to find the best point in the direction of the antenna by this method.

Further, for example, when adjusting the direction of the antenna, a reception system for displaying a value related to an electric field strength such as an AGC (automatic gain control) voltage and adjusting the direction of the antenna while monitoring the value. Have existed conventionally.

That is, the configuration of the main part of the receiving system is as shown in FIG. In FIG.
The received signal from the communication satellite received by the antenna 1 is the SU
Sent to converter 2. In the SU converter 2, the SHF band (about 12.5 GHz) to the UHF band (1.
3 GHz).

The signal received via the SU converter 2 is sent to a tuning circuit 30. In the channel selection circuit 30,
A signal from the SU converter 2 and a local oscillation signal from a local oscillator (local oscillator) 34 are
The signal of the desired channel is extracted by mixing by 1 and sent to the AGC amplifier 32. The signal amplified by the AGC amplifier 32 is supplied to a PLL (Phase Locked Loop) circuit 3.
3 and output from the terminal 41. The terminal 41 is
The signal is sent to the signal processing block at the subsequent stage of the receiving device. In addition,
To extract the desired channel from the received signal,
This is realized by supplying tuning data via a terminal 42 to a microcomputer 35 for controlling the local oscillator 34. An AFC (automatic frequency control) output from the PLL circuit 33 is also sent to the microcomputer 35.

The AGC output (AGC voltage) of the AGC amplifier 32 is converted into digital data by an analog / digital (A / D) converter 43 and sent to an electric field strength display device 44, where the device 44 converts the digital data into digital data. A value related to the electric field strength is displayed.

However, in the above-mentioned method using the information related to the electric field strength, particularly when the above-mentioned small antenna is used, since the satellite is raised by about 4 ° as described above, it is affected by the adjacent satellite. For example, the direction in which the electric field strength is the highest (the direction of the antenna) is not always the direction in which the reception state is the best (the direction of the satellite transmitting the signal to be received).

Therefore, the present invention has been proposed in view of the above-described circumstances, and has as its object to provide an antenna adjustment method that makes it easy to find an optimum antenna direction.

[0023]

The antenna adjustment method of the present invention has been proposed to achieve the above-mentioned object. A transmission signal transmitted from a communication satellite is received by a parabolic antenna, and the antenna is adjusted by the parabolic antenna. The gain of the received signal is reduced by the attenuator, the number of data errors of the received signal whose gain is reduced by the attenuator is counted by the counting means, and the number of data errors counted by the counting means is displayed on the display means. The direction of the parabolic antenna is adjusted based on the number of data errors displayed on the means.

That is, the antenna adjusting method of the present invention
In a receiving apparatus having an attenuator whose gain can be varied, an antenna is first adjusted in a general direction at full gain, and then the gain of a received signal is deliberately reduced by the attenuator so that a reception data error occurs. By monitoring the error and fixing the antenna in the direction in which the frequency of occurrence of the error is the least, it is easy to install the antenna in the best direction.

Here, the attenuator may be composed of, for example, noise generating means for generating noise, and combining means for adding noise from the noise generating means to the received signal.

Other operations similar to those of the above-described attenuator (operation of lowering the gain of the received signal) are, for example, to cover a part or the whole of the antenna to equivalently reduce the antenna area, or to reduce the antenna area equivalently. This can be achieved by covering the side (surface) of the primary radiator facing the main reflection surface with aluminum foil, a cloth wetted with water, or the like.

By covering the side facing the main reflection surface of the primary radiator with the cloth wetted with water, the same effect (action) as the above-described rain attenuation can be obtained.

[0028]

According to the antenna adjustment method of the present invention, it is possible to intentionally lower the gain of the received signal by the attenuator to increase the frequency of occurrence of errors (the number of errors) of the received data.
Therefore, with this data error occurrence frequency increased,
By searching for the antenna direction with the lowest data error occurrence frequency, it is possible to easily find the optimum antenna installation direction.

[0029]

Embodiments of the present invention will be described below with reference to the drawings.

In the antenna adjusting method according to the first embodiment of the present invention, as shown in FIG. 1, the receiving device includes a detachable attenuator for reducing the gain of a received signal received by an antenna (for example, a parabolic antenna) 1. (Attenuator) 20 and an error counting circuit 21 for counting the number of data errors of the received signal.
And a display device 22 for displaying the number of data errors counted by the counting circuit 21.

In this embodiment, the present invention is applied to a receiving apparatus for receiving the audio broadcast signal from the communication satellite (CS).

In FIG. 1, a received signal from a communication satellite (CS) received by the antenna 1 is first sent to an SU converter 2. In the SU converter 2,
From SHF band (about 12.5 GHz) to UHF band (1.3 G
Hz).

The signal received via the above-mentioned SU converter 2 is sent to a tuning circuit 3. The channel selection circuit 3 performs a process of selecting, for example, any one channel from 30 channels (channels corresponding to transponders of communication satellites).

The signal of one channel selected by the tuning circuit 3 is an audio broadcast signal band (for example, f _c = 402 MH)
After passing through a band-pass filter 4 for extracting the signal z), the signal is sent to an MSK demodulation circuit 5 for performing MSK demodulation on the signal in the audio broadcast signal band. The 24 MHz data obtained by MSK demodulation by the MSK demodulation circuit 5 is decoded by the Viterbi decoding circuit 6. This Viterbi decoding circuit 6
12 MHz data (ie, a 2 Mbps PC corresponding to the above-described B mode of satellite broadcasting)
(A total of 12 Mbps data with 6 M audio data bundled)
Are demultiplexed by a demultiplexer 7 and sent to a selector 8 having six selected terminals. The data selected from the six data by the selector 8 is sent to the descramble circuit 9.

Here, the audio broadcast signal is scrambled so that a person who does not have a contract with a broadcaster cannot receive the audio broadcast signal because the broadcast is a pay broadcast. Therefore,
The descrambling circuit 9 performs a process of descrambling the scramble. The data descrambled by the descrambling circuit 9 is passed through a deinterleave circuit 10 for deinterleaving to a BCH code (Bose Chaudhuri).
After passing through an error correction circuit 11 for performing error correction using a Hocquenghem code), a decompression circuit 12 for protecting upper bits is provided.
Sent to

The data passed through the expansion circuit 12 is converted into an analog audio signal by a digital / analog (D / A) converter 13 and output from a terminal 14. This terminal 14 is connected to an amplifier, a speaker, and the like.

By the way, the BCH (63.5) used in the low-order part of the audio broadcasting by the communication satellite (CS) is used.
6) The error correction code is a so-called SEC / DED (one-bit error correction / two-bit error detection) code, and is always one bit or more in a syndrome calculation for performing error correction processing.
Errors up to 2 bits can be accurately detected. Since this error detection must be always detected when performing error correction, any receiver can receive 1 bit out of 63 bits in the frame structure of the PCM audio signal in the format of the broadcast satellite (BS). The number of errors up to 2 bits can be detected.

The counting of the number of errors is performed by the error counting circuit 21. That is, the error counting circuit 21 counts the number of times an error detected by the error correction circuit 11 has occurred in an arbitrary fixed time cycle. The value (the number of errors) counted by the error counting circuit 21 is displayed on the display device 22. As the display device 22, for example, a plurality of LEDs
(Light Emitting Diode) is used to change the number of lit LEDs, for example, in order to display the number of errors to the user in an easily understandable manner.

The antenna 1 is provided by the receiver as described above.
Is adjusted to the optimal direction, for example, the following procedure is taken.

First, it is assumed that the direction of the antenna 1 is roughly adjusted. Here, the antenna 1 and the SU converter 2
, The detachable attenuator 20 is inserted and connected.
Thereby, the gain of the signal received by the antenna 1 is
It is lowered by passing through the attenuator 20.

As described above, when the gain of the received signal decreases, the number of errors detected by the error correction circuit 11 increases, and the count value of the error counting circuit 21 also increases. The count value of the error is displayed on the display device 22.
Will be displayed.

At this time, the user or the like adjusts the direction of the antenna 1 while watching the display of the error count value displayed on the display device 22. Specifically, the direction of the antenna 1 is adjusted to the direction in which the number of errors is minimized.

Thereafter, the attenuator 20 is removed, and the antenna 1 is returned to the original full gain state. Thereby, the direction of the antenna 1 becomes the best position.

In the antenna adjusting method according to the second embodiment of the present invention, the attenuator may include, for example, noise generating means for generating noise and combining means for adding noise from the noise generating means to the received signal. Can be composed of In the case of the second embodiment, the combining means of the attenuator is inserted and connected between the SU converter 2 having the configuration shown in FIG. 1 and the tuning circuit 3, and the combining means is connected to the noise generating means. Try to send the noise.

Further, the antenna adjusting method according to the third embodiment uses the gain of the received signal electrically like the attenuator 20 of the first embodiment or the noise generating means and the combining means of the second embodiment. The same operation as that for reducing the gain (the operation for reducing the gain of the received signal) can be achieved, for example, by partially or entirely covering the antenna 1 to reduce the antenna area equivalently. The primary radiator (primary horn) can be realized even by using a mechanical filter, such as covering the side (surface) facing the main reflection surface with aluminum foil or a cloth wetted with water. Can be. The primary radiator may be integrated with the SU converter.

Here, by covering the side facing the main reflection surface of the primary radiator with the cloth wetted with water, the same effect (operation) as the above-described rain attenuation can be obtained.

As described above, in the antenna adjusting method of the present embodiment, the receiving device has the attenuator capable of changing the gain, and firstly adjusts the antenna in the general direction at full gain, and then intentionally uses the attenuator. The antenna is installed in the best direction by lowering the gain of the received signal so that a received data error occurs, and fixing the antenna in the direction in which the frequency of the error occurrence is the least while monitoring the received data error. It is easy to do.

Further, in the antenna adjustment method of the present embodiment, even if the receiving apparatus erroneously receives a signal from an adjacent satellite, the signal from the adjacent satellite cannot be descrambled. Cannot be monitored, so that the antenna 1 is not mistakenly oriented in the direction of the adjacent satellite.

[0049]

As described above, in the antenna adjusting method of the present invention, the receiving apparatus has the attenuator for reducing the gain of the received signal received by the antenna, and the attenuator reduces the gain of the received signal. In this state, the number of data errors in the received signal is counted and monitored, and the antenna is fixed in the direction in which the frequency of occurrence of errors is the least, so that it is easy to install the antenna in the optimum direction.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram illustrating a schematic configuration of a receiving apparatus according to a first embodiment of the present invention.

FIG. 2 is a block circuit diagram illustrating a configuration of a main part of a conventional receiving apparatus that adjusts the direction of an antenna based on a value related to an electric field strength.

[Explanation of symbols]

 1 Antenna 2 SU converter 3 Tuning circuit 4 Bandpass filter 5 MSK demodulation circuit 6 Viterbi decoding circuit 7 Demultiplexer 8 Selector 9 Descramble circuit 10 Deinterleave circuit 11 Error correction circuit 12 Decompression circuit 13 D / A converter 20 Attenuator 21 Error counter circuit 22 Display device

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) H04B ⁷ /14-7/22 H04B 1/16 H01Q 15/00-19/32 H04H 1/00-9 / 00

Claims (1)

(57) [Claims] 1. A received signal transmitted from a communication satellite is received by a parabolic antenna, the gain of the received signal received by the parabolic antenna is reduced by an attenuator, and the data of the received signal whose gain is reduced by the attenuator. The number of errors is counted by counting means, the number of data errors counted by the counting means is displayed on a display means, and the direction of the parabolic antenna is adjusted based on the number of data errors displayed on the display means. Antenna adjustment method.