JP2000299655A - CS communication system, CS tracking method, CS receiver - Google Patents

Abstract

(57) [Summary] PROBLEM TO BE SOLVED: To reliably track a communication satellite by a receiving antenna mounted on a mobile body with good responsiveness and without erroneous tracking target. SOLUTION: A control channel belonging to the same downlink as a designated information channel is selected (S320), and the direction of a receiving antenna unit is controlled with a C / N level peak of the transmission data as a tracking target (S330). . As a result of the determination based on the satellite identification information provided by the selected control channel, if the radio wave being received by the receiving antenna unit is not from the intended communication satellite (S350-N), The same processing is repeated with a peak different from the tracking target peak as a tracking target (S370). As described above, since the tracking control of the satellite is performed using the control channel dedicated to the transmission of the control information, the extraction of the satellite identification information and the determination of the communication satellite can be quickly performed. As a result, it is possible to quickly track the target communication satellite without error.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is suitable for tracking the direction of a receiving antenna mounted on a mobile object in accordance with the movement of the mobile object so that radio waves can be satisfactorily received from a communication satellite (CS). The present invention relates to a CS communication system, a CS tracking method, and a CS receiving device.

[0002]

2. Description of the Related Art Conventionally, a BS tuner that receives a radio wave from a broadcasting satellite (BS) and reproduces a video signal and an audio signal is mounted on a vehicle, and the video and audio reproduced by the BS tuner are provided on the vehicle. On-vehicle BS that can be viewed on a remote receiver
Broadcast viewing devices are known.

[0003] In general, when receiving transmitted radio waves from artificial satellites, including broadcast satellites, good reproduction of video and audio must be performed unless the directivity of the receiving antenna is accurately directed to the target artificial satellite. Can not. For this reason, the in-vehicle BS broadcast viewing and listening apparatus uses a receiving antenna having a movable azimuth and elevation angle, and even if the relative positional relationship with the artificial satellite changes according to the traveling state of the vehicle (such as the traveling direction). Tracking control is required to control the direction of the receiving antenna so that the directivity of the receiving antenna always points accurately to the target artificial satellite.

Specifically, the reception level of a reception signal obtained from a reception antenna is monitored, and control is performed so that the reception level is always the best, that is, the reception antenna always faces the direction in which the reception level becomes a peak. Is done. by the way,
In recent years, video and audio services have been provided using not only broadcast satellites but also communication satellites (CS). In particular, communication satellites are considering services that provide various types of digital information in addition to video and audio, and it is desired that these services be made available to various types of in-vehicle information devices.

[0005]

However, since there are a large number of communication satellites, simply performing tracking control of the satellites using only the reception level of the received signal will not allow transmission of radio waves from a desired communication satellite. There is a problem in that it is not always possible to receive the signal, and there is a possibility that the signal may be locked so as to receive a transmission radio wave from a different satellite.

[0006] On the other hand, in a downlink provided from a communication satellite to a CS receiver, control information including program information indicating the contents of communication information is generally included in communication information between users. Since the control information includes satellite identification information indicating the name of the satellite providing the downlink, the satellite identification information is transmitted from the communication satellite. It is conceivable to extract from the demodulated data obtained by demodulating the received signal and determine whether or not the satellite locked by the tracking control is a desired communication satellite based on the extracted satellite identification information. .

However, the ratio of control information to communication information is extremely small, and it takes time to extract control information from a huge amount of data transmitted on the downlink. In the case of performing digital broadcasting, it is possible to set a plurality of channels for one downlink. However, each channel is simply processed in the same manner as in the case where the above-mentioned channel is not divided, and is divided. In each channel, the ratio of control information to communication information is still low, and when tracking control is performed using such satellite identification information, the responsiveness of tracking control deteriorates. There was a problem that it would.

The present invention has been made in order to solve the above problems.
An object of the present invention is to enable a tracking of a communication satellite by a receiving antenna mounted on a moving body to be performed with good responsiveness and without erroneous tracking.

[0009]

In the CS communication system according to the first aspect of the present invention, the downlink provided by each transponder mounted on a communication satellite is set in advance. To identify a communication channel for transmitting communication information between users by data transmission using the main carrier and a communication satellite that is a source of the downlink by data transmission using a pilot carrier different from the main carrier. And a control channel for transmitting control information including at least satellite identification information.

That is, in the present invention, a control channel for providing only control information is provided separately from a communication channel. The CS tracking method according to the third aspect of the present invention uses the CS communication system according to the first aspect, detects a reception level of transmission data of a control channel, sets a peak of the reception level as a tracking target, and sets the peak of the reception level at the peak. A first procedure for tracking the direction of the receiving antenna so as to receive a radio wave from the communication satellite, and receiving the signal by the receiving antenna based on satellite identification information obtained by demodulating control channel transmission data. It is determined whether or not the radio wave is from the target communication satellite, and as a result of the determination, if the radio wave is not from the target communication satellite, the peak of the reception level previously targeted for tracking is And a second procedure of repeating the first procedure with different peaks as new tracking targets.

That is, since the control channel is designed to transmit only control information, the satellite identification information can be easily extracted in a short time in the second procedure.
It is possible to quickly determine a communication satellite using the satellite identification information. Therefore, according to the CS tracking method of the present invention, not only can the target communication satellite be tracked without being mistaken, but also the lock can be quickly performed in a direction in which radio waves from the target communication satellite can be satisfactorily received.

The reception level may be a signal component level, a C / N level which is a ratio between a carrier component and a noise component, or an S / N which is a ratio between a signal component and a noise component.
/ N level. Further, in the CS tracking method of the present invention, the target communication satellite is automatically tracked using the control channel. Therefore, in particular, the CS communication system to be used determines whether the communication channel is used or not. Regardless, if the control channel is configured to constantly transmit the control information, even if the provision of the communication information by the communication channel to be used is suspended, the communication satellite that provides the desired communication channel can be reliably established. It is possible to perform tracking, and it is possible to reliably prevent a useless tracking operation from being repeated because a desired communication channel cannot be found.

Next, in the CS receiving apparatus according to the present invention, the receiving antenna receives a radio wave from a communication satellite, and the level detecting means extracts transmission data of the control channel from a received signal of the receiving antenna. The tracking means detects the reception level of the transmission data, and the tracking means sets the direction of the reception antenna so as to receive the radio wave from the communication satellite at the peak of the reception level detected by the level means. Let me follow.

The demodulation means demodulates the transmission data of the same control channel as that for which the level detection means has detected the reception level, and determines the demodulation means based on the satellite identification information obtained by the demodulation by the demodulation means. Determines whether the radio wave being received by the receiving antenna is from a target communication satellite. As a result, when it is determined that the radio wave being received is not from the intended communication satellite, the restarting means sets a new tracking target peak different from the peak of the reception level previously targeted for tracking. The tracking means is restarted as a target.

That is, a CS communication apparatus according to the present invention is an apparatus for realizing the CS tracking method according to claim 3.
By using the communication device of the present invention, it is possible to obtain exactly the same effects as the CS tracking method according to the third aspect. If the receiving antenna is configured so as to be able to receive radio waves from the elevation angle direction in which the target communication satellite exists, the tracking means can change the azimuth in the horizontal plane, and the The directivity can be directed to a desired communication satellite, and the configuration for changing the direction of the receiving antenna can be simplified.

By the way, the high-frequency signal from the receiving antenna is converted into an intermediate frequency signal by a converter, and this converter is generally separated from other parts of the device like the receiving antenna, and It is often installed outdoors where it is exposed to rain and wind. Also, the local signal mixed with the high frequency signal to generate the intermediate frequency signal is
It is desirable to oscillate at a stable frequency because it affects the stability of the intermediate frequency signal and, consequently, the reception quality.

However, the oscillator provided in the converter for generating the local signal is affected by a severe environment (temperature or humidity) change, so that it is difficult to perform stable oscillation, and sufficient frequency stability is obtained. Try to get
Very expensive and large oscillators must be used.
For this reason, generally, an AFC (Automatic Frequency Control) that maintains a constant frequency by feedback control.
By providing a (roll) circuit, the oscillation frequency is stabilized.

However, since the AFC circuit takes a long time to pull in a stable frequency, the frequency cannot be stabilized sufficiently immediately after the power is turned on, and until the direction of the receiving antenna is locked to the target communication satellite. However, there have been problems such as the deterioration of the responsiveness and the deterioration of the reception quality.

Therefore, in the CS receiver according to the fifth aspect, the low noise converter receives the supply of the reference signal having a stable frequency from the supply destination of the intermediate frequency signal via the transmission line of the intermediate frequency signal, and And a local signal is generated based on the

That is, the supply destination of the intermediate frequency signal refers to a device installed indoors such as a tuner, and a reference signal having a stable frequency is supplied to the device installed in a place where environmental changes are relatively small. By providing an oscillator for generating a signal, it is possible to generate a local signal having a stable frequency using a cheaper and smaller device, and
Even immediately after the power is turned on, automatic tracking of a satellite with good responsiveness and high reception quality can be realized.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. [First Embodiment] FIG. 1 is a block diagram showing the overall configuration of a vehicle-mounted CS receiver according to a first embodiment to which the present invention is applied.

However, the in-vehicle CS receiving device is a device mounted on a vehicle to use a service provided by a communication satellite, and can always receive a radio wave from a desired communication satellite with a receiving antenna. Automatic tracking of satellites according to the movement of the vehicle, and reproduction of digital data provided through an arbitrary communication channel provided in the communication satellite from a reception signal obtained by receiving radio waves from the communication satellite do it,
The data is output to various information devices via receiving equipment connected to the device.

The communication satellite of the CS communication system used by the on-board CS receiving apparatus of the present embodiment includes a plurality of transponders for relaying broadcast waves from the ground, and each downlink provided for each transponder. An information channel for providing communication information between users and a control channel for providing control information are set on a line from the communication satellite to the CS receiver. The control information includes, in addition to the satellite name and the transponder number which are the source of the downlink, the satellite position, the source user name, the main carrier transmission specifications (modulation method, coding rate of error correction code, system Clock, center frequency (reception frequency)
Etc. are included.

The transmission data relayed by the transponder of the communication satellite is obtained by encoding digital data with an error correction code and then phase-modulating a carrier with the encoded data. Is used as the data encoded by the scrambler.

However, in the information channel, data transmission is performed according to the main carrier transmission specification of the control information, while in the control channel, data transmission is performed in the same fixed system in any downlink. Is to be done. In this embodiment, the transponder uses 12.251 GHz as the downlink transmission radio wave.
5 (a), each downlink has a bandwidth of 36 MHz, and the information channel is a main channel. 34.5MHz bandwidth around carrier,
The control channel has a bandwidth of 1 MHz centering on a pilot carrier having a frequency lower by 35.5 MHz than the main carrier.

Data transmitted and received between end-to-end users using the information channel is called transport stream (TS) data. In this embodiment, a plurality of logical channels can be set on each information channel, and packet data is transmitted independently for each logical channel. Therefore, the TS data is obtained by multiplexing the packet data of all the logical channels set on the information channel.

Then, as shown in FIG.
The S receiving device 1 includes a receiving antenna unit 3 for receiving a transmission radio wave from a communication satellite of the CS communication system, a step motor 5 for driving the receiving antenna unit 3 to rotate, and reception from the receiving antenna unit 3. Signal is 951MHz ~ 14
A low-noise block converter (hereinafter simply referred to as a converter) 7 for converting into an intermediate frequency (CS-IF) signal in a 31 MHz band, and a drive signal for driving the step motor 5 based on the intermediate frequency signal from the converter 7 is output and received. Automatic tracking processing for controlling the rotational position of the antenna unit 3,
An indoor unit 9 is provided for selecting a communication channel in accordance with an instruction from an information device connected to the device and performing a reception process for reproducing and outputting digital data supplied via the channel.

The receiving antenna unit 3 includes a turntable (not shown) that rotates by a predetermined angle (for example, 0.1 °) in a horizontal plane in conjunction with the stepping operation of the stepping motor 5, and a turntable on the turntable. And a planar antenna as a receiving antenna installed in the antenna.

In order to control the rotation angle of the turntable with high precision by the step motor 5, the step motor 5 and the turn table are connected via a well-known speed reduction mechanism constituted by gears, belts and the like. . Specifically, the rotation angle of the turntable with respect to the rotation angle of the step motor 5 is set to be 1/10, and in this embodiment, the step motor 5 that rotates by 1 ° is used. . That is, by appropriately setting the speed reduction ratio by the speed reduction mechanism, the accuracy of the rotation angle of the turntable can be arbitrarily set.

The receiving beam (directivity) of the planar antenna is designed to have an elevation angle capable of satisfactorily receiving a radio wave from a communication satellite located at 110 ° east longitude on a geostationary satellite orbit. By adjusting only the rotation angle of the antenna unit 3 in the horizontal plane, it is possible to track the target communication satellite without adjusting the elevation angle direction.

Next, in the converter 7, as shown in FIG. 2, the amplifier 10 amplifies the high-frequency signal supplied from the receiving antenna section 3, and the amplified high-frequency signal is
1 mixes with a local signal (frequency 11.3 GHz) to generate an intermediate frequency signal, and the amplifier 12 amplifies the intermediate frequency signal, and an output terminal Tc to which a transmission cable to the indoor unit 9 is connected. It is configured to supply to.

In the converter 7, a signal passing filter 13 provided between the amplifier 12 and the output terminal Tc is provided.
Allows the intermediate frequency signal amplified by the amplifier 12 to pass only to the output terminal Tc side, and a reference signal (frequency 22.07) supplied from the indoor unit 9 via the output terminal Tc.
0312 MHz) without being passed to the amplifier 12 side. A branch circuit 16 branches a part of a signal generated by a voltage controlled oscillator 15 capable of controlling an oscillation frequency, and a PLL is provided based on the branched signal and a reference signal separated by a signal passing filter 13. Circuit 14 controls the oscillation state of voltage controlled oscillator 15. As a result, the signal generated by the voltage controlled oscillator 15 becomes 128
It has twice the frequency (ie 2.825 GHz) and is locked to the phase of the reference signal.

Further, in the converter 7, the signal generated by the voltage controlled oscillator 15 whose oscillation state is controlled in this manner is
The frequency multiplier 17 increases the frequency four times (ie, 11.3 GHz).
z), and a band-pass filter (BPF) 18
Generates a local signal by extracting only a signal component having a frequency of 11.3 GHz. The generated local signal is amplified by the amplifier 19 and supplied to the mixer 11.

That is, the converter 7 uses the reference signal supplied from the indoor unit 9 to stabilize the oscillating frequency of the voltage controlled oscillator 15 and thus generates a local signal having a stable frequency. The intermediate frequency signal generated by the mixer 11 to which the signal is supplied, that is, the intermediate frequency signal supplied to the indoor unit 9 has stable reception quality with a small frequency error.

Next, in the indoor unit 9, as shown in FIG. 1, the intermediate frequency signal input via the input terminal Ti to which the transmission cable from the converter 7 is connected is branched into two by the branch circuit 22. One is supplied to the channel selection demodulation unit 23 and the other is supplied to the tracking control unit 27. However, a signal passing filter 21 is provided between the input terminal of the intermediate frequency signal from the converter 7 and the branch circuit 22, and the reference signal generated by the reference signal oscillator 20 having high frequency stability is input. The intermediate frequency signal that passes only to the terminal Ti and is input from the input terminal Ti passes only to the branch circuit 22 side.

Then, in the channel selection demodulation unit 23 of the indoor unit 9, the amplifier 30 amplifies the intermediate frequency signal branched by the branch circuit 22, and the direct demodulation circuit 31 is designated from the amplified intermediate frequency signal. The signals of the communication channels are transmitted to a pair of orthogonal baseband signals (hereinafter, I and Q).
Signal) and a low-pass filter (LPF) 3
2 removes unnecessary high frequency components from the I and Q signals. Note that the direct demodulation circuit 31 can be easily configured by using, for example, Philips TDA8060TS or the like.

The A / D conversion / error correction circuit 33
However, each of the I and Q signals that have passed through the LPF 32 is sampled and converted into digital data.
The phase component is extracted from the Q signal to generate demodulated data, and furthermore, the demodulated data is coded by an error correction code, so that it is decoded and, if there is an error in the decoded data, this is corrected. And output. The data output from the channel selection demodulation unit 23 in this manner is TS data.

The tuning control circuit 34 of the tuning demodulation unit 23
In accordance with the “information channel selection signal” indicating the information channel to be demodulated, the modulation scheme of the data transmitted on the information channel, and the coding rate of the error correction code, the signal of the designated information channel is I , Q signal so that the frequency of the local signal supplied to the direct demodulation circuit 31 is changed, and the band of the I and Q signals changes according to the modulation method.
The PF 32 is configured to change the upper limit band. Further, the A / D conversion / error correction circuit 33 switches the processing content at the time of demodulation and decoding (error correction) according to the modulation scheme and coding rate specified by the same “information channel selection signal”. It is configured.

The output of the channel selection demodulation unit 23 has T
When the S data is scrambled, a connector 24 for attaching and detaching a descrambler for restoring the S data is provided. However, when a descrambler is not connected to the connector 24, a short-circuiting connector for passing the TS data from the channel selection demodulation unit 23 to the TS data processing unit 25 as it is is connected.

Next, the TS data processing unit 25 extracts and decomposes the packet of the logical channel specified by the “logical channel selection signal” from the TS data (ie, the multiplexed packet data), A packet extraction circuit 35 for assembling received data in units, and a connector 26 which encodes output data to receiving equipment (information equipment) connected to the apparatus 1 so as to conform to a predetermined standard (10Base-T in the present embodiment). And an encoder / decoder 36 for decoding input data input from the receiving equipment (information equipment) via the connector 26 and encoded by a code conforming to the predetermined standard, A reception process for controlling the operation of each unit of the device based on the input data decoded by the decoder 36, the tracking status notified from the tracking control unit 27, and the like. (Hereinafter, referred to as a receiving MCU) 37 and a backup battery 38 are normally charged with power supplied from a vehicle-mounted battery (not shown), and a power supply from the vehicle-mounted battery is generated for some reason. If supply is disrupted,
A power management circuit 39 for discharging the backup battery 38 and supplying power to each unit of the device.
And

The receiving MCU 37 is composed of a CPU, RO
It is a well-known device mainly composed of M, RAM, IO ports and the like. Then, as input data from the receiving equipment (information equipment), a “CS reception request” requesting reception on the specified information channel and logical channel, and a “channel switching request” requesting switching of the information channel and logical channel to be received. , A "research request" for re-tracking the communication satellite by the receiving antenna unit 3 and the like are defined, and a "tracking status" indicating the tracking control state of the communication satellite is input from the tracking control unit 27. The receiving process proceeds according to the input data from the information devices and the “tracking status” from the tracking control unit 27.

In the receiving MCU 37, an "information channel selection signal" for specifying an information channel to be demodulated by the channel selection demodulator 23, and a logical channel for the reception data to be assembled by the packet extraction circuit 35. In addition to generating a “logical channel selection signal” for controlling the tracking control unit 27, a “start command” output when a “CS reception request” is input, and a “channel switching request” A "research command" to be output when a "search request" is input is defined.

On the other hand, based on the intermediate frequency signal from the branch circuit 22, the tracking control section 27 of the indoor unit 9 allows the control channel selecting circuit 40 to control the signal of the control channel designated by the "control channel selecting signal". Is converted into a second intermediate frequency signal of a 60 MHz band and extracted. The control channel tuning circuit 40 mixes the output of the oscillator 41 with the intermediate frequency signal from the branch circuit 22 by mixing the output of the oscillator 41 with the oscillator 41 whose oscillation frequency is variable according to the “control channel tuning signal”. A mixer 42 for generating a signal, an amplifier 43 for amplifying the output of the mixer, a band-pass filter 44 for extracting a frequency component serving as a second intermediate frequency signal from the output of the amplifier 43,
And an amplifier 45 for amplifying the output of F44.

In the tracking control section 27, the branch circuit 46 branches the second intermediate frequency signal generated by the control channel selection circuit 40 into two, and demodulates one of the branched second intermediate frequency signals. The demodulator 47 demodulates the data, and the error correction circuit 48 decodes the demodulated data encoded by the error correction code, and corrects any error in the decoded data. On the other hand, the other second intermediate frequency signal branched by the branch circuit 46 is amplified by the amplifier 49, and based on the amplified second intermediate frequency signal, the C / N detection circuit 50 A reception level signal corresponding to the ratio of the noise component is generated, and the A / D converter 51 converts the reception level signal into a digital value.

Further, the tracking control unit 27 outputs a driver circuit 53 for driving the step motor 5 in accordance with the "motor drive signal" and a "azimuth displacement signal" corresponding to a change in the traveling direction of the vehicle on which the device is mounted. Gyro unit 5
4, digital data output from the error correction circuit 48 (that is, control information provided by the control channel), A /
Drive control of the driver circuit 53 based on the digital data output from the D converter 51 (ie, the reception level of the transmission data of the control channel), the “azimuth displacement signal” from the gyro unit, and the “command” from the receiving MCU 37. And a tracking control MCU 52 for executing an automatic tracking process or the like for controlling the direction of the receiving antenna unit 3 so that a radio wave from a target communication satellite can be satisfactorily received.

The tracking control MCU 52 includes a CPU,
This is a well-known device mainly composed of a ROM, a RAM, an IO port, and the like. The “tracking status” to be notified to the receiving MCU 37 is a state in which the receiving antenna unit 3 can receive radio waves from a target communication satellite well. Is output when the receiving antenna unit 3 is searching for a position where the radio wave from the communication satellite can be received satisfactorily. .

Here, the reception process executed by the reception MCU 37 and the automatic tracking process executed by the tracking control MCU 52 will be described with reference to the flowcharts shown in FIGS. First, the receiving process of the receiving MCU 37 will be described. This processing is started when the power of the apparatus 1 is turned on.

When this process is started, as shown in FIG. 3, first in S110, it is determined whether or not a “CS reception request” has been received from the receiving equipment (information equipment) via the connector 26, and a negative determination is made. If so, the process repeats the same steps to stand by. On the other hand, when the “CS reception request” is received and the determination is affirmative, the process proceeds to S120.

In the “CS reception request”, a communication satellite, an information channel, a logical channel, and the like, which are desired to be received, are specified. In S 130, a communication satellite to be tracked, A “search command” indicating a control channel belonging to the same downlink as the target information channel is transmitted to the tracking control MCU 52.

In S130, the tracking control MCU 5
It is determined whether or not the “tracking status” notified from 2 is set to “locked”. If a negative determination is made, the process repeats the same steps to wait, while an affirmative determination is made. Is located at a rotational position where the radio wave from the target communication satellite can be satisfactorily received.
Is determined to be locked, and the flow shifts to S140.

In S140, the tracking control MCU 52 transmits the control information acquired from the control channel to the tracking control MCU 5
2 so that demodulation of transmission data of a target information channel and reproduction of reception data of a target logical channel can be performed based on the main carrier data indicated in the read control information. A channel selection signal "and a" logical channel selection signal "
3 and the packet extraction circuit 35 to select the target information channel and logical channel, and in particular, the tuning and demodulation unit 23 sets the modulation method and the decoding rate.

In S150, based on the validity of the TS data output from the channel selection demodulation unit 23, the TS data processing unit 25 processes the TS data, that is, the TS data is reproduced by the packet extraction circuit 35. The processing for supplying the received data to the receiving equipment (information equipment) connected to the connector 26 via the encoder / decoder 36 is started.

At S160, the tracking control MCU is used.
It is monitored whether or not the “tracking status” from 52 changes to “search”. If an affirmative determination is made, the process proceeds to S170, where the TS data output from the channel selection demodulator 23 is invalid. Then, the process for the TS data in the TS data processing unit 25 is stopped, and the process returns to S130.

On the other hand, if a negative determination is made in step S160, that is, if the "tracking status" remains "locked", the flow shifts to step S180, where the receiving facility (information equipment) issues a "channel switching request". Determine whether or not there has been input,
If a negative determination is made, the process proceeds to S190, and it is determined whether or not a “research request” has been input from the receiving facility (information device). If this is also a negative determination,
It returns to S160.

On the other hand, a "channel switching request" or a "research request" is input from the receiving equipment (information equipment), and S1 is input.
If a positive determination is made in 80 or S190, S20
After returning to 0 and transmitting a “research command” to the tracking control MCU 52, the process returns to S160.

As will be described later, the tracking control MCU 5
2 receives the “re-search command”, changes the “tracking status” to “search”, so that immediately after executing S400, an affirmative determination is made in S160, and the processing of TS data in the TS data processing unit 25 is stopped. (S170).

Next, an automatic tracking process of the tracking control MCU 52 will be described. This processing is performed by the tracking control MCU.
Is "search command" from the receiving MCU 37 (S120).
) Is received. As shown in FIG. 4, when this processing is started, first in S310, the reception MCU is started.
In step S320, the control channel to be tuned together with the "search command" or a "re-search command" to be described later is selected by the tuning circuit 40. A "control channel selection signal" is output so as to be controlled.

At S330, the C / N level input via the A / D converter 51 is monitored, and the receiving antenna unit 3 receives a radio wave from a communication satellite at the peak of the C / N level. By controlling the driving of the stepping motor 5 by outputting a “motor driving signal”,
To control the rotational position of. At this time, the rotation direction when driving the receiving antenna unit 3 for the first time is to be performed in accordance with a preset initial driving direction, and in the initial state, it is set to any arbitrary direction.

At S340, demodulated data, that is, control information provided by the selected control channel is read from the error correction circuit 48. At S350, the satellite identification information in the control information is referred to. It is determined whether or not the radio wave being received by the receiving antenna unit 3 is from a target communication satellite indicated in a “search command” or a “re-search command” described later. If a negative determination is made, that is, if the signal is not a radio wave from the target communication satellite, the flow shifts to S360 to set the "tracking status" to "search", and in S370, the A / D converter 51
Drive the stepping motor 5 until the change of the C / N level inputted through the switch from the decreasing direction to the increasing direction,
It returns to S330.

In other words, the automatic tracking is performed again so that the receiving antenna unit 3 receives the radio wave at the peak of the C / N level again, but the peak that has been tracked first is not again tracked. In order to do this, S370 is performed. On the other hand, if the determination in S350 is affirmative, that is, if the radio wave being received by the receiving antenna unit 3 is from a target communication satellite, the process shifts to S380 and the “tracking status” is Determine whether it is set to 'lock'. When a negative determination is made, that is, when the “tracking status” is set to “search”, the process proceeds to S390, and after the “tracking status” is set to “locked”, the process proceeds to S400. On the other hand, if the “tracking status” has already been set to “locked”, the process directly proceeds to S400. In step S390, the content of the control information acquired via the error correction circuit 48 is stored together with the setting of the "tracking status". The control information stored at this time is the same as that of S1 of the reception process described above.
At 40, it is read into the receiving MCU 37.

In S400, the "azimuth displacement signal" is read from the gyro unit 54, and it is determined whether or not the azimuth in the traveling direction of the vehicle on which the device 1 is mounted has changed. , S410, and sets the initial driving direction when the receiving antenna unit 3 is rotationally driven to a direction that cancels the change in the azimuth angle, and returns to S330.

If a negative determination is made in S400, that is, if there is no change in the azimuth, the flow shifts to S420 to determine whether a "research command" has been received from the receiving MCU 37. And if not received, S3
Then, the process proceeds to S30, where the tracking control is continued without changing the peak to be tracked. On the other hand, if the “research command” has been received, the process returns to S310 to indicate the “research command”. The tracking control is redone from the beginning for the control channel.

As described above, in the CS communication system used by the CS receiving apparatus 1 of the present embodiment, the control channel for transmitting only control information is provided on the downlink provided by the communication satellite. Is provided separately from the information channel for transmitting the control information, and the control information is always transmitted on the control channel.

According to the CS receiving apparatus 1 of this embodiment, since the communication satellite is automatically tracked using the control channel, the information channel is provided regardless of the use state of the information channel. Radio waves from communication satellites can be reliably received, and it is possible to reliably prevent unnecessary tracking control from being performed without finding an information channel.

Further, according to the CS receiving apparatus 1 of the present embodiment, it is determined whether or not the communication satellite is the target communication satellite by using the satellite identification information in the control information. Extraction, and further, determination of a communication satellite using this satellite identification information can be performed promptly, and the receiving antenna unit 3 is quickly locked in a direction in which radio waves from the target communication satellite can be received well. Can be.

Further, in the CS receiving apparatus 1 of the present embodiment, the converter 7 receives the supply of the reference signal having a stable frequency from the indoor unit 9 via the transmission cable for transmitting the intermediate frequency signal, and uses the PLL circuit. It is designed to generate a stable local signal. Therefore, since the oscillator 20 for generating the reference signal can be arranged in the indoor device 9 that is not easily affected by environmental changes, it is possible to use a cheaper and smaller device as compared with the case where the oscillator 20 is provided in the converter 9.
Not only can a compact device suitable for in-vehicle use be constructed, but also because a fast-response PLL circuit is used without using an AFC circuit, local signals can be quickly stabilized and the response of tracking control immediately after power-on is achieved. Performance and reception quality can be improved.

As the information device connected to the CS receiving apparatus 1 of this embodiment, for example, a desktop computer, a notebook personal computer, or a dedicated computer for in-vehicle use can be used. However,
The dedicated computer for in-vehicle use is a computer specially designed to be efficiently installed in a vehicle and to be easily operated in the vehicle. In this case, for example, a network card compliant with the PCI standard or the PCMCIA standard may be used as the receiving equipment.

That is, according to the CS receiving apparatus 1 of the present embodiment, various computers can be easily connected as long as a network card is prepared. Further, as a receiving facility, a hub device having an interface corresponding to the 10Base-T standard may be connected, and a plurality of information devices may be simultaneously connected via the hub device.

In this embodiment, the tuning circuit 40, C / N
The detection circuit 50 and the A / D converter 51 are level detection means, the tuning circuit 40, the demodulation circuit 47, and the error correction circuit 48 are demodulation means, S320 and S330 are tracking means, and S340 and S3.
50 corresponds to the determination means, S370 corresponds to the restart means, and S320 and S330 correspond to the first procedure, S340 and S3.
50 and S370 correspond to a second procedure. Second Embodiment Next, a second embodiment will be described.

The CS receiving apparatus 1a of the present embodiment is different from the CS receiving apparatus 1 of the first embodiment only in that the configuration of the indoor unit 9a is partially different. Will be omitted, and the description will focus on the differences between the configurations. That is, the indoor device 9a of the CS receiving device 1a of the present embodiment.
As shown in FIG. 6, instead of the TS data processing unit 25, a driver circuit 35a for realizing an RS-422 interface, a receiving MCU 37a, a backup battery 38, and a power management circuit 39 are provided. Instead, a high-speed data port 26a including an input / output terminal of the driver circuit 35a and a serial data input / output terminal of the receiving MCU 37a is provided. The backup battery 38 and the power management circuit 39 are exactly the same as those in the first embodiment, and the receiving MCU 37a omits the processing for the TS data and receives the serial data from the high-speed data port 26a. Receiving equipment (information equipment) via output terminal
The configuration is exactly the same as that of the first embodiment, except that the input data from the. That is, in the present embodiment, in the receiving process executed by the receiving MCU 37a, the information indicating that the output data from the driver circuit 35a is valid in S150 of the receiving process shown in FIG. The configuration is exactly the same except that information indicating that the output data is invalid is output to the information device via the serial data input / output terminal.

In the CS receiving apparatus 1a according to the present embodiment having the above-described configuration, parts other than the driver circuit 35a and the receiving MCU 37a provided in place of the TS data processing unit 25 are exactly the same as in the first embodiment. It operates to automatically track the communication satellite using the control channel, determines whether the communication satellite is the target communication satellite using the satellite identification information in the control information, and transmits the intermediate frequency signal to the converter 7. The supply of the reference signal having a stable frequency from the indoor unit 9 via the transmission cable to be performed and the generation of a stable local signal using the PLL circuit are performed. Exactly the same effect can be obtained.

Note that, in the CS receiving apparatus 1a of the present embodiment,
As the receiving equipment, for example, if an interface card having a configuration corresponding to the TS data processing unit 25 in the first embodiment is used, similarly to the CS receiving apparatus 1 in the first embodiment, a notebook personal computer or a dedicated computer for in-vehicle use Etc. can be easily connected.

That is, as shown in FIG. 7, the interface card 60 includes a receiver circuit 61 for receiving data from the driver circuit 35a via a connector 66 connectable to the high-speed data port 26a and decoding the data into TS data. ,
A packet extraction circuit 62 for extracting and decomposing a packet of a specified logical channel from the TS data decoded by the receiver circuit 61 to assemble received data for each logical channel, and an information device connected via a connector 67 Output data to a predetermined standard (PCMCI in this embodiment)
A) is coded so as to conform to A) and is supplied to the connector 67, and is input from the information device via the connector 67;
An encoding / decoding device 64 for decoding input data encoded by a code conforming to the above-mentioned predetermined standard, and the present embodiment based on the input data decoded by the encoding / decoding device 64 , A command such as a “CS reception request”, a “channel switching request”, or a “research request” that specifies an information channel to be received by the CS receiving apparatus 1a. The packet extraction circuit 6 outputs the packet to the receiving device 1a or based on the same input data.
Control MC for generating a signal specifying the logical channel 2
U63.

Note that the standard applied to the encoder / decoder 64 is not limited to the PCMCIA standard, but may be a standard that is suitable for the information equipment to be connected. Third Embodiment Next, a third embodiment will be described.

The CS receiving apparatus 1b of the present embodiment is different from the CS receiving apparatus 1a of the second embodiment only in that the configuration of the indoor unit 9b is partially different. Will be omitted, and the description will focus on the differences between the configurations. That is, the indoor device 9 of the CS receiving device 1b of the present embodiment.
In FIG. 8B, as shown in FIG. 8, the driver circuit 35a and the connector 24 for connecting the scrambler are omitted from the CS receiving apparatus 1a, and the output of the channel selection demodulator 23 is directly connected to the output terminal 26b. ing. In addition, channel selection demodulation unit 2
3, in place of the A / D conversion / error correction circuit 33,
An A / D conversion / demodulation circuit 33a is provided, and the demodulated TS data is supplied to the output terminal 26b as the output of the channel selection demodulation unit 23.

The receiving MCU 37a is connected to the RS232
A control signal is input / output to / from a receiving facility (information device) via a connector 28 compatible with the C interface. According to the CS receiving apparatus 1b of the present embodiment configured as described above, the parts other than the A / D conversion / demodulation circuit 33a operate in exactly the same manner as the second embodiment, and use the control channel to control the communication satellite. Automatic tracking is performed, and it is determined whether or not the communication satellite is the target communication satellite by using the satellite identification information in the control information. Further, the converter 7 transmits the frequency from the indoor unit 9 via the transmission cable for transmitting the intermediate frequency signal. , The stable reference signal is supplied, and a stable local signal is generated using the PLL circuit. Therefore, the same effects as those of the CS receivers 1 and 1a of the first and second embodiments can be obtained. Can be.

When the CS receiving apparatus 1b of the present embodiment is used, the user of the receiving equipment (information equipment) communicates with a provider who provides information via the information channel by using the information channel. The coding method (error correction code and coding rate) of the data to be transmitted can be arbitrarily set without being restricted by the function of the CS receiving apparatus 1b, and when the information channel is used, more various coding methods can be used. A method can be adopted. [Fourth Embodiment] Next, a fourth embodiment will be described.

The CS receiving apparatus 1c of the present embodiment differs from the CS receiving apparatus 1 of the first embodiment only in the configuration of the indoor unit 9c, and therefore the same components are denoted by the same reference numerals. Will be omitted, and the description will focus on the differences between the configurations. That is, the indoor device 9c of the CS receiving device 1c of the present embodiment.
As shown in FIG. 9, from the CS receiving apparatus 1 of the first embodiment, the channel selecting demodulator 23 and the scrambler connector 2
4, the TS data processing unit 25 is omitted. And
An amplifier 30 for amplifying the intermediate frequency signal branched by the branch circuit 22 is provided, and its output is connected to the output terminal 26c, that is, the output terminal 26b is configured to output the intermediate frequency signal. I have.

The tracking control MCU 52a is connected to the RS2
A control signal is input / output to / from a receiving facility (information device) via a connector 28a compatible with the 32C interface. In other words, all the processing performed by the configuration omitted from the CS receiving apparatus 1 of the first embodiment is handled by the receiving equipment (information equipment), and therefore, the tracking control MCU is used.
52a is configured to transmit / receive a “command” or “tracking status” to / from a receiving facility (information device) via the connector 28a.

In the CS receiving apparatus 1c according to the present embodiment configured as described above, except for the omitted parts, the CS receiving apparatus 1c according to the first embodiment.
It operates in exactly the same way as the receiving device 1, performs automatic tracking of communication satellites using the control channel, determines whether or not the communication satellite is the target communication satellite using the satellite identification information in the control information,
Since the converter 7 receives the supply of the reference signal having a stable frequency from the indoor unit 9 via the transmission cable for transmitting the intermediate frequency signal, and generates a stable local signal using the PLL circuit, It is possible to obtain exactly the same effects as those of the CS receiving apparatus 1 according to the first embodiment.

When the CS receiving apparatus 1c of this embodiment is used, the user of the receiving equipment (information equipment) uses the information channel with a provider that provides information via the information channel. The data transmission parameters (modulation scheme, error correction scheme, etc.) can be arbitrarily set without being restricted by the function of the CS receiving apparatus 1c, so that when the information channel is to be used, various parameters can be more flexibly set. Other methods can be adopted.

Although some embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and may be implemented in various modes without departing from the gist of the present invention. Can be. For example, in the first to third embodiments, separate MCUs are provided for the receiving MCU and the tracking control MCU. However, when the processing capability of the MCU is high, these are realized by one MCU. You may.

In the above embodiment, the case where only one main carrier is provided for one downlink has been described.
As shown in (b), a plurality of main carriers may be provided. Further, in the above embodiment, a case where one information channel corresponds to one main carrier has been described, but a configuration may be adopted in which a plurality of information channels correspond to one main carrier. .

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an entire configuration of a CS receiving apparatus according to a first embodiment.

FIG. 2 is a block diagram illustrating a configuration of a converter.

FIG. 3 is a flowchart illustrating the content of a reception process.

FIG. 4 is a flowchart illustrating the content of an automatic tracking process.

FIG. 5 is an explanatory diagram illustrating a configuration of a downlink provided by a communication satellite.

FIG. 6 is a block diagram illustrating an entire configuration of a CS receiving apparatus according to a second embodiment.

FIG. 7 is a block diagram illustrating a configuration of a receiving facility for a CS receiving apparatus according to a second embodiment.

FIG. 8 is a block diagram illustrating an entire configuration of a CS receiving apparatus according to a third embodiment.

FIG. 9 is a block diagram illustrating an entire configuration of a CS receiving apparatus according to a fourth embodiment.

[Explanation of symbols]

1, 1a to 1c CS receiving device 3 Receiving antenna unit 5 Step motor 7 Converter 9
a to 9c: Indoor equipment 10, 12, 19, 30, 43, 45, 49 ... Amplifier
11, 42 mixer 13, 21 signal filter 14 PLL circuit 15 voltage-controlled oscillator 16, 22, 46 branch circuit 17 multiplier circuit 18, 44 band-pass filter 20 reference signal oscillator 23 channel selection Demodulation unit 24 ... Scrambler connection connector 25 ... TS data processing unit 26,28,28a ... Connector 26a ... High speed data port 26b, 26c ... Output terminal 27 ... Tracking control unit 31 ... Direct demodulation circuit 33 ... A / D conversion / Error correction circuit 33a A / D conversion / demodulation circuit 34 Tuning control circuit 35 Packet extraction circuit 35a Driver circuit
36 encoder / decoder 37, 37a receiving MCU 38 backup battery 39 power management circuit 40 control channel tuning circuit 41 oscillator 47 demodulator 48 error correction circuit 50 C / N detection Circuits 51, 57 A / D converter
53 ... Driver circuit 54 ... Gyro unit 52,52a ... Tracking control MCU

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 5C025 AA21 BA11 DA04 DA07 5C064 DA05 DA08 DA09 5J021 AA01 CA06 DA02 DA04 DA05 DA07 EA04 FA17 FA20 FA21 FA23 FA25 FA26 FA32 FA33 HA03 HA07 JA07 5K072 AA26 BB04 BB13 BB14 BB13 FF12 GG02 GG06 GG13

Claims (5)

[Claims] 1. CS for data transmission via a communication satellite
In the communication system, a downlink provided by each transponder mounted on the communication satellite is a communication channel for transmitting communication information between users by data transmission using a preset main carrier; and A communication channel for transmitting control information including at least satellite identification information for identifying a communication satellite that is a source of the downlink by data transmission using different pilot carriers. system. 2. The CS communication system according to claim 1, wherein said control channel constantly transmits said control information regardless of whether or not said communication channel is used. 3. The direction of a receiving antenna used in the CS communication system according to claim 1 or 2 mounted on the mobile object is adjusted so that radio waves from the communication satellite can be satisfactorily received. A CS tracking method for tracking according to movement, wherein a reception level of transmission data of the control channel is detected,
A first procedure of tracking the direction of the receiving antenna so as to receive a radio wave from the communication satellite at the peak with the peak of the reception level being a tracking target, and demodulating transmission data of the control channel. Based on the obtained satellite identification information, it is determined whether the radio wave being received by the receiving antenna is from a target communication satellite, and as a result of the determination, the radio wave from the target communication satellite And a second step of repeating the first procedure with a peak different from the peak of the reception level previously tracked as a new track target when there is no CS tracking method. 4. A CS receiving apparatus used in the CS communication system according to claim 1 or 2, wherein: a receiving antenna for receiving a radio wave from the communication satellite; and a receiving signal from the receiving antenna. Level detection means for extracting the transmission data of the control channel and detecting the reception level of the transmission data; and targeting the peak of the reception level detected by the level detection means to track the communication satellite at the peak. Tracking means for tracking the direction of the receiving antenna so as to receive the radio wave from, demodulation means for demodulating the transmission data of the control channel, based on the satellite identification information obtained by demodulation in the demodulation means, Determining means for determining whether or not the radio wave being received by the receiving antenna is from a target communication satellite; and When it is determined that the signal is not from a communication satellite, a restarting means for restarting the tracking means, with a peak different from the peak of the reception level previously tracked as a new tracking target, A CS receiving apparatus, comprising: 5. A high-frequency signal output from the receiving antenna by receiving a radio wave from the communication satellite,
A low-noise converter that mixes with the local signal and converts the signal into a lower-frequency intermediate frequency signal, wherein the low-noise converter is connected to the intermediate-frequency signal transmission line via a transmission line of the intermediate-frequency signal and has a stable frequency reference. The CS receiving apparatus according to claim 4, wherein the CS signal is supplied, and the local signal is generated based on the reference signal.