JPH05160763A - Satellite communication equipment - Google Patents

Abstract

PURPOSE:To prevent the mis-sweep of a carrier by without increasing a transmission rate even when the sweep range of AFC is widened by transmitting a communication data signal string of an adjacent carrier while the arrangement is replaced and decoding the signal at a receiver side. CONSTITUTION:Communication data subject to error correction coding by an error correction coding circuit 2 are inputted to a data rearrangement circuit 15. A rearrangement control circuit 16 controls the rearrangement of data so that adjacent channels are arranged differently. A signal inputted to a modulator 4 is modulated and sent from a data transmission terminal 5. Data inputted from a data reception terminal 6 are demodulated by a demodulator 7 and inputted to a data rearrangement circuit 15'. The data decoded by the data rearrangement circuit 15' are inputted to an error correction decoding circuit 8, in which sweeping of the carrier is continued by an AFC 14 till Viterbi synchronization is taken. In this case, data other than an object channel are not correctly decoded and the data are not synchronized by the error correction decoding circuit 8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention is used for automatic frequency control. In particular, it relates to a technique for preventing erroneous carrier pull-in when narrow band signals are arranged adjacent to each other.

[0002]

2. Description of the Related Art The structure of a conventional example will be described with reference to FIG. FIG. 4 is a diagram for explaining a conventional example.

FIG. 4A is a block diagram of a conventional device.
Communication data is input from the data input terminal 1 to the error correction coding circuit 2. The carrier ID inserting circuit 11 inserts a carrier ID for identifying a carrier for each channel into the output of the error correction coding circuit 2. This signal is input to the modulator 4 and the output is sent out from the data sending terminal 5. The signal form is as shown in FIG.

Communication data arrives at the data receiving terminal 6 via the satellite 10. The communication data input to the demodulator 7 is demodulated, and by the carrier ID identification circuit 12 therein,
It is identified whether the received signal is due to the carrier of interest. If the received carrier wave is the target, the carrier ID identification circuit 12 instructs the AFC 14 to stop the carrier wave sweep. If they are different, the AFC 14 continues the carrier sweep until the purpose is further achieved.

In satellite communication, the center frequency of the carrier is searched by a frequency sweeping means called AFC in order to compensate for the center frequency shift of the carrier due to frequency fluctuations of the satellite and the system. In the case where the carrier is arranged, the carrier to be searched is searched on both the left and right sides of the carrier to be searched, so that it is impossible to know which carrier is actually the carrier to be searched, and thus a different carrier may be caught. Therefore, there is a method in which data is frame-structured, carrier ID bits are multiplexed in frame bits on the transmitting side, and the receiving side refers to the carrier ID bits and continues the operation of the AFC 14 until the carrier of the carrier ID to be searched for. It is taken.

[0006]

In this conventional carrier sweep method, extra information bits such as a sync word channel ID are added to the transmission data to prevent erroneous sweeps, resulting in an increase in transmission speed and an increase in hardware scale. There was a problem.

The present invention has been made against such a background, and provides a satellite communication device capable of preventing erroneous sweeping of carrier waves without increasing the transmission rate of communication data even if the sweep range of AFC is widened. To aim.

[0008]

SUMMARY OF THE INVENTION The present invention provides a data input terminal for inputting communication data, an error correction coding circuit for error correction coding the data input from the data input terminal, and this error correction coding circuit. A modulator for modulating the communication data output from the device, a data transmission terminal for transmitting the communication data modulated by the modulator, and data for receiving the communication data transmitted from the data transmission terminal and arriving via a satellite. A reception terminal, a demodulator that demodulates communication data from the data reception terminal, an error correction decoding circuit that performs error correction decoding on the output of this demodulator, and a carrier wave pull-in that pulls in a carrier wave for receiving the communication data. In the satellite communication device including a section, the carrier wave pulling section is provided for an adjacent carrier wave of the signal string of the communication data output from the error correction coding circuit. Means for rearranging differently ordering the communication data signal sequence, characterized in that it comprises a means for restoring a signal sequence of the communication data reordering the order in which they are outputted from the demodulator.

Further, it is preferable that the rearrangement means includes means for mutually exchanging two subsequent burst data signals.

Further, the error correction decoding circuit is provided with a sync detection output terminal, and the carrier wave pull-in section is provided with means for fixing a reception frequency and a phase when a sync state is sent to the sync detection output terminal. The means for rearranging is
It is desirable to include means for stopping the rearrangement operation when the synchronization state is sent to the synchronization detection output terminal.

[0011]

[Operation] The signal rearrangement circuit converts the signal sequence of communication data,
Sorting is performed according to the regularity from the sorting control circuit. The regularity is to rearrange differently at least between channels having adjacent carriers. Although the contents of communication data for each channel are different, the order of signal trains is regulated, and the regulation is broken by this data rearrangement circuit.

This communication data is sent back to the ground via a satellite, but the receiving side instructs the data rearrangement circuit to perform a restoration procedure that uses the regularity in which the target channels are rearranged, and waits. .. When the communication data arrives at the data receiving terminal, the AFC searches for the carrier wave of the target channel and sweeps it. If the carrier wave swept at this time is for the target channel, the communication data is correctly restored by the data rearrangement circuit and input to the error correction decoding circuit. The error correction decoding circuit can synchronize the error correction decoding only when the communication data is correctly restored, but it does not synchronize the error correction decoding if it is not, so that whether or not the swept carrier is the intended one can be identified. It When the carrier is identified as the target carrier, the error correction decoding circuit issues a sweep stop instruction to the AFC,
FC stops the sweep by fixing the frequency and phase. At the same time, the rearrangement control circuit also receives the instruction and stops the rearrangement of the signal sequence.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the device of the embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

According to the present invention, a data input terminal 1 for inputting communication data, an error correction coding circuit 2 for error correction coding the data input from the data input terminal 1, and an output from the error correction coding circuit 2. The modulator 4 for modulating the communication data thus transmitted, the data transmission terminal 5 for transmitting the communication data modulated by the modulator 4, and the communication data transmitted from the data transmission terminal 5 and arriving via the satellite 10 A data receiving terminal 6 for receiving, a demodulator 7 for demodulating communication data from the data receiving terminal 6, an error correction decoding circuit 8 for error correction decoding the output of the demodulator 7, and In the satellite communication device including a carrier wave pulling unit 3 for pulling in a carrier wave, the carrier wave pulling unit 3 is provided next to the signal string of the communication data output from the error correction coding circuit 2. A data rearrangement circuit 15 as means for rearranging the communication data signal sequence of the carrier wave differently, and a data rearrangement circuit as means for restoring the communication data signal sequence rearranged from the demodulator 7 15 ^' and are included.

The rearrangement circuits 15 and 15 ^' are
This is a configuration including means for interchanging the following two burst data signals.

Further, the error correction decoding circuit 8 is provided with a synchronization detection output terminal 17, and the carrier wave pull-in unit 3 is provided with means for fixing the reception frequency and phase when the synchronization state is transmitted to the synchronization detection output terminal 17. The rearrangement circuits 15 and 15 ^′ provided in the rearrangement control circuit 16 include means for stopping the rearrangement operation according to an instruction from the rearrangement control circuit 16 when the synchronization state is sent to the synchronization detection output terminal 17.

Next, the operation of the apparatus of the present invention will be described with reference to FIGS. FIG. 2 is a diagram showing data rearrangement control. FIG. 3 is a diagram showing a communication data signal sequence in the sweep range of the AFC.

Communication data is input from the data input terminal 1 and input to the error correction coding circuit 2. The error correction coding in the apparatus of the present invention is based on the Viterbi decoding method.
The error correction coded communication data is input to the data rearrangement circuit 15. For example, when the transmission channel is 1CH and the rearrangement control signal from the rearrangement control circuit 16 is at the high level, the data rearrangement circuit 15 selects the B side and outputs it to the Y side, so that the input to the modulator 4 is as shown in FIG. As shown in FIG. 5, P and Q are opposite to those when not passing through the data rearrangement circuit 15. Rearrangement control circuit 1
6 controls rearrangement so that adjacent channels are arranged differently as shown in FIG. The signal input to the modulator 4 is modulated and transmitted from the data transmission terminal 5.

On the other hand, the data inputted from the data receiving terminal 6 is demodulated by the demodulator 7 and the data rearrangement circuit 15
^'Is entered. In the data rearrangement circuit 15 ^' , a rearrangement control signal for restoring communication data corresponding to the selected reception channel, for example, 1CH is input from the rearrangement control circuit 16 and stands by. By this rearrangement control signal, the communication data of 1CH is correctly restored. This signal is input to the error correction decoding circuit 8 and carrier sweep by AFC is continued until Viterbi synchronization is achieved. At this time, since the rearrangement rules on the sending side are different for the data of 2CH and 3CH, they are not synchronized, but when the carrier of 1CH is swept, it is determined that Viterbi synchronization has been achieved and correct decoding has been performed, and the error correction decoding circuit 8 detects synchronization. Output terminal 17
Signal to instruct the AFC 14 to stop the carrier sweep. The AFC 14 fixes the frequency and phase and stops the sweep. At the same time, the rearrangement control circuit 16 also receives the signal from the synchronization detection output terminal 17 and stops the rearrangement of the signal sequence.

At this time, correct decoded data is output from the data output terminal 9.

In the embodiment of the present invention, the Viterbi decoding system is used, and the simple selecting means by the data rearrangement circuits 15 and 15 ^' is used. However, the encoding system or the decoding system and the circuit configuration are not limited to this. .. Further, although the rearrangement is shown by the rearrangement of P and Q, it is also possible to adopt a method of dividing the data into blocks.

Although the rearrangement control circuit 16 is shown to be commonly connected to the transmitting side and the receiving side by a wire means in the apparatus of the embodiment of the present invention for convenience of description, it is separately provided on the transmitting side and the receiving side. It is also possible to have a configuration provided for.

[0023]

EFFECTS OF THE INVENTION Even if the AFC range is widened and the sweep range is widened, erroneous carrier sweep can be prevented without increasing the transmission rate.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing data rearrangement control of the device of the embodiment of the present invention.

FIG. 3 is a diagram showing a communication data signal sequence in an AFC sweep range of the device of the present invention.

FIG. 4 is a diagram illustrating a conventional example.

[Explanation of symbols]

1 Data Input Terminal 2 Error Correction Encoding Circuit 3 Carrier Wave Pulling In 4 Modulator 5 Data Sending Terminal 6 Data Reception Terminal 7 Demodulator 8 Error Correction Decoding Circuit 9 Data Output Terminal 10 Satellite 11 Carrier ID Insertion Circuit 12 Carrier ID Identification Circuit 13 carrier ID control circuit 14 AFC 15, 15 ^' data rearrangement circuit 16 rearrangement control circuit 17 synchronization detection output terminal

Claims (3)

[Claims] 1. A data input terminal for inputting communication data, an error correction coding circuit for error correction coding the data input from the data input terminal, and communication data output from the error correction coding circuit. A modulator that modulates,
A data transmission terminal for transmitting communication data modulated by this modulator, a data reception terminal for receiving the communication data transmitted from this data transmission terminal and arriving via a satellite, and communication data from this data reception terminal A satellite communication device comprising: a demodulator for demodulation, an error correction decoding circuit for error correction decoding an output of the demodulator, and a carrier wave pulling unit for pulling a carrier wave for receiving the communication data, The unit rearranges the order in which the communication data signal sequence of the communication data output from the error correction encoding circuit is different for adjacent communication data signal sequences of the adjacent carrier, and the order output from the demodulator is rearranged. And a means for restoring a signal sequence of the communication data, the satellite communication device. 2. The satellite communication device according to claim 1, wherein the rearrangement means includes means for mutually exchanging two subsequent burst data signals. 3. The error correction decoding circuit is provided with a synchronization detection output terminal, and the carrier wave pulling unit is provided with means for fixing a reception frequency and a phase when a synchronization state is transmitted to the synchronization detection output terminal, The satellite communication device according to claim 1, wherein the rearrangement means includes means for stopping the rearrangement operation when a synchronization state is sent to the synchronization detection output terminal.