JPH0410258B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a frequency division multiple access communication device suitable for satellite communication. In particular, it relates to a device in which the frequency fluctuation of the transmission path is large compared to the transmission speed. SCPC communication method (Single Channel Per,
Frequency Division Multiple Access (FDMA) is a frequency division multiple access method (FDMA) that allocates a separate radio carrier wave for each channel of audio or data signals for transmission.
means.

〔overview〕

The present invention provides a frequency division multiple access communication device suitable for satellite communication that transmits an SCPC signal with channel information included in the digital signal, and detects the SCPC on the receiving side.
When the signal channel information differs from the desired channel information, the number of different channels is calculated and the receiver frequency is changed to ensure tuning to the desired SCPC signal.

[Conventional technology]

Conventionally, frequency division multiple access communication devices have used a pilot carrier transmission method or a signal detection method using a frequency sweep in a receiving section to eliminate harm caused by frequency fluctuations present in a transmission path.

[Problem that the invention seeks to solve]

However, in such conventional frequency division multiple access communication equipment, the pilot method requires a pilot receiver at each receiving station, which increases costs, and the frequency sweep method in the receiving section has the disadvantage that the transmission speed is relatively low. Although this method is effective when the transmission path frequency fluctuation is larger than the transmission path frequency fluctuation, it has the following disadvantages when the transmission speed decreases. In other words, from the perspective of effective use of transmission paths,
When multiplexing SCPC signals on the frequency axis and using a transmission path, in order to pass as many signals as possible through the same transmission path, the frequency interval (frequency separation) between each SCPC signal is made as small as possible.
In the frequency sweep method, the range to be swept needs to be greater than the frequency fluctuation that occurs in the transmission path, but if the frequency separation is less than the amount of frequency fluctuation,
Since the receiver detects and tunes to any one of the SCPC signals within the sweep range, it has the disadvantage that it cannot reliably tune to the desired SCPC signal.

The present invention solves the above-mentioned drawbacks, and aims to provide a frequency division multiple access communication device that can reliably tune to a desired SCPC signal even on a transmission line with large frequency fluctuations.

[Means for solving problems]

A plurality of transmitters including a modulation circuit that occupies one of the channels and modulates a carrier wave assigned to the occupied channel with a transmission signal, receives the outputs of the plurality of transmitters, and receives the signals by frequency sweeping. In the SCPC communication device, each of the transmitting units multiplexes information of the channel it occupies onto the SCPC signal and transmits the signal to the modulating circuit. The receiver includes a signal separation circuit that separates the information of the occupied channel multiplexed into the SCPC signal from the output of the demodulation circuit, and a signal separation circuit that separates the information of the occupied channel that is multiplexed into the SCPC signal from the output of the demodulation circuit, and the output of the signal separation circuit and the desired channel to be input. and control means for providing a control signal for sweeping the frequency to the demodulation circuit based on information on the demodulation circuit.

[Effect]

In the transmitting section, a signal multiplexing circuit multiplexes the information on the occupied channel into the SCPC signal and transmits it, and on the receiving side, the signal separating circuit separates the information on the occupied channel multiplexed into the detected SCPC signal and selects the desired channel. If the information differs, the control means gives a control signal to the demodulation circuit to change the frequency. Through the above operations, a desired channel can be detected correctly, and tuning to a desired SCPC signal can be ensured.

〔Example〕

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

FIG. 1 is a block diagram of a frequency division multiple access communication device according to an embodiment of the present invention. In FIG. 1, the frequency division multiple access communication device includes a transmitting section 10 that occupies one of a plurality of channels, and a receiving section 20 that receives the SCPC signal of this occupied channel. The transmitter 10 includes an input terminal 11 to which an SCPC signal to be transmitted is input, and an input terminal 12 to which information about an occupied channel is input. Furthermore, the transmitter 10 includes a signal multiplexing circuit 13 and a modulation circuit 14.
and an output terminal 15. Input terminal 11,
12 is connected to a signal multiplexing circuit 13. The signal multiplexing circuit 13 is a circuit that multiplexes information on channels occupied by SCPC signals.

The output and input terminal 12 of signal multiplexing circuit 13 are connected to modulation circuit 14 . The modulation circuit 14 is a circuit that modulates the carrier wave assigned to the channel it occupies with the output of the signal multiplexing circuit 13. Modulation circuit 1
The output of 4 is connected to output terminal 15 and sent out.

The receiving unit 20 includes an input terminal 21 to which the output of the modulation circuit 14 is input, and an input terminal 22 to which information about the occupied channel is input. Furthermore, the receiving section 2
0 includes a demodulation circuit 23, a signal separation circuit 24, a frequency control circuit 25, and an output terminal 26. The demodulation circuit 23 inputs the output of the transmitter 10, sweeps the frequency according to the control signal output from the frequency control circuit 25, detects a desired channel, and selects the desired channel.
This is a circuit that demodulates SCPC signals.

The signal separation circuit 24 receives the signal from the output of the demodulation circuit 23.
This circuit separates the SCPC signal from the information on the occupied channel multiplexed with the SCPC signal.

The frequency control circuit 25 inputs the information of the occupied channel multiplexed with the SCPC signal output from the signal separation circuit 24 and the information of the desired channel, and performs control to sweep the frequency at the frequency interval of the carrier wave corresponding to the difference between the two pieces of information. This circuit provides a signal to the demodulation circuit 23.

A desired SCPC signal output from the signal separation circuit 24 is connected to an output terminal 26.

The operation of the SCPC communication device having such a configuration will be explained. FIG. 2 is a frame configuration diagram of an SCPC signal of the frequency division multiple access communication device of the present invention. In Fig. 2, A ₁ to A ₂ are synchronization signals, B ₁ ,
_B2 indicates channel information signal and C indicates data.
FIG. 3 is a diagram showing a frequency arrangement of the frequency division multiple access communication device of the present invention. In Figure 3,
CH ₁ to CH _o represent channels, and D represents a transmission line frequency fluctuation range. In FIG. 1, the transmission data input from the input terminal 11 and the desired channel information input from the input terminal 12 are the signal multiplexing circuit 1.
3, resulting in a signal with a frame structure as shown in FIG. In Figure 2, synchronization signal A is data signal C.
This is a frame synchronization signal for easily separating the channel information signal B and the channel information signal B on the receiving side. The output signal of the signal multiplexing circuit 13 is modulated by a modulation circuit 14 into a format suitable for the transmission line medium, and sent out to the transmission line. The receiving section 20 uses an SCPC as shown in FIG.
A frequency-multiplexed signal is applied to the input terminal 21 and supplied to the demodulation circuit 23 . Demodulation circuit 23
performs a frequency sweep, and when it detects the SCPC signal, it stops sweeping and enters a synchronized state. The demodulated signal is input to the signal separation circuit 24, and after frame synchronization is established, channel information is detected.

Here, in FIG. 3, the desired channel is channel CH ₃ , and the frequency sweep is channel CH ₂ ~
This is done in the range of CH ₄ , and demodulation circuit 2 is installed on channel CH _2.
The operation of the frequency control circuit 25 will be explained using the case where the frequency control circuit 25 is synchronized. The channel information output by the signal separation circuit 24 is channel CH ₂ , and the desired channel information set externally is channel CH _3. Based on this difference, the frequency control circuit 25 sets the frequency to the demodulation circuit 23. Executes a frequency sweep for the separation and selects the desired channel CH ₃ .
can be received.

As described above, this embodiment can provide a stable communication line even on a transmission line with extremely large frequency fluctuations.

FIG. 4 is a block diagram of a receiving section of a frequency division multiple access communication apparatus according to another embodiment of the present invention. In FIG. 4, the same parts as in FIG. 1 are designated by the same reference numerals, and 35 is a comparison circuit. The comparison circuit 35 compares the desired channel information applied to the input terminal 22 and the channel information output from the signal separation circuit 24.
The comparison circuit 35 controls the demodulation circuit 23 and performs frequency sweep until they match. In addition,
Frequency sweeping can be similarly performed when the channel information output from the signal separation circuit 24 has a higher frequency than the desired channel information.

〔Effect of the invention〕

As described above, the present invention has the excellent effect of detecting a desired channel even on a transmission line with extremely large frequency fluctuations and being able to reliably tune to a desired SCPC signal.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of a frequency division multiple access communication device according to an embodiment of the present invention, FIG. 2 is a frame configuration diagram of an SCPC signal of the frequency division multiple access communication device of the present invention, and FIG. 3 is a frequency division multiple access communication device according to the present invention. A diagram showing a frequency arrangement of a multiple access communication device. FIG. 4 is a block configuration diagram of a receiving section of a frequency division multiple access communication device according to another embodiment of the present invention. 10... Transmitting section, 11, 12, 21, 22... Input Terminal, 13...Signal multiplexing circuit, 14...Modulation circuit, 1
5, 26... Output terminal, 20... Receiving section, 23... Demodulation circuit, 24... Signal separation circuit, 25... Frequency control circuit, 35... Comparison circuit, _A1 , _A2 ... Synchronization signal, _B1 ,
B ₂ ...Channel information signal, C...Data signal, CH ₁
~CH _o ...Channel, D...Transmission line frequency fluctuation range.

Claims (1)

[Claims] 1. A plurality of transmitting sections including a modulation circuit that occupies one of the plurality of channels and modulates a carrier wave assigned to the occupied channel with a transmission signal, and an output of the plurality of transmitting sections. In the SCPC communication device, each of the transmitting units includes a receiving unit including a demodulation circuit that receives the signal, detects the channel to be received by frequency sweep, and demodulates the transmitted signal, and each of the transmitting units includes information on the channel it occupies in the SCPC signal. and a signal multiplexing circuit for multiplexing the signal and providing it to the modulation circuit, and the receiving section includes a signal separation circuit for separating occupied channel information multiplexed into the SCPC signal from the output of the demodulation circuit; 1. A frequency division multiple access communication device, comprising: control means for providing the demodulation circuit with a control signal that sweeps the frequency based on information on desired output and input channels.