KR0179598B1 - If frequency mixing apparatus in satellite communication system - Google Patents

Abstract

The present invention relates to a redundant transmission intermediate frequency combination apparatus of a satellite communication system capable of performing stable frequency combining operation by duplexing the configuration of the combination apparatus in combining a plurality of intermediate frequencies to be transmitted to generate one intermediate frequency. A frequency combining means for combining a plurality of input intermediate frequency signals into a predetermined frequency signal, and first attenuation means for attenuating the intermediate frequency signal output from the frequency combining means to a level suitable for a system, and Separating means for separating the signal attenuated by the first attenuation means into first and second intermediate frequency signals, first and second amplifying means for amplifying the intermediate frequency signal output through the separating means, and an external selection signal According to the intermediate frequency signal output from the first and second amplifying means to a level suitable for future systems And a second damping means which hinge is characterized in that configured.

Description

Dual Transmission Intermediate Frequency Combination System of Satellite Communication System

1 is an overall system configuration for explaining the outline of a general satellite communication system.

FIG. 2 is a block diagram showing the configuration of the central control station 2 in FIG.

3 is a circuit diagram showing a dual transmission intermediate frequency combination apparatus of a satellite communication system according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1: satellite 2: central control station

3A, 3B: base station 11A, 11B: switchboard

12A, 12B: Telephone 13A, 13B: Data Terminal

14A, 14B: Facsimile 21: Antenna

22: orthogonal mode converter 23: low noise amplifier

24: frequency down converter 25, 26: SCPC channel unit

27: frequency up converter 28: high power amplifier

29: network control unit 30: network management system

41: frequency combiner 42, 44: attenuator

43a, 43b: amplifier 45: regulator

46a, 46b: Current detector RY1a, RY1b, RY2, RY3a, RY3b: relay

CP1a, CP1b, CP2a, CP2b: Comparators

VR1a, VR1b, VR2a, VR2b: Variable resistor

The present invention relates to a transmission intermediate frequency combination apparatus for generating a single intermediate frequency by combining a plurality of intermediate frequencies to be transmitted in a communication system using satellites, and in particular, a satellite configured to perform a stable frequency combination operation. A redundant transmission intermediate frequency combination apparatus of a communication system.

Recently, with the rapid development of communication technology, satellite communication, which enables subscribers who are located at remote sites to make calls through satellites, has become increasingly common. Since such satellite communication does not require a separate signal line for a call, It is mainly used as a long distance communication between countries or as a communication method in a mountainous country such as Korea.

In the above-mentioned satellite communication, there are two types of PAMA (Pre Assignment Multiple Access) method for allocating communication channels for each subscriber according to the channel allocation method and Demand Assignment Multiful Access (DAMA) method for allocating communication channels according to the subscriber's request. In general, in the satellite communication system for communication between subscribers, many DAMA methods are adopted in consideration of the cost and the effectiveness of the communication channel.

1 is a block diagram showing the overall system configuration of a general satellite communication system according to the DAMA method.

In Fig. 1, reference numeral 1 is a satellite having a plurality of communication channels, 2 is a central control station for controlling the entire satellite communication system, and 3 (3A, 3B) is an exchanger (11A, 11B) or a telephone (12A, 12B). Communication function between the various terminals through data transmission and reception with the central control station 2 as well as an interface function for terminals such as data terminals 13A and 13B and facsimile 14A and 14B, such as a computer. The base station that provides.

In FIG. 1, reference numeral S denotes a service channel for transmitting and receiving control data, and T denotes a traffic channel for transmitting and receiving data or voice.

In the above-described configuration, the central control station 2 transmits a control message through a service channel in a normal state and then communicates the state of each base station 3 based on a response message transmitted from the base station 3. It performs a polling function to check the available capacity or the utilization status of the communication channel. When there is a call request from a specific base station, for example, the base station 3A to a terminal having jurisdiction over the base station 3B, it is determined whether the base station 3B is in a state in which communication is possible based on the information obtained in the polling process. In the case of the communicable state, the available traffic channel T of the satellite is allocated to both base stations 3A and 3B so that both base stations 3A and 3B can directly communicate with each other.

Subsequently, when the communication between the base stations 3A and 3B is terminated and the communication termination signal is applied through the service channel S from the base station 3A, which has been requested for communication, the central control station 2 is applied to both base stations. By executing the communication termination process, the traffic channel T provided to the base stations 3A and 3B is released.

2 is a block diagram showing the configuration of the central control station 2 described above.

In FIG. 2, reference numeral 21 is an antenna for transmitting / receiving an satellite 1, an uplink signal, and a downlink signal, and 22 is an antenna 22 using frequency polarization characteristics. Orthogonal Mode Transducer (OMT) for separating and transmitting and receiving signals transmitted and received through 23, 23 is a low-noise amplifier for low-noise amplifying downlink frequency signals of 12.25 ~ 12.75GHz input through the orthogonal mode converter (22) LNA (Low Noise Amplifier), 24 is a frequency down converter (DC) for converting a frequency signal applied through the low noise amplifier 23 into an intermediate frequency signal IF of 70 MHz, for example, 25 is the frequency down converter. SCPC (Single Channel Per Carrier) channel unit that demodulates, decodes and outputs the intermediate frequency signal (IF) applied from (24).

Further, reference numeral 26 denotes an SCPC channel unit for encoding, modulating and outputting a message output from the network controller 29 to be described later, and 27 denotes an IF signal of 70 MHz output from the SCPC channel unit 26, for example, from 14.0 to A frequency up converter (UC) for converting microwaves to 14.5 GHz to generate an uplink frequency signal, and a high power amplifier (HPA) for amplifying an uplink frequency signal output from the frequency up converter 27. Amplifier.

In addition, reference numeral 29 is a polling function that checks the state of each base station 3 based on a response message transmitted from the base station 3 after transmitting a control message to each base station 3 through the SCPC channel unit 25. If there is a call request from a specific base station, the base station determines whether the other base station can communicate with each other based on the information obtained in the polling process. ) Is a network control unit that performs system control such that both base stations directly communicate with each other by allocating the "

In addition, reference numeral 30 denotes a network management system for managing the overall network of the satellite communication system by the system administrator to manage the network control unit 29.

That is, in the above configuration, when the network control unit 29 generates a message for each base station and outputs the message to the SCPC channel unit 26, the SCPC channel unit 26 encodes and modulates the message, such as 70 MHz. The intermediate frequency signal is converted and output, and the intermediate frequency signal is converted into an uplink frequency signal of, for example, 14.5 GHz by the frequency increase converter 27. The uplink frequency signal is output through the high power amplifier 28, the quadrature mode converter 22, and the antenna 21, and then transmitted to each base station 3 through the satellite 1 in FIG. .

Meanwhile, the response message received from the base station 3 through the satellite 1 to the antenna 21, that is, the downlink frequency signal of 12.25 GHz is transmitted through the quadrature mode converter 22 and the low noise amplifier 23 to the frequency down converter. It is applied to (24) is converted into an intermediate frequency signal of 70MHz, then applied to the SCPC channel unit 25, demodulated and decoded is applied to the network control unit 29.

Then, the network control unit 29 controls the entire communication system by controlling the status detection or call processing of each base station based on the message information from the SCPC channel unit 25.

However, in the above-described apparatus, since the central control station 2 controls the plurality of base stations 3 to provide communication functions for various subscribers coupled to each base station 3, the central control station 2 ), The problem occurs that the whole communication system is paralyzed.

In addition, since the central control station 2 manages a plurality of base stations 3, it is often necessary to transmit and receive a plurality of intermediate frequencies to demodulate or modulate.

Therefore, in the conventional satellite communication system, the SCPC channel for modulating or demodulating the data transmitted and received by the central control station 2 to the base station 3 or the data transmitted and received by the base station 3 to the central control station 2. Multiplexing of units has also been considered to deal with any abnormal conditions.

However, when the SCPC channel units are multiplexed as described above, the modulated intermediate frequency signals outputted from the multiplexed SCPC channel units multiplexed in FIG. 2 are converted into one intermediate frequency signal, and then converted into one intermediate frequency signal. If such a frequency combination is realized only through parallel connection of signal lines, the level of the transmitted frequency signal becomes unstable due to deterioration of signal level and the like. If the amplification means outputs through the amplification means, when the level of the frequency signal outputted by the amplification means is changed, the frequency detection operation of another system that receives the signal may become insufficient or the receiver may be damaged. .

Accordingly, the present invention has been made in view of the above circumstances, and aims to stabilize the overall satellite communication system by combining a plurality of intermediate frequency signals into one intermediate frequency signal and stabilizing the level of the combined intermediate frequency signals. It is possible to provide a redundant transmission intermediate frequency combination device of a satellite communication system, which is capable of not affecting the operation of the entire system even when an abnormality occurs in the intermediate frequency combination device. There is this.

The dual transmission intermediate frequency combining apparatus of the satellite communication system according to the present invention for realizing the above object comprises: frequency combining means for combining a plurality of input intermediate frequency signals into a predetermined frequency signal, and outputting from the frequency combining means; First attenuating means for attenuating the intermediate frequency signal to a level suitable for the system, separating means for separating the attenuated signal by the first attenuating means into first and second intermediate frequency signals, output through the separating means First and second amplifying means for amplifying the intermediate frequency signal, respectively; switching means for selectively outputting the intermediate frequency signal output from the first and second amplifying means according to an external selection signal, and outputting from the switching means. And second attenuating means for attenuating the intermediate frequency signal to a level suitable for future systems. The.

In addition, the present invention provides a first and second current detection means for detecting an abnormal state of the operating power supplied to the first and second amplifying means and automatically shuts down the operating power supplied to the amplifying means when an abnormality occurs. Characterized in that further comprises.

The first and second current detecting means may be configured to output an abnormal signal indicating an abnormal state of the operating power supply.

According to the present invention having the above-described configuration, by combining a plurality of intermediate frequency signals into one intermediate frequency signal and stabilizing the level of the combined intermediate frequency signals, the stability of the entire satellite communication system can be achieved.

Further, by amplifying the amplifying means for amplifying the combined intermediate frequency, it is possible to prevent the entire system from being affected by the abnormal state of the amplifying means.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

3 is a block diagram showing a dual transmission intermediate frequency combination apparatus of a satellite communication system according to an embodiment of the present invention.

In Fig. 3, reference numeral 41 denotes a frequency combiner which combines a plurality of intermediate frequency signals (five in this embodiment) IF1 to IF5 as one intermediate frequency signal, and 42 denotes this frequency combiner 41. Is a first attenuator for attenuating the level of the intermediate frequency signal output from the system to a level suitable for the system according to the selection signals S1 to S3.

Further, reference numeral 50 denotes a first divider for separating the intermediate frequency signal output from the first attenuator 42 into two identical intermediate frequency signals, and 43a and 43b are intermediate frequency signals output from the first divider 50. As the first and second amplifiers to amplify the, respectively, the first and second amplifiers 43a and 43b have their amplification degree determined based on the attenuation level attenuated in the process of being distributed in the first divider 50. .

Further, reference numerals RY1a and RY1b are first and second relays for selectively outputting intermediate frequency signals input from the amplifiers 43a and 43b according to the selection signals S7 and S8. When S8) becomes low level and current flows through the corresponding coil, the intermediate frequency signal inputted is output to the ground side through the resistors R11a and R11b, while the selection signals S7 and S8 become high level. The intermediate frequency signal is output to the relay RY2 which will be described later.

Further, reference numeral RY2 is a third relay for selectively outputting an intermediate frequency signal input from the first and second relays RY1a and RY1b according to the selection signal S9, which means that the selection signal S9 is high. When the level is reached, the intermediate frequency signal input from the first relay RY1a is output, while when the selection signal S9 becomes low level, the intermediate frequency signal input from the second relay RY1b is output.

Here, reference numerals D2a to D2c are diodes for preventing back electromotive force by the coils of the first to third relays RY1a, RY1b, and RY2, and R11a and R11b are resistors for limiting current.

Further, reference numeral 44 denotes a second attenuator for attenuating and outputting an intermediate frequency signal output from the third relay RY2 to a signal level suitable for a circuit of a later stage, and 45 denotes the first and second amplifiers 43a and 43b. Is a regulator to apply constant voltage.

On the other hand, reference numerals RY3a and RY3b are installed in power supply lines applied from the regulator 45 to the first and second amplifiers 43a and 43b, respectively, to interrupt the operating power supplied to the corresponding amplifiers 43a and 43b. As the fourth and fifth relays, the relays RY3a and RY3b are applied to the first and second amplifiers 43a and 43b according to detection signals from the current detectors 46a and 46b, respectively, which will be described later. The voltage is interrupted.

Reference numerals 46a and 46b denote first and second current detectors for detecting abnormal states of currents applied to the first and second amplifiers 43a and 43b.

Here, the first current detector 46a is configured to detect that the first comparator CP1a and the supply current rise above the predetermined level to detect that the supply current supplied to the first amplifier 43a falls below a predetermined level. It is comprised with the 2nd comparator CP2a which detects.

In the first and second comparators CP1a and CP2a, the voltage supplied to the first amplifier 43a is coupled to the inverting terminal (-) and the non-inverting terminal (+), respectively. In addition, the resistors R5a and R6a and the variable resistor VR1a are connected in series between the power supply line to the first amplifier 43a and the ground for supplying the reference voltage of the first comparator CP1a and the resistance ( The connection point of R5a) (R6a) is coupled to the non-inverting terminal (+) of the first comparator CP1a, and a power supply line to the first amplifier 43a for supplying a reference voltage of the second comparator CP2a. The resistors R7a and R8a and the variable resistor VR2a are connected in series between the grounds, and the connection points of the resistors R7a and R8a are coupled to the inverting terminal (-) of the second comparator CP2a.

In addition, a resistor R4a is provided between the connection point of the resistors R5a and R7a to the power supply line to the first amplifier 43a and the connection point of the first and second comparators CP1a and CP2a. The drop voltage of the resistor R4a changes according to the amount of current flowing through the power supply line. Accordingly, the first and second comparators CP1a and CP2a may detect a variation range of the amount of current supplied to the first amplifier 43a based on the voltage difference between the both ends of the resistor R4a.

In addition, in the above configuration, the variable resistors VR1a and VR2a are used to appropriately adjust the reference voltages for the first and second comparators CP1a and CP2a, wherein the first and second comparators CP1a and CP2a are used. Denotes reference voltages set by the variable resistors VR1a and VR2a, that is, reference voltages applied to the non-inverting terminal (+) of the first comparator CP1a and the inverting terminal (-) of the second comparator CP2a, respectively. When V1 and V2 are supplied and the supply voltage to the first amplifier 43a is VO, a low level voltage is output in the case of V1 VOV2, and a high level voltage is output in the case of VOV1 or VOV2.

The output signals of the first and second comparators CP1a and CP2a are applied to the fourth relay RY3a through an AND gate AND1a and coupled to the anode side of the reverse current preventing diode D1a. .

In addition, the power supply voltage Vcc is coupled to the output terminals of the first and second comparators CP1a and CP2a through a resistor R9a, and an abnormal signal FAIL1 indicating an abnormal state of the power supply from the coupling node is provided. It is supposed to be output.

In addition, the power supply voltage Vcc applied to the combined node of the diode D1a and the fourth relay RY3a prevents the fourth relay RY3a from being turned off due to an instantaneous voltage abnormality of the present circuit. It is for.

In addition, since the configuration and operation method of the second current detector 46b are substantially the same as those of the first current detector 46a, detailed description thereof will be omitted.

That is, in the above configuration, the intermediate frequency signal output from the attenuator 42 is separated into two intermediate frequency signals through the first divider 50, and the dual frequency signals are duplicated to the first and second amplifiers 43a and 43b. Each amplification duplicates the intermediate frequency signal.

The intermediate frequency signals output from the first and second amplifiers 43a and 43b are selectively output through the first to third relays RY1a, RY1b and RY2 and the second attenuator 44.

In addition, the switching states of the first to third relays RY1a, RY1b, and RY2 are controlled according to selection signals S7 to S9 from the outside. For example, in the initial operation state, the selection signals ( S7 and S8 are set to the high level, and the selection signal S9 is set to the low level so that the intermediate frequency signals output from the first amplifier 43a receive the first and third relays RY1a and RY2 and the second. It is output through the attenuator 44.

Meanwhile, when an abnormality in the supply current supplied to the first amplifier 43a is detected by the first current detector 46a in the above operating state, the first or second comparator CP1a, of the first current detector 46a, may be detected. The output of CP2a) becomes low level. Accordingly, a low level signal is output from the AND gate AND1a, and a current flows through the coil of the fourth relay RY3a, so that the fourth relay RY3a is turned off to be supplied to the first amplifier 43a. The operating current is blocked and the low level abnormal signal FAIL1 is output through the resistor R9a of the first current detector 46a.

That is, in the normal state, the first current detector 46a maintains the outputs of the first and second comparators CP1a and CP2a at the high level as described above. Therefore, in this case, the cathode side of the diode D1a and the output level of the AND gate AND1a are set to a high level so that no current flows through the coil of the fourth relay RY3a so that the first amplifier from the regulator 45 is provided. Normal operation power is supplied to 43a.

At this time, the power supply voltage Vcc is outputted to the abnormal signal output terminal FAIL1 through the resistor R9a, thereby outputting a high level normal signal.

On the other hand, in the above operating state, when the supply current value supplied from the regulator 45 to the first amplifier 43a is lowered below a certain value due to an abnormal state of the first amplifier 43a or the like, the first current detection unit ( As the voltage drop value of the resistor R4a of 46a is lowered, the voltage applied to the non-inverting terminal (+) of the first comparator CP1a is lower than the voltage applied to the inverting terminal (−) of the first comparator ( The low level voltage is output from CP1a). That is, the output terminal of the first comparator CP1a is set at the low level.

Accordingly, the power supply voltage Vcc applied through the resistor R9a is lowered to the ground level by the output of the first comparator CP1a, thereby outputting the low level abnormal signal through the abnormal signal output terminal FAIL1. . Then, the output of the AND gate AND1a is lowered to a low level so that the power supply voltage Vcc flows to the output terminal side of the AND gate AND1a through the coil of the fourth relay RY3a, and thus the fourth relay RY3a. By turning off, the operating power supplied to the first amplifier 43a is cut off, thereby preventing a malfunction of the first amplifier 43a.

Further, in a normal operating state, when the supply current value supplied from the regulator 45 to the first amplifier 43a rises above a predetermined value due to an abnormal state of the first amplifier 43a, the first current detector 46a. As the voltage drop by the resistor R4a increases, the voltage applied to the inverting terminal (-) of the second comparator CP2a becomes higher than the voltage applied to the non-inverting terminal (+) of the second comparator CP2a. From the low level voltage is output.

Accordingly, the power supply voltage Vcc applied through the resistor R9a is lowered to the ground level by the output of the second comparator CP2a, thereby outputting the low level abnormal signal through the abnormal signal output terminal FAIL1. . Then, the output of the AND gate AND1a is lowered to a low level so that the power supply voltage Vcc flows to the output terminal side of the AND gate AND1a through the coil of the fourth relay RY3a, and thus the fourth relay RY3a. By turning off, the operating power supplied to the first amplifier 43a is cut off, thereby preventing a malfunction of the first amplifier 43a.

On the other hand, after detecting the abnormal state of the first amplifier 43a based on the abnormal signal FAIL1 output from the first current detector 46a, the administrator selects the select signals S7 and S8 at low level and selects the signals. When the step S9 is changed to the high level, the intermediate frequency signal output from the first amplifier 43a is blocked from being applied to the second attenuator 44 and the intermediate frequency output from the second amplifier 43b. The signal is output to the second attenuator 44 through the second and third relays RY1b and RY2.

Therefore, since the normal intermediate frequency signal is quickly output again through the second attenuator 44, the first amplifier 43a in which the abnormality has occurred in a stable state can be replaced or repaired.

In addition, when an abnormality occurs in the second amplifier 43b again in the normal operation state of the second amplifier 43b, the second current detector 46b operates similarly to the first current detector 46a described above. As a result, the operating current applied to the second amplifier 43a is cut off, and the abnormal signal FAIL2 is output accordingly. In this case, the selection signals S7 and S8 are again set at a high level and the selection signal S9. ) Is changed to the low level so that the intermediate frequency signal outputted through the first amplifier 43a can be outputted through the second attenuator 44.

That is, according to the embodiment, when an error occurs in one amplifier of the intermediate frequency combination device, an error signal indicating the abnormal state is output and the operation of the corresponding amplifier is immediately stopped. Then, only by changing the selection signal, the other amplifier replaces the amplifier that has generated more than that and performs the amplifier function.

Therefore, the abnormal state of the amplifier can be easily determined, and the stability of the entire satellite communication system can be achieved.

In addition, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the technical scope of the present invention.

As described above, according to the present invention, the stability of the entire satellite communication system can be achieved by combining a plurality of intermediate frequency signals into one intermediate frequency signal and stabilizing the level of the combined intermediate frequency signals. By double-decoding the intermediate frequency combination device, it is possible to realize a redundant transmission intermediate frequency combination device of the satellite communication system, which does not affect the operation of the entire system even when an error occurs in the intermediate frequency combination device.

Claims (3)

Frequency combining means for combining a plurality of input intermediate frequency signals into a predetermined frequency signal, first attenuation means for attenuating the intermediate frequency signal output from the frequency combining means to a level suitable for a system, and the first attenuation means Separating means for separating the attenuated signal by means into first and second intermediate frequency signals, first and second amplifying means for amplifying the intermediate frequency signal output through the separating means, respectively, according to an external selection signal. Switching means for selectively outputting the intermediate frequency signal output from said first and second amplifying means, and second attenuating means for attenuating the intermediate frequency signal output from said switching means to a level suitable for future systems. Dual transmission intermediate frequency combination apparatus of the satellite communication system, characterized in that. The method of claim 1, wherein the first and second current detections respectively detect abnormal conditions of the operating power supplied to the first and second amplifying means, and automatically cut off the operating power supplied to the corresponding amplifying means. A redundant transmission intermediate frequency combination apparatus of a satellite communication system, characterized in that it further comprises a means. The apparatus of claim 2, wherein the current detecting means outputs an abnormal signal indicating an abnormal state of an operating power source.