KR0179602B1 - If frequency distributing device in satellite communication system - Google Patents

Abstract

The present invention relates to a receiving intermediate frequency distribution device of a satellite communication system that can cope with multiplexing of a receiving device by dividing two intermediate frequencies of a received frequency signal in a satellite communication system. Attenuation means for attenuating to a predetermined level, amplifying means for amplifying the signal attenuated by the attenuation means, and distribution means for distributing and outputting an intermediate frequency signal amplified by the amplifying means into a plurality of intermediate frequency signals. A receiving intermediate frequency distribution apparatus of a satellite communication system, comprising: a resistance value provided in a power supply line to the amplification means, and a voltage drop value of the resistance means by comparing a voltage value between both ends of the resistance means; First comparison means for detecting the following, and a voltage value between both ends of said resistance means Comparing the second power supply means for detecting that the voltage drop value by the resistance means is greater than or equal to the second value greater than the first value, and the operating power applied to the amplification means according to the output levels of the first and second comparison means. And a switching means for interrupting the supply.

Description

Receiving Intermediate Frequency Mixer in 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 receiving intermediate frequency distribution apparatus of the satellite communication system according to the prior art.

Figure 4 is a circuit diagram showing a receiving intermediate frequency divider in 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: reception intermediate frequency distribution device 42, 44: attenuator

43: amplifier 44: divider

45 regulator 46 current detector

RY1: Relay CP1, CP2: Comparator

VR1, VR2: Variable resistor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system using satellites, and more particularly, to a receiving intermediate frequency divider of a satellite communication system capable of coping with multiplexing of a receiving device by distributing a plurality of intermediate frequencies of a received frequency signal.

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 multiplexing the SCPC channel unit as described above, it is necessary to distribute and apply the intermediate frequency signal received from the frequency down converter 24 to the plurality of SCPC channel units 25 in FIG. If the same frequency distribution is realized by simply connecting signal lines in parallel, there is a possibility that data detection at the subsequent stage may become unstable due to a drop in signal level.

Accordingly, the present applicant has developed and applied for a reception intermediate frequency distribution device of a satellite communication system that is capable of distributing and outputting an input intermediate frequency signal into a plurality of stable intermediate frequency signals.

3 is a block diagram showing an intermediate frequency distribution apparatus of the satellite communication system.

In FIG. 3, reference numeral 41 denotes an intermediate frequency signal input through an input terminal, that is, a level of an intermediate frequency signal IF in applied from the frequency down converter 24 in FIG. 2 according to the selection signals S1 to S3. The first attenuator is to attenuate the input signal 0.5 dB when the selection signal S1 is 1, 1 dB when the selection signal S2 is 1, and 2 dB when the selection signal S3 is 1, respectively. .

Further, reference numeral 42 denotes a second attenuator for attenuating the output signal output from the first attenuator 41 according to the selection signals S4 to S6, which is 4 dB when the selection signal S4 is 1. When the input signal S5 is 1, 8 dB is attenuated, and when the input signal S6 is' 1, 16 dB is attenuated.

That is, the first and second attenuators 41 and 42 may adjust the level of the intermediate frequency signal IF in input from the frequency down converter 24 of FIG. 2 according to the predetermined selection signals S1 to S6. Attenuated to the appropriate signal level in the circuit section.

In FIG. 3, reference numeral 43 denotes an amplifier for amplifying the intermediate frequency signal output from the second attenuator 42, and 44 denotes a plurality of output stages IF1 to IF5. In this case, the amplifier 43 amplifies and outputs the intermediate frequency signal as an amplification level for compensating the level of the signal generated in the distribution process by the divider 44.

Reference numeral 45 is a regulator for applying a constant voltage to the amplifier circuit 43, C1 and C2 are smoothing capacitors, and R1 to R3 are resistance voltage divider circuits for impedance matching.

In the above configuration, when the intermediate frequency signal is input from the frequency down converter 24, the first and second attenuators 41 and 42 first attenuate the level of the input signal to a signal level suitable for the system.

Then, the intermediate frequency signal output from the second attenuator 42 is amplified in advance by the amplifier 43 in consideration of the amount attenuated at the time of frequency distribution by the divider 44, and then distributed through the divider 44. Will print it out.

Therefore, when the data is detected by demodulating the intermediate frequency signal output through the divider 44 later, it is possible to prevent the original data from being insufficiently detected due to instability of the signal level. By using channel units, it is possible to effectively cope with system capacity expansion.

However, the above-described conventional receiving intermediate frequency signal distribution apparatus has the following problems.

That is, when the operating power is changed, the amplifier 43 becomes unstable in the amplification operation for the received intermediate frequency signal, and the level of the intermediate frequency signal output from the divider 44 becomes insufficient. The data detection in 25 is insufficient.

In addition, the amplifier 43, when the operating voltage rises above a certain level, the level of the output signal is greatly increased by the excessive amplification operation, in this case SCPC receiving the intermediate frequency signal output from the divider 44 The channel unit 25 is affected and may be damaged in severe cases.

Accordingly, the present invention was made in view of the above circumstances, and when an abnormality occurs in the operating power supply of the amplifier amplifying the intermediate frequency signal, the supply of the operating power is interrupted and an abnormal signal indicating the abnormal state is output. It is an object of the present invention to provide a receiving intermediate frequency distribution apparatus of a satellite communication system.

The reception intermediate frequency distribution apparatus of the satellite communication system according to the present invention for realizing the above object comprises attenuation means for attenuating a plurality of intermediate frequency signals input to a predetermined level, and amplification for amplifying the signal attenuated by the attenuation means. And a distribution means for distributing and distributing the intermediate frequency signal amplified by the amplifying means into a plurality of intermediate frequency signals, the receiving intermediate frequency distribution apparatus of the satellite communication system comprising: a power supply line to the amplifying means A first comparison means for detecting that the voltage drop between the resistance means provided at the first and second ends of the resistance means is less than or equal to the first value, and comparing the voltage values between both ends of the resistance means. Second comparing means for detecting that the voltage drop is greater than or equal to the second value greater than the first value, and the first and second ratios; And switching means for interrupting the supply of operating power applied to the amplifying means according to the output level of the teaching unit.

The present invention also provides an abnormal signal output means for outputting an abnormal signal indicating that the power supply is abnormal when the voltage drop value of the resistance means is detected by the first and second comparing means to be less than the first value or more than the second value. Characterized in that further comprises a.

According to the present invention having the above-described configuration, when an abnormality occurs in the operating power supply of the amplifying means for amplifying the intermediate frequency signal in amplifying and distributing the receiving intermediate frequency, the supply of the operating power is cut off and the abnormal state is detected. Since the abnormal signal indicating is outputted, the system administrator can easily recognize the abnormal state and can prevent the circuit of the subsequent stage from being damaged by the abnormal operation of the amplifying means.

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

4 is a block diagram showing a receiving intermediate frequency distribution apparatus of the satellite communication system according to an embodiment of the present invention. In FIG. 4, the same reference numerals are attached to the same parts as in FIG. 3, and the detailed description thereof is omitted.

In FIG. 2, reference numeral RY1 is a relay provided to the power supply line applied from the regulator 45 to the amplifier 43 to relay the operating power supplied to the amplifier 43. The operating voltage applied to the amplifier 43 is interrupted in accordance with the detection signal from the current detection unit 46 to be described.

In addition, reference numeral 46 denotes a current detector for detecting an abnormal state of the current applied to the amplifier 43. The first comparator CP1 detects that the supply current supplied to the amplifier 43 falls below a predetermined level. ) And a second comparator (CP2) for detecting that the supply current rises above a certain level.

In the first and second comparators CP2 and CP3, the voltage supplied to the amplifier 43 is coupled to the inverting terminal (−) and the non-inverting terminal (+), respectively. In addition, resistors R5 and R6 and variable resistor VR1 are connected in series between the power supply line to the amplifier 43 and the ground to supply the reference voltage of the first comparator CP2, and the resistor R5. A connection point of R6 is coupled to the non-inverting terminal (+) of the first comparator CP1, and is connected between a power supply line to the amplifier 43 and a ground for supplying a reference voltage of the second comparator CP2. R7 and R8 and the variable resistor VR2 are connected in series, and a connection point of the resistors R7 and R8 is coupled to the inverting terminal (-) of the second comparator CP2.

In addition, a resistor R4 is provided between the connection point of the resistors R5 and R7 to the power supply line to the amplifier 43 and the connection point of the first and second comparators CP1 and CP2. The drop voltage of the resistor R4 changes according to the amount of current flowing through the power supply line. Accordingly, the first and second comparators CP1 and CP2 can detect a variation range of the amount of current supplied to the amplifier 43 based on the voltage difference between the both ends of the resistor R4.

In addition, in the above configuration, the variable resistors VR1 and VR2 are used to appropriately adjust the reference voltages for the first and second comparators CP1 and CP2, wherein the first and second comparators CP1 and CP2. Denotes reference voltages set by the variable resistors VR1 and VR2, that is, reference voltages applied to the non-inverting terminal (+) of the first comparator CP1 and the inverting terminal (-) of the second comparator CP2, respectively. When the supply voltage to the amplifier 43 is referred to as V1 and V2, 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 CP1 and CP2 are applied to the relay RY1 side through the AND gate AND1 and coupled to the anode side of the reverse current preventing diode D1.

In addition, the power supply voltage Vcc is coupled to the output terminals of the first and second comparators CP1 and CP2 through a resistor R9, and an abnormal signal FAIL 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 D1 and the relay RY1 is for preventing the relay RY1 from being turned off due to an instantaneous voltage abnormality of the present circuit.

Next, the operation of the device having the above configuration will be described.

First, in the normal state, the outputs of the first and second comparators CP1 and CP2 are maintained at the high level as described above. Therefore, in this case, the cathode side of the diode D1 and the output level of the AND gate AND1 are set to a high level so that the current flows from the relay RY1 through the coil so that the regulator 45 to the amplifier 43 can be avoided. Normal operating power is supplied.

At this time, the power supply voltage Vcc is outputted to the abnormal signal output terminal FAIL through the resistor R9, thereby outputting a high level normal signal.

On the other hand, in the above operating state, when an abnormality occurs in the operating power supplied from the regulator 45 to the amplifier 43 and the supply current value drops below a certain value, the resistance R4 of the current detector 46 is reduced. As the voltage drop value is lowered, the voltage applied to the non-inverting terminal (+) of the first comparator CP1 is lower than the voltage applied to the inverting terminal (-) side, thereby lowering the voltage of the first comparator CP1. Will be output. That is, the output terminal of the first comparator CP1 is set at the low level.

Accordingly, the power supply voltage Vcc applied through the resistor R9 is lowered to the ground level by the output of the first comparator CP1, thereby outputting the low level abnormal signal through the abnormal signal output terminal FAIL. . Then, the output of the AND gate AND1 is lowered to the low level, so that the power supply voltage Vcc flows to the output terminal side of the AND gate AND1 through the coil of the relay RY1, whereby the relay RY1 is turned off and the amplifier As the operating power supplied to the 43 is cut off, the malfunction state of the amplifier 43 is prevented.

In addition, in a normal operation state, when an abnormality occurs in the operating power supply supplied from the regulator 45 to the amplifier 43 and the supply current value rises above a certain value, the voltage caused by the resistance R4 of the current detector 46 is increased. As the drop value increases, the voltage applied to the inverting terminal (-) side of the second comparator CP2 becomes higher than the voltage applied to the non-inverting terminal (+) side, thereby outputting a low level voltage from the second comparator CP2. .

Accordingly, the power supply voltage Vcc applied through the resistor R9 is lowered to the ground level by the output of the second comparator CP2, thereby outputting the low level abnormal signal through the abnormal signal output terminal FAIL. . Then, the output of the AND gate AND1 is lowered to the low level, so that the power supply voltage Vcc flows to the output terminal side of the AND gate AND1 through the coil of the relay RY1, whereby the relay RY1 is turned off and the amplifier As the operating power supplied to the 43 is cut off, the malfunction state of the amplifier 43 is prevented.

Therefore, according to the above embodiment, when an abnormality occurs in the operating power applied to the amplifier 43, the operating power to the amplifier 43 is cut off and the abnormal state signal is output to the outside. The abnormal state can be easily recognized, and the circuit of the subsequent stage can be prevented from being damaged by the abnormal operation of the amplifier 43.

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, when an error occurs in the operating power supply of the amplifier for amplifying the intermediate frequency signal, the satellite communication can cut off the supply of the operating power supply and output an abnormal signal indicating the abnormal state. The reception intermediate frequency distribution device of the system can be realized.

Claims (2)

Attenuation means for attenuating the input intermediate frequency signal to a predetermined level, amplifying means for amplifying the signal attenuated by the attenuation means, and distributing the intermediate frequency signal amplified by the amplifying means into a plurality of intermediate frequency signals. In the receiving intermediate frequency distribution apparatus of the satellite communication system comprising a distribution means for outputting by means of: resistance means provided in the power supply line to the amplification means, by comparing the voltage value between both ends of the resistance means by the resistance means First comparing means for detecting that the voltage drop value is less than or equal to the first value, second comparing means for detecting that the voltage drop value of the resistance means is greater than or equal to the second value greater than the first value by comparing the voltage values between both ends of the resistance means; A switch for interrupting the supply of operating power applied to the amplifying means according to the output levels of the first and second comparing means It means for reception of the satellite communication system, characterized in that configured to include the intermediate frequency distribution unit. 2. The abnormal signal output according to claim 1, wherein when the voltage drop value of the resistance means is detected by the first and second comparing means to be less than the first value or more than the second value, an abnormal signal outputting an abnormal signal indicating that the power supply is abnormal. A receiving intermediate frequency distribution apparatus for a satellite communication system, characterized in that it further comprises a means.