KR19990057171A - Monitoring and control method of center fish in phaser - Google Patents

Abstract

The center PCCB in the pager sat and a control method thereof, the center PCCB receives the status of the base station transmitted by the base station controller, collects the status information of each base station input from each base station to send to the master PCCB, and conversely It transmits various commands inputted from PCCB to each base station, and plays a role of media for control, management and communication between network management system and base station. Center PCCB is in charge of 16 base stations and checks the status and responds accordingly. Sends the master PCCB to the network management system, receives the control command from the network management system, and transmits the control command to the corresponding base station.

Description

Monitoring and control method of center fish in phaser

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pager system, and more particularly, to a center fish and a method of controlling the same in a pager sat for efficiently operating communication between a central station and a terminal station in a wireless call data satellite transmission system using a green light satellite.

In general, a radio call data satellite transmission system is a system for transmitting radio call data through a satellite, and is a one-way data transmission system in which a path between base stations is replaced by a link using a satellite in a conventional leased line in a TDX-PS.

1 is a block diagram of a general radio call data satellite transmission system.

As shown therein, the central station 10 receives the radio call signal and modulates the radio call signal to the satellite; The base station 10 is composed of a plurality of base stations 30 for receiving and restoring radio call signals transmitted from satellites.

The central station 10 of the radio call data satellite transmission system includes a subscriber matching unit (PCIB) for converting an analog paging signal of an exchange into a digital; A channel card (QSP, Quad Synchronous Processor) 13 for synchronizing the clocks of the channel I / O data of the subscriber matching unit 11 and compensating for the deviation between the system clock and the reception clock; A multiplexer 12 coupled to multiplex the signals of the digitally switched exchanges with an interlink (ILC, Intermachine Link Module) 14 to process data between the channel and the intermachine link; A modulator (15) for modulating the baseband signal input from the multiplexer (12) to output a signal of an intermediate frequency band; A radio frequency transmitter (RF) 16 for transmitting an intermediate frequency band signal input from the modulator 15 to a satellite as a high frequency signal; A network control unit (NCL) connected to the multiplexer 12 to perform control of the multiplexer 12; It is connected to the subscriber matching section 11, the modulating section 15, the high frequency transmitting section 16 and the network control section 17, and is responsible for the respective control, and periodically polling the state of each device Local PCCB (18) to transmit to the master PCCB 19, the control information transmitted from the Network Management System (NMS, Network 20) to each device of the central station 10 (Paging Central Control Block) (18) Wow; It is connected to the local PCCB 18 and collects the state information of the terminal station collected by the base station control unit 38 of the base station 30 as well as each device of the central station 10 to transmit to the network management unit 20. A master PCCB 19; A center PCCB (20) connected to the master PCCB (19) for performing communication between the central station (10) and the base station (30); A modem 21 for transmitting / receiving data to / from a base station connected by a dedicated line according to a communication execution command of the center PCCB 20; Connected to the master PCCB 19, it is composed of a network management unit 22 for managing the configuration and status of the entire radio call data satellite transmission system.

In addition, the base station 30 of the radio call data satellite transmission system, the high-frequency receiver 31 for low-noise amplifying the signal received from the satellite and converts it into an intermediate frequency signal; A demodulator (32) for restoring a signal output from the high frequency receiver (31) to an original signal; An interlink 34 connected to the demodulator 32 to demultiplex data from a signal demodulated by the demodulator 32, and a link between the interlink 34 to compensate for a deviation between a system clock and a reception clock; A demultiplexer 33 having a channel card 35 for demultiplexing a signal transmitted from a satellite into a digital signal; A Paging Remote Interface Block (PRIB) 36 for restoring digital data of the demultiplexer 33 to an FSK analog paging signal; A network controller 37 connected to the demultiplexer 33 to control the demultiplexer 33; The demodulator 32, the demultiplexer 33, and the subscriber subscriber matching unit 36 periodically collect states and transmit them to the center PCCB unit 20 through the modem 21 of the central station 10. And a base station controller (PRCB, Paging Remote Control Block) 38 that controls the devices of the base station 30 according to the command of the network manager 22.

The operation of the general radio call data satellite transmission system configured as described above is as follows.

First, the central station 10 of the paging data satellite transmission system converts the analog paging signal of the paging data exchanger into digital in the subscriber matching unit 11 and inputs it to the multiplexer 12. Then, the multiplexer 12 synchronizes the clocks of the channel input / output data in the channel card 13, compensates for the deviation between the system clock and the reception clock, and then, in the interlink 14, between the channel module and the intermachine link. Will process the data. By encoding and modulating with binary phase shift keying (BPSK), an intermediate frequency (IF) signal having a bandwidth of 250 KHz / 500 KHz is transmitted to the high frequency transmitter 16. Then, the high frequency transmitter 16 inputs the output signal of the modulator 15 to the attenuator to be adjusted by the uplink power control (UPC) and the beacon receiver, and performs the redundancy control to be transmitted to the outdoors. The signal transmitted to the outdoors is distributed by the outdoor power divider and transmitted to the transmitter. The transmitter is then amplified to a predetermined uplink frequency and power level, and the signal from the outdoor transmitter selected by the waveguide switch is connected to the feeder of the antenna to emit radio waves to the satellite.

Accordingly, the plurality of base stations 30 of the radio call data satellite transmission system amplify the small signal received from the satellite by the high frequency receiver 31 to low noise and convert the small signal into an IF signal. The demodulator 33 then restores the original data by BPSK demodulation, descrambling, discrete decoding, and R = 1/2 k = 7 Viterbi decoding of the signal output from the high frequency receiver 31. The restored data is demultiplexed in the interlink 34 of the demultiplexer 33 and transferred to the channel card 35. Then, the subscriber register matching unit 36 restores the digital data of the channel card 35 to the analog paging signal and transmits the radio pager through the transmitter so that the user's radio pager can receive the radio page signal.

The center PCCB 20 collects the terminal station state data transmitted by the base station control unit 38 and outputs it to the master PCCB 19. In contrast, the center PCCB 20 transmits various commands inputted from the master PCCB 19 to each terminal station to manage the network. It acts as an intermediary for control, management and communication between the system 22 and the terminal stations. The center PCCB 20 has 15 pieces, and one center control unit 20 can handle up to 240 terminal stations in charge of 16 terminal stations, and check the state of these 240 terminal stations. The appropriate response is output to the master PCCB 19 to be forwarded to the network management system 22. It also has a routing function of receiving a control command from the network management system 22 and transmitting the control command to a corresponding terminal station.

The center PCCB 20 has a system interface for communicating with the network management system 22 and a modem interface for communicating with the base station controller 38 of the base station 30 through the master PCCB 19.

As described above, since the center PCCB (PagerSat Central Control Block) of the central station transmits and receives commands and data between a plurality of base stations and a network management system, there is a problem of efficiently managing data transmitted and received therebetween.

The present invention has been proposed to solve the above problems,

An object of the present invention is to provide a center PCCB and a method of controlling the same in a phaser system that efficiently implements monitoring and control of communication between a central station and a terminal station in a wireless data satellite transmission earth station system. To provide.

In order to achieve the above object, the center PCCB of the present invention receives a state of a base station transmitted by a base station control unit, collects state information of each base station inputted from each base station, sends it to the master PCCB, and, on the contrary, various commands input from the master PCCB. It plays the role of media of control, management and communication between network management system and base station by delivering to each base station.The center PCCB is in charge of 16 base stations and checks the status and sends the appropriate response to the master PCCB. Notifies the management system, receives the control command from the network management system and transmits the control command to the base station.

1 is a block diagram showing the configuration of a monitoring and control unit of a radio call satellite transmission system.

2 is an external interface block diagram of a center PCCB.

3 is a block diagram showing the configuration of a center PCCB according to the present invention.

4 is a block diagram showing the configuration of the loopback selection unit according to the present invention. 5 is a block diagram showing the internal structure of a central processing unit constituting a center PCCB according to the present invention.

6 is a flow chart showing a software timer interrupt routine according to the present invention.

7 is a configuration diagram of a software buffer and a pointer of the center PCCB.

8 is a flow chart showing an unresponsive decision routine.

9 (A) and (B) are flowcharts showing the main routine of the control software of the center PCCB according to the present invention.

<Explanation of symbols for main parts of the drawings>

41 .. Central treatment unit 42 .. Address latch

43..Input / output processing unit 44 .... Clock dispenser

45 .... address decoder 46 .... timer

47 ... Pyrom 48 ... Rem

49 ... Watchdog 50 ... latch

51 .... Serial input / output 52 .... loopback selector

53 .... TTL converter 54 .... RS232 input

55 .... RS232 output part 57 .... Modem check part

Hereinafter, the operation and the effect of the embodiment according to the technical idea of the present invention will be described in detail.

2 shows an external interface block diagram of the center PCCB.

In the phaser system, the center PCCB 20 of the central station 10 receives a base station state transmitted by the base station controller 38 through a modem interface, collects state information of each base station input from each base station, and collects the master PCCB ( 19), and, conversely, various commands input from the master PCCB 19 are transmitted to each base station through a modem interface, thereby serving as a medium for control, management, and communication between the network management system 22 and the base station. One center PCCB 20 is in charge of 16 base stations to check the status of the 16 base stations to send a response appropriate to the status to the master PCCB 19 to inform the network management system 22. It also has a routing function of receiving a control command from the network management system 22 and transmitting the control command to a corresponding base station.

As shown in FIG. 2, the interface between the center PCCB 20 and the master PCCB 19 is RS485 (RS422), asynchronous, 19,200 bps, and the modem interface between the center PCCB 20 and the base station controller 38. CCITT V.26 A / B, asynchronous, 2,400bps is to communicate with the base station at 2,400bps and the master PCCB (19) at 19,200bps. Since the system interface uses a single bus line, when several center PCCBs 20 communicate with the master PCCB 19, the command sent from the master PCCB 19 is received by all the center PCCs 20 and the center PCCBs. (20) should be able to determine the validity of the command for this, and when sending a response from the center PCCB (20) to the master PCCB (19) at the same time a conflict may occur if one center PCCB using RS485 Only 20 transmits.

3 is a block diagram showing the configuration of the center PCCB according to the present invention. In the radio call data satellite transmission system, the center PCCB 20 includes a central processing unit 41 for controlling the overall operation of the center PCCB 20, as shown in FIG. An address latch unit 42 connected to the central processing unit 41 to latch an address; An input / output processor (43) connected to the address latch unit (42) to process input / output with a bidirectional transmitter / receiver; A clock divider 44 for dividing the clock of the central processing unit 41 by two; A decoder (45) connected to the central processing unit (41) to perform decoding and generate an interrupt decode; A timer (46) for providing a timer function to the central processing unit (41); A programmable read only memory (PROM) 47 for storing a program to be executed in the central processing unit 41; A random access memory (RAM) 48 for storing data processed by the central processing unit 41; A watch dog (49) for monitoring the congestion state of the central processing unit (41); A latch unit 50 connected to the central processing unit 41 for temporarily holding or storing data; A serial communication unit (51) for performing serial communication between the master PCCB (19) and the base station controller (38) under the control of the central processing unit (41); A loopback selector 52 connected to the serial communication unit 51 to perform a loopback test according to loopback selection; A TTL converter 53 for performing TTL (Transistor Transistor Logic) conversion between the serial communication unit 51 and the base station controller 38; An RS232 input / output unit (54) (55) for performing an RS-232 interface between the loopback selector (52) and the base station controller (38); The TTL converter 53 and the RS232 input / output units 54 and 55 are connected to the base station controller 38 through a modem to transmit data between the center PCCB 20 and the base station controller 38. A connecting portion 56; And a modem mounting checking unit 57 for checking whether or not a modem is mounted between the center PCCB 20 and the base station controller 38.

4 is a block diagram showing the configuration of the loopback selection unit according to the present invention. As shown in FIG. 4, a control latch unit 61 for determining whether to perform loopback according to a loopback address control signal (LACS) which is a loopback address setting signal symbol when setting loopback; The first to fourth selectors 62 to 65 test loopbacks of the signals input from the serial communication unit 51 and the RS232 input unit 54 according to the control signal of the control latch unit 61.

The central processing unit 41 controls each unit, receives a 11.0592 MHz clock signal from the crystal oscillator (XTAL), generates a 19,200 Hz data clock to control the serial input / output port, and a data bus (D0) for inputting / outputting data. -D7), an address bus A0-A15 for outputting an address signal, a control bus / RD, / WR for outputting a control signal, and a clock signal are output to each unit. The control mode of the serial input / output port uses the standard asynchronous communication mode of start (1 bit) + data (8 bit) + stop (1 bit).

The serial input / output unit 51 is a device for inputting / outputting data between an external device and the central processing unit 41. The serial input / output unit 51 is composed of 17 input / output ports and includes eight 8274 chips and the central processing unit ( Use the serial port of 41). The address arrangement of the center PCCB 20 uses the PAL16L8 chip, and the ROM area (0000H-7FFFH: 32 Kbytes), the I / O area (8000H-8FFFH: 4Kbytes), and the RAM (9000H-FFFFH: 28 Kbytes) To distribute. The address decoder 45 receives the address signals A2-A5 from the CPU 41 and generates 16 chip select signals to select each unit.

The modem mounting confirmation unit 57 outputs the mounting signals INSCH0-INSCH15 output from the modem to the ports P0 and P1 of the central processing unit 41. The central processing unit 41 checks ports P0 and P1 to check the mounting / dismounting of the modem. For the 16 modems (M0-M15), '1' when mounted and '0' when mounted are stored bit by bit.

4 is a block diagram showing the configuration of the loopback selection unit according to the present invention.

The loopback selector 52 may include a control latch unit 61 for determining whether to perform loopback according to a loopback address control signal (LACS) which is a loopback address setting signal symbol when setting the loopback; The first to fourth selectors 62 to 65 test loopbacks of the signals input from the serial communication unit 51 and the RS232 input unit 54 according to the control signal of the control latch unit 61.

The loopback selector 52 selects one serial input / output port at the time of loopback selection so that four serial input / output ports enter the loopback state, and a signal output from the serial input / output port is input again. When the loopback is not selected, a signal output from the base station controller 38 of the base station is input.

5 is a block diagram showing the internal structure of the central processing unit 41 constituting the center PCCB according to the present invention.

The main routine means unit 66 initializes, outputs data to the base station controller 38 and processes data input from the base station controller 38. The interrupt service means 67 inputs / outputs data to the master PCCB 19, receives data from the base station controller 38, and stores the data in the database means 68. The database means 68 stores the data input from the main routine means 66 and the interrupt service means 67 and outputs the stored data to the main routine means 66 and the interrupt service means 67. The calculation processing unit 69 receives a command from the master PCCB 19, receives data from each unit, and processes the command.

Fig. 6 is a flow chart showing the software timer interrupt routine according to the present invention, and Fig. 7 shows the configuration of the software buffer and pointer of the center PCCB.

The basic operation of the center PCCB 20 has a polling function and a control function, and when a polling command is input to the center PCCB 20 from the master PCCB 19 when the polling function is performed, as shown in FIG. 6. The software timer interrupt routine is executed to store the data read from the master PCCB 19 in the buffer rxbuf_m in step S61, accept the polling instructions by one byte, and calculate a checksum. If all polling commands are accepted (the polling command consists of, for example, 4 bytes), the checksum sent from the master PCCB 19 is compared with the checksum calculated from the center PCCB 20. If the checksum is correct, the sequence of the command is determined using the sequence variable siseq_m, and flags (flag_m and flag_m1) are set to match the type of the command. After setting the channel of the flag according to the number of channels sent in polling, in step S62, when the center PCCB 20 takes 19,200 bps interrupt routine 8 times to exchange data with each base station controller 38 at 2,400 bps. Each time, the data read by one byte from the base station controller 38 is stored in each receiving buffer rxbuf_0. The first interrupt receives 1 byte from the # 0,1 base station controller and the second interrupt receives 1 byte from the # 2,3 base station controller. The 8th interrupt receives 1 byte from the # 14,15 base station controller and the 9th interrupt receives 1 byte from the # 0,1 base station controller. The corresponding base station controllers 38 # 0,38 # 1, .. 1 byte if the status of the serial port (# 0) and 8274 serial input / output ports (# 1 to # 15) connected to the., 38 # 15 is received character enabled (if there is data sent from the base international fisherman 38). It receives each of them and stores them in the receiving buffer (rcbuf_0) and determines whether it is a polling response or a control response using a sequence variable siseq_0 to set a flag_0. The center PCCB 20 has 16 input buffers (rxbuf_0 + 0, rxbuf_0 + 1, ..., rxbuf_0 + 15) and 16 output buffers (txbuf_0 + 0, txbuf_0 + 1,) to communicate with the base station controller 38. ..., txbuf_0 + 15) and pointers to each buffer.

In step S63, if there is data to be sent from the transmission buffer (txbuf_m) to the master PCCB 19, the contents of the transmission buffer are transmitted by one byte. If there is no data to be sent, the polling response data stored in the rmt buffer is transmitted by one byte to the master PCCB (19). To send).

When performing a control function, if a control command for the center PCCB 20 is input from the master PCCB 19, an interrupt routine is executed to receive the control command by 1 byte and calculate a checksum. Accepting all control commands compares the checksum sent and the checksum calculated by the center. If the checksum is correct, in the case of a control command to be transmitted to the base station, the value is stored in the transmission buffer (tx74buf), and in the case of the command to the center PCCB 20, a flag (flag_m1) indicating the state of the center PCCB 20 is set. do. Specifies a path for transmitting a control command for a device to be transmitted from the main routine to the base station. At this time, the data of the transmission buffer tx74buf is stored in the corresponding base station output buffer txbuf_0.

In the main routine, if there is no response from the base station or if the response is properly received, if there is data to be sent to the output buffer of each base station, one byte is sequentially transmitted to the corresponding base station.

The center PCCB 20 may transmit a response to the master PCCB 19 only when there is a polling command input from the master PCCB 19. That is, the center PCCB 20 can send a response or receive a control command by checking its own input / output status only when polling is performed periodically (continuously). Since the center PCCB 20 receives the state information of the base station from the 16 base station controllers 38 and collects the state information of the base station, when the state data input request is received from the master PCCB 19, the center PCCB 20 must set priority and transmit important data. The highest priority is a case in which no response from each base station (when communication is suddenly disconnected) occurs. In this case, the address of the base station is transmitted as a response. Next, when a state change of the base station or center PCCB 20 occurs, the changed state information of the base station or center PCCB 20 is transmitted. If there is no state change, if no communication with any base station, and sends the status information of the center PCC 20 itself, if not communicating with several base stations, the status information of the center PCC 20 is sequentially Send it to

(1) Non-response base station check

The communication status between the base station and the center PCCB 20 of the central station can be seen in three ways. It can be divided into when the communication is not working and when the communication is in progress (in this case, the response is received correctly and the checksum is received the wrong response). Base station no response refers to a case in which communication is normally performed and a response is not received from the base station at any moment. To check this, the center PCCB 20 uses the base station input checkin and the no response checkin. When the base station input checkin receives a correct response up to the checksum value, the port setting value for the base station is set to 0, the corresponding address is set to 0 for the base station, and the corresponding address is assigned to the base station. It is recognized as a valid address. The non-response check routine checks whether the response is received correctly or not, and sends a control command to accept the base station input to specify the condition.

8 is a flow chart showing an unresponsive decision routine.

In step S81, the checksum is checked to determine whether a response has been properly received from the base station. If it is properly received, the process proceeds to step S83. If not properly received, it is determined whether a response is received in step S82. If a response is being received, the process returns to the main routine, and if it is not receiving a response, the input / output condition is specified in step S83. In step S84, it is determined whether there is content to be sent to the base station output buffer. If there is a content to be sent, the process returns to the main routine, and if there is no control command to be transmitted to the base station, the condition is specified to send a polling command in step S85 and the number of polling counts is reduced. In step S86, it is determined whether the polling count value is "0". If the polling count value is not "0", the process returns to the main routine, and if the polling count value is "0", it is determined in step S87 whether it is equal to each base station setting value. If the polling count is reduced to the same state as before until 0, then the base station is determined to be non-responsive and returned to the main routine. If the polling count value is "0", it is determined whether it is equal to each base station setting value in step S87. In the same case, the process returns to the main routine, and if not, the data is updated in step S88, and the process returns to the main routine.

(2) Base station status change check

When the base station input check routine receives an input, it compares whether it is the same as the previously input value, and if it is wrong, changes to the base station are stored. If a change to the base station occurs in the pass check routine, the state of the changed base station is first transmitted to the master PCCB 19, and if there is no change, the states of the base station and center PCCB 20 being communicated are sequentially transmitted. When no base station is communicating, only the state of the center PCC 20 is transmitted to the master PCCB 19.

(3) Routing of control command to each base station

When the center PCCB 20 is initially powered on, the address of the base station connected with the center PCCB 20 may not be known until the polling response is received from the base station. However, whenever a polling response is received from a base station connected to an SIO port, the ports (PRCBs [0]-[15]) for each port are reassigned. When sending a control command from the master PCCB 19 to the base station based on this address value, the center PCCB 20 checks whether the address of the sent base station is the base station connected with the base station and stores it in the corresponding output buffer and stores the corresponding base station at the output port. To be sent to. In addition, when the address is broadcast, the same command is stored in all base station output buffers to send control commands to the base station. This method is flexible regardless of which base station is connected to the center PCCB 20, and no response is received from the base station in the middle.

(4) Serial input / output port test method:

The center PCCB 20 communicates with the sixteen base station controllers 38. If any one communication port fails, the center PCCB 20 may not communicate with the corresponding base station. At this time, the test is performed to check whether the communication port of the center PCC 20 is a problem. That is, when the input is received using the loopback selection circuit, the output from the center PCCB 20 is accepted again or a response from the base station is received as the input. If the control command is sent to the serial I / O port in the loopback state, the control command is output to the corresponding terminal station, but the output again has a problem with the serial I / O port. In the loopback state, since the polling command to the base station is meaningless, the polling command is not transmitted to the terminal station.

9A and 9B are flowcharts showing the main routine of the control software of the center PCCB according to the present invention.

In step S401, the initialization process is performed, and in step S402, a display indicator (e.g., a light emitting diode (LED)) showing whether the device is operating is turned on / off every second, and the power state is checked. In step S403, after communication with the base station, it is determined whether there is a change to the 16 base stations and the center PCCB 20 by determining whether the change check register that stores the number value input from the base station is the initial value. If it is a value, in step S404, a subroutine for checking the state change of the base station controller 38 and the center PCCB 20 is executed, and the flow proceeds to step S405. Steps S405 to S407, which are routines for sending polling commands or control commands, are performed.

In step S405, it is determined whether channel 0 has been transmitted. If transmission is complete, the flow advances to step S408. If transmission is not completed, it is determined in step S406 whether the serial port can be transmitted. If the serial port is not transmittable, the flow advances to step S408. If the serial port is transmittable, the polling command is transmitted in step S407 according to the transmission sequence, and the control command is read from the transmission buffer and transmitted. In step S408, the routine (step S405 to step S407) is performed from channel 1 to channel 15.

In step S410, it is determined whether the data of the state storage buffer has changed. If the data of the state storage buffer has not changed, in step S411, the routine is selected according to the lower four bits of the state storage buffer. Whenever the interrupt service routine is called 16 times in step S411, each base station control section 3713 performs a routine for checking whether there is no response, and proceeds to step S413.

In step S410, if the data in the state storage buffer is changed, in step S413, port 0 and port 1 are checked to determine whether or not the modem is mounted according to the contents. Each bit 0-15 of the modem check buffer consisting of 2 bytes is stored with "1" when mounted and "0" when mounted. In step S414, it is determined whether a control command to be transmitted to the base station controller 38 exists in the output buffer. If the control command is in the output buffer, it is determined in step S415 whether the command stored in the output buffer is a broadcast control command. In the case of the broadcast control command, the control command stored in the output buffer is transmitted to all base station controllers 17, ... in step S417. If it is not a broadcast control command, the command stored in the output buffer is transmitted to the base station controller 17.

When the control command to be transmitted is not present in the output buffer in the determination of step S414, it is determined in step S418 whether there is a loopback setting command. If there is no loopback setting command, the process returns to the initialization step, and if there is a loopback setting command, in step S419, a value according to the loopback is set in the buffers PRCBs for storing the addresses of the base station controllers 38.

As described above, according to the present invention, the performance and reliability of the system can be improved by efficiently implementing the monitoring and control of the communication between the central station and the terminal station in the radio call data satellite transmission earth station system.

Claims (9)

In the center PCCB of a system that transmits radio call data via satellite, A central processing unit for controlling overall operation of the center PCCB; An address latch unit connected to the central processing unit to latch an address; An input / output processing unit connected to the address latch unit to process input / output with a bidirectional transmitter / receiver; A serial communication unit for performing serial communication between a master PCCB and a base station control unit under control of the central processing unit; A loopback selector connected to the serial communication unit to perform a loopback test according to loopback selection; A TTL converter for performing TTL (Transistor Transistor Logic) conversion between the serial communication unit and the base station controller; An RS232 input / output unit configured to perform an RS-232 interface between the loopback selector and the base station controller; And a modem mounting checking unit for checking whether the modem is mounted between the center PCCB and the base station controller. According to claim 1, The center PCCB receives the status of the base station transmitted by the base station controller, collects the status information of each base station input from each base station to send to the master PCCB, on the contrary, various commands input from the master PCCB A center fish cake in a pager chart, which serves as a medium for control, management, and communication between a network management system and a base station by transmitting to a base station. The base station of claim 1, wherein the center PCCB is in charge of 16 base stations, checks the state, sends a response corresponding to the state to the master PCCB, and informs the network management system, and receives a control command from the network management system. A center fish ratio in a pager sheet comprising a routing function for transmitting a control command to the system. The interface between the center PCCB and the master PCCB is RS485 (RS422), asynchronous, 19,200 bps, and the modem interface between the center PCCB and the base station controller is CCITT V.26 A / B, asynchronous, 2,400. bps, which communicates with the base station at 2,400 bps and the master PCCB at 19,200 bps. The method of claim 1, wherein the loopback selector comprises: a control latch unit configured to determine whether to perform loopback according to a loopback address control signal (LACS) which is a loopback address setting signal symbol when setting the loopback; And a first to fourth selectors (62 to 65) for loopback of signals input from the serial communication unit and the RS232 input unit according to the control signal of the control latch unit. The method of claim 1, wherein the loopback selector selects one serial input / output port when the loopback is selected so that four serial input / output ports are looped back, and signals output from the serial input / output port are input again. , When the loopback is not selected, the center fish ratio of the phaser map, characterized in that the signal output from the base station control unit of the base station is input. In the control method of the center PCCB of the system for transmitting the radio call data through the satellite, Executing a software timer interrupt routine when a polling command for the center PCCB is input from the master PCCB; Storing data read by one byte from the base station controller in each receiving buffer (rxbuf_0) every time the 19,200 bps interrupt routine takes 8 times to exchange data with each base station controller at 2,400 bps; Transmitting the contents of the transmission buffer by one byte if there is data to be sent to the master PCCB from the transmission buffer (txbuf_m), and transmitting polling response data stored in the rmt buffer to the master PCCB by one byte if there is no data to send Control method of center fish ratio in phaser satin. 8. The method of claim 7, wherein the software timer interrupt routine comprises: storing data read from the master PCCB in a buffer (rxbuf_m), receiving a polling command by one byte, and calculating a checksum; Comparing the checksums sent from the master PCCB with the checksums calculated by the center PCCB when all of the polling commands are accepted; If the checksum is correct, determining a form of an instruction in sequence using a sequence variable siseq_m and setting flags (flag_m, flag_m1) according to the form of the instruction; And setting the channel of the flag according to the number of channels sent in polling. In the control method of the center PCCB of the system that transmits the radio call data through the satellite, perform the initialization process, turn on / off the monitor indicator showing whether the device is operating every second, and check the power status A first step of doing; A second step of determining whether there is a change to 16 base stations and a center PCCB by determining whether the change check register storing the number value input from the base station is an initial value after communicating with the base station; A third step of executing a subroutine for checking a state change of the base station controller and the center PCCB at an initial value, and transmitting a polling command or a control command to 16 base station controllers if not at the initial value; A fourth step of transmitting a polling command from channel 0 to channel 15 according to a transmission sequence, and reading and transmitting a control command from a transmission buffer; It is determined whether the data of the state storage buffer is changed. If the data of the state storage buffer is not changed, the routine is selected according to the lower 4 bits of the state storage buffer, and each base station control unit is executed each time the interrupt service routine is called 16 times. A fifth step of performing a routine to check whether the response is no response; In the fifth step, when the data of the state storage buffer is changed, the port 0 and the port 1 are checked to determine whether the modem is mounted according to the contents, and whether the control buffer to be transmitted to the base station controller is in the output buffer. And a sixth step of transmitting the data to the base station controller.