KR960015852B1 - Synchronization detecting method in base - Google Patents

Abstract

The method improves the communication performance in a satellite system by interfacing multi-user mobile stations with a central station to transceive precise informations, and comprises the steps of: extracting an id bit to read a registered id from a dip switch of the terminal; requesting any output type signal from the central station at "turn on" of the terminal to end the step; detecting the output type signal for the signal to check any FIT synch signal to repeat this step for no FIT synch signals; detecting the id among the FIT synch signal for any FIT synch signal; checking the detected id with the setup id to repeat the output type signal-detecting step for no match otherwise tracking the id bit to synchronize it.

Description

Micro terminal earth station synchronization detection method by pit signal extraction

1 is a block diagram of a miniature terminal earth station system for the present invention.

2 is a diagram illustrating a configuration of a pit signal.

3 is a block diagram of a pit signal extraction device of the present invention, a miniature terminal earth station system.

4 is a signal timing diagram for FIG.

5 is an operational flowchart of a method of finding an identifier bit in a pit signal extraction method of a micro terminal earth station system according to the present invention.

6 is an operation flowchart of a method of finding timing synchronization in a pit signal extraction method of the micro terminal earth station system of the present invention.

* Explanation of symbols for main parts of the drawings

1: Clock divider 2: RAM

3: ROM 4: Control Logic

10: central station 20: terminal station

30: network management system 40: large computer

50: user terminal

The present invention relates to a synchronization detection method of a micro terminal earth station system (hereinafter referred to as VAST System) which enables accurate information transmission by interconnecting terminals of a plurality of user terminal stations and a central station large computer using satellites. In particular, in order to synchronize the communication between the central station and the terminal station, the pit signal extraction is used to extract three subchannels (Framming, Identification, Timing, or FIT) signals made by the central station and use them as system synchronization. The present invention relates to a miniature terminal earth station synchronous detection method.

As shown in FIG. 1, the micro terminal earth station (VAST) system for the present invention includes a central station 10 for controlling all networks using satellites; Various terminal stations 20 communicating through the central station 10; A network management system 30 for controlling communication between the terminal station 20 and the central station 10; A large computer 40 storing information for providing all services; It consists of a user terminal 50.

Data from the central station 10 to the terminal station 20 is sent through one or more consecutive carriers, called outbound data, and on the contrary, several terminal stations 20 have one carrier. The data is sent to the central station 10 by sharing the data, which is called inbound data.

Various channel access protocols are used to share one input type carrier with multiple terminal stations 20. The most popular ones are random-aloha and slotted-aloha. Aloha).

The bit stream sent from the central station 10 has two different types of information. The first is a data packet exchanged between the central station 10 and the terminal station 20, and one outbound carrier is a plurality of terminal stations. It has a number of packets sent to each packet, and each packet has the appropriate address information so that a particular terminal station 20 can accept it.

The second type of information is the synchronization information for the transmitting device of the terminal station 20. This signal is called a FIT defined in the present invention, which is generated by the central station 10 modulator and transmitted to the terminal station 20 receiving device. Is extracted and used for synchronization for the transmission of the terminal station 20.

As shown in FIG. 2, the FIT signal consists of a total of 9 bits of " 11111111 " in one slot. The biggest purpose of this framing bit is the terminal station. It is used to separate the FIT information and data packets from the bit stream input by.

Identification bits consist of 9 bits per slot, and are used to find only outbound broadcast waves used by a specific terminal station 20 among the outbound carriers.

A pit signal extracting device for extracting the pit channel as shown in FIG. 3, comprising: a clock divider 1 for dividing an input clock; A RAM 2 for receiving and storing a value divided by the clock divider 1; A ROM 3 for outputting an output value of the RAM 2 and a state value stored by the received data; It consists of a control logic section 4 which is operated by the output of this ROM 3 and extracts pit data.

Referring to the operation and effects of the present invention configured as described above in detail.

The received data Rx-Data received from the central station 10 is 66.666 [kbps].

The clock CLK of 66.666 [KHz] extracted from the decode of the terminal station 20 is divided by 75 divider 1A of the clock divider 1, and the divided frequency is 66.666 / 75 = 0.888KHz. , Period is 1.13ms. The divided output becomes the input addresses A ₀ -A ₇ of the RAM 2.

On the other hand, when the FIT signal is generated at the central station 10, 64 [kbps] data and 2.666 [kbps] pit signal are inserted as shown in FIG.

That is, in the framing bit 0 (F0) to the bit 1 (F1) 75 (F ₀ and I ₀ is because in 25-bit (F ₀ to I ₀ immediately before the data only has 24-bit a) in I ₀ T ₀ 25 bits, Since FI is also 25 bits in T ₀ , which is 75 bits in total), 75 bits (1A) are required to extract the framing (F) bits, and the identifier (I) bit and the timing (T) bit are also the same.

The output of the 25th frequency divider 1B is in conjunction with the pit synchronizing signal as shown in FIG. 4A, which is output from the control logic section 4, and the pit data as shown in FIG. Is provided as a clock of the pit clock.

Here, the clock of each pit signal is

66.666 [KHz] ÷ 75 = 0.888 [KHz]

And the pit overall clock is

0.888 [KHz] * 3 = 2.666 [KHz].

The coefficient of the clock divider 1 is incremented every received data bit, and the RAM 2 is re-stored by the 75-bit value output from the clock divider 1 and by the ROM 3. It also contains the Rx-Data value.

The ROM 3 stores a constant value which is part information of a specific terminal station 20 for each address, for comparison with each received data.

When the batt information of the received data Rx-Data and the pit information F of the stored ROM 3 coincide, the terminal station 20 synchronizes the carrier and recognizes the received data as its own.

The ROM 3 synchronizes the received data Rx-Data and stores it back into the RAM 2 before the address counter is incremented for the next state, which becomes the address of the new ROM 3.

Once the carrier is synchronized and the received data (Rx-Data) is recognized as its own, this data goes to the control logic section 4.

This control logic section 4 is extracted by the 25 divider 1B of the clock divider 1 as a synchronization block of the pit channel.

When the last bit 8 (F8) of the framing pattern occurs in the received data (Rx-Data), the ROM (3) outputs data (D0-D7) and through the control logic section 4 (a) of FIG. Output the same FIT-Sync signal.

As shown in (b) of FIG. 4, the pit data FIT-Data is countered every 25 data bits by the 25 divider 1B of the clock divider 1 so that the identifier (1) bit is used. And timing (T) bits are extracted from the received data (Rx-Data).

On the other hand, the pit clock FIT-CLK of the control logic section 4 is used to extract each pit signal by 25 division of the received clock as shown in FIG.

The operation sequence of searching for the identifier bit during the operation may include: reading the registered self identifier number from the dip switch of the terminal station 20 in advance (A1); The central station 10 serves all the terminal stations 20 24 hours a day, 7 days a week, and the terminal station 20 communicates whenever necessary, so that any terminal station 20 is turned on first. (A2) asking whether there is an output form signal to determine whether there is a synchronization signal among the output form signals; Finding an output type signal if there is an output type signal in step A2, and then determining whether there is a pit synchronization signal among the output type signals, and searching for the output type signal again when there is no bit synchronization signal; Finding an identifier bit in the pit synchronization signal when the pit synchronization signal is present in the step A3; Determining whether the found identifier bit is the same as the identifier preset in the specific terminal station 20, and if the identifier is different, finding the output type signal again (A5); If the identifiers are the same, step A6 is performed in order to track and synchronize the self identifier bits.

Timing bits also consist of nine bits per slot, which are used to synchronize the slots for the entire network station 20 for Slotted-Aloha. The timing bit information sequentially increases from 00 to 99, and repeats in one super frame, that is, 100 slot cycles.

In the case of Slotted-Aloha, each terminal station 20 is assigned a slot number accessible from the network management system 30 of the central station 10 through an initialization process.

Assuming that a specific terminal station 20 has been allocated 1, 50, 80 slots from the network management system 30, the timing synchronization process for the terminal station 20 is shown in FIG. (20) receives a slot from the network management system 30 and transmits data to the central station 10 when the timing coincides with the slot so as to receive a specific slot number from the network management system 30 (B1). Wow ; (B2) having a timing bit which is sequentially incremented from 0 to 99 after being assigned a slot number and is repeated every 100 slots; Since the timing bits are 9 bits per slot, storing the timing bits of 9 bits (B3); After storing the timing bits, judging whether there is any transmission data from the central station 10, and if there is no transmission data, allocating the timing bits again (B4); If there is transmission data, the terminal station 20 compares the slot number allocated from the network management system 30 with the timing bit, determines whether the timing bit matches, and if the slot number and the timing bit do not coincide, allocates timing bits again. (B5) and; Processing data at the beginning of the next frame information of the synchronization information repeated with F. I. T when the slot number and timing bit coincide; It judges whether or not the data processing is completed. If the data processing is not finished, the data is processed until the data processing is completed. If the data processing is completed, a new timing bit, that is, an increased timing number, is stored in the ROM 3 for the next data transmission. The operation is sequentially performed at step B7 of storing.

Therefore, since all terminal stations 20 belonging to one output form have the same specific slot number at the same time, synchronization with respect to the slot is possible.

As described in detail above, the present invention can improve communication performance by interconnecting a plurality of user terminals and a central station in a system using satellites, thereby enabling accurate information transfer, and a user's confidence in the system. There is an effect to improve.

Claims (3)

In order to synchronize the synchronization between the central station and the terminal station in order to extract the synchronization signal from the data stream on a data packet basis, the central station 10 generates three subchannel FIT signals and transmits the data to the terminal station together with the data. Miniature terminal earth station by pit extraction, characterized in that the station finds synchronization by extracting the Framing, I, and Timing bit signals sequentially and repeatedly over a certain data period. Synchronous Detection Method. The method of claim 1, wherein the order of finding the identifier bits during the operation comprises: reading the identifier bits from the dip-switch of the extracting terminal station (20); The central station 10 serves all the terminal stations 20 24 hours a day, 7 days a week, and the terminal station 20 communicates whenever necessary, so that any terminal station 20 is turned on first. (A2) asking whether there is an output form signal to determine whether there is a synchronization signal among the output form signals; If there is an output type signal in step A2, the output type signal is found, and the presence or absence of a pit synchronizing signal is determined among the output type signals. Determining the presence or absence of a signal and finding an output type signal again when there is no pit synchronization signal (A3); Finding an identifier bit of the pit synchronization signal if there is a pit synchronization signal (A4); Determining whether the found identifier bit is the same as the identification set in advance in the specific terminal station 200, and if the identifier is different, finding the output type signal again (A5); And if the identifiers are the same, tracking and synchronizing the magnetic identifier bits (A6) to operate sequentially. The timing bit synchronization process according to claim 1, wherein the timing bit synchronization process is assigned to the terminal station 20 from the network management system 30 to transmit data to the central station 10 when the timing coincides with the slot. Receiving a specific slot number from the network management system 30 for transmission (B1); (B2) having a timing bit which is sequentially incremented from 0 to 99 after being assigned a slot number and is repeated every 100 slots; The timing bits are 9 bits per slot, so storing the timing bits of 9 bits (B3); Determining whether there is any transmission data from the central station 10 after storing the timing bits, and if the transmission data are not present, assigning timing bits again (B4); If there is transmission data, the terminal station 20 compares the slot number allocated from the network management system 30 with the timing bit to determine whether the slot is identical and if the slot number and the timing bit do not coincide, the terminal station 20 receives the timing bit again. (B5); Processing data at the beginning of the next frame information of the synchronization information repeated in F. I. T if the slot number and timing bit coincide; It is judged whether or not the data processing is completed, and when the data processing is finished, a small terminal earth station is operated sequentially by storing a new timing bit (i.e., an increased timing number) in the ROM 3 (B7) for the next data transmission. Synchronous Detection Method.