CN1117224A - Method of and apparatus for sampling fit (framing, identification and timing) signals in the vsat - Google Patents
Method of and apparatus for sampling fit (framing, identification and timing) signals in the vsat Download PDFInfo
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- CN1117224A CN1117224A CN94113353A CN94113353A CN1117224A CN 1117224 A CN1117224 A CN 1117224A CN 94113353 A CN94113353 A CN 94113353A CN 94113353 A CN94113353 A CN 94113353A CN 1117224 A CN1117224 A CN 1117224A
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/204—Multiple access
- H04B7/212—Time-division multiple access [TDMA]
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- Computer Networks & Wireless Communication (AREA)
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- Synchronisation In Digital Transmission Systems (AREA)
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Abstract
The invention relates to a VSAT (Very Small Aperture Terminal) system which uses satellites for sending and receiving data between user terminals of a plurality of data terminals and a large-scale computer of central equipment, in particular to a method and a device, which are used for directly extracting three sub channels from the user terminals, namely, FIT (Framing, Identification and Timing) signal which is generated by the central equipment and using the FIT signal for implementing communication synchronization between the central equipment and the data terminals.
Description
The present invention relates to a kind of VSAT (very small aperture terminal) system, this system can transmit and receive data between the mainframe computer of the user terminal of a plurality of data terminals and central equipment by adopting satellite, and The present invention be more particularly directed to a kind of method and a kind of device, the method and device are used for directly extracting three subchannels from user terminal, the i.e. FIT that produces by central equipment (framing, identification and regularly) signal, and be used for the FIT signal is used for communication synchronization between central equipment and the data terminal.
Existing VSAT system comprises: a central equipment, and it is by adopting satellite control all-network; A plurality of data terminals are used for communicating by letter with central equipment; A network operation system is used to control communicating by letter between central equipment and the data terminal; A mainframe computer is used to store the data that send and receive by network; And a plurality of user terminals.
In existing VSAT system, data are sent to data terminal by a carrier wave single or several successive (carrier) from central equipment.This data that are sent to data terminal from central equipment are called as " outbound data ".
On the contrary, all data terminals are common keeps a single carrier wave and sends data to central equipment.Be called as " inbound data " from data terminal to this data that central equipment sends.
For " inbound data ", can keep this single carrier wave jointly for making all data terminals, use several channel access agreements.In these agreements, widely used is Aloha (Random-Aloha) and time slot A loha (Slotted-Aloha) at random.
Have two kinds of different information from central equipment to the bit stream that data terminal sends.
A kind of information is the packet that exchanges between central equipment and data terminal.A single departures carrier wave has several bags, and they are sent to several data terminals, and each bag has suitable address date.Therefore, bag that specific data terminal can accept to have the proper address data.
Another kind of information is the synchrodata that is used for the dispensing device of data terminal.Synchronized data signal is made of FIT (framing, identification and timing) signal, and is produced by a modulator of central equipment, and is taken a sample by the receiving system of data terminal.Synchronized data signal is used for the synchronous of data terminal.
The identifier position is made up of 9 bits of corresponding each time period (Slot), and is used for only searching for the departures carrier wave that is used by a particular data terminal.
Therefore in existing satellite communication system, the FIT signal can not directly be taken a sample from the user terminal of data terminal, and the use to the user terminal of data terminal causes many restrictions.
An object of the present invention is provides a kind of and is used for directly from the take a sample method and apparatus of FIT (Framing, Identification andTiming) signal of the user terminal of the data terminal of VSAT (Very Small Aperture Terminal) system for solving the problem that runs in the prior art.
According to the present invention, this VSAT system comprises a central equipment and a plurality of data terminal; The method of sampling FIT signal comprises the following steps: in the VSAT system
(a) three subchannels are taken a sample, framing, identification and timing (FIT) signal of promptly taking a sample and being produced by central equipment are so that the communication synchronization between central equipment and the data terminal; With
(b) the FIT signal is used for the synchronous of VSAT system.
According to the present invention, be used for comprising at the device that the VSAT system takes a sample to the FIT signal:
A system clock frequency divider is used for the system clock frequency division;
A RAM is used to store the frequency division value that is produced by Clock dividers;
A ROM is used for providing a state value according to the output valve of RAM and the data that receive from central equipment; And
Control logic device is used for the output valve sampling FIT data from ROM.
From the following detailed description of being done in conjunction with the accompanying drawings, can more be expressly understood above and other objects of the present invention, feature and advantage, in the accompanying drawing:
Fig. 1 is the block diagram of VSAT of the present invention system;
The position that Fig. 2 illustrates the FIT signal of Fig. 1 constitutes;
Fig. 3 is the block diagram that is used for the device of the FIT signal being taken a sample in the VSAT system according to of the present invention;
Fig. 4 A, 4B and 4C are the sequential schematic diagrames of the FIT signal of Fig. 3;
Fig. 5 is an algorithm routine figure, and it illustrates the identifier bit search utility that extracts the method for FIT signal according to of the present invention in the VSAT system;
Fig. 6 is an algorithm routine figure, and the timing Synchronous Processing program according to the method for the FIT signal of taking a sample in the VSAT system of the present invention is shown.
Fig. 1 is the block diagram of a VSAT (very small aperture terminal) system, and this system has adopted method and apparatus of the present invention.This VSAT system comprises: a central equipment 10, and it is used for controlling via satellite all-network; A plurality of data terminals 20, they are used for communicating with central equipment 10; A network operation system 30, it is used to control communicating by letter between central equipment 10 and the data terminal 20; A mainframe computer 40, it is used to store the data that send and receive by network 30; And a plurality of user terminals 50.
Fig. 2 illustrates the formation of FIT (framing, identification and the timing) signal among Fig. 1.In this FIT signal, framing bits were made up of a value " 011111111 " that adds up to 9 bits corresponding to each time period, and were used to separate from the incoming bit stream that inputs to data terminal FIT signal and packet.
Fig. 3 be one according to the block diagram that in VSAT, is used for device that the FIT signal is taken a sample of the present invention.As shown in Figure 3, this is used for the device of FIT sample of signal is comprised: a system clock frequency divider 1, and it is used for the input system clock division; A RAM (random access memory) 2, it is used to store the numerical value by Clock dividers 1 frequency division; A ROM (read-only memory) 3 is used for producing a state value according to the output valve of RAM2 and the data that receive from central equipment; And control logic device 4, be used for output valve sampling FIT data from ROM3.
According to the present invention, the course of work of this device is as described below.
As shown in Figure 1, (Rx-Data) is 66.666 (kbps) to the data that receive from central equipment 10.The clock of one 66.666 (kbps) that extracts from the decoder of data terminal 20 is by one 75 times frequency dividers (1A) frequency division of Clock dividers 1.Output behind the frequency division becomes the Input Address (A0-A7) of RAM2.
The output signal of central equipment 10 is made up of the FIT signal of the data and 2.666 (kbps) of 64 (kbps), and the latter and is 75 bits from the bit number of framing bits 0 (F0) to 1 (F1) as shown in Figure 2.Therefore, in order to be taken a sample in framing (F) position, 75 times frequency divider needs.This also is applicable to identifier position and timing position.
25 times of frequency dividers (1B) generation FIT synchronizing signal (it produces (seeing Fig. 4 A), FIT clock (seeing Fig. 4 B) and FIT data (seeing Fig. 4 C) by control logic device 40, and by control logic device 40 outputs, here:
Each clock of FIT signal is 66.666 (KHz) ÷ 75=0.888 (KHz),
And total clock of FIT signal is 0.888 (KHz) * 3=2.666 (KHz).
The counting of Clock dividers 1 is accompanyed or follow each data bit increase that central equipment 10 receives.Storage comes from 75 bit values of Clock dividers 1 (Rx-Data), the latter is stored once more by ROM3 with the data that received in RAM2.
Store a predetermined value in the address of each ROM3, this value is the FIT data of a particular data terminal 20, is used for and compares from each data that central equipment 10 receives.
When the FIT data consistent stored the data that receive from central equipment 10 and the ROM3, a carrier wave in this particular data terminal 20 by synchronous, and this particular data terminal 20 to identify the data that received are itself.
ROM3 receives data from central equipment 10, and (Rx-Data) also synchronizes them.Data after the synchronization were stored among the RAM2 increase the address counting for next step before again.
In case carrier wave by synchronously and also the data that received (Rx-Data) be identified as particular data terminal 20 to have, then synchronously and the data that identify be transferred into control logic device 4.
Control logic device 4 is lock units of synchronous usefulness of adaptive (fit) channel of FIT channel, and by 25 times of frequency divider 1B samplings of Clock dividers 1.
(when producing the Rx-Data), ROM produces data by control logic device 4, and (D0-D7) and FIT as shown in Figure 4 be (the signal of FIT-Sync) synchronously from the data that received as framing bits F8.
Shown in Fig. 4 C, for from the data that received (sampling identifier position I and position T regularly the Rx-Data), the FIT data (FIT-Data) by 25 times of frequency divider 1B of Clock dividers 1 by between per 25 data bits every reinstalling.
Shown in Fig. 4 B, (FIT-Clk) is used for 25 times of frequency dividers by Clock dividers 1 to each FIT sample of signal from the FIT clock of control control device 4.
After in a manner described to the FIT sample of signal, the identifier position is searched for by identifier position search utility shown in Figure 5.This identifier position search utility may further comprise the steps: (a) read the self-identifying symbol numbering (steps A 1) of being deposited in advance by a dual inline type (DIP) switch of data terminal 20; (b) when a selectable data terminal 20 is connected, judge whether to exist the output signal of central equipment, in from the output signal of central equipment 10, whether have a synchronizing signal (steps A 2) so that judge; (c) when not having output signal, finish this program, and when having output signal, the search output signal is so that judge whether there is the FIT (signal (steps A 3) of FIT-Sync) synchronously in output signal; (d) when not having the FIT synchronizing signal, search for output signal once more, and when having the FIT synchronizing signal, search identifier position (steps A 4) from the FIT synchronizing signal; (e) judge the identifier position search whether with a particular data terminal 20 in predetermined identifier position identical (steps A 5); And (f) when those identifier positions not simultaneously, search for output signal once more, and when those identifier positions are identical, follow the tracks of (tracing) self-identifying symbol position and also make identifier bit synchronization (steps A 6).
Regularly the position comprises 9 bits altogether corresponding to each time period, and be used to be implemented under the time slot A loha condition with respect to time period of each data terminal 20 of network synchronously.
Regularly bit data from 00 to 99 order increases, and promptly repeats in the cycle of 100 time periods in the cycle of a frame the highest (superframe).
Under the situation that adopts time slot A loha, each data terminal 20 is by initialize routine given access time segment number from network operation system 30.
Fig. 6 illustrates the timing Synchronous Processing program relevant with a particular data terminal 20, and this particular data terminal 20 is endowed 1,50 and 80 time segment number from network operation system 30.This timing Synchronous Processing program comprises the following steps: that (a) gives certain period of time numbering (step B1) to a particular data terminal 20 from network operation system 30; (b) obtain from 00 to 99 order increases and repeat (step B2) during cycle of 100 time periods timing position; (c) corresponding each time period of storage is the timing position (step B3) of 9 bits; (d) judge whether to exist any data (step B4) that from central equipment 10, receive; (e) when not having the data that receive from central equipment, whether position unanimity (step B5) regularly therewith of the time period numbering of distributing is judged in one of sub-distribution position regularly again, and when having the data that receive from network operation system 30; (f) when this time segment number when regularly the position is inconsistent therewith, distribute regularly bit once more, and, data are handled (step B6) when this time segment number therewith regularly during the unanimity of position; And (g) whether judgment data is handled and to be finished, and when data processing is finished after, store a new timing position, that is, store the timing of an increase for transfer of data next time and number in ROM3.
As mentioned above, each data terminal has certain period of time numbering simultaneously, and this makes and can carry out synchronously with respect to this time period.
In a word, according to the method and apparatus that is used for extracting in the VSAT system FIT signal of the present invention, but the direct sample of FIT signal also can be used as the synchronizing signal of this system in user terminal.In addition, a plurality of user terminals and central equipment be interface mutually, realizes correct message transmission thus, and can improve the communication performance and the reliability of this system.
More than the content that discloses in explanation and the accompanying drawing for convenient providing is provided, is not as a kind of qualification only.Essential scope of the present invention is limited by its claim, and these claims should be considered as the suitable expansion on the prior art basis.
Claims (4)
1. one kind is used in VSAT (very small aperture terminal) system FIT (framing, identification and the regularly) device that signal is taken a sample, and this system comprises a central equipment and a plurality of data terminal, and this device comprises:
A Clock dividers, it is used for the clock that inputs to described system is carried out frequency division;
A RAM, it is used to store the value by described Clock dividers institute frequency division;
A ROM, it is used for according to producing a state value from the output valve of described RAM with from the data that described central equipment receives; And
Control logic device, it is used for the output valve sampling FIT data from described ROM.
One kind to be used in VSAT (very small aperture terminal) system be the method that FIT (framing, identification and regularly) signal is taken a sample to three subchannels, this VSAT system comprises a central equipment, a plurality of data terminal and a network operation system, and this method comprises the following steps:
(a) framing that three subchannels are promptly produced by central equipment, identification and timing (FIT) signal are taken a sample, so that the communication synchronization between described central equipment and described data terminal;
(b) search identifier position from the FIT signal of sampling; With
(c) described FIT signal is used for described VSAT system synchronously.
3. according to the method for claim 2, the step (b) of wherein searching for described identifier position comprises the following steps:
(a) read the self-identifying symbol numbering of having been deposited by the dual in line switch of data terminal;
(b) when a selectable data terminal is connected, judge whether to exist output signal, so that judge in the signal that central equipment produces whether have synchronizing signal from central equipment;
(c) when not coming from the output signal of central equipment, end operation, and when existence came from the output signal of central equipment, the search output signal is search FIT synchronizing signal from output signal also;
(d) when not having the FIT synchronizing signal in the output signal of central equipment, the output signal of searching for central equipment once more, and when in the output signal of central equipment the FIT synchronizing signal being arranged, search identifier position from described FIT synchronizing signal;
(e) judge whether the identifier position that is searched is identical with the predetermined identifier position in a specific described data terminal; With
(f) when those identifier positions not simultaneously, search for another output signal again, and when those identifier positions are identical, follow the tracks of described self-identifying symbol position and make described identifier bit synchronization.
4. according to the method for claim 2, wherein, the synchronous step that the FIT signal of sampling is used for described VSAT system comprises the following steps:
(a) distribute the certain period of time numbering from the network operation system to data terminal;
(b) making regularly, from 00 to 99 order increases and repeats during 100 cycles;
(c) corresponding each time period of storage is the timing position of 9 bits;
(d) judge whether to exist any data that receive from central equipment;
(e) when not from data that central equipment receives, whether position unanimity regularly therewith of the time period numbering of being distributed by central equipment is judged in position when sub-distribution is certain again, and when existing from data that central equipment receives;
(f) when this time segment number when regularly the position is inconsistent therewith, the data in the next frame data of the synchrodata in the described FIT signal are handled in the regularly position of reallocate, and when this time segment number therewith regularly during unanimity; With
(g) whether judgment data is handled and to be finished, and when data processing finishes, stores a new timing position, i.e. the timing numbering that one of storage has increased in ROM is so that transfer of data next time.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1019930029733A KR960015852B1 (en) | 1993-12-27 | 1993-12-27 | Synchronization detecting method in base |
| KR29733/1993 | 1993-12-27 | ||
| KR29733/93 | 1993-12-27 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1117224A true CN1117224A (en) | 1996-02-21 |
| CN1074873C CN1074873C (en) | 2001-11-14 |
Family
ID=19372747
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN94113353A Expired - Fee Related CN1074873C (en) | 1993-12-27 | 1994-12-26 | Method of and apparatus for sampling fit (framing, identification and timing) signals in the vsat |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP2896856B2 (en) |
| KR (1) | KR960015852B1 (en) |
| CN (1) | CN1074873C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1113486C (en) * | 1996-07-17 | 2003-07-02 | 通用电气公司 | Satellite commnication system utilizing parallel concatenated coding |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4888769A (en) * | 1985-12-06 | 1989-12-19 | Tiw Systems, Inc. | TDMA terminal controller |
| JP2595602B2 (en) * | 1988-01-11 | 1997-04-02 | 日本電気株式会社 | Satellite communication earth station transmission / reception method |
| AU636190B2 (en) * | 1991-01-21 | 1993-04-22 | Nec Corporation | Spread packet communication system |
| JP2808954B2 (en) * | 1991-11-13 | 1998-10-08 | 国際電信電話株式会社 | Unmodulated signal detection and frequency pull-in device |
-
1993
- 1993-12-27 KR KR1019930029733A patent/KR960015852B1/en not_active IP Right Cessation
-
1994
- 1994-12-26 CN CN94113353A patent/CN1074873C/en not_active Expired - Fee Related
- 1994-12-27 JP JP6325600A patent/JP2896856B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1113486C (en) * | 1996-07-17 | 2003-07-02 | 通用电气公司 | Satellite commnication system utilizing parallel concatenated coding |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH07212286A (en) | 1995-08-11 |
| KR960015852B1 (en) | 1996-11-22 |
| JP2896856B2 (en) | 1999-05-31 |
| CN1074873C (en) | 2001-11-14 |
| KR950020017A (en) | 1995-07-24 |
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