KR100284318B1 - Method and apparatus for data transmission in channel modem for satellite communication system - Google Patents

Abstract

The present invention provides a channel modem for a satellite communication system that detects a message synchronization signal of data applied to a channel modem in a burst mode and transmits predetermined provisional data to an input data string when a message synchronization signal is not detected. A data processing method and apparatus thereof, comprising: information data having the same size as the information data size in a state where a channel modem for a satellite communication system that performs a modulation / demodulation function on input data is set to a burst mode for transmitting and receiving voice data. Information transmitted based on the message synchronization signal detected in the message synchronization signal detection step of detecting the message synchronization signal of the data string inputted to the demultiplexer of the channel modem. A data processing step of demultiplexing the data, and the message synchronization If the call detecting step, the message is not a synchronization signal is detected, characterized in that is configured to read out the stored home security data including home security data transmission step of transmitting information data, instead.

Description

Method and apparatus for data transmission in channel modem for satellite communication system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a channel modem of a satellite communication system. In particular, when a message synchronization signal of a data applied to a channel modem is detected in a burst mode, when a message synchronization signal is not detected, predetermined provisional data is loaded into an input data string. A data processing method and a device in a channel modem for a satellite communication system to be transmitted.

The satellite communication system is equipped with an interface function for satellites having a plurality of communication channels, a central control station for controlling the entire satellite communication system, and data terminals such as switches, telephones, computers, and terminals such as fax machines. It is configured to include a base station that provides a function.

In addition, in the satellite communication system, the central control station periodically performs a polling operation to check the status of each base station, and when there is a call request from the base station, allocates an available communication channel and channel modem to enable communication between subscribers. Will be provided.

On the other hand, a channel modem allocated from the central control station is a modulation and demodulation device that performs a function of demodulating and decoding an input signal, and encoding and modulating an input signal, which generally adds a predetermined synchronization signal to input data. Transmit and process data in burst form.

Next, a data transmission process in a channel modem for a satellite communication system will be described with reference to the drawings.

1 is a diagram illustrating a voice data transmission format in a channel modem for a satellite communication system.

In the figure, (A) shows a synchronization signal added to the data applied from the base station. The message synchronization signal, that is, a SOM (Start Of Message: SOM) signal and a unique word, is added to the input voice data. Signal, followed by a POSTAMBLE signal.

In addition, (B) in the figure shows a burst data frame of the data area shown in (A), the 8-bit SOM signal generated by the multiplexer of the channel modem at the beginning for each data in the voice data frame Next, a two-bit flag (FLAG) signal for notifying the status of data, voice data of up to 1260 bits, 8-bit signal bits, and 2-bit noise level data are added in this order.

On the other hand, the synchronization signal is data added for synchronization at the receiving side of the channel modem. In particular, the SOM data added at the time of data transmission is detected to determine whether there is information on the data. At this time, the data for which the SOM data is not detected is not transmitted to the next stage.

Therefore, when an error occurs in the SOM data during voice data transmission, a problem occurs that the voice data being transmitted is cut off because the SOM data is not detected.

Accordingly, the present invention has been made in view of the above circumstances, and when the SOM signal is not detected during voice data transmission in burst mode, randomly set predetermined data is transmitted to the next stage instead of voice data, thereby interrupting the voice signal. An object of the present invention is to provide a data processing method and apparatus in a channel modem for a satellite communication system that can prevent a phenomenon.

1 is a diagram showing a transmission format of data transmitted in a channel modem for a satellite communication system.

2 is a block diagram showing the internal configuration of a channel modem for a satellite communication system according to an embodiment of the present invention.

3 is an operational flowchart for explaining the operation of the apparatus according to the present invention;

*** Explanation of symbols for the main parts of the drawing ***

1: MPH, 2: UPH,

3: bus interface, 4: echo suppressor,

5: voice detection unit, 6: pressure compensator,

7: multiplexer (MUX), 8: encoder,

9: TX motor, 10: modulation and demodulation unit,

11: RX unit, 12: decoder,

13: demultiplexer (DEMUX), 14: temporary data storage unit,

15: SOM detection failure threshold storage unit, 16: timer,

17: noise generating unit, 20: control unit.

A data processing method in a channel modem for a satellite communication system according to the first aspect of the present invention for realizing the above object is a burst mode in which a channel modem for a satellite communication system transmitting and receiving voice data performs a demodulation function on input data. In the state set to, the information data storage step of storing the information information of the same size as the information data size, the message synchronization signal detection step of detecting the message synchronization signal of the data string input to the demultiplexer of the channel modem, the message synchronization A data processing step of demultiplexing the information data transmitted on the basis of the message synchronization signal detected in the signal detection step; and if the message synchronization signal is not detected in the message synchronization signal detection step, the stored provisional data is read Configured to include provisional data transmission step of transmitting data instead It is characterized by.

Further, in order to achieve the above object, a data processing apparatus in a channel modem for a satellite communication system according to a second aspect of the present invention, demodulates an input intermediate frequency signal by a demodulation means, and the demodulated data is RX. In a channel modem for a satellite communication system which is input to a demultiplexing means through a synchronizer and a decoder, the base noise data included in the received data is extracted and transmitted to a noise generating means to be described later. Demultiplexing means for detecting the message synchronization signal generated by the < RTI ID = 0.0 > information < / RTI > and only data having information, and temporary information data storing predetermined data to be transmitted instead of information data when the message synchronization signal is not detected by the demultiplexing means. Storage means, SOM failure that stores threshold data on the maximum number of message synchronization signal detection failures A counter for counting the number of counting thresholds, a counter for counting the current message synchronization signal detection failure count, and if the data relating to the message synchronization signal detection result are received by the demultiplexing unit, the counter is incremented based on this, and the counter value of the counter is increased. And if the data of the SOM failure count threshold storage means match, the provisional data is transmitted to the demultiplexing means. If the count value of the counter does not match the data of the SOM fail count threshold storage means, the received data is not transmitted. It characterized in that it comprises a control means for controlling to prevent.

That is, according to the above, when the message synchronization signal data is not detected due to a temporary error during a call between subscriptions in the burst mode, by transmitting predetermined data instead of the information data, it is possible to prevent the audio signal from being cut off. .

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

2 is a block diagram showing the configuration of a channel modem for a satellite communication system according to the present invention.

In the drawing, reference numeral 1 denotes a main PCM highway bus (MPH) for transmitting and receiving voice and data, and 2 denotes a utility PCM highway bus (UPH) for transmitting and receiving various control data with a CPM controlling the entire apparatus.

Further, reference numeral 3 denotes a bus interface for performing an interface function with the MPH bus 1 and the UPH bus 2, and 4 denotes an echo memory for removing echoes of voice data transmitted from the bus interface 3. Claim 5 detects the presence or absence of the voice data output through the echo suppressor 4, outputs the ON / OFF signal of the voice data accordingly, and in the section where no voice data exists. It is a voice detector that calculates a noise index and outputs predetermined basis noise data in order to put an appropriate backgrand noise.

On the other hand, reference numeral 6 denotes a compensator which transmits voice band data by encoding a 64 Kbps PCM signal into a 32 Kbps ADPCM signal using a μ-law method or an A-law method, or decodes an input 32 Kbps ADPCM signal into a 64 Kbps PCM signal. 7 denotes a message synchronization signal (Start Of Message) which is used to obtain a frame synchronization signal at the receiving side by multiplexing the basis noise data applied from the voice detector 5 to the data transmitted from the compensator 6. A multiplexer (MUX) for adding data (hereinafter referred to as SOM) 8 is an encoder that scrambles and differentially encodes data transmitted from the multiplexer 7.

Further, reference numeral 9 adds a synchronization signal to the front and rear ends of the signal transmitted from the encoder 8 to generate burst data, and according to the voice on / off signal applied from the voice detector 5. 10 is a TX device for multiplexing burst data, 10 modulates a signal inputted from the TX device 9, up-converts the modulated signal, generates and outputs an intermediate frequency, and downconverts the input intermediate frequency. The demodulation unit outputs the demodulated data.

On the other hand, reference numeral 11 is an RX synchronizer for synchronizing the receiving end of the data demodulated and output by the demodulation unit 10, and 12 is a decoder for decoding data transmitted in a manner corresponding to the encoder 8. For example, when the transmitted signal is encoded by the convolution coding method, the received signal is decoded by the Viterbi decoding method.

Further, reference numeral 13 is input based on the detection of the SOM signal generated by the multiplexer 7 while extracting the base noise data included in the received signal and transmitting it to the noise generator 16 which will be described later. It is a demux (DEMUX) that demuxes the data.

On the other hand, reference numeral 14 is a provisional data storage unit for storing predetermined data to be transmitted instead of the information data when the SOM signal is not detected in the demultiplexer 13, 15 is a threshold data on the number of times of SOM detection failure The stored SOM failure threshold storage unit, 16 is a counter for counting the current number of SOM detection failures, 17 is applied by the demultiplexer 13 in accordance with the data on / off signal transmitted from the RX unit 11 A noise generator that generates noise based on the basis noise data, wherein a noise signal output from the noise generator 16 is added to speech data applied from the compensator 6 to the echo suppressor 4.

That is, in burst mode for transmitting and receiving voice data, QPSK modulates a signal transmitted from a transmitter, and transmits the modulated signal to another terminal station via satellite through an IF stage and an RF stage. Through the steps, the system is synchronized to demodulate and output the signal sent from the original transmitter.

At this time, in the channel modem performing the modulation / demodulation process, a predetermined synchronization signal, that is, signals of the type shown in FIG. 1 is added to the voice data input to the transmitting end and transmitted, and the receiving end is based on the detection of the synchronization signal. As data is processed, the voice data transmission method will be described with reference to the operation flowchart shown in FIG.

First, in the state where the channel modem for the satellite communication system is set to the burst mode for transmitting and receiving voice data, the modulated demodulation unit 10 demodulates the input intermediate frequency (IF) signal, and the demodulated data is RX synchronization unit 11. When the SOM data is input to the demultiplexer 13 through the decoder 12 and the decoder 12, the SOM data is detected from the input data stream. In this case, the SOM data is preset data among the systems, for example, ″ 1101 ″ and the like. The SOM data is detected by comparing the first 8 bits of the data string defined as 8-bit data.

Subsequently, when data related to the SOM data detection result is received from the demultiplexer 13 (ST1), the controller 20 checks whether the received data is the SOM detection failure data (ST2). If it is determined that is not the SOM detection failure data, 1260 bits of information data are demultiplexed based on the flag data transmitted after the SOM data and transmitted to the compensator 6 (ST3).

On the other hand, if the data received from the demultiplexer in step ST2 is SOM detection failure data, the controller 20 drives the counter 16 to increase the current SOM detection failure count by ″ 1 ″ (ST4), and the counter 16 It is determined whether the current number of SOM detection failures is equal to the data stored in the SOM detection failure threshold storage unit 15 (ST5). If the current number of failures of detection of the SOM does not match the SOM detection failure threshold, the false information data The provisional data stored in the storage unit 14 is read and loaded on the transmitted data stream (ST6). Here, the data stored in the provisional data storage 14 is data transmitted instead of the information data, for example, " 0000... 000 ″ can be arbitrarily set by the user, and the size of data is set to 1260 bits equal to the size of information data.

In addition, when the current SOM detection failure count of the counter 16 matches the data stored in the SOM failure threshold storage unit 15 in step ST4, the controller 20 does not transmit the data of the corresponding data string (ST7). .

Thereafter, the controller 20 notifies the occurrence of an error by sending a predetermined error message to the CPM.

That is, the data corresponding to the information data is stored in advance, and when the SOM data is not detected in the input data string, the stored information data is transmitted instead of the transmitted information data, and in the voice data mode By setting the number of SOM detection failures in consideration of the subscriber listening without speaking for a predetermined time, even if SOM data is not detected, the provisional data is not transmitted when the number of SOM detection failures is greater than the set value.

Therefore, when SOM data is not detected due to a temporary error during a call between subscriptions, predetermined data is transmitted instead of information data, thereby preventing the voice signal from being interrupted.

In addition, this invention is not limited to the said Example, It can variously deform and implement within the range which does not deviate from the technical summary of this invention.

As described above, according to the present invention, when SOM data is not detected due to a temporary error during a call between subscriptions in the burst mode, predetermined data is transmitted instead of information data, thereby preventing the voice signal from being interrupted.

Claims (3)

In the state that the channel modem for the satellite communication system performing the modulation / demodulation function on the input data is set to the burst mode for transmitting and receiving voice data, A provisional data storage step of storing provisional data having the same size as the information data size; A message synchronization signal detecting step of detecting a message synchronization signal of a data string inputted to a demultiplexer of a channel modem, A data processing step of demultiplexing the information data transmitted based on the message synchronization signal detected in the message synchronization signal detection step; And if the message synchronization signal is not detected in the message synchronization signal detection step, data stored in the channel modem for a satellite communication system, comprising: a provisional data transmission step of reading stored provisional data and transmitting the information instead of the information data. Treatment method. The method of claim 1, In the provisional data transmission step, the threshold value of the maximum number of message synchronization signal detection failures of the input data stream is set so that the provisional data is transmitted instead of the information data only when the threshold is less than the threshold. Data processing method. A channel modem for a satellite communication system in which an intermediate frequency signal to be input is demodulated by a demodulation means, and the demodulated data is input to a demultiplexing means via an RX synchronization device and a decoder. Demultiplexing means for extracting the base noise data contained in the received data and transmitting it to the noise generating means to be described later, and detecting the message synchronization signal generated by the multiplexer on the receiving side to demux only the data with information. and, Temporary information data storage means for storing predetermined data to be transmitted instead of information data when the message synchronization signal is not detected by the demultiplexing means; SOM failure count threshold storage means for storing threshold data on the maximum number of message synchronization signal detection failure times; A counter for counting a current message synchronization signal detection failure count, When the data relating to the message synchronization signal detection result is received by the demultiplexing means, the counter is incremented based on this, and when the count value of the counter and the data of the SOM failure count threshold value storage means coincide, the provisional data is stored. And a control means for transmitting to the demultiplexing means and controlling not to transmit the received data if the count value of the counter and the data of the SOM failure count threshold value storing means do not match. Data transmission device in