KR100287768B1 - Amplitude Error Compensator of Channel Modem for Satellite Communication System - Google Patents

Abstract

The present invention relates to an amplitude error compensator in a channel modem for a satellite communication system, which is capable of estimating an amplitude error of data input to a demodulation device.

In the present invention, a demodulation apparatus for a channel modem for a satellite communication system that demodulates an input frequency signal of a predetermined level into I and Q data, and estimates and compensates an error for the I and Q demodulated data. Error detecting means for detecting an error component generated through satellites in the I and Q demodulated data, amplitude error data extracting means for extracting only amplitude error data from the detected error data, and set reference value with the extracted amplitude error data A data comparing means for comparing amplitude data, data applied from the data comparing step based on a carrier lock signal, or "; 0"; switching means for switching data, and amplitudes arbitrarily converted and set by the input data and the system designer according to the situation. A data multiplication means for multiplying a variable, and a data sum for synthesizing the multiplied data and the subsequent converted data Means for limiting and outputting the synthesized transmitted data within a set data range, and data converting means for performing Z inverse transform processing along with root processing of inverse function data based on a reference amplitude variable. do.

Description

Amplitude Error Compensator of Channel Modem for Satellite Communication System

The present invention relates to a channel modem of a communication system using satellites, and more particularly, to an amplitude error compensating device in a channel modem for a satellite communication system, which is capable of estimating and outputting an amplitude error of data input to a demodulation device. .

With the recent rapid development of communication technology, wireless communication is being spread and activated to transmit and receive voice signals or data through airwave transmission network rather than the conventional wired network, so that subscribers located at remote sites can perform mutual communication through satellites. Satellite communication is becoming more and more common.

1 is a block diagram showing the internal configuration of a channel modem for a general satellite communication system.

In the figure, reference numeral 11 denotes a voice / data processor that performs an interface function between the UPH bus and the MPH bus and the channel unit processor 12, which will be described later, and specifically processes voice and data transmitted and received through an airwave transmission network. Data Processor (hereinafter referred to as SDP), and 12 is a channel unit processor (hereinafter referred to as CUP) that controls the overall configuration of the channel modem.

Further, reference numeral 13 denotes a transmission frequency synthesizer for synthesizing and outputting a predetermined frequency signal for generating an intermediate frequency signal, for example, 112.512 MHz ± 20 MHz, based on the control data from the channel unit processor 12, 14 is a reception frequency synthesizer for synthesizing and outputting a predetermined frequency signal for receiving an intermediate frequency signal, for example, 112.384 MHz ± 20 MHz, based on the control data from the channel unit processor 12.

Reference numeral 15 denotes a modulator for outputting a 512KHz modulated signal by BPSK or QPSK modulating the I, Q channel data output from the SDP 11, and 16 denotes a 512KHz output from the modulator 15. An intermediate frequency generator generates and outputs an intermediate frequency signal of 70 MHz ± 20 MHz based on a modulation signal and a frequency of 112.512 MHz ± 20 MHz and a reference frequency of 42 MHz applied from the transmission frequency synthesizer 13.

Reference numeral 17 denotes an intermediate frequency signal for outputting a modulated signal of 384 KHz based on the received 70 MHz ± 20 MHz intermediate frequency signal, the frequency of 112.384 MHz ± 20 MHz applied from the receiving frequency synthesizer 14 and the reference frequency of 42 MHz. A demodulator 18 is a demodulator for demodulating and outputting I and Q channel data from a 384 KHz modulated signal applied by the intermediate frequency signal receiver 17, and 19 stores frequency data for each frequency ID. Look-up Table.

In the above configuration, when a predetermined frequency ID is input through the UPH bus, the CUP 12 reads the frequency data corresponding to the corresponding frequency ID into the lookup table 19 to transmit the synthesizer 13 and the receive frequency synthesizer ( 14), the frequency signal (112.512 MHz ± 20 MHz, 112.384 MHz ± 20 MHz) having a variable range of 20 MHz is output-controlled from the corresponding frequency synthesizer.

In the intermediate frequency signal generator 16, a 20 MHz variable is mixed by mixing a frequency signal (112.512 MHz ± 20 MHz) applied from the transmission frequency synthesizer 13 to a 512 KHz modulated signal output from the modulator 15. An intermediate frequency signal (70 MHz ± 20 MHz) having a range is generated, and in the intermediate frequency signal receiving unit 17, a frequency signal having a variable range of 20 MHz is again applied to the intermediate frequency signal having a variable range of 20 MHz (112.384 MHz). By mixing ± 20 MHz), a frequency signal of 384 KHz corresponding to a predetermined communication channel is detected.

On the other hand, the demodulator demodulates a 384KHz signal modulated by the QPSK method into I, Q data and outputs it. The high frequency component of the transmission data causes interference between adjacent signals, or a signal transmitted earlier is delayed. When mixed with the signal transmitted later, the amplitude data of the information data is distorted.

In addition, since information data is amplified or attenuated and transmitted through various systems including satellites, when the amplitude data of the information data applied to the demodulator is larger than the level set in the demodulator, the amplitude data is not detected. There is a problem that the error estimation is not made.

Accordingly, the present invention was created in view of the above circumstances, and when demodulating the data input to the demodulator of the channel modem, by estimating and compensating for the amplitude error of the input data, accurate demodulation of the information data can be performed. The purpose of the present invention is to provide an amplitude error compensation device for a channel modem for a satellite communication system.

1 is a block diagram showing the internal configuration of a channel modem for a general satellite communication system.

Figure 2 is a block diagram showing the internal configuration of the amplitude error estimation device 50 of the channel modem for satellite communication system according to the present invention.

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

51: error data detection unit, 52: amplitude data extraction unit,

53: data comparison unit, 54: switching unit,

55: multiplier, 56: data conversion unit,

57: data synthesis unit, 58: limiter.

The amplitude error compensation device of the channel modem for satellite communication system according to the present invention for demonstrating the above object, demodulates the input frequency signal of the predetermined level into I, Q data, A channel modem demodulation device for estimating / compensating an error and outputting the error, comprising: error detecting means for detecting an error component generated through satellites in the I and Q demodulated data, and an amplitude in the detected error data; Amplitude error data extracting means for extracting only error data, data comparing means for comparing the extracted amplitude error data with set reference amplitude data, data applied from the data comparing step based on a carrier lock signal, or "; 0"; Switching means for switching, multiplying input data with amplitude variable that system designer arbitrarily converts and sets according to the situation Calculation means, data synthesizing means for synthesizing the multiplied data and subsequent converted data, data limiting means for restricting and outputting the synthesized and transmitted data within a set data range, and routing inverse function data based on a reference amplitude variable. And data conversion means for performing Z inverse conversion processing.

That is, according to the present invention having the above-described configuration, the amplitude error component is estimated and compensated to maintain a constant level of amplitude data transmitted by being randomly amplified or attenuated by passing through various systems such as satellites. The error rate of the data can be reduced.

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 2 is a block diagram showing the internal configuration of the amplitude error compensation device according to the present invention.

In the figure, reference numeral 51 denotes an error data detection unit for detecting an error component of input data. Although not shown, the error data detector 51 detects signal data from data applied from the matched filter means of the demodulator, takes a complex conjugate of the detected data, calculates the magnitude of the signal, and matches the matched filter. Error data is detected by multiplying the signal applied from the means with the signal size data taking the complex conjugate.

Subsequently, the data output from the error data detection unit 51 is applied to the amplitude data extraction unit 52, and is output as complex data such as 1 + j0.

Meanwhile, the amplitude data extracting unit 52 extracts only data corresponding to the amplitude data from the complex-type error data input from the error data detecting unit 51 and outputs the data corresponding to the amplitude data to the data comparing unit 53. When data input from 51) is 1 + j0, only “; 1”; data is extracted and output.

The data comparator 53 compares the reference amplitude data set at the time of system design with the data input from the amplitude data extractor 52 and outputs data corresponding to the difference between the two data to the switching unit 54. Here, the reference amplitude data is set as "; 2 "; corresponding to the size of the normal reference level by defining a reference level of the input data as 1 + j1.

Although not shown, the switching unit 54 performs a switching operation based on the input of the carrier lock signal of the demodulator. When the carrier lock signal is input, the switching unit 54 multiplies the data input from the data comparator 53. 55), and before the carrier lock signal is inputted, "; 0 "; data is input to the multiplier 55.

The multiplier 55 multiplies the data input through the switching unit 54 with an amplitude variable that is arbitrarily set by the system operator and outputs the data to the data synthesis unit 57. Here, the amplitude variable is arbitrarily changed and set by the system operator on the basis of the experimental value or the statistical value according to the state of the system. The amplitude variable corresponds to the slope of the amplitude error estimation function when the amplitude error estimation is performed.

On the other hand, the data applied from the multiplier 55 is input as the input data of the data synthesizing unit 56, and the input data of the data synthesizing unit 56 is applied as the input data of the limiter 58.

The limiter 58 is a device for limiting the range of input data to within a specific range. For example, the limiter 58 limits the size of the input amplitude data to within the range of -1 to +1.

Although not shown, the data converter 56 is a data converter that delays data applied from the limiter 58 based on reference amplitude data applied from an open loop of a demodulator. The data is delayed by performing a root process on the inverse function of Z, and performing a Z inverse transform process on the routed data.

That is, the data is delayed based on the reference amplitude data until the data input to the limiter 58 is within the set data range, and it is combined with the data input from the multiplier 55 to limit the data range. Will be performed.

Subsequently, when the data input to the limiter 58 is within the set data range, the input data is output to the next stage to estimate and compensate the error of the amplitude data.

That is, the error is detected from the data input from the matched filter of the demodulator, the amplitude error component is extracted from the detected error components, and the magnitude of the amplitude error component can be known based on the difference with the set reference amplitude data. When the magnitude of the amplitude error component is obtained, the "; 0 "; data or amplitude error component data is switched with the multiplier depending on the presence or absence of the carrier lock signal, and the reference amplitude until the input amplitude error component matches the specific data. The amplitude error component is estimated and compensated based on the variable.

Therefore, according to the above, the amplitude error component is estimated and compensated to maintain a constant level of amplitude data transmitted by random amplification or attenuation due to various systems such as satellites, thereby reducing the error rate of the data according to the amplitude error. Can be reduced.

On the other hand, the present invention is not limited to the above embodiments and can be modified in various ways without departing from the technical spirit of the present invention.

For example, it may be used as a device for estimating and compensating for an amplitude error in a data modulation and demodulation device of a general voice communication system.

As described above, according to the present invention, the amplitude error component is estimated and compensated to maintain a constant level of amplitude data that is randomly amplified or attenuated by passing through various systems such as satellites. It is possible to reduce the error rate.

Claims (1)

A demodulation apparatus for a channel modem for a satellite communication system that demodulates an input frequency signal of a predetermined level into I and Q data, and estimates and compensates an error for the I and Q demodulated data. Error detecting means for detecting an error component generated through the satellites in the I and Q demodulated data; Amplitude error data extracting means for extracting only amplitude error data from the detected error data; Data comparison means for comparing the extracted amplitude error data with the set reference amplitude data; Switching means for switching data or "; 0"; data applied from the data comparing step based on the carrier lock signal; A data multiplication means for multiplying the input data with an amplitude variable that the system designer arbitrarily converts and sets according to a situation; Data synthesizing means for synthesizing the multiplied data and the subsequent converted data; Data limiting means for limiting and outputting the synthesized and transmitted data within a set data range; An amplitude error compensator for a channel modem for a satellite communication system, comprising: a data conversion means for performing Z inverse conversion processing and route processing of inverse function data based on a reference amplitude variable.