KR20020095747A - Adapt signal compensating method - Google Patents

Abstract

PURPOSE: A method of compensating an adaptive signal is provided to automatically sense and evaluate characteristics of a transmission medium by using an AGC(Automatic Gain Control) voltage, and to use the sensed characteristics as waveform compensating parameters of transmission signals, thereby reducing signal distortion, delay, and attenuation, and improving transceiving capacities. CONSTITUTION: An inputted signal is firstly compensated, and is secondly amplified. A DC value is inputted by detecting a power part only with the use of a detecting TR for more than limited peak value of a secondly-amplified receiving signal. A voltage detected from the detecting TR is compared with a limited detecting voltage to turn on/off an SW TR. A compared result is inputted to an AGC input pin. An inputted value is periodically checked in an IC. A PWM output pulse width is increased in an on-state. The PWM output pulse width is reduced in an off-state to control bias of an amplifier.

Description

Adaptive signal compensating method using automatic gain control voltage and delay recognition

The present invention relates to an adaptive signal compensation technique through automatic gain control voltage and delay recognition used in a communication system.

In general communication systems, a medium exists between both parties. For example, in a telephone line for a telephone, a LAN line for a network, a cable for transmitting cable TV, and a wireless telephone, the space itself becomes a medium for communication. Only through such media, communication systems can be established, and accordingly, numerous studies have been conducted to analyze the characteristics of such media to create the most suitable communication method and signal type for each media.

In particular, communication systems have become complicated, and techniques for sharing such media and efficiently using them in order to provide communication services to more people have been developed. Among them, FDM and TDM are the most used. That is, in this case, the frequency of the transmission medium is assigned to each communication service provider. In this case, the user cannot use the entire frequency band or the time domain of the medium. Thus, a channel having a limited bandwidth is allocated to an individual. This is called a band-limited channel, and a signal propagating in such a channel often causes delay and frequency distortion (ISI) as well as attenuation of the signal depending on the frequency of the signal and the shape of the waveform. Therefore, in general, various techniques have been applied to transmit / receive modems in communication systems to reduce distortion, delay, and attenuation of these signals, and to improve transmission / reception performance.

Signal attenuation is through AGC technology, and signal delay and distortion have been used for channel call technology. Recently, inverse modeling technology of digital filter using DSP technology has been used. However, this technology has had to be limited in developing simpler and cheaper communication systems, such as using expensive DSP chips or cores of such processors, and the algorithm itself is very complicated and takes up a lot of memory.

The present invention relates to a distance-applied signal compensation technique using AGC voltage control that can be used in a communication system using a telephone line or another communication medium. The present invention uses an expensive DSP chip while reducing signal distortion, delay and attenuation, and improving transmission and reception performance. It was developed to provide low-cost systemization without the need.

1 is a diagram showing a transmission pulse and a reception pulse,

2 is a diagram illustrating transmit, correct and receive pulses.

According to the present invention, the first amplified input signal, and the second amplified received signal detects more than a limited peak value in the diode with only the detection of the power portion, inputs a DC value, and detects the detected voltage in the detection TR. SW TR is turned on / off in comparison with voltage and the result is input to AGC input pin, and the input value is periodically checked by IC, increasing the PWM output pulse width in on-phase and decreasing the PWM output pulse width in off-state. It is characterized by adjusting the bias.

The present invention made as described above is a distance-applied signal compensation technique using AGC voltage control available in a communication system using a telephone line or another communication medium will be described in detail below with reference to the drawings.

First, as shown in FIG. 1, when the data to be transmitted by the transmitter is made into a rectangular pulse (see FIG. 1B) and transmitted through a communication line, a general distortion and attenuation appear at the receiver. Analyzing these distortions and attenuations, we find the following laws.

① Signal attenuation and signal delay distortion increase in proportion to the length of the communication line.

② The signal delay distortion phenomenon has a minimum delay over a certain value even when the distance of the telephone line is short.

When such a distortion signal is received at the receiver, proper data cannot be recovered. First, the first compensation technique is AGC, which controls the attenuation of the signal. It uses a general AGC that calculates the power of the received signal and converts the value into digital data when the energy accumulated in the peak detector exceeds a certain value, and adjusts the amplifier bias by changing the pulse width of the PWM pulse. The circuit and configuration operation principle of the AGC system used in the present invention

First, the input signal is first amplified and secondly amplified again, and the received signal detects more than a limited peak value in the diode by detecting only the power portion as a detection TR, inputs a DC value, and compares the voltage detected in the detection TR with a limited detection voltage. SW TR is turned on / off and the result is input to AGC input pin, and the input value is periodically inspected by IC, increasing the PWM output pulse width in the on-phase and decreasing the PWM output pulse width in the off state to reduce the bias of the amplifier. Will be adjusted.

Here, PWM is a modulation system in which a signal having a different pulse width is integrated through a condenser, and at the output, different DC values are obtained according to the pulse width.

In addition, the second compensation technique is a signal waveform compensation technique that compensates for the deformation of the waveform of the transmission signal through the communication medium, causing delay and distortion. This method mainly uses the technique of analyzing the distorted received signal waveform of the receiver, and compensating for the reverse in the transmitter, generally called an equalizer.

Therefore, the design of the equalizer is important to accurately grasp the characteristics of the transmission medium and to efficiently compensate for it, and in the present invention, the distortion is different according to distance and frequency in a communication environment using a wired transmission network (telephone line or the like). As a compensation technique for the transmission signal having the over-deformation characteristic, the AGC control voltage is used to automatically detect and evaluate the characteristics of the transmission medium and use it as a waveform correction parameter of the transmission signal.

In addition, the present invention takes advantage of the tendency that the delay and distortion characteristics of a wired communication medium including a telephone line generally have linear characteristics proportional to distance. In other words, the attenuation characteristic of the signal indicated by the AGC gain is also proportional to the distance even in the case of a wire which is made of the same material. In this case, the attenuation characteristic according to the distance is the same as the AGC attenuation. The peak voltage of the AGC is input from the detector, or the output information of the AGC PWM output provides accurate information for determining the attenuation and delay characteristics of the received signal. Therefore, the present invention extracts these AGC parameters to compensate for the distortion of the signal.

That is, if the distortion compensation is a signal having the above-described delay characteristics, as shown in FIG. 2, if the delay signal obtained by inverting the signal to be sent by one tap is added to the next delay tap (see FIG. 2B), the signal to be transmitted is As shown in FIG. 2C, the received signal is finally compensated for by the signal distortion at the transmitting end, and passes through the transmission line, so that a signal closer to the transmitted signal is received. The present invention performs signal compensation using two delay taps in consideration of characteristics of a general telephone line, which can be utilized according to characteristics of various wired networks.

The present invention relates to a distance-applied signal compensation technique using AGC voltage control that can be used in a communication system using a telephone line or another communication medium. The present invention uses an expensive DSP chip while reducing signal distortion, delay and attenuation, and improving transmission and reception performance. It is a useful and effective invention that does not have to provide a low-cost systemization.

Claims (1)

The amplified input signal is first amplified, and the second amplified received signal detects more than a limited peak value in the diode with only the detection part of the power, inputs a DC value, and compares the voltage detected in the detection TR with a limited detection voltage. SW TR is turned on / off and the result is input to AGC input pin, and the input value is periodically inspected by IC, increasing the PWM output pulse width in on phase and adjusting the bias of the amplifier by decreasing PWM output pulse width in off state. Adaptive signal compensation method using automatic gain control voltage and delay recognition.