KR100350450B1 - Apparatus and method for detecting a fault in signal path of a transmitter - Google Patents

Abstract

The present invention relates to a technique for detecting a failure in a transmitter. The transmitter receives an input signal having a first power value and transmits an output signal having a second power value. The technique determines an error value based on the difference between the first power value and the second power value, and a threshold that indicates the maximum amount of difference that can occur between the first power value and the second power value. Implemented by comparing with values. Here, the error value exceeding the threshold indicates that a failure has occurred in the transmitter.

Description

Apparatus and method for detecting a fault in a signal path of a transmitter {APPARATUS AND METHOD FOR DETECTING A FAULT IN SIGNAL PATH OF A TRANSMITTER}

The present invention relates to a wireless communication system, and more particularly, to an apparatus and method for detecting a failure in a signal path of a transmitter.

The use of mobile phones has increased dramatically in recent years due to the apparent convenience and advantages. Besides. The use and consumption of mobile phone services has also increased. The increase in mobile phone service has led to an increase in base stations. In a mobile telephone system, each base station has a transmitter for transmitting radio frequency signals throughout the corresponding service area. For example, the base station transmitter transmits a radio frequency (RF) signal to one or more mobile stations located in the service area. According to the operation mode of the mobile telephone service system, each base station transmitter has a typical structure for supporting a special modulation scheme.

For example, referring to FIG. 1, a configuration of a base station transmitter 10 supporting a conventional special modulation scheme is shown. FIG. 1 illustrates a block configuration of a base station transmitter supporting a quadrature phase shift keying (QPSK) modulation scheme in a code division multiple access communication system. Referring to FIG. 1, the base station transmitter 10 includes a modulator 12, serially connected amplifiers 14, and an antenna 16. The modulator 12 includes an oscillator 11 for generating an RF carrier signal, a phase shifter 12b for generating a quadrature RF carrier signal from an in-phase RF carrier signal, It consists of two mixers 12c and an adder 12d. The two mixers 12c output an I modulated signal and a Q modulated signal by multiplying the I (in-phase) RF carrier signal and the Q (quadrature) RF carrier signal corresponding to the I signal and the Q signal, respectively. . The adder 12d adds the I modulated signal obtained by the QPSK modulation and the Q modulated signal to output a QPSK modulated signal. The QPSK modulated signal is then passed to serially connected amplifiers 14 and transmitted via an antenna 16. The amplifiers 14 here comprise at least an RF amplifier 14a and a power amplifier 14b.

In the code division multiple access scheme, the magnitude (amplitude) of the I modulated signal and the Q modulated signal vary according to the amount of traffic carried by the respective signals. In other words, in the code division multiple access scheme, the amount of traffic carried by the I modulated signal and the Q modulated signal is directly related to the number of mobile stations with which the base station attempts or communicates. In addition, the magnitude (amplitude) of the I modulated signal and the Q modulated signal is adjusted by the number of mobile stations with which the base station attempts or performs communication. For example, when the number of mobile stations with which the base station attempts to communicate increases, the magnitude (amplitude) of the I modulated signal and the Q modulated signal increases in proportion to the increase in the number of mobile stations.

As a result, the magnitude variation of the I modulated signal and the Q modulated signal in the code division multiple access scheme coincides with the variation of the average power of the signals. In addition, the variation of the average power of the I modulated signal and the Q modulated signal is directly or in proportion to the average power of the QPSK modulated RF signal transmitted through the serially connected amplifiers 14 and the antenna. That is, since the average power of the transmitted QPSK modulated signal is changed, it is difficult to detect when a failure occurs in the signal path of the base station transmitter 10. For example, if there is a partial failure in the RF power amplifier 14b, the QPSK modulated signal is transmitted at a low power level. Here, if the amount of traffic carried on the I modulated signal and the Q modulated signal is reduced, RF power measurement may fail at the output of the power amplifier.

In the related art, in order to solve such a detection failure, the power level of the QPSK modulated RF signal transmitted from the base station transmitter 10 is monitored, and the power level is controlled through the I modulated signal (or Q modulated signal). There is a way to correlate with the amount of traffic being transmitted. However, this solution requires a complicated processing algorithm for tracking the amount of traffic carried on the QPSK modulated signal and the I modulated signal (or the Q modulated signal) transmitted from the base station transmitter 10. In other words, this solution has the problem of excessive time and cost.

As described above, there is a need for a technique capable of solving the above-described problem of fault detection according to the prior art and overcoming the problem of detection failure.

It is therefore an object of the present invention to provide an apparatus and method for detecting a failure in a signal path of a transmitter.

A transmitter for detecting a failure according to the present invention for achieving the above object, for example, the base station transmitter in a mobile phone service system, the input having a first power value, bandwidth and center frequency A signal is received and an output signal having a first power value is transmitted. The output signal is a signal derived from the input signal. That is, the input signal is a modulation signal such as Q modulation (or I modulation), and the output signal is a QPSK modulation RF signal. Therefore, the first power value is an average power value of the input signal. The second power value is an average power value of the output signal.

The fault detection technique is implemented by determining an error value based on a difference between the first power value and the second power value. The error value is compared with a threshold value representing a maximum amount of a difference between the first power value and the second power value. Here, an error value exceeding the threshold indicates a failure of the transmitter.

In general, a portion of the input signal is coupled to a first detection circuit, the first detection circuit detecting the first power value of the input signal. The first detection circuit generates a first voltage value corresponding to the first power value. Similarly, a part of the output signal is connected to a second detection circuit, the second detection circuit detecting the second power value of the output signal. The second detection circuit generates a second voltage value corresponding to the first power value.

According to a first aspect of the present invention, the error value may be determined by a difference between the first voltage value and the second voltage value. The error value is converted into digital corresponding to the error value. The digital corresponding to the error value is compared with a threshold for determining whether the transmitter is faulty.

According to a second aspect of the present invention, the first voltage value is converted into digital corresponding to the first voltage value, and the second voltage value is converted into digital corresponding to the second voltage value. In order to determine the error value, a difference between a digital corresponding to the first voltage value and a digital corresponding to the second voltage value is calculated. The error value is then compared with a threshold for determining whether the transmitter is faulty.

1 is a diagram illustrating a base station transmitter supporting a QPSK modulation scheme in a code division multiple access mobile communication system according to the prior art.

2 illustrates a base station transmitter having a fault detection circuit for detecting a fault in a signal path according to an embodiment of the present invention.

3 illustrates a base station transmitter having a failure detection circuit for detecting a failure in a signal path according to another embodiment of the present invention.

4 illustrates a base station transmitter having a failure detection circuit for detecting a failure in a signal path according to another embodiment of the present invention.

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

In the following description and the annexed drawings, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent to those skilled in the art that the present invention may be practiced without these specific configurations. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

2 illustrates a base station transmitter having a failure detection circuit for detecting a failure in a signal path of a base station transmitter 20 according to an embodiment of the present invention. The base station transmitter of FIG. 2 has a structure similar to that of the conventional base station transmitter of FIG. 1 and supports a QPSK modulation scheme in a code division multiple access (CDMA) mobile communication system. to be. Therefore, the base station transmitter 20 according to the present invention has the components provided in the existing base station transmitter 10, which uses the same reference numerals.

Referring to FIG. 2, a modulator 12, a series of amplifiers 14, an antenna 16, and fault detection circuitry are provided. The fault detection circuit may include a first detection circuit for detecting an average power of a Q modulated signal as an input signal, a second detection circuit for detecting an average power of a QPSK modulated RF signal as an output signal, and an average from the two detection circuits. The processor is configured to compare the powers to obtain a difference, and to compare the power with a preset threshold value to determine whether the transmitter is faulty. The modulator 12 includes an oscillator 11 for generating an RF carrier signal, a phase shifter 12b for generating a quadrature RF carrier signal from an in-phase RF carrier signal, It consists of two mixers 12c and an adder 12d. The two mixers 12c output an I modulated signal and a Q modulated signal by multiplying the I (in-phase) RF carrier signal and the Q (quadrature) RF carrier signal corresponding to the I signal and the Q signal, respectively. . The adder 12d adds the I modulated signal obtained by the QPSK modulation and the Q modulated signal to output a QPSK modulated signal. The QPSK modulated signal is then passed to serially connected amplifiers 14 and transmitted via an antenna 16. The amplifiers 14 here comprise at least an RF amplifier 14a and a power amplifier 14b.

As noted above, the base station transmitter 20 according to the present invention includes the fault detection circuitry for detecting a fault in the signal path of the base station transmitter 20. First, a description will be made of detecting the average power of the Q modulated signal as an input signal. In order to detect the average power of the Q (quadrature) modulated signal, the resistor 22 has a relatively low frequency baseband in the Q modulated signal. A small portion of base-band energy is removed to couple to the first detection circuit 24. In the present embodiment, although the resistor 22 is used as a resistance coupling element for connecting the Q modulation signal to the first detection circuit 24, other resistance coupling elements may be used. For example, a capacitor, a transformer, or an optical coupling may be used. As shown, the first detection circuit 24 includes a diode 24a and a capacitor 24b. However, the first detection circuit 24 may use any equivalent circuit for detecting the average power of the Q modulated signal. In addition, the input signal is detected by connecting the Q modulation signal to the first detection circuit 24, but as another example, the I modulation signal is connected to the first detection circuit 24 to connect the I modulation signal. May be detected. The first detection circuit 24 generates a DC voltage corresponding to the average power of the Q modulated signal. The DC voltage is amplified in a first amplifier circuit 26 having a variable gain element 28 that can adjust the gain.

Next, referring to detecting the QPSK modulated RF signal as an output signal, the RF coupler 30 leaks a small portion of the QPSK modulated RF signal amplified by the serially connected amplifiers 14. ) To the second detection circuit 32. For example, the RF coupler 30 may include a microstrip coupler for an edge couple or a portion of the QPSK modulated RF signal to detect an average power of the QPSK modulated RF signal. Any type of coupler can be used to provide the same. One end of the RF coupler 30 is grounded through a resistor 34. Similarly to the first detection circuit 24, the second detection circuit 32 also includes a diode 32a and a capacitor 32b. Here, the second detection circuit 32 may use any other practical equivalent circuit capable of detecting the average power of the QPSK modulated RF signal. The second detection circuit 32 generates a DC voltage corresponding to the average power of the QPSK modulated RF signal. The DC voltage is amplified in a second power amplifier 34 having a variable gain element 36 that can adjust the gain.

Hereinafter, a method of determining whether a failure occurs in the signal path of the transmitter 20 with the average power of the detected input signal (Q modulated signal) and output signal (QPSK modulated RF signal) will be described. The first amplification circuit 26 and the second amplification circuit 34 respectively provide the generated DC voltages to a differential circuit 38, and the differential circuit 38 compares the two DC voltages. An error voltage signal indicating an difference between the two DC voltages is provided to an A / D converter 40. The A / D converter 40 converts the error voltage signal into a digital signal corresponding to the error voltage signal and provides it to the processor 42 for processing. Here, it can be seen that the gain of the first amplifier 26 and the gain of the second amplifier 34 are adjusted through the variable gain elements 28 and 36, respectively. This means that the fault detection circuitry is initialized on a predetermined basis by the amplification circuits 26 and 36 with the variable gain elements 28 and 36, thereby causing any gain in the signal path of the base station transmitter 20. Or loss can be calculated. On the other hand, the serially connected amplifiers 14 gain the QPSK modulated RF signal to be accommodated in the amplifier circuits 26 and 24 with the variable gain elements 26 and 24. Thus, the average powers corresponding to the two DC voltage signals can be accurately compared. Here, in another alternative, the DC voltage signals corresponding to the average power are compared in the differential amplifier 38 without gain adjustment, and the error voltage signal obtained as a result of the comparison is converted into a digital signal in the A / D converter 40. The processor 42 may then calculate any gain or loss in the signal path of the base station transmitter 20. In this case, the variable gain elements 28 and 36 are not necessary.

The processor 42 receives the digital signal corresponding to the error voltage signal from the A / D converter 40 and compares the digital signal corresponding to the error error voltage signal with a preset threshold. The preset threshold is specifically stored in the processor 42 or in a memory accessed by the processor 42. And the threshold value is a maximum allowable value of the error voltage signal in consideration of an environment such as, for example, temperature, electromagnetic interface (EMI), and electrical properties (eg, device operating parameters, frequency signal). It is decided. Therefore, if the digital corresponding to the error voltage signal does not exceed the preset threshold, the processor 42 is free from the signal path of the base station transmitter 20, and the transmitter 20 is operating normally. To judge.

On the other hand, if the digital corresponding to the error voltage signal exceeds the predetermined threshold value, the processor 42 may determine that the signal path of the base station transmitter 20 has failed and respond appropriately. For example, the processor 42 will drive a redundant base station transmitter to send a signal or notify the system controller that a failure has occurred to send traffic to another path.

Hereinafter, a detailed operation for detecting the failure in the signal path of the base station transmitter according to the present invention will be described in detail.

First, the operating principle of the fault detection circuit is that if the power of the input signal (e.g., the Q modulated signal) is increased, the power of the output signal (QPSK modulated amplified by the series-connected amplifiers 14) Due to the fact that the RF signal) will be increased equally or proportionally. On the other hand, if the power of the input signal (e.g., the Q modulated signal) is reduced, then the power of the output signal (QPSK modulated RF signal amplified by the serially connected amplifiers 14) is equally or proportional. Will be reduced. The difference between the power of the Q modulated signal and the power of the QPSK modulated RF signal (e.g., the error voltage signal) does not exceed the preset threshold if the base station transmitter 20 operates normally without failure.

Here, any gain or loss in the signal path of the base station transmitter 20 compares the respective average powers detected by the first detection circuit 24 and the second detection circuit 32 in the differential circuit 38. It can be seen that the error voltage signal obtained as a result of the comparison is calculated by the processor 42 after converting the digital signal from the A / D converter. In this case, the preset threshold is adjusted based on the power of the input signal (e.g., the power of the Q modulated signal). Therefore, the processor 42 must know the value of the power (i.e., the Q modulated signal) of the input signal. 3 illustrates a base station transmitter having a failure detection circuit for detecting a failure in a signal path of a base station transmitter 20 according to another embodiment of the present invention. Referring to FIG. 3, the configuration of FIG. 2 is the same as that of FIG. 2, and only the DC voltage corresponding to the average power of the Q modulated signal is converted into digital corresponding to the DC voltage, and the digital is converted into the processor 42. It is different in that it is provided in. Here, if the A / D converter 40 operates in a time-sharing manner, the above-described conversion (referring to digital conversion of a DC voltage representing an average power of a Q modulated signal) is performed by the error voltage. This can be done with signal conversion. Meanwhile, as illustrated in FIG. 3, a separate A / D converter 44 for converting the average power of the input signal (Q modulated signal) into a digital signal may be configured. The A / D converter 44 converts the average power corresponding to the input signal output from the amplifying circuit 26 into a digital signal and provides the same to the processor 42. Then, the processor 42 recognizes the average power of the input signal, and determines the threshold value corresponding to the maximum allowable value of the error voltage signal with reference to the input signal. Thereafter, the processor 42 compares the error value output from the A / D converter 40 with the determined threshold value, and determines that a failure occurs when the error value is larger than the threshold value. Also, as noted earlier, in this case the variable gain elements 28 and 36 are not necessary.

4 illustrates a base station transmitter having a failure detection circuit for detecting a failure in a signal path of a base station transmitter according to another embodiment of the present invention. Referring to FIG. 4, the average power represented by the digital power is directly converted by converting the DC voltage corresponding to the average power of the Q modulated signal, which is the input signal, into digital, and converting the average power of the QPSK modulated RF signal into digital. To the processor 42. Then, the processor 42 obtains an error value by comparing the two average powers represented by the digital, and compares the error value with a preset threshold to determine whether there is a failure. If the A / D converter 40 operates in a time sharing scheme, the above conversions (convert the average power of the input signal to digital and the average power of the output signal to digital) may be performed in parallel. As another example, a separate A / D converter 44 may be configured to perform the above-described digital conversions in different A / D converters. In this case, the gain adjusting elements 28 and 36 and the differential circuit 38 are not necessary.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.

As described above, the present invention sets an error that may occur between an input signal (I modulated signal and a Q modulated signal) and an output signal (QPSK modulated RF signal) in a transmitter, and detects a difference between the two signals to detect a disturbance of the transmitter. By detecting, it is possible to detect the failure of the transmitter more easily and stably.

Claims (25)

A method for detecting a failure in a transmitter receiving an input signal having a first power value and transmitting an output signal having a second power value, Determining an error value based on a difference between the first power value and the second power value; Comparing the error value with a threshold indicating a maximum allowable value between the first power value and the second power value, If the error value exceeds the threshold value, indicating a failure of the transmitter. The method of claim 1, The input signal is an amplitude modulated signal, and the output signal is a modulated RF signal. The method of claim 1, Detecting a first power value of the input signal, and generating a voltage value corresponding to the first power value. The method of claim 3, Amplifying the voltage value to calculate any gains or losses in the transmitter. The method of claim 3, And converting the voltage value into digital corresponding to the voltage value. The method of claim 1, The first power value is characterized in that the average power value of the input signal. The method of claim 1, Detecting a second power value of the output signal and generating a voltage value corresponding to the second power value. The method of claim 7, wherein Amplifying the voltage value to calculate any gains or losses at the transmitter. The method of claim 7, wherein And converting the voltage value into digital corresponding to the voltage value. The method of claim 1, And the second power value is an average power value of the output signal. The method of claim 1, Converting the error value into digital corresponding to the error value, And the digital corresponding to the error value is compared with the threshold value to detect the failure of the transmitter. An apparatus for detecting a failure in a transmitter that receives an input signal having a first power value and transmits an output signal having a second power value, A differential circuit for determining an error value based on a difference between the first power value and the second power value; A comparison circuit for comparing the error value with a threshold indicating a maximum allowable value between the first power value and the second power value, And if the error value exceeds a threshold, it indicates a failure of the transmitter. The method of claim 12, The input signal is a Q (quadrature) modulated signal, and the output signal is a modulated RF signal. The method of claim 12, And said modulating signal is an amplitude modulating signal. The method of claim 12, And a detection circuit for detecting a first power value of the input signal and generating a voltage value corresponding to the first power value. The method of claim 15, And an amplifier circuit for amplifying the voltage value to calculate any gains or losses in the transmitter. The method of claim 15, And a converter for converting the voltage value into a digital corresponding to the voltage value. The method of claim 15, And a coupler for coupling a portion of the input signal to the detection circuit. The method of claim 12, And the first power value is an average power value of the input signal. The method of claim 12, And a detection circuit for detecting a second power value of the output signal and generating a voltage value corresponding to the second power value. The method of claim 20, And an amplifier circuit for amplifying the voltage value to calculate any gains or losses in the transmitter. The method of claim 20, And a converter for converting the voltage value into a digital corresponding to the voltage value. The method of claim 12, And the second power value is an average power value of the output signal. The method of claim 12, And the differential circuit obtains a difference between a first power value corresponding to the first power value and a second voltage value corresponding to the second power value. The method of claim 12, And a converter for converting the error value into digital corresponding to the error value. And the digital corresponding to the error value is compared with the threshold value to determine whether the transmitter is faulty.