KR20040085359A - Power Detector and Detecting Method using Digital Signal Processing - Google Patents

Abstract

PURPOSE: A power detector by using a digital signal processing and a method for measuring the same are provided to exactly measure the power of the reception signal and the voltage standing wave ratio(VSWR) of the antenna without changing the characteristics due to the temperature change. CONSTITUTION: A power detector by using a digital signal processing includes an analog down conversion module(221), a digital power detector module(222) and a power detector control module(223). The analog down conversion module(221) translates the received radio frequency(RF) signal to an intermediate frequency(IF) bandwidth. The digital power detector module(222) converts the translated analog signal of IF bandwidth into a digital signal, translates the digital signal into baseband and measures the power of the digital signal. And, the power detector control module(223) controls the analog down conversion module(221) and the digital power detector module(222), calculates the power and the VSWR of the signal based on the output value of the digital power detector module(222) by using the digital signal process and analyzes the characteristics for each frequency bandwidth.

Description

Power detector using digital signal processing and its measuring method {Power Detector and Detecting Method using Digital Signal Processing}

The present invention relates to a power meter using digital signal processing (DSP), a measuring method thereof, and a computer-readable recording medium for realizing the method. Regarding a power meter capable of accurately measuring power and standing standing wave ratio (VSWR) without changing characteristics according to the change, and a measurement method thereof and a computer-readable recording medium recording a program for realizing the method. will be.

In general, the base station or the relay device of the mobile communication system measures the power of the signal transmitted by the mobile terminal in order to control the power. That is, if the power of the mobile terminal measured at the base station or the relay device is small, more power is required, and if the measured power of the mobile terminal is large, the power is required to be reduced.

In order to control power in the base station or the relay device as described above, the power of the signal transmitted from the mobile terminal must be accurately measured, and this role is a power detector (PD).

1 is an exemplary configuration diagram of a base station to which a power meter according to the prior art is applied. As shown in FIG. 1, the signal transmitted from the mobile terminal is distributed in both directions by the directional coupler 110 between the portion 120 for measuring the standing wave ratio and the portion 130 for measuring the received power.

The portion 120 for measuring the standing wave ratio includes: a fixed attenuator 121 for attenuating the signal strength to an appropriate intensity for signal processing; an amplifier 122 for amplifying the attenuated signal; And a detector 123 for converting power into a voltage and an analog-digital converter 124 for converting the analog signal converted to the voltage into a digital signal.

On the other hand, the portion 130 for measuring the power of the signal includes a fixed attenuator 131 for attenuating the signal strength to an appropriate intensity for signal processing, and a detector 132 for converting the power of the attenuated signal into voltage. And an analog-digital converter 133 for converting the analog signal converted into the voltage into a digital signal.

In addition, the signals digitally converted by the analog-digital converters 124 and 133 are input to the controller 140, and the controller 140 calculates the power and standing wave ratio of the received signal using the digitally converted signals. This is done.

That is, in the conventional power meter after detecting the signal using the detector (123, 132) implemented as an integrated circuit (IC) without down-converting the radio frequency (RF) signal transmitted through the air to the baseband The power is measured by converting the detected signal into digital.

However, since ICs are sensitive to temperature changes, conventional power detectors are also sensitive to temperature changes, and since the step of detecting a signal is performed in an analog manner, the resolution capable of expressing power is lowered to accurately measure power. There is a problem that cannot be done.

The present invention has been proposed to solve the above problems, and a power meter capable of accurately measuring power and standing wave ratio (VSWR) without changing characteristics due to temperature change by using digital signal processing and its measurement It is an object of the present invention to provide a computer-readable recording medium storing a method and a program for realizing the method.

1 is an exemplary configuration of a base station to which a power meter according to the prior art is applied.

2 is a block diagram of a base station to which a digital power meter according to the present invention is applied;

3 is a detailed block diagram of an embodiment of the analog down converter of FIG. 2;

4 is a detailed block diagram of an embodiment of the digital power detector of FIG.

FIG. 5 is a detailed block diagram of an embodiment of the signal strength meter of FIG. 4. FIG.

FIG. 6 is a detailed flowchart illustrating a control operation process, a power calculation process, and a frequency analysis process performed in the power meter controller of FIG. 2.

* Explanation of symbols for the main parts of the drawings

110: directional coupler

120, 310, 410: part for measuring standing wave ratio

130, 320, 420: part for measuring received power

140: control unit 121, 131, 312, 322: fixed attenuator

122, 316: amplifiers 123, 132: detectors

124, 133, 411, 421: Analog-Digital Converter (ADC)

210: directional coupling means

220: power detector (Power Detector, PD)

221: Analog Down Conversion Module (ADCM)

222: Digital Power Detector Module (DPDM)

223: Power Detector Control Module (PDCM)

230: modem means or display means

311, 313, 321, 323: Band Pass Filter (BPF)

314, 324,: mixer

315, 325: Low Pass Filter (LPF)

330: frequency synthesizer

421, 422: Numercal Controlled Oscillator (NCO)

423 digital filter

413, 424: Signal Strength Indicator (SSI)

510 loop filter 511 integrator

512 loop gain 513, 530 multiplier

520: comparator 521: threshold

522: adder

The apparatus of the present invention for achieving the above object is applied to a base station or a repeater, and in a power meter using a digital signal processing (Digital Signal Processing, DSP), the received RF (Radio Frequency) signal is an intermediate frequency (Intermediate Frequency, Analog downconverting means for downconverting to the IF) band; Digital power measurement means for converting the down-converted IF band analog signal into a digital signal and then down-converting to a base band to measure power of the down-converted digital signal; And controlling the analog downconverting means and the digital power measuring means, and calculating power and standing wave ratios of signals based on output values of the digital power measuring means using digital signal processing and analyzing characteristics for each frequency band. Power meter control means.

On the other hand, the present invention, a method for measuring power in a power meter applied to a base station or a repeater, the method comprising: a first step of converting the received radio frequency (RF) signal into an intermediate frequency (IF) band; Converting the down-converted IF band analog signal into a digital signal; A third step of down converting the IF band signal converted into the digital signal to a base band; And a fourth step of measuring power and standing wave ratio of the received signal by measuring the strength of the digital signal down-converted to the baseband.

On the other hand, the present invention, applied to a base station or a repeater, a power meter equipped with a processor, a first function for down-converting the received RF (Radio Frequency) signal to an intermediate frequency (IF) band; A second function of converting the down-converted IF band analog signal into a digital signal; A third function of down-converting a signal of the IF band converted to the digital signal to a base band; And a computer-readable recording medium having recorded thereon a program for realizing a fourth function of measuring the power and standing wave ratio of the received signal by measuring the strength of the digital signal down-converted to the baseband.

The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a block diagram of a base station to which a digital power meter according to the present invention is applied, and a signal transmitted from the mobile terminal is received by the directional combining means 210 and input to the power detecting means 220. The power detection unit 220 is an analog down conversion module (Analog Down Conversion Module, ADCM, 221) for down-converting the input received signal, for converting the down-converted signal to digital and then measuring the power of the signal. The power and standing wave ratio of the received signal is calculated using the digital power detector module (DPDM) 222 and the measured power of the signal, and the analog down converter 221 and the digital power controller 222 And a power detector control module (PDCM) 223 for generating a necessary control signal. Then, the power measured by the power detecting means 220 is transmitted to the modem means or the display means 230 to be modulated or displayed.

FIG. 3 is a detailed block diagram illustrating an analog downconverter of FIG. 2. FIG. As shown in FIG. 3, the analog down-conversion unit 221 applied to the present invention includes two portions, a portion 310 for measuring the standing wave ratio of the received signal and a portion 320 for measuring the power of the received signal. Are largely distinguished.

First, the portion 310 for measuring the standing wave ratio of the received signal excludes a signal of a band supported by a power amplifier (hereinafter referred to as 'PA') from the signal received by the directional coupling means 210. Band pass filter (BPF) 311 to remove signal components, fixed attenuator 312 to attenuate the signal strength to an appropriate level for signal processing, and PA support in the signal attenuated by the fixed attenuator Mixer for down-converting the RF (Radio Frequency) signal passed through the band pass filter 313 and the band pass filter 313 to remove the signal components except the signal of the band (Intermediate Frequency, IF) signal ( 314, low pass filter (LPF) for removing unwanted signal components and noise in bands other than the band of interest in the signal downconverted by mixer 314. And an amplifier 316 for amplifying the signal from which noise or the like has been removed by the low pass filter 315.

On the other hand, the portion 320 for measuring the power of the received signal is a portion for measuring the standing wave ratio of the received signal except that an amplifier for amplifying a signal from which noise or the like is removed by a low pass filter. The configuration is the same as that of 310. In addition, a signal input to the mixers 314 and 324 for downconverting the RF signal into an intermediate frequency (IF) signal is generated by the signal generator 330 and jointly provided.

Meanwhile, when detecting power between the power amplifier and the input / output router, the band pass filters 311 and 321 may be removed.

4 is a detailed block diagram of an embodiment of the digital power measurement unit of FIG. 2. As shown in FIG. 4, the digital power measurement unit 222 is also largely divided into two parts, a part 410 for measuring the standing wave ratio of the received signal and a part 420 for measuring the power of the received signal.

First, the portion 410 for measuring the standing wave ratio of the received signal is an analog-to-digital converter 411 for converting the analog IF signal transmitted from the analog downconverter 221 into a digital IF signal. And a numerically controlled oscillator 412 for down-converting the converted signal into a digital baseband signal and a signal strength indicator (SSI) 413 for measuring the strength of the down-converted digital baseband signal.

On the other hand, the portion 420 for measuring the power of the received signal is an analog-to-digital converter 421 for converting the analog IF signal transmitted from the analog down-conversion unit 221 into a digital IF signal, the conversion to the digital IF signal A numerically controlled oscillator 422 for downconverting the converted signal into a digital baseband signal, a digital filter 423 and a digital filter for selecting a signal of interest for all channels or for each channel for the downconverted digital baseband signal. A signal strength meter 424 for measuring the power of the output signal.

In this case, the digital power oscillators 412 and 422 and the digital filter 423 are controlled using the control signals of the power meter controller 223 in the process of detecting the digital power to measure the power of each channel as well as the entire band. The frequency characteristics can be analyzed. That is, when the digital filter 423 selects a channel of interest by the control signal of the power meter controller 223, the power of the signal of the selected channel is measured.

5 is a detailed block diagram illustrating an exemplary embodiment of the signal strength meter of FIG. 4. The power of the signal is indirectly measured by the signal strength meter shown in FIG. 5 and the principle is as follows.

In order to keep the output value of the multiplier 530 constant as a threshold, the output value of the loop filter 510 fed back to the multiplier 530 should be adjusted according to the change of the input signal of the multiplier 530. Accordingly, the comparator 520 compares the output of the multiplier 530 with the threshold value 521 and transmits the difference value to the loop filter 510, and the loop filter 510 has a loop gain ( Multiply by 512) and transfer to the multiplier. Through this process, the output of the multiplier 530 may maintain a threshold regardless of the change in the input signal of the multiplier 530. That is, when the input signal of the multiplier 530 decreases, the output signal of the loop filter 510 increases, so that the output signal of the multiplier 530 maintains the threshold 521, and conversely, the input signal of the multiplier 530 increases. If the output signal of the loop filter 510 is increased. Therefore, using the output signal of the loop filter 510 can indirectly measure the power of the signal.

The power meter controller 223 sets the local frequency of the analog down converter 221 and controls the digital filter 423 and the signal strength meters 413 and 424 of the digital power measurer 222. The power meter controller 223 calculates power and standing wave ratios of signals using the output signals of the signal strength meters 413 and 424 of the digital power meter 222, and analyzes frequency characteristics.

6 is a detailed flowchart illustrating a control operation process, a power calculation process, and a frequency analysis process performed by the power meter controller of FIG. 2.

As shown in FIG. 6, when a signal is input to the power meter controller 223 (601), it is determined whether the set values of the analog down-converter 221 and the digital power measurer 222 are changed (602). If the set value is changed, the local frequency of the analog down-converter 221 and the digital filter 423, the numerically controlled oscillators 411 and 412 of the digital power measurement unit 222, and the signal strength meters 413 and 424. After resetting according to the changed value (603 to 606), the power of the input signal is measured and the standing wave ratio is calculated (607 and 608). However, when the set value is not changed, the power of the input signal is measured while calculating the standing wave ratio while maintaining the set values of the analog down-converter 221 and the digital power measuring unit 222 (607 and 608). .

Meanwhile, operations performed by the power meter controller 223 are implemented using digital signal processing.

As described above, the method of the present invention may be implemented as a program and stored in a recording medium (CD-ROM, RAM, ROM, floppy disk, hard disk, magneto-optical disk, etc.) in a computer-readable form. Since this process can be easily implemented by those skilled in the art will not be described in more detail.

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and various substitutions, modifications, and changes are possible in the art without departing from the technical spirit of the present invention. It will be clear to those of ordinary knowledge.

The present invention as described above, by applying the digital signal processing (Digital Signal Processing, DSP) method to accurately measure the power of the received signal and the Standing Voltage Ratio (Voltage Standing Wave Ratio, VSWR) of the antenna without changing the characteristics of the temperature change It can be effective.

In addition, the present invention has the effect of effectively diagnosing and monitoring the base station and the relay by analyzing the frequency characteristics of the signal for each band or each channel using the down-converted signal for power measurement.

Claims (8)

Applied to a base station or a repeater, the power measuring device using digital signal processing (Digital Signal Processing, DSP), Analog downconverting means for downconverting the received RF signal to an intermediate frequency (IF) band; Digital power measurement means for converting the down-converted IF band analog signal into a digital signal and then down-converting to a base band to measure power of the down-converted digital signal; And Power for controlling the analog downconverting means and the digital power measuring means, calculating power and standing wave ratio of a signal based on an output value of the digital power measuring means using digital signal processing, and analyzing characteristics for each frequency band Meter control means Power meter using a digital signal processing comprising a. The method of claim 1, The portion for measuring the standing wave ratio of the digital power measuring means, An analog-digital converter for converting the analog IF signal transmitted from the analog downconverting means into a digital IF signal; A numerically controlled oscillator for down converting the signal converted into the digital IF signal into a digital baseband signal; And Signal strength measuring unit for measuring the strength of the down-converted digital baseband signal Power meter using a digital signal processing comprising a. The method of claim 1, The portion for measuring power of the digital power measuring means, An analog-digital converter for converting the analog IF signal transmitted from the analog downconverting means into a digital IF signal; A numerically controlled oscillator for down converting the signal converted into the digital IF signal into a digital baseband signal; A digital filter for selecting a band of interest currently for the down-converted digital baseband signal; And Signal strength measuring unit for measuring the power of the signal of the band selected by the digital filter Power meter using a digital signal processing comprising a. The method of claim 2 or 3, The signal strength measuring unit, A comparator for detecting a difference between a change in an input signal value and a threshold; A loop filter for detecting a change in the input signal by multiplying and integrating the difference detected by the comparator with a loop gain; And A mixer for multiplying and mixing the output and input signals of the loop filter Power meter using a digital signal processing comprising a. In the method for measuring power in a power meter applied to a base station or repeater, A first step of down-converting the received radio frequency (RF) signal to an intermediate frequency (IF) band; Converting the down-converted IF band analog signal into a digital signal; A third step of down converting the IF band signal converted into the digital signal to a base band; And A fourth step of measuring power and standing wave ratio of the received signal by measuring the strength of the digital signal down-converted to the baseband Power measurement method comprising a. The method of claim 5, wherein The fourth step, Detecting a difference between the change of the digital signal down-converted to the baseband and a predetermined threshold value; A sixth step of integrating the detected difference by multiplying a loop gain; And A seventh step of measuring power and standing wave ratio of the received signal according to the change of the integral value Power measurement method comprising a. The method of claim 5, wherein Generating a control signal of the power meter, measuring power for each frequency band of the received signal, and analyzing a characteristic thereof; Power measurement method further comprising. Applied to the base station or repeater, the power meter with a processor, A first function of down converting the received RF signal into an intermediate frequency (IF) band; A second function of converting the down-converted IF band analog signal into a digital signal; A third function of down-converting a signal of the IF band converted to the digital signal to a base band; And A computer-readable recording medium having recorded thereon a program for realizing a fourth function of measuring the power and standing wave ratio of the received signal by measuring the strength of the baseband downconverted digital signal.