CN103281274A - Digital predistortion measurement system and power value calibration measurement method thereof - Google Patents
Digital predistortion measurement system and power value calibration measurement method thereof Download PDFInfo
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- CN103281274A CN103281274A CN2013101481220A CN201310148122A CN103281274A CN 103281274 A CN103281274 A CN 103281274A CN 2013101481220 A CN2013101481220 A CN 2013101481220A CN 201310148122 A CN201310148122 A CN 201310148122A CN 103281274 A CN103281274 A CN 103281274A
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Abstract
The invention discloses a digital predistortion measurement system and a power value calibration measurement method of the system. The system comprises a predistortion digital processing unit, and an uplink transmission unit and a coupling loop transmission unit which are connected with the predistortion digital processing unit, wherein the uplink transmission unit comprises a digital-analog converter (DAC), an upper frequency converter, a power amplifier coupler and a power meter which are sequentially connected; the coupling loop transmission unit comprises a lower frequency converter and an analog-digital converter (ADC); the coupler, the lower frequency converter and the ADC are sequentially connected; and the upper frequency converter is connected with the lower frequency converter by a local oscillator. The digital predistortion measurement system can be used for the subsequent digital predistortion measurement process according to the frequency value to be tested obtained by measurement and the sampling target value corresponding to the rated power value, and effectively avoids the measuring error caused by coupling loop insertion loss and nonlinearity, thus improving the measurement accuracy and improving the improvement effect of digital predistortion treatment for the intermodulation distortion of a power amplifier.
Description
Technical field
The present invention relates to the technical field of short wave communication, particularly a kind of digital pre-distortion measuring system and performance number thereof calibration method of measurement.
Background technology
Be the make decision principal element of communication distance of identical natural environmental condition in short wave communication field transmitting power, for improving transmitting power, add a stage power amplifier at digital modulator and D/A output usually.Because the non-linear meeting of power amplifier produces non-linear modulation to two or more frequencies of input signal, generates many combination frequency signals, i.e. Intermodulation Interference.Intermodulation Interference can cause interference to the communication of adjacent channel, can influence its normal collection of letters effect if Intermodulation Interference falls in the passband of contiguous receiving equipment, and some signal powers of disturbing are excessive, then can barrage reception equipment order communication interrupt fully.
For eliminating or alleviating the Intermodulation Interference problem, need improve the linearity of power amplifier.Currently be applicable to that the linearization technique of high power amplifier is power amplifier characteristic compensation, i.e. pre-distortion technology.Existing LUT look-up table predistortion scheme is by the measurement to the non-linearity of power amplifier degree, generate reverse than positive system, and with its calibration coefficient storage in corresponding look-up table, the static loading used at work.This method can only the distortion of compensating non-linear static amplifier, and the linearisation of kinematic nonlinearity degree in the amplifier is not provided.For overcoming this restriction, there is method to propose multidimensional lookup table digital baseband pre-distortion technology, the dynamic change of envelope amplitude, frequency or power by instantaneous input signal and real time altering parameter reference.
No matter adopt the technical method of which kind of pre-distortion system, its system realizes block diagram all as shown in Figure 1, and difference is the Processing Algorithm difference in the predistortion digital processing element.In system block diagram shown in Figure 1, carrying out pre-distortion parameters when being the power amplifier feature measurement, power samples level with predistortion digital processing element and ADC junction is with reference to target value, owing to there be Insertion Loss and nonlinear device in the band in the coupling circuit, therefore can cause having error in the predistortion measuring process, and the calibration effect after the reduction compensation.
Summary of the invention
The shortcoming that the objective of the invention is to overcome prior art provides a kind of digital pre-distortion measuring system with not enough.
Another object of the present invention is to, a kind of performance number calibration method of measurement based on the digital pre-distortion measuring system is provided.
In order to reach above-mentioned first purpose, the present invention by the following technical solutions:
Digital pre-distortion measuring system of the present invention, comprise the predistortion digital processing element, and the uplink unit that is connected with the predistortion digital processing element and coupling circuit transmission unit, described uplink unit comprises DAC digital to analog converter, upconverter, power amplifier coupler and the power meter that is linked in sequence; The coupling circuit transmission unit comprises low-converter and ADC analog to digital converter, and described coupler, low-converter and ADC analog to digital converter are linked in sequence, and also connect by local oscillator between described upconverter and the low-converter.
Preferably, described predistortion digital processing element also is connected with control unit, described control unit is given the predistortion digital processing element for sending control command, and described control command comprises that calibration is regulated, begun to frequency setting, power output, calibration and measurement are calibrated, begun to measure and finish in affirmation.
Preferably, described control unit is connected with human-computer interaction interface, and described human-computer interaction interface is used for showing state, the parameter of current power amplifier feature measurement, scale value and the measurement result of current power amplifier output power value correspondence.
Preferably, described coupler comprises power attenuator, high transformation ratio line transformer and the forward and reverse detection measuring circuit of measuring the amplitude control of coupled signal for calibration, described power attenuator links to each other with line transformer respectively with forward and reverse detection measuring circuit, and its output connects uplink unit and coupling circuit transmission unit respectively.
In order to reach above-mentioned second purpose, the present invention by the following technical solutions:
The performance number calibration method of measurement of digital pre-distortion measuring system of the present invention comprises the steps:
S1, frequency values and the initialization power grade of current system are set by human-computer interaction interface;
S2, begin calibration and measure, the predistortion digital processing element produces to be measured required baseband signal and generates radiofrequency signal by the DAC digital to analog converter, is input in the power amplifier to be measured;
S3, the power indication by observing power meter are also regulated power grade and are arranged corresponding rated power size is adjusted in power output;
S3, confirm scale value, success back system on human-computer interaction interface, and is stored in the scale value echo of current frequency and performance number correspondence in the predistortion digital processing element simultaneously;
After S4, the current scale value success of affirmation, control unit sends control command makes predistortion digital processing element automatic switchover frequency to next frequency values to be measured place, repeats previous action corresponding scale value measurement under all frequency values subsequently and finishes;
S5, treat that the calibration of whole frequency values is finished after, operating system begins the power amplifier feature measurement, this moment, the predistortion digital processing element can be input in the power amplifier according to the required test signal of gained scale value generation, and finish the measuring process that remains whole power amplifier characteristic compensations automatically, after finishing, measurement the result can be reported human-computer interaction interface.
Preferably, set successfully among the step S1 after, the parameter that power amplifier returns has operating state, frequency, power and ACK.
Return operating state, fault message and forward and reverse performance number parameter when preferably, step S3 carries out.
Preferably, after all surveying work is finished, select to open or close predistortion function by human-computer interaction interface, select to open then when transmitter is in emission state, by the predistortion digital processing element when finishing filtering to sampled audio, modulation and automatic gain control, will by parameter lookup table index such as frequency and power to penalty coefficient to filtering and the modulation after base-band audio signal handle, namely finish the preposition predistortion of final-stage power amplifier is handled, the analog radio-frequency signal after the processing is input to and carries out power amplification in the power amplifier.
The present invention has following advantage and effect with respect to prior art:
1, the present invention can avoid the measure error that coupling circuit causes, and improves the effect that predistortion is improved the communication equipment intermodulation distortion.
2, the present invention proposes the performance number calibration method of measurement of digital pre-distortion measuring system, improved the accuracy of measurement result, promoted the improve effect of digital pre-distortion processing to the power amplifier intermodulation distortion.
3, the present invention has increased monitoring and the control to predistortion measuring process, intermediate object program, has guaranteed the safe, reliable of measuring process, is applicable to high-power communication equipment more.
4, simple, the easy row of measuring system improvement project of the present invention and calibration method of measurement, improvement cost is low, efficiency-cost ratio is high, has more practicality.
Description of drawings
Fig. 1 is the structure chart of digital pre-distortion measuring system in the prior art;
Fig. 2 is the structure chart of digital pre-distortion measuring system of the present invention;
Fig. 3 is the flow chart of performance number calibration method of measurement of the present invention.
Embodiment
The present invention is described in further detail below in conjunction with embodiment and accompanying drawing, but embodiments of the present invention are not limited thereto.
Embodiment
As shown in Figure 2, digital pre-distortion measuring system of the present invention mainly comprises human-computer interaction interface, control unit, predistortion digital processing element, DAC digital-to-analogue conversion, ADC analog-to-digital conversion, upconverter, low-converter, local oscillator, power amplifier, coupler, power meter.
Upconverter and low-converter, local oscillator, DAC, ADC and power amplifier interconnect in the system, have constituted the uplink unit of systematic survey and emission state work, are responsible for realizing the function of signal filtering, analog-modulated, digital-to-analogue conversion and power amplification.
Coupler connects power amplifier, power meter and low-converter, has constituted the coupling circuit transmission unit, the output signal of power amplifier need be can't harm transmission on the one hand, shows performance number accurately by power meter; Needing on the other hand is coupled obtain with output signal with frequently, homophase but the relative less coupled signal of amplitude is used for carrying out the power amplifier feature measurement.For being applicable to the calibration measurement, the present invention improves coupler, has increased power attenuator in coupling circuit, can select corresponding power attenuation grade by analog switch, corresponding adjusting feedback signal size.
The predistortion digital processing element, it links to each other with control unit, accepts corresponding control command, comprises that frequency setting, power output regulate (coarse adjustment and fine setting), begin calibration, confirm scale value, begin to measure, finish calibration and measurement etc.Measure by normal communications signal processing capacity such as original baseband signal filtering, modulation, automatic gain control and predistortion except finishing for improved predistortion digital processing element, the correlation function of compensation, also realized in the calibration measuring process, producing the permanent width of cloth measuring-signal of single carrier, and can be according to control unit order dynamic adjustments signal amplitude, simultaneously sampled signal is separated the mediation detection and handle, obtain calibrating measurement result.
Newly-increased human-computer interaction interface, it is the interactive interface between system equipment and the operating personnel, can show state, the parameter of current power amplifier feature measurement, the scale value of current power amplifier output power value correspondence, measurement result etc.Operating personnel comprise beginning/end measurement, begin calibration, confirm scale value, signal power adjusting etc. the process control of power amplifier feature measurement simultaneously, all realize by this interface.
Newly-increased control unit connects human-computer interaction interface and predistortion digital processing element, the operational order of being responsible for human-computer interaction interface is assigned conveys to the predistortion digital processing element, gives interface display with corresponding measurement state and the loopback as a result of processing unit feedback simultaneously.
As shown in Figure 3, the performance number of digital pre-distortion measuring system of the present invention calibration method of measurement comprises the steps:
S1, frequency values and the initialization power grade of current system are set by human-computer interaction interface;
S2, begin calibration and measure, the predistortion digital processing element produces to be measured required baseband signal and generates radiofrequency signal by the DAC digital to analog converter, is input in the power amplifier to be measured;
S3, the power indication by observing power meter are also regulated power grade and are arranged corresponding rated power size is adjusted in power output;
S3, confirm scale value, success back system on human-computer interaction interface, and is stored in the scale value echo of current frequency and performance number correspondence in the predistortion digital processing element simultaneously;
After S4, the current scale value success of affirmation, control unit sends control command makes predistortion digital processing element automatic switchover frequency to next frequency values to be measured place, repeats previous action corresponding scale value measurement under all frequency values subsequently and finishes;
S5, treat that the calibration of whole frequency values is finished after, operating system begins the power amplifier feature measurement, this moment, the predistortion digital processing element can be input in the power amplifier according to the required test signal of gained scale value generation, and finish the measuring process that remains whole power amplifier characteristic compensations automatically, after finishing, measurement the result can be reported human-computer interaction interface.
Below in conjunction with technical scheme of the present invention this calibration method of measurement is done concrete elaboration: system normally moves the back arranges current system by human-computer interaction interface frequency values and initial power grade, arranging successfully, the back power amplifier should have relevant parameter to return, beginning calibration subsequently measures, the predistortion digital processing element can produce to be measured required baseband signal and generates radiofrequency signal by DAC, is input in the power amplifier to be measured.Power indication by observing power meter is subsequently also regulated power grade and is arranged corresponding rated power size is adjusted in power output, confirm scale value then, success back system can be with the scale value echo of current frequency and performance number correspondence on human-computer interaction interface, and is stored in simultaneously in the predistortion digital processing element.
After confirming current scale value success, control unit can send control command makes predistortion digital processing element automatic switchover frequency to next frequency values to be measured place, repeats previous action corresponding scale value measurement under all frequency values subsequently and finishes.After treating that whole frequency values calibrations are finished, operating system begins the power amplifier feature measurement, this moment, the predistortion digital processing element can be input in the power amplifier according to the required test signal of gained scale value generation, and finish the measuring process that remains whole power amplifier characteristic compensations automatically, after finishing, measurement the result can be reported human-computer interaction interface.Because the scale value measuring process has obtained coupler and the power meter place sampled value size of power-handling capability correspondence accurately, therefore avoided Insertion Loss and the non-linear measure error that causes of coupling circuit.
After all surveying work is finished, can select to open or close predistortion function by human-computer interaction interface, select to open then when transmitter is in emission state, by the predistortion digital processing element when finishing filtering to sampled audio, modulation and automatic gain control, will by parameter lookup table index such as frequency and power to penalty coefficient to filtering and the modulation after base-band audio signal handle, namely finish the preposition predistortion of final-stage power amplifier is handled, the analog radio-frequency signal after the processing is input to and carries out power amplification in the power amplifier.Handle owing in the predistortion digital processing element, carried out preposition predistortion, therefore by power amplifier the time, can non-linearly carry out calibration to it, can effectively reduce intermodulation distortion.
Above-described embodiment is preferred implementation of the present invention; but embodiments of the present invention are not restricted to the described embodiments; other any do not deviate from change, the modification done under spiritual essence of the present invention and the principle, substitutes, combination, simplify; all should be the substitute mode of equivalence, be included within protection scope of the present invention.
Claims (8)
1. digital pre-distortion measuring system, it is characterized in that, comprise the predistortion digital processing element, and the uplink unit that is connected with the predistortion digital processing element and coupling circuit transmission unit, described uplink unit comprises DAC digital to analog converter, upconverter, power amplifier coupler and the power meter that is linked in sequence; The coupling circuit transmission unit comprises low-converter and ADC analog to digital converter, and described coupler, low-converter and ADC analog to digital converter are linked in sequence, and also connect by local oscillator between described upconverter and the low-converter.
2. digital pre-distortion measuring system according to claim 1, it is characterized in that, described predistortion digital processing element also is connected with control unit, described control unit is given the predistortion digital processing element for sending control command, and described control command comprises that calibration is regulated, begun to frequency setting, power output, calibration and measurement are calibrated, begun to measure and finish in affirmation.
3. digital pre-distortion measuring system according to claim 2, it is characterized in that, described control unit is connected with human-computer interaction interface, and described human-computer interaction interface is used for showing state, the parameter of current power amplifier feature measurement, scale value and the measurement result of current power amplifier output power value correspondence.
4. digital pre-distortion measuring system according to claim 3, it is characterized in that, described coupler comprises power attenuator, high transformation ratio line transformer and the forward and reverse detection measuring circuit of measuring the amplitude control of coupled signal for calibration, described power attenuator links to each other with line transformer respectively with forward and reverse detection measuring circuit, and its output connects uplink unit and coupling circuit transmission unit respectively.
5. the performance number of digital pre-distortion measuring system according to claim 4 calibration method of measurement is characterized in that, comprises the steps:
S1, frequency values and the initialization power grade of current system are set by human-computer interaction interface;
S2, begin calibration and measure, the predistortion digital processing element produces to be measured required baseband signal and generates radiofrequency signal by the DAC digital to analog converter, is input in the power amplifier to be measured;
S3, the power indication by observing power meter are also regulated power grade and are arranged corresponding rated power size is adjusted in power output;
S3, confirm scale value, success back system on human-computer interaction interface, and is stored in the scale value echo of current frequency and performance number correspondence in the predistortion digital processing element simultaneously;
After S4, the current scale value success of affirmation, control unit sends control command makes predistortion digital processing element automatic switchover frequency to next frequency values to be measured place, repeats previous action corresponding scale value measurement under all frequency values subsequently and finishes;
S5, treat that the calibration of whole frequency values is finished after, operating system begins the power amplifier feature measurement, this moment, the predistortion digital processing element can be input in the power amplifier according to the required test signal of gained scale value generation, and finish the measuring process that remains whole power amplifier characteristic compensations automatically, after finishing, measurement the result can be reported human-computer interaction interface.
6. the performance number of digital pre-distortion measuring system according to claim 5 calibration method of measurement is characterized in that, set successfully among the step S1 after, the parameter that power amplifier returns has operating state, frequency, power and ACK.
7. the performance number of digital pre-distortion measuring system according to claim 5 calibration method of measurement is characterized in that, step S3 returns operating state, fault message and forward and reverse performance number parameter when carrying out.
8. the performance number of digital pre-distortion measuring system according to claim 5 is calibrated method of measurement, it is characterized in that, after all surveying work is finished, select to open or close predistortion function by human-computer interaction interface, select to open then when transmitter is in emission state, by the predistortion digital processing element in the filtering of finishing sampled audio, in the time of modulation and automatic gain control, will by parameter lookup table index such as frequency and power to penalty coefficient to filtering and the modulation after base-band audio signal handle, namely finish the preposition predistortion of final-stage power amplifier is handled, the analog radio-frequency signal after the processing is input to and carries out power amplification in the power amplifier.
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| CN105305980A (en) * | 2015-11-12 | 2016-02-03 | 电子科技大学 | Feedback type pre-distortion linearization method |
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| CN109088640A (en) * | 2017-06-14 | 2018-12-25 | 意法半导体 (Alps) 有限公司 | The linearisation of radio signal transmission chain |
| CN112468222A (en) * | 2020-11-25 | 2021-03-09 | 中国科学院微小卫星创新研究院 | Environmental channel simulation system and method |
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