CN113466774A - System and method for realizing automatic calibration of frequency spectrograph power under condition of adapting to ADC linear characteristic - Google Patents
System and method for realizing automatic calibration of frequency spectrograph power under condition of adapting to ADC linear characteristic Download PDFInfo
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Abstract
本发明涉及一种适应ADC线性特性情形下实现频谱仪功率自动校准的系统，包括变频模块，用于把待测量信号下变频至ADC可采样的、固定频率的中频信号，并消除由于模块自身频响特性而造成变频不同频率待测信号为中频信号时的幅度差值；中频模块，所述的中频模块的输入端与所述的变频模块的输出端相连，用于将固定频率的中频信号进行补偿放大。本发明还涉及一种基于该系统实现适应ADC线性特性情形下的频谱仪功率自动校准的方法。采用了本发明的适应ADC线性特性情形下实现频谱仪功率自动校准的系统及其方法，可以极大的缩减工作量，在校准频点带宽内，频率响应可以进行线性估算，并且保持ADC工作在高线性状态下，提高了频谱仪整机的线性度，提高了操作效率，具有广泛的应用范围。
The invention relates to a system for realizing automatic power calibration of a spectrum analyzer under the condition of adapting to the linear characteristics of an ADC. The amplitude difference when the signal to be measured at different frequencies of the frequency conversion is an intermediate frequency signal caused by the response characteristics; the intermediate frequency module, the input end of the intermediate frequency module is connected with the output end of the frequency conversion module, and is used for the fixed frequency intermediate frequency signal. Compensate for magnification. The invention also relates to a method for realizing automatic calibration of the power of a spectrum analyzer under the condition of adapting to the linearity of the ADC based on the system. By adopting the system and method for realizing automatic calibration of spectrum analyzer power under the condition of adapting to the linear characteristic of ADC of the present invention, the workload can be greatly reduced. Under the high linearity state, the linearity of the whole spectrum analyzer is improved, the operation efficiency is improved, and it has a wide range of applications.
Description
Technical Field
The invention relates to the technical field of instrument and meter calibration, in particular to the technical field of frequency spectrograph power calibration, and specifically relates to a system and a method for realizing automatic calibration of frequency spectrograph power under the condition of adapting to ADC linear characteristics.
Background
The spectrum analyzer is an instrument for researching the spectrum structure of electric signals, is used for measuring signal parameters such as signal distortion degree, modulation degree, spectrum purity, frequency stability, intermodulation distortion and the like, can be used for measuring certain parameters of circuit systems such as amplifiers, filters and the like, and is a multipurpose electronic measuring instrument. Modern spectrum analyzers are capable of analyzing electrical signals in all radio bands from very low frequencies below 1Hz to the sub-millimeter band of 30 GHz. The circuit structure of the analog part is shown in fig. 1 and fig. 2.
As a measuring instrument, there is a strict demand for an index of high linearity. With the development of communication technology, the bandwidth of signals is continuously improved, and the 5G standard requires that the bandwidth of signals below the carrier frequency 6GHz reaches 100MHz, and the bandwidth of signals above the carrier frequency 6GHz reaches 300MHz or even wider. An increase in signal bandwidth means a decrease in signal-to-noise ratio, which requires a higher linearity of the meter to ensure that the resulting tuning is small enough not to affect the signal-to-noise ratio of the signal under test.
Similarly, the power measurement is also strictly required, and the power measurement accuracy of modern spectrum analyzers requires that the frequency below 3GHz reaches +/-0.5 dB, and the frequency below 6GHz reaches +/-1.0 dB or even lower. The frequency response characteristic of the radio frequency device inevitably causes the output power of a radio frequency front end, and uncertainty exists in a measurement frequency band of the spectrum analyzer; even under the same frequency and different reference levels, the output power of the radio frequency front end causes uncertainty due to errors when the input step attenuator and the gain adjustable intermediate frequency amplifier change the attenuation amount and the gain. To sum up, in order to meet the requirements of measurement accuracy and linearity, the rf front end needs to perform point-by-point measurement in the whole measurement band, perform accurate output power measurement under different reference level settings, and perform power compensation on the frequency response characteristic of the device, so as to ensure that the ADC always operates in a high linearity region.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a system and a method for realizing automatic calibration of frequency spectrograph power under the condition of meeting the requirements of small calibration workload, high calibration efficiency and wider application range and adapting to ADC linear characteristics.
In order to achieve the above object, the system and method for realizing automatic calibration of spectrometer power in case of adapting to ADC linear characteristic of the present invention are as follows:
the system for realizing the automatic calibration of the frequency spectrograph power under the condition of adapting to the ADC linear characteristic is mainly characterized by comprising:
the frequency conversion module is used for down-converting the signals to be measured with wide frequency and wide amplitude to intermediate frequency signals which can be sampled by the ADC and have fixed frequency, and eliminating amplitude difference values caused by the frequency response characteristics of the module when the signals to be measured with different frequency are converted into intermediate frequency signals, so that the amplitude of the intermediate frequency signals passing through the intermediate frequency module is in an amplitude interval with high ADC linearity;
and the input end of the intermediate frequency module is connected with the output end of the frequency conversion module and is used for compensating and amplifying the intermediate frequency signal with fixed frequency within the range of 0-50 dB by taking 1dB as stepping when the amplitude of the signal to be measured changes.
Preferably, the frequency conversion module includes an input step attenuator, a low pass filter, a frequency converter, a gain adjustment attenuator and a gain amplifier, the input step attenuator, the low pass filter, the frequency converter, the gain adjustment attenuator and the gain amplifier are connected in sequence, an input end of the frequency converter is connected to the local vibration source, and the gain adjustment attenuator is used for adjusting the frequency response of the frequency conversion module by changing the attenuation.
Preferably, the frequency module includes an intermediate frequency step attenuator, a gain amplifier and four groups of fixed gain amplifiers with bypass function, the intermediate frequency step attenuator, the gain amplifier and the four groups of fixed gain amplifiers are connected in sequence, and the intermediate frequency step attenuator is used for adjusting the attenuation amount to correct the error value of the intermediate frequency gain.
Preferably, the system comprises calculating the total path power, in particular:
the total path power is calculated according to the following formula:
Pow_In－ATT－Freq_Resp－Gain_Adjust+Gain+IF_Gain＝－7dBFS；
the method comprises the steps of obtaining a power value of a signal to be detected, obtaining an ATT value of the signal to be detected, obtaining a Freq _ Resp value of a device of a frequency conversion module, obtaining a Gain value of a Gain compensation circuit In the frequency conversion module, obtaining a Gain sum of Gain amplifiers In the frequency conversion module and an intermediate frequency module, and obtaining an IF _ Gain which is 0-70 dB and 0.25dB step of the intermediate frequency Gain.
The method for realizing the automatic calibration of the frequency spectrograph power under the condition of adapting to the ADC linear characteristic based on the system is mainly characterized by comprising the following steps:
(1-1) configuring a signal source to output the highest frequency of a signal to be detected;
(1-2) configuring the attenuation amount of an input attenuator, a gain adjustment attenuator and configuring the input power of a signal source;
(1-3) judging whether the output power of the signal source is greater than the preset calibration power, if so, not completing the calibration, and continuing the step (1-4); otherwise, the calibration is finished, and the calibration program is skipped to finish the calibration;
(1-4) configuring a first calibration point of the intermediate frequency gain and configuring an intermediate frequency step attenuator;
(1-5) measuring a power value accessed to the ADC by using a power meter;
(1-6) judging whether the reading of the power meter meets the error requirement, if so, completing the calibration with the intermediate frequency gain of 0 dB; otherwise, controlling the intermediate frequency step attenuator to adjust by calculating the attenuation quantity required to be increased;
and (1-7) recording the attenuation amount of the current intermediate frequency step attenuator and recording as an error correction value of the intermediate frequency gain 0 dB.
Preferably, the method further includes a step of automatically calibrating the frequency response error, which specifically includes the following processing procedures:
(2-1) configuring signal source power, intermediate frequency gain and input step attenuator attenuation, and performing frequency response calibration;
(2-2) judging whether the current attenuation is larger than a preset calibration attenuation, if so, inputting the frequency response calibration of all the attenuation of the step attenuator, and continuing the step (2-3); otherwise, the frequency response calibration of all the attenuation quantities of the input step attenuator is finished, and the calibration procedure is skipped to finish the calibration;
(2-3) configuring the signal source to be the highest point of the frequency of the signal to be detected;
(2-4) judging whether the sending frequency of the current signal source is greater than the minimum calibration frequency, if so, not completing the frequency response calibration under the attenuation of the current input step attenuator, and entering the next calibration; otherwise, the frequency response calibration under the attenuation quantity of the current input step attenuator is finished;
(2-5) carrying out frequency response calibration under other attenuation quantities of the input step attenuator, and configuring the attenuation quantity of the input step attenuator, the signal source output frequency to the highest frequency point and the intermediate frequency gain;
(2-6) correcting the current intermediate frequency gain by using the corrected value obtained after the intermediate frequency gain is corrected;
(2-7) a gain-adjusted attenuator configuration;
(2-8) measuring a power value accessed to the ADC by using a power meter;
(2-9) judging whether the reading of the power meter meets the error requirement, if so, finishing the calibration of the current attenuation amount and frequency value; otherwise, calculating the attenuation quantity to be increased, and controlling the intermediate frequency step attenuator to adjust;
and (2-10) recording the attenuation amount of the gain adjustment attenuator as a frequency response error correction value of the attenuation amount and the frequency value corresponding to the currently input step attenuator.
Preferably, the method further comprises the steps of:
(1-8) controlling the input power of the signal source to be reduced by 1dB, increasing the intermediate frequency gain by 1dB, and continuing to calibrate under the condition that the intermediate frequency gain is 1 dB.
Preferably, the method further comprises the steps of:
and (2-11) reducing the frequency of the signal source by 10MHz, and calibrating the frequency response of the second frequency point.
By adopting the system and the method for realizing the automatic calibration of the power of the frequency spectrograph under the condition of adapting to the linear characteristic of the ADC, the workload can be greatly reduced, the frequency response can be linearly estimated in the bandwidth of the calibration frequency point, the ADC is kept to work in a high linear state, and the linearity of the whole frequency spectrograph is improved. The whole calibration process is completed by a preset program, so that the operation efficiency is improved, and the method has a wide application range.
Drawings
Fig. 1 is a schematic diagram of ADC linearity characteristics of a system for implementing automatic calibration of spectrometer power in a situation of adapting to ADC linearity characteristics according to the present invention.
Fig. 2 is a schematic diagram of a frequency conversion module of the system for realizing automatic calibration of spectrometer power under the condition of adapting to ADC linear characteristics according to the present invention.
Fig. 3 is a schematic diagram of an intermediate frequency module of the system for implementing automatic calibration of spectrometer power in case of adapting to ADC linear characteristics according to the present invention.
Fig. 4 is a flow chart of the automatic calibration of the intermediate frequency error of the method for realizing the automatic calibration of the spectrometer power under the condition of adapting to the linear characteristic of the ADC according to the present invention.
Fig. 5 is a flow chart of the automatic calibration of the frequency response error of the method for realizing the automatic calibration of the spectrometer power under the condition of adapting to the linear characteristic of the ADC according to the present invention.
Detailed Description
In order to more clearly describe the technical contents of the present invention, the following further description is given in conjunction with specific embodiments.
Referring to fig. 1 to fig. 3, the system for implementing automatic calibration of spectrometer power under the condition of adapting to the linear characteristic of ADC according to the present invention includes:
the frequency conversion module is used for down-converting the signals to be measured with wide frequency and wide amplitude to intermediate frequency signals which can be sampled by the ADC and have fixed frequency, and eliminating amplitude difference values caused by the frequency response characteristics of the module when the signals to be measured with different frequency are converted into intermediate frequency signals, so that the amplitude of the intermediate frequency signals passing through the intermediate frequency module is in an amplitude interval with high ADC linearity;
and the input end of the intermediate frequency module is connected with the output end of the frequency conversion module and is used for compensating and amplifying the intermediate frequency signal with fixed frequency within the range of 0-50 dB by taking 1dB as stepping when the amplitude of the signal to be measured changes.
As a preferred embodiment of the present invention, the frequency conversion module includes an input step attenuator, a low pass filter, a frequency converter, a gain adjustment attenuator, and a gain amplifier, the input step attenuator, the low pass filter, the frequency converter, the gain adjustment attenuator, and the gain amplifier are sequentially connected, an input end of the frequency converter is connected to the local vibration source, and the gain adjustment attenuator is used to adjust the frequency response of the frequency conversion module by changing the attenuation.
As a preferred embodiment of the present invention, the frequency module includes an intermediate frequency step attenuator, a gain amplifier, and four sets of fixed gain amplifiers with bypass function, the intermediate frequency step attenuator, the gain amplifier, and the four sets of fixed gain amplifiers are connected in sequence, and the intermediate frequency step attenuator is used to adjust an attenuation amount to correct an error value of the intermediate frequency gain.
As a preferred embodiment of the present invention, the system includes calculating the total path power, specifically:
the total path power is calculated according to the following formula:
Pow_In－ATT－Freq_Resp－Gain_Adjust+Gain+IF_Gain＝－7dBFS；
the method comprises the steps of obtaining a power value of a signal to be detected, obtaining an ATT value of the signal to be detected, obtaining a Freq _ Resp value of a device of a frequency conversion module, obtaining a Gain value of a Gain compensation circuit In the frequency conversion module, obtaining a Gain sum of Gain amplifiers In the frequency conversion module and an intermediate frequency module, and obtaining an IF _ Gain which is 0-70 dB and 0.25dB step of the intermediate frequency Gain.
Referring to fig. 4 to 5, the method for automatically calibrating the power of the spectrometer based on the above system to adapt to the linear characteristic of the ADC according to the present invention includes the following steps:
(1-1) configuring a signal source to output the highest frequency of a signal to be detected;
(1-2) configuring the attenuation amount of an input attenuator, a gain adjustment attenuator and configuring the input power of a signal source;
(1-3) judging whether the output power of the signal source is greater than the preset calibration power, if so, not completing the calibration, and continuing the step (1-4); otherwise, the calibration is finished, and the calibration program is skipped to finish the calibration;
(1-4) configuring a first calibration point of the intermediate frequency gain and configuring an intermediate frequency step attenuator;
(1-5) measuring a power value accessed to the ADC by using a power meter;
(1-6) judging whether the reading of the power meter meets the error requirement, if so, completing the calibration with the intermediate frequency gain of 0 dB; otherwise, controlling the intermediate frequency step attenuator to adjust by calculating the attenuation quantity required to be increased;
(1-7) recording the attenuation of the current intermediate frequency step attenuator, and recording as an error correction value of the intermediate frequency gain 0 dB;
(1-8) controlling the input power of the signal source to be reduced by 1dB, increasing the intermediate frequency gain by 1dB, and continuing to calibrate under the condition that the intermediate frequency gain is 1 dB.
Preferably, the method further includes a step of automatically calibrating the frequency response error, which specifically includes the following processing procedures:
(2-1) configuring signal source power, intermediate frequency gain and input step attenuator attenuation, and performing frequency response calibration;
(2-2) judging whether the current attenuation is larger than a preset calibration attenuation, if so, inputting the frequency response calibration of all the attenuation of the step attenuator, and continuing the step (2-3); otherwise, the frequency response calibration of all the attenuation quantities of the input step attenuator is finished, and the calibration procedure is skipped to finish the calibration;
(2-3) configuring the signal source to be the highest point of the frequency of the signal to be detected;
(2-4) judging whether the sending frequency of the current signal source is greater than the minimum calibration frequency, if so, not completing the frequency response calibration under the attenuation of the current input step attenuator, and entering the next calibration; otherwise, the frequency response calibration under the attenuation quantity of the current input step attenuator is finished;
(2-5) carrying out frequency response calibration under other attenuation quantities of the input step attenuator, and configuring the attenuation quantity of the input step attenuator, the signal source output frequency to the highest frequency point and the intermediate frequency gain;
(2-6) correcting the current intermediate frequency gain by using the corrected value obtained after the intermediate frequency gain is corrected;
(2-7) a gain-adjusted attenuator configuration;
(2-8) measuring a power value accessed to the ADC by using a power meter;
(2-9) judging whether the reading of the power meter meets the error requirement, if so, finishing the calibration of the current attenuation amount and frequency value; otherwise, calculating the attenuation quantity to be increased, and controlling the intermediate frequency step attenuator to adjust;
(2-10) recording the attenuation amount of the gain adjustment attenuator as a frequency response error correction value of the attenuation amount and the frequency value corresponding to the current input step attenuator;
and (2-11) reducing the frequency of the signal source by 10MHz, and calibrating the frequency response of the second frequency point.
In the specific embodiment of the present invention, a circuit and a method for implementing automatic calibration of a spectrometer are provided, which can adapt to the linear characteristics of an ADC, ensure the measurement linearity of the spectrometer, reduce the calibration workload, improve the calibration efficiency, and have a wider application range.
The circuit and the method for automatically calibrating the power of the frequency spectrograph, which are suitable for the linear characteristic of the ADC, comprise a frequency conversion module, a frequency conversion module and a frequency correction module, wherein the frequency conversion module is used for converting a broadband and wide-width signal to be measured into an intermediate-frequency signal which can be sampled by the ADC and has a fixed frequency, and eliminating an amplitude difference value when the signal to be measured with different frequencies is converted into the intermediate-frequency signal due to the frequency response characteristic of the module, so that the amplitude of the intermediate-frequency signal after passing through the intermediate-frequency module is in an amplitude interval with high linearity of the ADC; and the input end of the intermediate frequency module is connected with the output end of the frequency conversion module and is used for compensating and amplifying the intermediate frequency signal with fixed frequency within the range of 0-50 dB by taking 1dB as stepping when the amplitude of the signal to be measured changes.
The linearity characteristic of ADC is shown in FIG. 1, taking ADC model "AD 9460" as an example, the optimal range of linearity is-15 to-7 dBFS, and 8dB power range which is 15 to 7dB less than the maximum measured power. Therefore, no matter the signal to be detected changes in two dimensions of frequency and amplitude, the amplitude of the signal sent to the ADC for detection is constant and is optimal in the interval of-15 dBFS to-7 dBFS, and the circuit is shown in figure 3. However, when the actual frequency conversion circuit processes a broadband signal with the same power, due to frequency response characteristics of devices, transmission lines, and the like, the power of converting a signal with a high frequency into an intermediate frequency signal is lower than the power of converting a signal with a low frequency into an intermediate frequency signal. If the power difference between the two intermediate frequency signals is larger than the maximum linearity interval of the ADC, the linearity of the circuit is deteriorated.
Note: for the convenience of calculation, the maximum measurement power of the ADC is calculated by taking +7dBm as the input power, and the value of-7 dBFS is 0 dBm.
As shown in fig. 2, the frequency conversion module is composed of an input step Attenuator (ATT), a Low Pass Filter (LPF), a frequency converter (Mixer), a Gain adjusting attenuator (Gain _ Adjust), and a Gain amplifier (Gain _ block). The gain adjusting attenuator adjusts the frequency response of the frequency conversion module by changing the attenuation amount, so that signals to be measured with different frequencies can be sent to the ADC with the signal power of-7 dBFS, and the optimal linearity of the circuit is ensured.
As shown in fig. 3, the intermediate frequency module is composed of an intermediate frequency step attenuator (IF _ ATT), a Gain amplifier (Gain _ block), and four sets of fixed Gain amplifiers with bypass function. The fixed gain amplifier and the intermediate frequency step attenuator are used in combination, gain change of 0.25dB step can be obtained, and the error value of the intermediate frequency gain is corrected by adjusting the attenuation amount through the intermediate frequency step attenuator.
Overall path power calculation: the calculation from "signal under test" to "intermediate frequency output" (pre-ADC) path is as follows:
pow _ In-ATT-Freq _ Resp-Gain _ Adjust + Gain + IF _ Gain ═ 7dBFS (equation 1)
Wherein, Pow _ In: the power of the signal to be measured, which is a definite value without error value;
ATT: the attenuation value of the 'input step attenuator' is 0-70 dB and 10dB step, the adjustment is carried out according to Pow _ In, the principle that-20 is greater than Pow _ In-ATT is less than or equal to-10 is followed, and the error value is determined by an array consisting of two parameters of frequency and attenuation;
freq _ Resp: all devices such as a frequency converter, a switch, a filter, a transmission line and the like in the frequency conversion module respond to signals to be detected with different frequencies;
gain _ Adjust: the gain value of the gain compensation circuit in the frequency conversion module is within the range of-20 to-5 dB, and the step is 0.25 dB. For compensating power loss caused by different frequency responses;
gain: the gain sum of the gain amplifiers in the frequency conversion module and the intermediate frequency module is used for compensating other power loss values in the path. When the input signal power is-10 dBm and the frequency is maximum, the equation 1 is ensured to be > -7dBFS
IF _ Gain: the intermediate frequency gain is 0-70 dB, the step is 0.25dB, the step precision and the gain error are realized by connecting an intermediate frequency step attenuator and a 10dB/20dB fixed gain amplifier in series, and the gain error is determined by the parameter of the gain value.
IF the whole link needs to be calibrated, only the IF _ Gain and the Gain _ Adjust need to be calibrated respectively.
As shown in fig. 4, the intermediate frequency error automatic calibration flow chart is shown, the intermediate frequency gain error is independent of the frequency and power of the signal to be measured, and is only related to the intermediate frequency gain value configured in the "intermediate frequency module", so that the frequency of the signal to be measured used in the intermediate frequency calibration is the initial frequency of the frequency response calibration and the maximum frequency of the signal to be measured, and the program automatically completes the calibration flow with the intermediate frequency gain of 0dB to 70dB and the step of 1 dB.
The method comprises the following steps: configuring a signal source to output the highest frequency of a signal to be detected;
step two: configuring the attenuation of an input attenuator to be 0 dB;
step three: the gain adjusting attenuator is configured to-5 dB to prevent the maximum frequency to be measured from being not the minimum power of the intermediate frequency signal;
step four: configuring the input power of a signal source to be-10 dBm;
step five: and judging whether the output power of the signal source is more than or equal to-80 dBm or not, if yes, indicating that the calibration is not finished, and if no, indicating that the calibration is finished, jumping out of the calibration program to finish the calibration.
Step six: the if gain is configured to the first calibration point "0 dB";
step seven: the intermediate frequency step attenuator is configured to be 0dB, and correction is not added by default;
step eight: measuring the power value accessed to the ADC by using a power meter;
step nine: and judging whether the reading of the power meter meets the error requirement of [ -7dBFS-acc/2, -7dBFS + acc/2] dBm, if not, calculating the attenuation quantity to be increased by 'acc × Round ((-7 dBFS-power meter reading)/acc'), and controlling the intermediate frequency step attenuator to adjust. If the reading of the power meter is judged to meet the error requirement, the calibration with the intermediate frequency gain of 0dB is completed;
note: "acc" is the attenuation step of the IF step attenuator, which is 0.25dB in this example.
Step ten: and recording the attenuation amount of the current intermediate frequency step attenuator as an error correction value of the intermediate frequency gain 0 dB. And then, controlling the input power of the signal source to be reduced by 1dB, increasing the intermediate frequency gain by 1dB, and continuing to calibrate under the condition that the intermediate frequency gain is 1 dB.
FIG. 5 is a flow chart of automatic calibration of frequency response error, wherein the frequency response error is determined by the attenuation of the input step attenuator and the frequency information of the signal to be measured, and the input step attenuator has 8 states of 0dB, -10dB, -20dB, -30dB, -40dB, -50dB, -60dB and-70 dB; the frequency change of the signal to be measured is represented by 10MHz stepping.
The method comprises the following steps: configuring the power of a signal source to be-10 dBm;
step two: configuring the intermediate frequency gain to be 0 dB;
step three: configuring the attenuation of an input step attenuator to be 0dB, and starting to carry out frequency response calibration;
step four: judging whether the current attenuation is more than or equal to-70 dB, if yes, indicating that the frequency response calibration of all the attenuation of the input step attenuator is not finished, entering the next calibration, and if no, indicating that the frequency response calibration of all the attenuation of the input step attenuator is finished, jumping out of the calibration program, and finishing the calibration;
step five: the signal source is configured to be the highest point of the frequency of the signal to be detected;
step six: judging whether the sending frequency of the current signal source is larger than or equal to the minimum calibration frequency, if yes, indicating that the frequency response calibration under the attenuation of the current input step attenuator is not completed, entering the next calibration, and if no, indicating that the frequency response calibration under the attenuation of the current input step attenuator is completed, needing to perform frequency response calibration under other attenuation of the input step attenuator, configuring the attenuation-10 dB of the input step attenuator, configuring the output frequency of the signal source to the highest frequency point, and configuring the intermediate frequency gain +10 dB;
step seven: correcting the current intermediate frequency gain by using a corrected value obtained after the intermediate frequency gain is calibrated;
step eight: the gain-adjusted attenuator is configured to-5 dB;
step nine: measuring the power value accessed to the ADC by using a power meter;
step ten: and judging whether the reading of the power meter meets the error requirement of [ -7dBFS-acc/2, -7dBFS + acc/2], if not, calculating the attenuation quantity to be increased by 'acc × Round ((-7 dBFS-power meter reading)/acc),' and controlling the intermediate frequency step attenuator to adjust. If the reading of the power meter is judged to meet the error requirement, the calibration of the current attenuation amount and the frequency value is finished;
step eleven: and recording the attenuation amount of the gain adjustment attenuator as a frequency response error correction value of the attenuation amount and the frequency value corresponding to the current input step attenuator. And then configuring the frequency of the signal source to reduce by 10MHz, and carrying out frequency response calibration of a second frequency point.
By adopting the system and the method for realizing the automatic calibration of the power of the frequency spectrograph under the condition of adapting to the linear characteristic of the ADC, the workload can be greatly reduced, the frequency response can be linearly estimated in the bandwidth of the calibration frequency point, the ADC is kept to work in a high linear state, and the linearity of the whole frequency spectrograph is improved. The whole calibration process is completed by a preset program, so that the operation efficiency is improved, and the method has a wide application range.
In this specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.
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| CN114401056B (en) * | 2021-12-29 | 2024-04-23 | 中电科思仪科技(安徽)有限公司 | Complete machine calibration system and method for 5G communication vector signal generator |
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