阅读说明：本技术 一种短波射频直采桥式矢量阻抗检测方法 (short-wave radio frequency direct acquisition bridge type vector impedance detection method ) 是由 邹晶晶 罗磊 于 2019-09-30 设计创作，主要内容包括：本发明公开了一种短波射频直采桥式矢量阻抗检测方法,包括如下步骤：步骤一、搭建桥式检测电路；步骤二、对耦合电压信号<Image he="81" wi="184" file="DDA0002222255000000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>进行射频直接采样；步骤三、通过两路采样信号的幅度和相位信息,计算得到负载阻抗值。与现有技术相比,本发明的积极效果是：本发明针对变频处理构架下,短波矢量阻抗检测器电路复杂、体积大、功耗高、数据处理复杂度高等问题,对电路处理构架、数据处理算法两方面进行改进,提出了一种短波射频直采桥式矢量阻抗检测(以下简称“桥式检测”)方法。本发明与传统方法相比,具有更简洁的电路处理构架,降低处理电路复杂度、功耗、体积,同时优化了数据处理算法,并在一定程度上提高了检测精度。(The invention discloses an short-wave radio frequency direct acquisition bridge type vector impedance detection method which comprises the following steps of building a bridge type detection circuit, and step two of coupling voltage signals Compared with the prior art, the method has the advantages that aiming at the problems of complex circuit, large volume, high power consumption, high data processing complexity and the like of a short wave vector impedance detector under a frequency conversion processing framework, the two aspects of the circuit processing framework and a data processing algorithm are improved, and short wave radio frequency direct sampling bridge type vector impedance detection (hereinafter referred to as bridge type detection) methods are providedThe detection accuracy is improved.)

1, short wave radio frequency direct sampling bridge type vector impedance detection method, characterized by comprising the following steps:

step , building a bridge type detection circuit;

step two, coupling voltage signals

and step three, calculating to obtain a load impedance value through amplitude and phase information of the two paths of sampling signals.

2. The short-wave RF direct acquisition bridge vector impedance detection method of claim 1, wherein the bridge detection circuit of step is characterized by reference bridge impedance Z₀And a signal sampling circuit, wherein R1 and R2 are pure resistors, and R1 and R2 are far greater than the load impedance Z_L。

3. The short-wave radio frequency direct sampling bridge vector impedance detection method of claim 2, wherein the load impedance value is calculated according to the following formula:

wherein: i U₀|、|U₁L is the amplitude of the sampled signal,is the phase difference.

4. The short-wave radio frequency direct sampling bridge vector impedance detection method of claim 3, wherein the amplitudes of the two sampling signals are obtained by calculating root mean square values of sampling point data.

5. The short-wave radio frequency direct sampling bridge vector impedance detection method of claim 3, wherein the phase difference is calculated by:

step, calculating the absolute value of the phase difference according to the following formula

Wherein:n is the number of sampling points;

second step, according to U₀And U₁The phase difference sign is determined.

6. The short-wave radio frequency direct sampling bridge vector impedance detection method of claim 5, wherein the method for determining the phase difference sign comprises comparing the time axes of the maximum points, defining the point with the maximum value first as the phase advance point of the sequence, defining the point with the maximum value later as the phase lag point of the sequence, counting the phase advance points and the lag points, determining as the phase advance if the phase advance points are more than the phase lag points, and determining as the phase lag if the phase lag points are more than the phase advance points, and defining as the phase lag if the phase lag points are more than the phase advance points.

Technical Field

The invention relates to an short-wave radio frequency direct acquisition bridge type vector impedance detection method.

Background

Vector impedance detection is a key functional module in a vector short-wave antenna tuner (hereinafter referred to as 'antenna tuner'), is the basis of a tuning algorithm executed by the antenna tuner, directly determines the tuning precision of the antenna tuner, provides accurate load impedance detection in a short-wave full frequency band by a high-precision vector impedance detection technology, and is a key technology for realizing a quick and high-precision antenna tuner.

The working principle of the frequency conversion processing framework is as follows: after the radio frequency signal is subjected to down-conversion, voltage and current vector signals on a load are obtained through an ADC (analog-to-digital converter), and the vector impedance definition formula is based on

The method is intuitive, the amplitude of the impedance is the phase difference of voltage and current signals, the voltage and current vector signal acquisition method is generally completed by adopting a coupler, a transformer is coupled with a radio frequency voltage signal, the current coupler is coupled with a current signal passing through a load, in order to reduce the influence of the coupler on the load impedance, the coupling coefficient is relatively small like , the coupled signal needs to be amplified and then subjected to subsequent down-conversion, filtering and other processing to obtain an intermediate frequency signal, the intermediate frequency signal is amplified and filtered and then subjected to low-frequency sampling, the amplitude and phase information of the low-frequency sampling signal is extracted from a digital domain, and the impedance value is obtained by calculation, and the processing framework is as shown in figure 1.

The circuit processing framework of the method is complex, load impedance is calculated through data processing after intermediate frequency sampling, Hilbert transform is often needed for extracting current and voltage signal amplitude and phase characteristics in the data processing, and algorithm complexity is high. In addition, in the engineering implementation, the coupler has natural frequency characteristics, and the imbalance of the two radio frequency processing circuits causes great influence on the impedance detection error (the error is 5% -10%). The inductive coupler in the detection mode has the advantages of large size, complex circuit and high power consumption, and is difficult to realize in equipment with limited volume and power consumption.

Under the radio frequency direct sampling framework, voltage and current signals representing load impedance directly enter a high-speed ADC for sampling without down-conversion processing, and data processing is carried out in a digital domain to obtain the load impedance. In this way, a down-conversion processing circuit does not exist, the circuit complexity is reduced, and the design with low power consumption and small volume can be realized.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides short-wave radio frequency direct sampling bridge type vector impedance detection methods.

The technical scheme adopted by the invention for solving the technical problems is that short-wave radio frequency direct acquisition bridge type vector impedance detection methods comprise the following steps:

step , building a bridge type detection circuit;

step two, coupling voltage signals

Performing radio frequency direct sampling;

and step three, calculating to obtain a load impedance value through amplitude and phase information of the two paths of sampling signals.

Compared with the prior art, the invention has the following positive effects:

aiming at the problems of complex circuit, large volume, high power consumption, high data processing complexity and the like of a short wave vector impedance detector under a frequency conversion processing framework, the invention improves two aspects of a circuit processing framework and a data processing algorithm, and provides short wave radio frequency direct acquisition bridge type vector impedance detection (hereinafter referred to as bridge type detection) methods.

1) In the aspect of hardware circuit implementation, based on a radio frequency direct acquisition circuit framework and parts such as a non-inductive coupler, a mixer, a filter, an amplifier and the like, the size and the power consumption of a detection circuit module are reduced, and detection errors introduced by a peripheral circuit are reduced;

2) a pure resistance network with better short-wave frequency characteristics is adopted to replace a voltage and current coupler, so that the detection error caused by the frequency characteristics of the coupler is reduced;

3) in the aspect of a data processing algorithm, the sampling data is directly processed without performing down-conversion, Hilbert conversion and other processing on the data, and the processing algorithm is simple and efficient.

Drawings

The invention will now be described, by way of example, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic block diagram of vector impedance detection for a variable frequency architecture;

FIG. 2 is a schematic block diagram of a bridge detection circuit architecture;

fig. 3 is a diagram illustrating an example of phase calculation.

Detailed Description

The bridge detection circuit structure adopted by the invention is shown in figure 2, and the detection circuit consists of a reference bridge impedance Z₀And a signal sampling circuit.

For any load Z ═ R + jX, it can be assumed that Z flows through₀Also flows into the load Z_LThe following formula holds:

wherein the content of the first and second substances,

obtained from ①②

Wherein

Sampling signal

And satisfies the following formula:

r1 and R2 in the signal sampling circuit are pure resistors, when R1 and R2 are far greater than Z_LIn time, after sampling, the detection signal is not influenced at the reference bridge impedance Z₀The phases at both ends are only scaled down equally in magnitude, so that the ratio of the vector voltages is available

Expressed as:

wherein | U₀|、|U₁L is the amplitude of the sampled signal,is the phase difference. To pair

Directly sampling, analyzing and processing the sampling point data, extracting phase and amplitude information, and calculating to obtain load impedance Z_L。

It can be seen that only the detector Z has to be determined₀The voltage vectors of the front end and the rear end can obtain the load Z_LSince ① is based on flow through Z₀Also flows through Z_LThis requires that the introduction of the branch U1 not affect Z_LI.e., the impedance of the U1 branch is much greater than the load branch impedance.

Extracting amplitude and phase information of two paths of signals based on sampling point data, substituting the amplitude and phase information into an impedance calculation formula ⑥ to obtain a load impedance value, calculating the RMS value of the amplitudes of two paths of sampling signals by the sampling point data to obtain a phase difference of the signals, and performing step of phase difference absolute value calculationThe second step determines the lead/lag relationship of U0 and U1 to determine the sign of the phase difference.

The determination of (2) is based on a correlation analysis method. Two-way sampling signal U₀(n) and U₁(n) can be represented as:

wherein T is_SIs the sampling period. Cross correlation function thereof

Wherein N is the number of the sampling points,

absolute value of phase difference

The phase advance and lag is judged based on the statistical thought, by judging the time when the maximum values of two paths of signals appear, counting the time when the maximum values appear and judging the phase difference sign according to the statistical result, the maximum value is defined as maximum value points of a sequence if the value of a certain point in the interval is larger than the values of all the points in the preamble in the interval and is simultaneously larger than the values of all the points in the postsequence in the interval in continuous sampling intervals.

The phase calculation process is exemplified below. FIG. 3 shows data when the detected signal is 2MHz and the number of samples is 128. Wherein: fig. 3 (top) is a time domain signal, fig. 3 (middle) is sample data, and fig. 3 (bottom) is a two-path signal maximum (non-0 point) sequence.

The absolute value of the phase difference is calculated by the formula ⑨

The U0 maximum point is the same as the U1 maximum point, and both lag behind U1, the phase difference is determined to lag, the phase difference sign bit "-", and therefore, the final phase difference: