CN103575749A

CN103575749A - Method for dynamically tracking parameters of microwave resonant cavity in density and moisture measurement of cigarette

Info

Publication number: CN103575749A
Application number: CN201310518234.0A
Authority: CN
Inventors: 王鸿山; 周奇峰; 张济民; 孙宏杰; 耿守本; 张玉安; 王德胜; 曾雄伟
Original assignee: CETC 41 Institute
Current assignee: CETC 41 Institute
Priority date: 2013-10-26
Filing date: 2013-10-26
Publication date: 2014-02-12
Anticipated expiration: 2033-10-26
Also published as: CN103575749B

Abstract

The invention discloses a method for dynamically tracking parameters of a microwave resonant cavity in the density and moisture measurement of a cigarette. The method comprises the following steps: firstly, acquiring the resonant frequency of the resonant cavity; and secondly, acquiring the 3dB bandwidth of the resonant cavity. According to the method, the change of the parameters of the resonant cavity during the density and moisture measurement of the cigarette through a microwave resonance method can be dynamically tracked in real time.

Description

In a kind of density of tobacco rod and moisture measurement, dynamically follow the tracks of the method for microwave cavity parameter

Technical field

The present invention relates to microwave cavity parameter tracking method field, be specially a kind of method of dynamically following the tracks of microwave cavity parameter in density of tobacco rod and moisture measurement.

Background technology

The basis of the measuring principle of density of tobacco rod and moisture distribution is microwave resonance method, its groundwork principle is, by cigarette transfer system, cigarette to be measured is sent to microwave cavity, when cigarette is passed through microwave electromagnetic field, difference due to its density and moisture, microwave electromagnetic field energy parameter is changed, the resonant parameter that is embodied in microwave cavity changes, and is mainly that resonance frequency and the three dB bandwidth of microwave cavity changes.In order accurately to obtain density of tobacco rod and moisture, need in real time, dynamically to follow the tracks of the variation of microwave cavity parameter.

Summary of the invention

The object of this invention is to provide a kind of method of dynamically following the tracks of microwave cavity parameter in density of tobacco rod and moisture measurement, to realize, microwave cavity parameter in cigarette measurement is changed to the object of following the tracks of.

In order to achieve the above object, the technical solution adopted in the present invention is:

In density of tobacco rod and moisture measurement, dynamically follow the tracks of a method for microwave cavity parameter, for microwave resonance method, measure density of tobacco rod and moisture microwave cavity parameter tracking, it is characterized in that: comprise the following steps:

(1) obtain resonant frequency:

Cigarette causes that by resonator cavity resonant frequency changes, the variation range of resonance frequency is in 1MHz left and right, detecting circuit by three Frequency points of sampling calculates new resonance frequency, and three Frequency points of sampling are respectively resonant frequency point f before resonator parameter changes ₁, compare f ₁the Frequency point f of little 1.4MHz ₀and compare f ₁the Frequency point f of large 1.4MHz ₂.Frequency point f ₀, f ₁and f ₂each self-corresponding detecting circuit value is designated as respectively A ₀, A ₁and A ₂, by following formula, can obtain the resonance frequency Freq of new resonator cavity,

Freq = \frac{A_{0} \times A_{2} \times (f_{2} + f_{0}) \times (f_{2} - f_{0}) + A_{1} \times A_{2} \times (f_{1} + f_{2}) \times (f_{1} - f_{2}) + A_{0} \times A_{1} \times (f_{0} + f_{1}) \times (f_{0} - f_{1})}{2 * (A_{0} \times A_{2} \times (f_{2} - f_{0}) + A_{1} \times A_{2} \times (f_{1} - f_{2}) + A_{0} \times A_{1} \times (f_{0} - f_{1}))}

(2) obtain resonator cavity three dB bandwidth:

Cigarette can cause that by resonator cavity resonator cavity 3dB changes equally, the variation range of resonator cavity 3dB is ± 6MHz in, the detecting circuit value at frequency place, 3dB left and right is half of resonant frequency point Freq place detecting circuit, in order to obtain new resonator cavity three dB bandwidth, centered by resonant frequency point Freq, take 1MHz as step-length, left, right each got respectively 6 Frequency points, according to a left side, the frequency values of six Frequency points in right side and each self-corresponding detecting circuit value, by interpolation algorithm, calculate a left side, the Frequency point at half place of resonant frequency point detecting circuit, right side, be microwave cavity three dB bandwidth left, the frequency of right side Frequency point, resonator cavity three dB bandwidth equals right side Frequency point frequency values and deducts left side Frequency point frequency values.

The present invention can in real time, dynamically follow the tracks of the variation of the resonator parameter while adopting microwave resonance method to measure density of tobacco rod and moisture.

Embodiment

In density of tobacco rod and moisture measurement, dynamically follow the tracks of a method for microwave cavity parameter, for microwave resonance method, measure density of tobacco rod and moisture microwave cavity parameter tracking, comprise the following steps:

(1) obtain resonant frequency:

Cigarette causes that by resonator cavity resonant frequency changes, the variation range of resonance frequency is in 1MHz left and right, detecting circuit by three Frequency points of sampling calculates new resonance frequency, and three Frequency points of sampling are respectively resonant frequency point f before resonator parameter changes ₁, compare f ₁the Frequency point f of little 1.4MHz ₀and compare f ₁the Frequency point f of large 1.4MHz ₂.Frequency point f ₀, f ₁and f ₂each self-corresponding detecting circuit value is designated as respectively A ₀, A ₁and A ₂, by following formula, can obtain the resonance frequency Freq of new resonator cavity.

Freq = \frac{A_{0} \times A_{2} \times (f_{2} + f_{0}) \times (f_{2} - f_{0}) + A_{1} \times A_{2} \times (f_{1} + f_{2}) \times (f_{1} - f_{2}) + A_{0} \times A_{1} \times (f_{0} + f_{1}) \times (f_{0} - f_{1})}{2 * (A_{0} \times A_{2} \times (f_{2} - f_{0}) + A_{1} \times A_{2} \times (f_{1} - f_{2}) + A_{0} \times A_{1} \times (f_{0} - f_{1}))}

(2) obtain resonator cavity three dB bandwidth:

Table 1: one group of measurement data table of the present invention

Table 2: the intermediate data that calculates resonance frequency

Table 3: the intermediate data that calculates three dB bandwidth

Table 1 represents the resonant parameter of resonant cavity, comprises after cigarette enters the front resonator parameter of resonator cavity and cavity parameters variation and adopts this method to calculate new resonant parameter.Table 1 and table 2 are the intermediate result of computation process.

Claims

1. in density of tobacco rod and moisture measurement, dynamically follow the tracks of a method for microwave cavity parameter, for microwave resonance method, measure density of tobacco rod and moisture microwave cavity parameter tracking, it is characterized in that: comprise the following steps:

(1) obtain resonant frequency:

Freq = \frac{A_{0} \times A_{2} \times (f_{2} + f_{0}) \times (f_{2} - f_{0}) + A_{1} \times A_{2} \times (f_{1} + f_{2}) \times (f_{1} - f_{2}) + A_{0} \times A_{1} \times (f_{0} + f_{1}) \times (f_{0} - f_{1})}{2 * (A_{0} \times A_{2} \times (f_{2} - f_{0}) + A_{1} \times A_{2} \times (f_{1} - f_{2}) + A_{0} \times A_{1} \times (f_{0} - f_{1}))}

(2) obtain resonator cavity three dB bandwidth: