JP2016070908A - Frequency measurement device, frequency measurement method and oscillation type sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique which can widen a section where frequency can be properly measured without making frequency conversion adjustable even while using a constitution hardly being large size.SOLUTION: A heterodyne unit 2 executes rise conversion forming a sum frequency component fs+fr with respect to a measured frequency fs and down conversion forming a differential frequency component |fs-fr|. If fs is too high to perform measurement with a first measuring instrument A, the differential frequency component |fs-fr| passes through a band pass filter 3 and if fs is too low to perform measurement with the first measuring instrument A, the sum frequency component fs+fr passes through the band pass filter 3 and proper measurement for each component can be performed with a second measuring instrument B. A processor 4 specifies which one of the sum frequency component fs+fr and the differential frequency component |fs-fr| passes through the band pass filter 3 from a measurement result of the first measuring instrument A and performs calculation of corresponding inverse conversion on a frequency represented by a measurement value of the second measuring instrument B in order to calculate fs.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a frequency measurement technique including a procedure for performing frequency conversion on a signal under measurement, and a sensing technique using the same.

  As a measuring instrument for measuring the frequency, for example, a reciprocal frequency counter (hereinafter referred to as a reciprocal counter) is used.

  As shown in FIG. 12A, the reciprocal counter counts the number of clock pulses CLK per period T of the signal under measurement S. Since the count value represents the length of the period T, the frequency can be specified by its reciprocal.

  In this method, the higher the frequency of the signal under measurement S, the lower the resolution because the number of counts decreases, and the lower the frequency of the signal under measurement S, the longer the time required for one measurement. For this reason, it may be desired to limit the frequency measurement range to a certain finite interval in consideration of trade-offs.

  Here, the reciprocal counter has been described, but in the same manner with other measuring instruments, in order to guarantee appropriate measurement that the measuring instrument can exhibit the desired performance, within a certain finite interval (hereinafter referred to as the appropriate interval). May be recommended.

  As disclosed in Patent Documents 1 to 3, if a frequency outside the appropriate section is to be measured, a known frequency conversion may be performed on the signal under measurement prior to measurement. By selecting the frequency conversion so that the converted frequency belongs to the appropriate section, measurement in the appropriate section becomes possible, and the frequency of the signal to be measured can be calculated using the corresponding inverse conversion operation.

JP 2014-9979 JP 2007-10593 JP 2009-5259 JP S57-52837

  In the techniques of Patent Documents 1 to 3, a configuration in which the frequency conversion is variable is essential in order to enable proper measurement of the frequency over a wider section than the appropriate section.

  Patent Document 4 discloses a concept in which a section in which a physical quantity to be measured can vary is shared by a plurality of measuring instruments. According to this idea, it is not necessary to make the frequency conversion variable. For example, when it is desired to extend the appropriate section to both sides, a measuring instrument that handles the proper section, a measuring instrument that handles a section lower than the proper section, and Three measuring instruments that handle the higher section than the appropriate section are required, and the configuration to be used increases.

  An object of the present invention is to provide a technique capable of expanding a section in which a frequency can be appropriately measured without using a variable frequency conversion while using a configuration that is difficult to increase in size.

  According to one aspect of the present invention, (a) the number of repetitions of a signal to be measured per known period, or a period or a time width depending on the period is measured by a first measuring instrument, and the measured value is the first A procedure for specifying the frequency of the signal under measurement based on the measured value, and (b) a procedure performed before or after the procedure (a), wherein the first appropriate frequency When considering the first to Nth (N ≧ 2) extended intervals different from the interval, the i-th frequency conversion converts the frequency of the i-th extended interval to the value in the second appropriate interval. And the frequency in the expansion section of jth (where i and j are any natural numbers from 1 to N where i ≠ j) is converted to a value outside the second appropriate section. An intermediate signal is formed by applying the known first to Nth frequency conversions to the signal to be measured. The frequency of the second appropriate section in the inter-phase signal is measured with a second measuring instrument, the number of repetitions per known period, or the period or time width depending on the period, and the measured value of the second measuring instrument And a frequency conversion identified from the first to Nth frequency conversions as a frequency conversion forming the frequency component of the second appropriate section, the number of repetitions of the signal under measurement per known period, Or a procedure for calculating the frequency of the signal under measurement using an operation for performing an inverse transformation of the frequency transformation specified by using a period or a time width dependent on the period measured by the first measuring instrument. A frequency measurement method is provided.

  In this specification, the fact that a certain section is different from another section means that at least one of the sections has a section that does not overlap with the other section. However, the first to Nth extended sections do not overlap with the first appropriate section, and the extended sections do not overlap each other.

  Since only the effect of the frequency conversion corresponding to the extended section to which the frequency of the signal under measurement belongs is used for the measurement by the second measuring instrument, the section in which the frequency can be measured appropriately without changing the frequency conversion is the first. It can be expanded by the Nth expansion section.

  Since the frequency conversion which formed the frequency component of the 2nd appropriate area is specified using the 1st measuring instrument, the 2nd measuring instrument is shared in the measurement of the frequency of the 1st-Nth expansion section. It can be used, and the configuration can be made difficult to increase in size.

Conceptual diagram of the frequency measuring device according to the embodiment, Conceptual diagram showing the gain of the bandpass filter, A graph of functions representing the first and second frequency transformations; A graph of functions representing the first and second frequency transformations; Conceptual diagram of a frequency measurement device according to another embodiment, A graph of functions representing the first and second frequency transformations; A graph of functions representing the first to fourth frequency transformations; A flowchart showing the processing procedure of the processor; A graph of functions representing the first and second frequency transformations; A graph of functions representing the first and second frequency transformations; Further, a conceptual diagram of a frequency measuring device according to another embodiment, Conceptual diagram of a frequency counter as a measuring instrument, The conceptual diagram of the oscillation type pressure sensor by an Example.

  In FIG. 1, the conceptual diagram of the frequency measuring device by an Example is shown.

  The distributor 1 simultaneously supplies the signal to be measured SA having the frequency to be measured fs to the first measuring device A and the heterodyne device 2. The distributor 1 can be composed of nodes, for example.

  The first measuring instrument A is composed of a reciprocal counter, and measures the period of the signal under measurement SA by counting the number of clock pulses per period. The count value is the measurement value of the first measuring instrument A.

  The heterodyne device 2 includes a local oscillation signal source 21 and a mixer 22. The local signal source 21 generates a local signal having a known frequency fr. The mixer 22 multiplies the local signal and the signal to be measured SA to form an intermediate signal having a sum frequency component of frequency fs + fr and a difference frequency component of frequency | fs−fr |.

  The intermediate signal is input to a band-pass filter (hereinafter referred to as BPF) 3. The BPF 3 has a fixed pass band, but the sum frequency component fs + fr may be allowed to pass or the difference frequency component | fs−fr | may be allowed to pass depending on the value of fs.

  The passing signal SB that has passed through the BPF 3 is input to the second measuring instrument B. The second measuring instrument B is also composed of a reciprocal counter, and measures the cycle of the passing signal SB by counting the number of clock pulses per cycle. The count value is the measurement value of the second measuring instrument B.

  The processor 4 acquires measured values from the first and second measuring instruments A and B, specifies the measured frequency fs by obtaining the reciprocal of the acquired measured values, and the like.

  FIG. 2 schematically shows the frequency dependence of the gain of BPF3.

  As shown in FIG. 2A, the lower cutoff frequency of BPF 3 is fL, and the upper cutoff frequency is fH. The section between fL and fH is the pass band P.

  In this example, the appropriate interval in which the first measuring instrument A can perform an appropriate measurement is equal to the appropriate interval in which the second measuring instrument B can perform an appropriate measurement, and the common appropriate interval M is the same as the pass band P. equal.

  The width fH−fL of the pass band P is equal to the frequency fr of the local oscillation signal. Therefore, when fs belongs to the section P (= M), both the sum frequency component fs + fr and the difference frequency component | fs-fr | are blocked by the BPF 3, and the passing signal SB can be zero. Therefore, when fs belongs to the section P, the first measuring instrument A can appropriately measure fs.

  As shown in FIG. 2 (B), even if fs is higher than the upper limit value fH of the appropriate section M, if fH + fr or less, the difference frequency component | fs-fr | passes through the BPF 3. This section H (fH <fs ≦ fH + fr) adjacent to the high frequency side of the appropriate section M will be referred to as the upper extended section.

  When fs belongs to the upper extended section H, fs itself is too high and cannot be properly measured by the first measuring instrument A, but the difference frequency component | fs-fr | can be properly measured by the second measuring instrument B. .

  As shown in FIG. 2C, even if fs is lower than the lower limit value fL of the appropriate section M, the sum frequency component fs + fr passes through the BPF 3 if it is equal to or greater than fL−fr. This section L (fL−fr ≦ fs <fL) adjacent to the lower section side of the appropriate section M will be referred to as a lower extended section.

  When fs belongs to the lower extended section L, fs itself is too low and cannot be properly measured by the first measuring instrument A, but the sum frequency component fs + fr can be properly measured by the second measuring instrument B.

  FIG. 3 shows a graph of y = fs + fr and y = | fs-fr |, that is, a dependency of the sum frequency component and the difference frequency component on the measured frequency fs, and a graph of y = fs.

  Hereinafter, the conversion of the measured frequency fs into the sum frequency component fs + fr is referred to as “upward conversion”, and the conversion into the difference frequency component | fs−fr | is referred to as “downward conversion”. The y axis shows the frequency after conversion.

  fs undergoes up-conversion and down-conversion at the heterodyne unit 2 at the same time. When fs belongs to the lower extended section L, the up conversion converts fs into a value in the pass band P, and the down conversion converts fs into a value outside the pass band P. When fs belongs to the upper extended section H, the down conversion converts fs to a value in the pass band P, and the up conversion converts fs to a value outside the pass band P.

  Thus, only the effect of the frequency conversion corresponding to the extended section to which fs belongs is selected by the BPF 3 among the up conversion and the down conversion. Since the passing signal SB has only a single frequency component, the frequency can be appropriately measured by the second measuring instrument B. The frequency represented by the measured value is assumed to be fB.

  However, what we want to know is the value of fs. In order to know fs from fB, it is necessary to specify which of up-conversion and down-conversion operations should be performed on fB. For that purpose, it suffices to specify whether fs belongs to the extended section L or H.

  The extended section to which fs belongs is specified using the measurement result of fs by the first measuring instrument A. The frequency of the extended section L or H cannot be measured properly and is inferior in the accuracy of the measurement value or the temporal resolution of the measurement, but it is sufficient if it can be specified whether fs belongs to the extended section L or H.

  If it is known that fs belongs to the lower extended section L, the value is fA1 obtained by performing an inverse conversion of the upward conversion (hereinafter referred to as reverse upward conversion) to fB, that is, an operation for reducing fr. If it is known that it belongs to H, its value is fA2 obtained by performing an inverse conversion of the downward conversion (hereinafter referred to as reverse downward conversion), that is, an operation of adding fr to fB.

  In this way, by specifying whether fB is the value after the up-conversion or the value after the down-conversion, the second measuring instrument B is commonly used for measuring the frequencies of the extended sections L and H. Can do.

  Table 1 summarizes the contents of the process for specifying fs and the conditions under which the process is performed.

  As shown in section (1), when the measured value of the first measuring instrument A represents a frequency less than fL (under) and the measured value of the second measuring instrument B represents the frequency of the appropriate section M ( Appropriate) represents that fs belonging to the lower extended section L has undergone an up-conversion, so the processor 4 uses the value obtained by performing the reverse up-conversion to the frequency represented by the measurement value of the second measuring instrument B. Identify.

  As shown in section (2), when the measured value of the first measuring instrument A represents a frequency exceeding fH (over), and the measured value of the second measuring instrument B represents the frequency of the appropriate section M ( Appropriate), because it indicates that fs belonging to the upper extended section H has undergone down-conversion, the processor 4 identifies fs with the value obtained by performing reverse down-conversion on the frequency represented by the measurement value of the second measuring instrument B. To do.

  When the frequency of the signal input to the first measuring device A is out of the appropriate section M, the frequency of the first measuring instrument A is higher or lower than the appropriate section M even if no specific measurement value is shown. What is necessary is just to show the measurement result which has the information amount which can specify whether it has deviated to the side.

  For example, the first measuring instrument A may output a signal indicating that fs has deviated from the appropriate interval M to the upper side, or a signal indicating that fs has deviated from the lower side. The processor 4 can determine whether the signal is “under” or “over” in Table 1. Examples of such a signal include a borrow signal and an overflow signal of a counter constituting the first measuring instrument A.

  As shown in section (3), the measurement value of the first measuring instrument A represents the frequency of the appropriate section M (appropriate), and the measurement result of the second measuring instrument B represents the frequency of the proper section M. When not (inappropriate), the processor 4 specifies fs with the frequency represented by the measurement value of the first measuring instrument A.

  Here, the measurement result of the second measuring instrument B is “unsuitable”, specifically, the frequency represented by the measured value of the second measuring instrument B exceeds the lower zero cross frequency of the BPF 3 and becomes fL. This includes not only the case where the amplitude of the passing signal SB exceeds zero, but also the case where the amplitude of the passing signal SB is zero, as well as the case where it belongs to a zone that exceeds fH and falls below the upper zero cross frequency of BPF3.

  That is, when fs belongs to the proper section M, the passing signal SB can be zero (see FIG. 2A), when the sum frequency component is below the proper section M, and when the difference frequency component is above the proper section M , The passing signal SB becomes zero. That the passage signal SB has become zero can be detected by the processor 4 through the measurement result of the second measuring instrument B, for example.

  As shown in section (4), when the measurement result of the first measuring instrument A is “under” and the measurement result of the second measuring instrument B is “inappropriate”, the processor 4 outputs an error. To do. In this case, fs is less than the lower extended section L.

  As shown in section (5), when the measurement result of the first measuring instrument A is “over” and the measurement result of the second measuring instrument B is “inappropriate”, the processor 4 gives an error. Output. In this case, fs exceeds even the upper extended section H.

  Next, with reference to FIG. 4, a modified example of ascending conversion and descending conversion will be described.

  In FIG. 4, the section ML at the lower end in the appropriate section M is referred to as a lower end section, and the section MH at the higher end in the appropriate section M is referred to as an upper end section.

  In this example, the up conversion further plays a role of converting the frequency of the lower end section ML into the value of the upper end section MH, and the down conversion plays a role of converting the frequency of the upper end section MH into a value of the lower end section ML. Fulfill further. As a result, in the end sections MH and ML, the second measuring device B can perform appropriate measurement. This can be realized by, for example, fH−fL> fr.

  Table 2 shows the contents of the process for specifying fs and the conditions under which the process is performed when the configuration of FIG. 4 is adopted. The following categories (6) and (7) are added to Table 1.

  As shown in section (6), when the measured value of the first measuring instrument A represents the frequency of the lower end section ML, and the measured value of the second measuring instrument B represents the frequency of the upper end section MH. , The processor 4 specifies fs with the inverse increase conversion of the frequency represented by the measurement value of the second measuring instrument B.

  Here, the measurement value of the second measuring instrument B, not the measurement value of the first measuring instrument A, is adopted because of the temporal resolution of the measurement by the reciprocal counter, that is, the short time required for one measurement. This is because the higher the frequency, the better. That is, in the case of category (6), it is advantageous to adopt the measurement value of the second measuring instrument B from the viewpoint of the temporal resolution of measurement.

  As shown in section (7), when the measured value of the first measuring instrument A represents the frequency of the upper end section MH and the measured value of the second measuring instrument B represents the frequency of the lower end section ML The processor 4 identifies fs with the frequency represented by the measurement value of the first measuring instrument A.

  Here, the measurement value of the first measuring instrument A, not the measurement value of the second measuring instrument B, is adopted from the viewpoint of the temporal resolution of the measurement. This is because it is advantageous to employ the measurement value of the measuring instrument A.

  In the above categories (6) and (7), even if the measurement result of the second measuring instrument B becomes “inappropriate” due to disturbance, etc., appropriate measurement is performed by the processing of category (3) in Table 1. Is secured. Thus, the reliability of the frequency measuring device can be improved by configuring the sections ML and MH in which appropriate measurements can be performed by both the first and second measuring instruments A and B.

  In Table 2, because the temporal resolution was emphasized under the use of the reciprocal counter, the measurement value representing the higher frequency was adopted. However, if the resolution (accuracy) of the measurement value is important, the lower frequency is selected. You may employ | adopt the measured value to represent.

  Next, another embodiment will be described with reference to FIGS.

  FIG. 5 shows a configuration for realizing frequency conversion by frequency division and multiplication. The signal under measurement SA is distributed to the frequency divider / multiplier 5. The frequency divider / multiplier 5 includes a distributor 51, a multiplier 52, a frequency divider 53, and an adder 54. The distributor 51 supplies the signal under measurement SA to the multiplier 52 and the frequency divider 53 simultaneously. The distributor 51 can be composed of nodes, for example.

  The multiplier 52 multiplies fs by n, and the frequency divider 53 multiplies fs by 1 / m. The adder 54 adds the multiplied signal and the divided signal, thereby forming an intermediate signal having a multiplied wave component of frequency n · fs and a divided frequency component of frequency fs / m. Here, n and m are natural numbers of 1 or more (except when both n and m are 1).

  FIG. 6 shows a graph of y = n · fs, y = fs / m, and y = fs. In FIG. 6, n, m ≧ 2.

  Hereinafter, conversion of the frequency fs to be measured into the multiplied wave component n · fs is referred to as multiplication conversion, and conversion into the divided frequency component fs / m is referred to as frequency division conversion. The y axis shows the frequency after conversion.

  In the multiplication conversion, the frequency in the lower extension section L is converted into a value in the appropriate section M, and the frequency in the upper extension section H is converted into a value outside the proper section M. In the frequency division conversion, the frequency in the upper extended section H is converted into a value in the appropriate section M, and the frequency in the lower extended section L is converted into a value outside the proper section M.

  In this example, the width of the lower extended section L is (fH−fL) / n, and the width of the upper expanded section H is m · (fH−fL).

  Also in this example, the processing of Tables 1 and 2 is read as an operation of multiplying "reverse rising conversion" by inverse conversion of multiplication conversion, that is, 1 / n, and "reverse falling conversion" is reverse conversion of frequency division conversion, that is, m It can be read and applied to the multiplication operation.

  Next, a modified example of the number of extended sections will be described with reference to FIGS.

  In FIG. 7, as indicated by the alternate long and short dash line, an extension section L2 is added by adding the frequency transformation y = ξ · fs, and an extension section H2 is added by adding the frequency transformation y = fs / η. The Here, ξ and η are natural numbers that satisfy ξ> n and η> m, respectively.

  This adds an adder for adding a signal of frequency ξ · fs multiplied by ξ and an adder for adding a signal of frequency fs / η divided by η, after the adder 54 of FIG. This can be achieved. Thus, it will be understood by those skilled in the art that a desired number of extended intervals can be constructed by repeatedly using addition.

  FIG. 8 is a flowchart when the configuration of FIG. 7 is adopted.

  The processor 4 refers to the measurement results of the measuring instruments A and B (S1). According to the result, the flow branches into four branches. In FIG. 8, the categories (1) to (5) correspond to the categories in Table 1.

  The process (S10) in the case of the category (3) and the process (S11) in the case of the category (4) or (5) are the same as the example in Table 1.

  The processing (S2 to 5) in the case of the section (1) and the processing (S6 to 9) in the case of the section (2) can be applied when fs continuously varies from the initial value in the appropriate section M. Hereinafter, these processes will be described on the premise that the repetition of measurement by the measuring instruments A and B is sufficiently fast with respect to fs fluctuation.

  When the determination result of S1 corresponds to the category (1), the processor 4 determines whether fs belongs to the extended section L1 or L2 (S2), and when fs belongs to the section L1, the second measuring instrument The fs is specified by the value obtained by performing the inverse transformation of the n multiplication conversion on the frequency represented by the measurement value of B (S3), and if belonging to the section L2, the fs is identified by the value obtained by performing the inverse transformation of the ξ multiplication transformation (S4). ).

  Next, the processor 4 determines whether the measurement result of the first measuring instrument A is “under” and the measurement result of the second measuring instrument B is “appropriate” (S5). If NO, return to S1. The processing (S6 to 9) in the case of section (2) is the same.

  Hereinafter, a method for specifying an extended section will be described with the determination of S2 as a specific example.

  At the first round of the loop processing of S2 to S5, that is, when the first branch from S1 to S2 is made, it is determined as “L1” in S2. This relies on the fs variation being continuous.

  In the second and subsequent rounds of the loop processing, the extended section to which fs belongs can be specified by the change in the measurement value of the second measuring instrument B. This point will be described with reference to FIG.

  As shown in FIG. 7, when fs shifts from the section L1 to L2, the frequency represented by the measurement value of the second measuring instrument B at the boundary between L1 and L2 is not changed from the value near fL to the value near fH. It changes continuously. The transition to the section L2 can be detected by this discontinuous change. Similarly, when fs returns from the section L2 to L1, the frequency represented by the measurement value of the second measuring instrument B changes discontinuously from a value near fH to a value near fL at the boundary between L2 and L1. , Return to section L1 can be detected.

  Thus, using the fact that the first reference section is L1, the extended section to which the current fs belongs can be specified by the relative displacement therefrom. It will be understood by those skilled in the art that the determination of S6 can be similarly performed.

  In the above example, the measurement result of the first measuring instrument A was only distinguished from “over” or “under” in addition to “appropriate”, but from S 1 the measurement result of the first measuring instrument A is fs. If it can be specified which of the extended sections L2, L1, H1, and H2 belongs to, the above loop processing is unnecessary, and S1 is performed each time the inverse transformation corresponding to the extended section is performed, as in the example of Table 1. It is also possible to perform processing to return to step (b).

  Next, with reference to FIG. 9 and FIG. 10, a modified example of the arrangement position of the appropriate section will be described.

  Up to now, an appropriate section (hereinafter referred to as the first appropriate section) in which proper measurement can be performed with the first measuring instrument A and an appropriate section (hereinafter referred to as the second appropriate section) in which appropriate measurement can be performed with the second measuring instrument B. Has been described as an example of a match with the appropriate section.

  However, the set describing the second appropriate interval is a concept different from the set describing the first appropriate interval and the extended interval. 3, 4, 6, and 7, the vertical axis M indicates the second appropriate section, and the horizontal axis M indicates the first appropriate section. The first appropriate section, the extended section, and the extended sections do not overlap each other, but it is arbitrary whether the second appropriate section overlaps with the first appropriate section or the extended section.

  For example, the second appropriate section may not overlap with the first appropriate section, or may overlap with the extended section. Since the second appropriate interval may overlap with the extended interval, the mapping from the latter to the former, that is, the frequency conversion, may include an identity mapping. The pass band P is matched with the second appropriate section MB.

  FIG. 9A shows an example in which the second appropriate section MB is arranged higher than the first appropriate section MA (in the figure, n is a natural number of 2 or more). The multiplication conversion converts the frequency of the lower extended section L into a value in the second appropriate section MB. The frequency conversion for converting the frequency of the upper extended section H into the value in the second appropriate section MB is an identity map (m = 1 in FIG. 5).

  FIG. 9B shows an example in which the second appropriate section MB is arranged in a lower range than the first appropriate section MA (in the figure, m is a natural number of 2 or more). The frequency division conversion converts the frequency of the upper extended section H into a value in the second appropriate section MB. The frequency conversion for converting the frequency of the lower extended section L into the value in the second appropriate section MB is the identity map (n = 1 in FIG. 5).

  FIG. 10 shows an example in which the second appropriate section MB is made different from the first appropriate section MA with an overlap. y = α · fs is a virtual mapping that maps the first appropriate section MA to the second appropriate section MB, and α ≠ 1.

  The multiplication conversion converts the frequency in the lower extended section L into a value in the second appropriate section MB, and converts the frequency in the upper extended section H into a value outside the second appropriate section MB. The frequency division conversion converts the frequency of the upper extended section H into a value within the second appropriate section MB, and converts the frequency of the lower extended section L into a value outside the second appropriate section MB.

  The multiplication conversion further plays a role of converting the frequency of the lower end section ML of the first appropriate section MA into the value of the upper end section MH ′ of the second appropriate section MB. It further plays a role of converting the frequency of the upper end section MH of the proper section MA into the value of the lower end section ML ′ of the second proper section MB.

  For example, the above-mentioned role of the multiplication conversion can be realized by (fL / α) <(fH / n), and the above-mentioned role of the division conversion is (fH / α)> (m · fL). realizable.

  When fs belongs to the section MH or ML, both the first and second measuring instruments A and B can perform appropriate measurement. Thus, the reliability of the frequency measuring device can be improved by configuring a section in which both the first and second measuring instruments A and B can perform appropriate measurement.

  Also in this example, the processing of Table 2 can be performed as in the example of FIG. In Tables 1 and 2, whether the measurement result of the first measuring instrument is “appropriate”, “over” or “under” is determined based on the first appropriate section MA, and the measurement result of the second measuring instrument is Whether “appropriate” or “inappropriate” may be determined based on the second appropriate section MB.

  When the measurement value representing the frequency of the first appropriate section MA is obtained by the first measuring instrument A and the measurement value representing the frequency of the second appropriate section MB is obtained by the second measuring instrument B, any measurement is performed. Whether to adopt a value may be determined by the magnitude relationship of the frequencies represented by these measured values.

  FIG. 11 is a conceptual diagram of a frequency measuring device according to another embodiment. The frequency converter 6 includes the heterodyne unit 2 shown in FIG. 1 or the frequency divider 5 shown in FIG.

  The pre-converter 7 performs variable known frequency conversion (hereinafter referred to as pre-conversion) on the input signal S0. For the pre-conversion, the heterodyne method, frequency division, multiplication, etc. are used. The signal subjected to the pre-conversion is the signal under measurement SA.

  The processor 4 calculates the frequency of the input signal S0 by performing an inverse conversion operation on the value of fs specified in the processing of Table 1 and FIG. 8, and based on the calculated frequency, Control the conversion. For example, the pre-conversion is controlled so that fs follows the median value of the first appropriate interval MA. Thereby, the further expansion of the area which can measure a frequency appropriately is achieved.

  Even if the pre-conversion control is not in time and fs suddenly deviates from the first appropriate section MA, if it belongs to the extended section L or H, this can be appropriately measured in real time by the second measuring instrument B. Conventionally, even if the same feedback control is performed, proper measurement cannot be performed at the moment when fs suddenly fluctuates.

  The embodiment of the frequency measuring device has been described above. For example, the following modifications are possible.

  In each of the above examples, the first appropriate section, the extended section, and the adjacent expanded sections are adjacent to each other, but there may be a gap between them. In this specification, “adjacent” means that two sections have a common end point at the boundary between them. Since these sections have no overlap, their end points are included in only one section. “Adjacent” means to allow a gap between them.

  In each of the above examples, the second appropriate section is matched with the pass band of BPF 3, but this need not be the case. For example, the second appropriate section may be included in the pass band of the BPF 3, or may be included from the lower zero cross frequency to the upper zero cross frequency of the BPF 3.

  In each of the above examples, the frequency converter is always operated. However, in principle, the signal to be measured SA is measured by the first measuring instrument A while the frequency converter is stopped, and fs is the first appropriate section. The processor may perform control for starting up the frequency converter and preparing for reference to the measurement value of the second measuring instrument B only when approaching the end point.

  In each of the above examples, the reciprocal counter constituting the measuring instrument measures the period of the signal under measurement. However, a time width depending on the period, such as an integral multiple of the period or a half period, may be measured.

  FIG. 12B shows a direct frequency counter (hereinafter referred to as a direct counter) as another example of a measuring instrument. The direct counter counts the number of repetitions of the signal under measurement S per known gate period G, for example, per second. The frequency of the signal to be measured S can be specified by the count value.

  With a direct counter, for example, if the frequency to be measured is too low, the number of counts is small and sufficient resolution cannot be obtained. If the frequency to be measured is too high, the count value is saturated and sufficient accuracy cannot be obtained. For this reason, the appropriate section is determined. One of the measuring instruments A and B may be a direct counter and the other may be a reciprocal counter.

  FIGS. 12A and 12B show the measured signal S having a rectangular wave, but the measured signal SA in FIGS. 1, 5, and 11 and the input signal S0 in FIG. Or a rectangular wave or other non-sinusoidal wave. The measuring instrument includes a shaping device such as a Schmitt trigger for shaping the signal given to itself into a rectangular wave as necessary. The measuring instrument 5 may be an analog type.

  FIG. 13 is a conceptual diagram of an oscillation type pressure sensor according to an embodiment.

  Hereinafter, for the sake of convenience, the symbols Cs and Ri (where i = 1 to 3) are used not only for the meanings of the reference numerals of the drawings but also for the variables representing the capacitance and the resistance.

  The oscillation circuit 8 includes an operational amplifier, a resistor R1 placed between the non-inverting input terminal of the operational amplifier and the ground, a resistor R2 placed on a feedback path from the output terminal of the operational amplifier to the non-inverting input terminal, and the operational amplifier. It comprises an astable multivibrator comprising a resistor R3 placed in a feedback path from the output terminal to the inverting input terminal, and a capacitor Cs placed between the inverting input terminal and the ground, and the oscillation frequency is 1 / An oscillation signal represented by {2.R3.Cs.log ((R1 + R2) / R1)} is output.

  The capacitor Cs has a structure in which the distance between the electrode plates changes and the capacitance Cs changes when pressure is applied. Since the capacitance Cs determines the oscillation frequency as in the above equation, the oscillation circuit 8 outputs an oscillation signal having an oscillation frequency corresponding to the pressure value.

  An oscillation signal is input to the frequency measuring device 9. The frequency measuring device 9 comprises the device shown in FIG. 1, FIG. 5, or FIG. 11, and the processor obtains a pressure value from the oscillation frequency specified in the processing of Table 1 or FIG. 8, and displays the pressure. . In order to obtain the pressure, a memory for storing a relational expression for associating the oscillation frequency with the pressure or a correspondence table may be further provided.

  In this example, a capacitor is used as the sensing element. However, the resistance whose resistance value changes due to the influence of heat, the inductor whose inductance changes due to the displacement of the core, and the resonance frequency that is affected by humidity and gas concentration. A changing crystal unit or the like can also be used. Further, the oscillation circuit can be configured by various harmonic oscillation circuits in addition to a relaxation oscillation circuit such as a multivibrator.

  As mentioned above, although this invention was demonstrated along the Example, this invention is not limited to these. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

  The frequency measuring device of the present invention is not limited to the measurement of a physical quantity in a transmission type sensor. For example, the frequency measuring apparatus measures all frequencies such as measurement of transmission / reception frequency in communication, monitoring of frequency in power supply, testing of integrated circuits, and inspection of electronic equipment. It can be used for applications.

1 ... distributor,
2 ... Heterodyne device (frequency converter),
21 ... Local signal source,
22 ... Mixer,
3 ... Band pass filter (filter),
4 ... Processor (calculation means),
5. Frequency divider / multiplier (frequency converter),
51. Distributor,
52 ... multiplier,
53 ... frequency divider,
54 ... Adder,
6 ... Frequency converter,
7 ... Pre-converter,
8: Astable multivibrator (oscillation circuit),
9: Frequency measuring device,
A ... First measuring instrument,
B ... Second measuring instrument,
SA: Signal to be measured,
SB ... Pass signal,
P ... pass band,
M ... appropriate section (first appropriate section, second appropriate section),
MA: first appropriate section,
MB ... 2nd proper section,
ML ... lower end section of the first appropriate section,
MH ... upper end section of the first appropriate section,
ML '... lower end section of the second appropriate section,
MH ′: upper end section of the second appropriate section,
L, L1 ... lower extended section (first extended section),
H, H1 ... upper extended section (second extended section),
L2 ... third extended section,
H2 ... Fourth extended section,
R1, R2, R3 ... resistance,
Cs: Capacitor (sensing element).

Claims (6)

A first measuring instrument for measuring the number of repetitions of the signal under measurement, or a period or a time width dependent on the period;
Considering the first to Nth (N ≧ 2) extended sections different from a first appropriate section, the i-th frequency transform converts the frequency of the i-th extended section to a certain The frequency in the second appropriate interval is converted and the frequency of the jth (where i and j are any natural numbers from 1 to N where i ≠ j) is the second appropriate frequency. A frequency converter that forms an intermediate signal by performing known first to Nth frequency conversions such as conversion to values outside the interval on the signal under measurement;
A filter that receives the intermediate signal, passes the frequency of the second appropriate section, and cuts off the frequency converted by the frequency converter to a value outside the second appropriate section;
A second measuring device for measuring a known number of repetitions per period of the passing signal that has passed through the filter, or a period or a time width depending on the period;
(A) A function for specifying the frequency of the signal under measurement based on the measured value when the measured value of the first measuring instrument represents the frequency of the first appropriate section, (B) the first measurement A function for specifying which of the first to N-th extended sections the frequency of the signal under measurement belongs to using the measurement result of the measuring instrument, and (C) the measurement value of the second measuring instrument is: When expressing the frequency of the second appropriate section, the measured value and the frequency of the extended section specified by the function (B) among the first to Nth frequency conversions are within the second appropriate section. A frequency measurement apparatus comprising: a calculation unit having a function of calculating a frequency of the signal under measurement using a calculation for performing an inverse conversion of the frequency conversion for converting to a value of   At least one of the first to Nth extension sections is disposed adjacent to the first appropriate section, and the frequency of the extension section of the first to Nth frequency transforms 2. The frequency measurement device according to claim 1, wherein the frequency conversion for converting into a value in the second proper section further plays a role of converting the frequency in the first proper section into a value in the second proper section.   At least one of the first to Nth extended sections is arranged in a lower area than the first appropriate section, and the remaining extended sections are arranged in a higher area than the first appropriate section. The frequency measuring device according to claim 1 or 2.   A program that causes a computer to function as the calculation means in the frequency measurement device according to any one of claims 1 to 3. (A) When the number of repetitions of the signal under measurement or the period or time width depending on the period is measured by the first measuring instrument, and the measured value represents the frequency of the first appropriate section , A procedure for identifying the frequency of the signal under measurement based on the measured value,
(B) A procedure performed before or after the procedure (a), and considering first to Nth (N ≧ 2) extended sections different from the first appropriate section, The i-th frequency conversion converts the frequency in the i-th extension section into a value in the second appropriate section, and j-th (where i and j are any natural numbers from 1 to N where i ≠ j. The frequency of the extended section of (1) is subjected to known first to Nth frequency conversions for conversion to values outside the second proper section to form an intermediate signal. , The frequency component of the second appropriate interval in the intermediate signal, the number of repetitions per known period, or the period or the time width depending on the period is measured by the second measuring instrument, and the second measuring instrument As the frequency conversion in which the measured value and the frequency component of the second appropriate section are formed, the first to Nth A frequency conversion identified from the frequency conversion, which is identified using the number of repetitions per known period of the signal under measurement, or the period or the time width depending on the period, measured by the first measuring instrument. And a procedure for calculating a frequency of the signal under measurement using an operation for performing an inverse conversion of the frequency conversion. By including a sensing element whose characteristic changes under the influence of the physical quantity to be sensed in a manner in which the characteristic determines the oscillation frequency, an oscillation signal having an oscillation frequency corresponding to the value of the physical quantity is output. An oscillation circuit;
A first measuring device for measuring the number of repetitions of the oscillation signal per known period, or a period or a time width depending on the period;
Considering the first to Nth (N ≧ 2) extended sections different from a first appropriate section, the i-th frequency transform converts the frequency of the i-th extended section to a certain The frequency in the second appropriate interval is converted and the frequency of the jth (where i and j are any natural numbers from 1 to N where i ≠ j) is the second appropriate frequency. A frequency converter that forms an intermediate signal by performing known first to Nth frequency conversions such as conversion to values outside the interval on the oscillation signal;
A filter that receives the intermediate signal, passes the frequency of the second appropriate section, and cuts off the frequency converted by the frequency converter to a value outside the second appropriate section;
A second measuring device for measuring a known number of repetitions per period of the passing signal that has passed through the filter, or a period or a time width depending on the period;
(I) a function of specifying the value of the physical quantity by the measured value when the measured value of the first measuring instrument represents the frequency of the first appropriate section; (II) of the first measuring instrument; Using the measurement result, the function of specifying which of the first to Nth extended sections the oscillation frequency belongs to, and (III) the measured value of the second measuring instrument is the second appropriate When the frequency of the section is expressed, the frequency of the extended section specified by the function (II) among the measured value and the first to Nth frequency conversions is converted into the value in the previous second appropriate section. An oscillation type sensor comprising: an arithmetic unit having a function of calculating a value of the physical quantity using an arithmetic operation that performs inverse conversion of frequency conversion.