SU1053018A1 - Device for measuring amplitude-frequency response - Google Patents

Abstract

A DEVICE FOR MEASURING AMPLITUDE-FREQUENCY CHARACTERISTICS containing a frequency synthesizer, two amplitude meters, the input of the first of which is connected to one of the input terminals of the device, and the output is connected to the first input of the first switch, a memory block, the output of which is connected to the input of the first comparison unit, The second comparator unit, the control unit, the second switch and the recorder, are different in that, in order to reduce the measurement time, a voltage divider, a third switch, two analog-to-digital conversions are entered into it. a body, two registers, a combinable adder, a cumulative adder, a third comparison unit, a code converter, a pulse generator and a division unit, and the first control input of the first register and. the memory unit, the control input of the first switch, the first and the second. The control inputs of the second register and accumulating adder are connected to the output bus of the control unit connected via the second switch to the second control input of the first register and through the third switch to the control input of the combinational adder, the second inputs of the second and third switches are voltage inputs logic levels, the output of the first comparison unit is connected to the second control input of the memory unit and to the input bus of the control unit connected to the first control input of the transducer the user of the codes and the output of the second comparison unit, the first input of which is connected to the first one. the information input of the code converter, the output of the accumulating adder and the control of the input of the frequency synthesizer, the first and second amplitude meters, and the second input of the second comparator unit is the fixed code input, the output of the third comparator unit is connected to the second control input of the code converter, the third control input the memory unit and the input bus of the control unit, the synchronization input of which is connected to the output r (Nerator. pulses, the output of the first amplitude meter through a divider The second input is connected to the second input terminal of the first switch, the amplitude of the second meter is connected to the high frequency synthesizer and the second input terminal of the device, and the output is connected to the input of the first analog-to-digital converter, the output of which is connected to the first input of the dividing unit, the second input of which the second analog-to-digital converter is connected to the output of the first switch, and the output is connected to the first information input of the combinational adder, the second information input of the code converter and the input :, in the first register output connected to the data input of the second adder combination, cyNBviaTOpa collecting information input coupled to an output of the second register and the first input of the third

Description

the comparison unit, the second input of which is a fixed code input, the output of the code converter is connected to the input of the recorder.

The device relates to a measurement technique and can be used to measure the amplitude-frequency characteristics (AFC) of multiresonant oscillatory systems, comb filters AND: measuring transducers of frequency dispersions of dielectric and magnetic properties of media with their non-destructive testing. A device is known for measuring the frequency response of a quadrupole comprising a series-connected modulating voltage generator, a sweep frequency generator, measured: a four-pole, two linear detectors, one of which is connected to. the output of the oscillating frequency generator is an electron-beam indicator, the horizon input, whose deviation is associated with. a modulating voltage generator output, two controllable dividers, two functional converters and a dividing unit ;. The drawbacks of the device are the low accuracy of the reproduction of the frequency response curve, due to the non-linearity of the oscillation law of the generator frequency and the impossibility of accurate measurement of the resonant frequency and passbands of the investigated quadruple. . . The closest in technical essence to the present invention is a device for automatically controlling the frequency response of filters containing a frequency synthesizer, a recorder, two comparison units, a memory unit whose output is connected to the input of the first comparison unit, two amplitude meters which are connected to one of the device's hard terminals, the control unit f, two controllable keys, an amplitude modulator, a slowly varying voltage generator, and a peak detector C2J. The disadvantages of the known device are considerable laboriousness and low accuracy of the control and narrowband filters and comb filters due to the considerable time spent on measuring the parameters of the 31 other amplifiers of the quadruple amplifiers adjacent to each other. The purpose of the invention is to reduce the time of measurement of the frequency response parameters. The goal is achieved by having a device for measuring amplitude-frequency characteristics containing a frequency synthesizer, two amplitude meters, the input of the first of which is connected to one: the first from the input terminals of the device, and the output is The first input of the first switch, the memory unit, the output of which is connected to the input of the first comparison unit, the second comparison unit, the control unit, the second switch and the recorder ;, the voltage divider is inserted, the third switch. Two analog-digital converters, two registers, combinational adder, accumulating adder, third comparison unit,. a code converter, a pulse generator and a split unit, with the first control input of the first register and the memory block, the control input of the first switch, the first and second control inputs of the second register and the accumulating adder connected to the output bus of the control unit connected through the second switch to the second control input of the first register and through the third switch to the control input of the combinational adder, the second inputs of the second and third switches are input voltages logic levels, the first comparison unit is connected with the second control to the input of the memory unit and the input bus of the control unit connected to the first control input of the code converter and the output of the second comparison unit, the first input of which is connected to the first information input of the code converter. the output of the accumulating adder and the control inputs of the frequency synthesizer, the first and second amplitude meters, and the second input of the second comparison unit is the input of a fixed code, the output of the third unit is equal to It is connected to the second control input of the code converter, the third control input of the memory unit and the input bus of the control unit, the clock input of which is connected to the output of the pulse generator, the output of the first MP meter and the voltage through the voltage divider connected to the second input of the first switch, the input the second amplitude meter is connected to the output of the frequency synthesizer, and to the second input terminal of the device, and the output is connected to the input of the first analog-to-digital converter, the output connected to the first input shares unit block, the second input of which is connected via the second analog-to-digital converter to the output of the first switch, and the output to the first information input of the combinational adder, the second information input of the code converter and the input of the first register output; connected to the second information input of the combinational adder, the information input of the accumulative adder is connected to the output of the second register and the first input of the third comparison unit, the second input of which is a fixed code input, the output of the code converter is connected to the recorder input.

Figure 1 shows the block diagram of the device; figure 2 - timing charts, he kdie device operation.

The device contains a frequency synthesizer 1, an output connected to the input of a test terminal 2, an input terminal 3 and 4 of the device, the first Amplitude Meter 5 consisting of a linear detector 6, a controlled divider 7 and a functional converter 8, the second measuring instrument 9 of amplitude consisting from linear detector 10, controlled divider 11 and functional converter 12, first analog-to-digital converter 13, input connected to output of the second meter 9 amplitude, dividing unit 14, voltage divider 15, first A second switch 16, a second analog-digital converter 17, an input connected to a transmitter of the first switch 16, and an output to one of the inputs of a dividing unit 14, the second input of which is connected to the output of a first analog-digital converter 13, VTS ; the input 19 of which is in the input of a fixed code, the second switch 20, the second input 21 of which is the input voltage of logic levels J the first register 22, the input connected to the output of the dividing block 14 accumulating adder 23, the third ne eklyuchatel 24, a second input 25 which is input voltage logic levels combinational adder 26, first information input of which is connected to the output of divider unit 14 and second information input - yield pervog-. go register 22, the third block 27

The second input 28 of which is a fixed code input, the second register 29, which is connected to the information input of the accumulating adder 23 and the first input of the third comparison block 27, memory block 30, connected to the output of the combinational adder 26, the first compare block 31 whose input is connected to the output of the block

10 30 memories, a 32 code converter, the first information input of which is connected to the output of the accumulator 23 accumulator, controlling the input of the frequency synthesizer 1, measuring the amplitude of the 5th and 5th and 9th amplitudes and the first input of the second comparison unit 18, the second information input The input of the converter 32 codes is connected to the output of the dividing block 14, the first and second

0, the control inputs of the converter 32 codes are connected to the input bus of the control unit 33, the synchronization input connected to the output of the pulse generator 34, the output of the converter of the code generator, is connected to the input of the recorder 35.

The device works as follows

The synthesizer produces 1 frequency on

0 a quadrupole under study 2 is a sinusoidal voltage with a frequency determined by the frequency cd,, and with a fixed amplitude. The frequency code is set using a pump accumulator 23. A voltage proportional to the amplitude of the input signal V of the object of measurement is removed from the output of the 9 amplitude meter and, after being converted to a digital code, by means of the first analog-digital converter 13; is supplied to the first input of the dividing unit 14. A voltage proportional to the amplitude of the output signal V2 of the measurement object is removed from

The 5 outputs of the second measure 11 5 amplitudes and are fed to the first input of the first transition switch 16 and through the voltage divider 15 to the second input of the same switch. Depending on the position of the first switch 16 in a single analog-to-digital converter 17, either a voltage proportional to the amplitude of the output voltage is converted into a digital code.

5 signal 2 measurement object, voltage, equal to l / V from voltage V2 ....

In this case, a digital code is generated at the output of the dividing unit 14, which corresponds to either the relation J

0 or relation) -И® and and and -, respectively, codes formed at the outputs of the second and first analog-digital converters 17 and 13.

5 The value of A {{) :: U, / U is numerically equal to the frequency response of the object under study at frequency f. the frequency of runs is a series of sequential values of f2,. .. f j ,. .. ff and the object under study 2 is a linear chain, then the values of A (f) are sequentially recorded at the output of the dividing block. A (f), ... A (f.), Giving a discrete representation of the frequency response of the measurement object. Since the frequency response of the measurement object is determined by calculating the ratio of the amplitude of the output voltage of the object to the amplitude of its input voltage, the instability of the amplitude of oscillations generated by the frequency synthesizer 1 does not affect the measurement accuracy. However, the transmission coefficients of the linear detectors 10 and 6 of both amplitude meters 9 and 5 are frequency dependent, which degrades the accuracy of measurements over a wide frequency range. To eliminate this phenomenon, both the 9 and 5 amplitude gauges, built according to the same schemes, include controlled dividers 11 and 7 and functional converters 12 and 8. In the 9 amplitude measurer, the output voltage of the linear detector 10 is multiplied by using a controlled divider 11 by the coefficient, the value of which is determined by the voltage applied to the control input of this, divides the output from the function converter 12, which is a code-type converter, into a voltage. Each group of codes often arriving at the input of the functional converter 12 corresponds to control voltages at its output which change the division ratio of the controlled divider 11. The law of conformity is selected when the device is transmitted so that the cascade connection ratio of the linear detector 10 and the controller Divisor Divider 11 was built over the entire operating frequency range. Amplitude meter 5 works the same way. The measurement process of the measurement response of the measurement object consists in step-by-step viewing of this characteristic in the frequency range. TO RLLOX. This scanner performs the device at variable frequency steps, the step size being determined by the frequency response itself. If the device is set to handle peaks, the scan goes on in a constant step until the device detects a frequency interval in which the maximum is localized, and then the step starts decreasing until the coordinate of the maximum on the frequency axis is will be fixed with the required accuracy, i.e. when the step l becomes not more than the specified value. After that, the initial step size is restored and the viewing is carried out with a constant step until a new maximum is encountered, etc. The processing of the minimum frequency response is the same. This procedure of operation of the device also makes it possible to determine the half-width values, for example, resonance peaks, i.e. frequency band between the coordinate. . the maximum and the frequency at which the frequency response value decreases to 1 / Y2 from the maximum after passing through a maximum (right of breadth). This makes the device; applicable for the study of resonant systems, for example, comb filters whose frequency response consists of a set of alternating local extremes. The accuracy of determining the coordinates of the extremes and their values depends on the bit width of both analog-to-digital-Btjx converters 9 and 5 and synthesizer 1 frequencies. Since, in practice, the accuracy of frequency synthesis is always higher than that of an analog-digital voltage converter, the error in determining the extremum is mainly determined by measuring the voltages and their analog-digital conversion. The accuracy limit for the proposed device is the frequency range cTf, at which the frequency response values at the points f Hf cTf are converted by analog-digital converters 9 and 5 into identical codes. Consequently, the measurement error depends on the steepness of the object's frequency response — the steeper it is, the higher the accuracy of determining the extremum coordinate. The actual error of the CTF device is in the order of 10 100 Hz. The search for maxima, minima, and bandwidths is performed by the device on the same principle, i.e. always looking for the minima of the non-investigated frequency response A (J, and the other function B () associated with A (f). So, when processing the minima, the function B (f is 6 () tO-A (f) | | -Xl (fH (), while (f / 5 A (, When processing the maxima, the function B (f) is equal to B ( ) (f) l, at the same time, -8 "in (, .c, ie, the coordinates of the minicars B (f) coincide with the coordinates of the maxima A (f /. When determining the half-width values of the band of resonant peaks (maxima) B ( ) is equal to ({) ((f1 where A (f G is the value of the maximum found with the coordinate axis on the frequency axis f. At the same time, the coordinate of the minimum B (f) coincides with the frequency value - + D, where dff is the right half-width of the resonant peak (typical type of graphs of functions B () for all three cases 2. The frequency control strategy for selecting the frequency of the next search step is determined by the frequency response values obtained in the three preceding steps, i.e. the selection of the frequency code „for the (n-I) -th step depends on the values B („-2) B (ri-i / and B (D corresponding to the frequencies (for (n-2) -th step, n-1 L- (nl) -ro step and for the n-th step. Step size . Are determined by the device by comparing the values of B (f g, 2) B (f n) B (fn) Storage of the values of B (f. J), B (fn.) And B (f, is performed in memory block 30, which consists of three working memory cells in order to facilitate the decree these values and. one to the full, through which it leads. content exchange of working memory cells. Each step number in memory block 30 corresponds to a fixed address: the values of B () are always placed in the working cell with the address .2, B (fn - f in the working cell with the address i and B („) in the working cell with address. Record each new value of B (either made at address O, or at address 2, i.e. a new value of B (replaces either value B (n) or B (f „.2 After writing, the contents of the work cells I is ordered in such a way that their addressing unambiguously corresponds to the time sequence of obtaining the values of B - ().: -:; At THIS, memory block 30 It can work in two modes: in the mode of finding the localization interval of minimum B (), the search (viewing) step remains constant, and the search (viewing) is continued until it satisfies the local / minimum condition i | B ( f,. (fn) (f pi) (-2) that is recorded by the first comparison block 31. In this case, each new value B (c +) is always written in place of B () / a and after recalculating the value of B (f, J placed in the working cell with the address adf (f ") - in the working cell with the address H, and the value B (n) in the working cell with the address 2, which corresponds to Belt sequence for obtaining these values. In the minimum B refinement mode (-f, which is automatically set after the given local minimum condition exists, step; r browse, (search) begins to decrease from the initial value of jf to the final value 2i equal to the accuracy of the measurement of the minimum coordinate B (on the frequency axis). The frequency of the next step. „... FO is chosen to be f. + -4g, or;., Gyr J f- 9 where, 2,3 ... is the number, step after the start of the refinement. The operation is written I. -jr is performed in register 25 I - 2 - by shifting its contents by bits to the right. If B (fr, .2 and In (p.) Less. B (n), then the frequency fn., - fn -, - if B (,.,) And) is less than B (,. - (-. In the first case, the value of B ( ,) is recorded instead of in (n), and in the second, instead of in (after reordering B (located in the working cell at address O-, B (& | at address 1, a) at address 2. Modes of localization interval search and refining the extremum coordinates are always alternated for any form of AFC. Once the localization interval is found, the comparison unit 31 switches the memory block 30 and the control block 33 to the refinement mode until the third comparison block 27 issues to the third ravl yuschy input memory unit 30 and the input control unit 33, bus signal switching these blocks again in search mode. Synchronization of memory block 30 is performed by connecting its first control input with the output bus of control block 33. The values fall into memory block 30 from the combinational adder 26, which always reads Kqjta A (J coming from the output of the dividing block 14 from the contents of the first register 22 (which is 0 or D / X from the found maximum value A ()) (i is the maximum frequency response number, if there are several of them.) The first register 22 is reset by a signal received at its first control input from the output bus of control block 33, and the number given by the separating unit 14 is recorded by the signal block 33 control events to the second control input of this register. The recording signal is blocked when devices are tuned to search for minima using the second switch 20 by hooking to the second control input of the register 22 of the logic level voltage applied to the second input 21 of the second switch 20, B-dependency from signals sent to the control of the input of the combinational adder 26 via the third switch 24, the adder outputs to memory block 30 either the difference of the numbers received at its information inputs or the module of this difference. Thus, using the first register 22, the switch 20, the combinational adder 26 and the third switch 24, all functions B (f) are calculated, Obtaining a value) A (i J, required when finding the width of the passbands, is achieved by using the divider 15 voltage, the frequency step code / jf is stored in the second register 29, the contents of KOTO can be shifted by one bit to the right, which corresponds to a decrease in the current step size uf by two times, or it can be set to an equalBm initial value steps lp The signals of the control block 33 are fed to the control inputs of this register. The current step value is monitored by the third comparison block 27, which informs the converter of the 32 codes and the control block 33 about the end-of-operation of the extremum in case the current step code recorded in the second register 29, it will become less or equal to the fixed code supplied to the second input 28. of this comparison unit. The accumulating adder 23, in the localization interval search mode, performs the step of adding its content value d, t, f, performs an incremental increase: TE booths frequency - p.oshagovy viewing frequency response, and the refinement mode performs an operation J f ,, + f p-i TF or --5g and g-setting accumulator. -. adder 23 to add to its contents the step code recorded in the second register 29, or to subtract this content from the control unit 33, to the output bus of which the damper 23 is connected with its second control input. The summation (subtraction) is also synchronized by the control unit 33, which outputs the actuation signals to the first control input of the accumulating adder 23, the contents of the accumulating adder 23 determines the frequency of the signal generated by the 1 frequency synthesizer, and is constantly compared by the second comparison unit 18 with the fixed the code of the upper cutoff frequency of the studied range Rd4d |, given on the second input 19 of this block, comparison. When the frequency code code is greater than or equal to the code, the second comparison unit 18 generates a signal informing the converter 32 of the codes and the control unit 33 of the completion of the measurement process of the object frequency response,. The control unit and, consequently, the entire device is contacted by pulses arriving at the clock input of the control unit 33 from the generator 34 impulse output. During each cycle of operation, the control unit 33 analyzes the information supplied to its input bus from the output of the first, second and third comparison blocks and feeds through the input bus control signals that tune to certain modes of operation of the first and second registers 22 and 29, the memory block 30, the combinable adder 26 and the accumulator, the accumulator 23, In one view, the range at frequencies from P; „in“ about max to determine either all the maxima A d, (j I, frequencies fj or the corresponding half-width values of the band, or all MINIMUM Aj, {, - J and frequencies f, -, their corresponding B In the first case, the processing cycle of each extremum consists of four parts: search for the localization interval of the i -th maximum of A (f) (or, equivalently, the minimum of B () 0-A ()), refine the coordinate of this maximum, search for the interval localization of the minimum of the function B () (1V) A (JA (), refinement; . coordinates 5 L, where D is the half-width of the band of the maximum. Since in the process of viewing the frequency response, the type of function B () changes, it requires rebuilding the operating modes of the first register 22 and the keynational adder 26 implementing the calculations of the functions B (). This is achieved by the fact that the second control input of the first register 22 and the control input of the combinational adder

26 is connected via switches 20 and 24 to control unit 33. Writing a value (1V2) A () to the first register 22 is carried out by applying a recording signal outputted by control unit 33 and fed to the second control input of the first register 22. At the same time, the first switch 16 by control unit 33 is shifted to the position at which the output of the titer 5 the amplitudes are connected via a divider 15 to the input of the second analog-digital converter 17, which leads to the appearance of the information input of the first register 22 of the value code (1 V) A {

These operations are performed: if the value and A are found, i.e. when the third block 27. comparison detects the end of the refinement process. Register 22 is zeroed immediately upon completion of the refinement process of the coordinate fj-f, after which the processing cycle of the next maximum frequency response, if any, is located at. subsequent viewing. In the second case, when looking for minimum frequency response A (f;, the function always takes the form

In (f) t | 0 - A {) (,

so control of the first register 22 and the combinational adder 26 is not required. Therefore, the second control input of the first register 22 through the second switch 20 is supplied from the second input 21 of the logic level voltage, which is written to the register 22 from the output of /, .. ".-:

Yes dividing block 14 is not produced-. The contents of this register, when searching for minima, frequency response, is always zero. Anoshogichno combinational adder 26 provides

using the third switch 24, outputting only the difference module O-A (f).

Converter 32 codes received. It processes and converts the data received at its first and second information inputs into a form suitable for output to recorder 35. The current frequency code is transmitted to the second information input of the generator of 32 codes from the output of accumulator 23, and the frequency response at this frequency arrives at the first information input from the output of the dividing block 14.

Depending on the goals and objectives;

0 measurements on the recorder 35 can display all the frequency response points or only its extreme values and frequencies corresponding to them, in the latter case, the values are derived

5 by the generator 32. codes only by the signal from the third block 27 of the comparison. ;

The gain in time of measurements of the frequency response, which contains one maximum, is 1.8 times, and the increase in productivity when measuring the parameters of the frequency response of a multiresonant system is more than five times higher than the productivity of labor on measuring the frequency characteristics of a similar class.

Claims (1)

A DEVICE FOR MEASURING AMPLITUDE-FREQUENCY CHARACTERISTICS, containing a frequency synthesizer, two amplitude meters, the input of the first of which is connected to one of the input terminals of the device, and the output - with the first input of the first switch, a memory unit whose output is connected to the input of the first comparison unit, the second comparison unit, the control unit, the second switch and the recorder, characterized in that, in order to reduce the measurement time, a voltage divider, a third switch, two analog-to-digital converters, d Va register, combinational adder, accumulating adder, third comparison unit, code converter, pulse generator and the divider unit, with this the first control input of the first register and. memory block, the control input of the first switch, the first and the second. · the control inputs of the second register and accumulating adder are connected to the output bus of the control unit connected via the second switch, to the second control input of the first register and through the third switch to the control input combinational adder, the second inputs of the second and third switches are the inputs of logic levels, the output of the first comparison unit is connected to the second control input of the memory unit and the input bus of the control unit connected to the first control input of the code converter and the output of the second comparison unit, the first input of which connected to the first. the information input of the code converter, the output of the accumulating adder and the control input of the frequency synthesizer, the first and second meters amplitude, and the second input of the second comparison unit is a fixed code input, the output of the third comparison unit is connected to the second control input of the code converter, the third control input of the memory block and the input the bus of the control unit, the synchronizing input of which is connected to the output of the pulse generator, the output of the first measuring instrument of the meter amplitude through the voltage divider under connected to the second input of the first switch, the input of the second The amplitude meter is connected to the output of the frequency synthesizer and to the second input terminal of the device, and the output is connected to the input of the first analog-to-digital converter, the output connected to the first input of the splitter unit, the second input of which is connected to the output of the first switch through the second analog-to-digital converter, and the output - to the first information input of the combinational adder, the second information input of the code converter and the input of the first register, the output connected to the second information input of the Combination adder, the information input of the accumulating adder is connected to the output of the second register and the first input of the third 5C „, 1053018 1053018 the comparison unit, the second input kotr = go is the input of a fixed code, the output of the code converter is connected to the input of the recorder. The device relates to the measurement technique and can be used to measure the amplitude-frequency characteristics (AFC) of multiresonant oscillatory systems, comb 5 filters and: measuring transducers of frequency dispersions of dielectric and magnetic properties of media with their non-destructive testing.