SU900209A1 - Frequency spectrum analyzer - Google Patents

Description

The invention relates to electrical measuring technology and can be used to isolate the harmonic components of periodic signals of complex shape, measure their amplitudes, and phase shifts. The closest to the proposed technical essence and the achieved result is the frequency spectrum analyzer, which consists of a group of analyzing filters, detectors, integrators, two switches, an indicator, switching bodies, an input device, a time interval generator, a key, a frequency divider, a pulse generator a pair of two counters, a coincidence circuit, a trigger, an interrupter, and a reference voltage source U. The disadvantage of this device is the impossibility of measuring the values of the phase shifts of the obtained r;) rmonic components of the complex signal under study and the impossibility of presenting g with the warming of the phase spectrum in real time. In addition, the shape of the signal is also affected by the magnitude of the initial phases of the component of the spectrum. Therefore, only the amplitude-phase-frequency ana 13 can give a complete picture of the signal spectrum. The purpose of the invention is to expand the functionality. The goal is achieved by the fact that in a frequency spectrum analyzer containing a group of series-connected analysis filters, detectors, integrators, the outputs of which are connected to the input igicator through one or two switches, the series-connected trigger, interrupter, switch and input unit are series-connected pulse generator and the first key, a pulse generator connected in series and a frequency divider, two counters, the outputs of which are connected to the element inputs coincide The inputs of the detectors are connected to the inputs of the second switch, and the source of the reference voltage, and the inputs of the second counter are connected to the outputs of the pulse generator and the coincidence element, an additional amplifier-limiter connected in series with the inputs of the detectors, an automatic switch, an amplitude detector, analog digital converter, digital-analog converter and the second key, the output of which is connected to the first input of the chopper, period meter, adder, series-connected blocks control and period meter, the third key connected between the voltage source and the third input of the chopper, the first reading unit, serially connected to the pulse generator digital digital phase meter with memory and the second reading unit, the delay element and the channel switch connected between the input unit and selective filters, the output of the automatic switch is connected to the second input of the digital phase meter and to the second input of the period meter, the third input of which is connected to the output of the frequency divider and the output - with the input of the first counter, the output of the analog-digital converter is connected to the first reading unit, the trigger input through the delay element is connected to the output of the coincidence element and to the input of the adder, the second input of which is connected to the output of the first key, and the output to the third input of the second counter, the input of the pulse former is connected to the output of the amplifier-limiter, whose input is connected to the output of the second switch, the second output of the circuit breaker is connected to the second input of the digital phase meter and the outputs of the control unit are connected to p is yuschimi inputs three keys zederzhki element and the adder.

- The drawing shows a block diagram of the device.

The analyzer contains a switch 1, an input unit 2, a group of selective filters 3, a group of detectors 4, a group of integrators 5, a per Bbrii switch 6, an indicator 7, a second switch 8, a driver 9

pulses, first key 10, frequency divider 11, pulse generator 12, pulse counters 13 and 14, coincidence element 15, trigger 16, interrupter 17, voltage source 18, limiting amplifier 19, automatic switch 20j amplitude detector 21, analog-to-digital converter 22, first reading unit 23, digital-to-analog converter 24, second key 25, period meter 26, adder 27, control unit 28, third key 29, digital phase meter 30 with memory, second reading unit

31, the delay element 32, the switch 33 channels.

The device operates in three modes.

In this case, it is possible to measure the amplitudes of the harmonic components both in the sequential and in the parallel analysis. DP sequential analysis provides calibration

on a test signal that measures accuracy. Calibration mode is also used when measuring the initial phases of the harmonic components.

In the mode of measuring the amplitudes of the harmonic components without calibration, the operation of the circuit is carried out as follows.

The switch 1 is fixed in the position in which the input jack is connected to the input unit 2, the key 25 is fixed in the open state. With such fixation of the switch 1 and key 25, the input signal is fed to the input unit 2 and then through the switch of channels 33 to the selected filter 3, where one of the harmonic components of the signal to which the filter is tuned is selected, after which the voltage of the filtered harmonics goes to the detector 4, the integrator 5, and then the signal voltage is connected through the first switch 6

to indicator 7 for indication.

Improving measurement accuracy is achieved by using a calibration with a test signal. In 5 of this mode, the scheme works as follows. The switch 1 is fixed in the second position, connecting the interrupter 17 to the input unit 2. The second switch 8 allows connection to any channel of the analyzer. The third switch 29 connects the source 18 of the reference voltage to the chopper 17, and the second switch 25 remains in the open state. In this case, the signal component of the selected channel is variable. A limiting amplifier 19, dG, its amplitude is limited, then the signal arrives at the pulse shaper 9 and after the first key 10 the generated pulses with a repetition period, the signal period of the selected channel are fed to the adder 27 and then control the operation of the second pulse counter 14 filling in this moment with pulses from the generator of 12 pulses. Consequently, the number of pulses recorded in the register of counter 14 will be proportional to the period of the selected harmonic signal. This number of pulses goes to one of the inputs of the multi-bit matching element 15. Its other input receives a continuous number of pulses from the output of the multi-bit shift register of the first meter 13. Counter 14 is filled with continuous pulse | w, coming from the generator 12 pulses through the divider frequency 11. The period meter 26 is blocked by the control unit 28 so that the pulses with the dividers 11 frequency are fed directly to the input of the pulse counter 13 and the signal from the automatic switch 20 to the counter 13 does not act. At the output of the match element 15, a signal appears every time, as soon as the number of pulses from the shift registers of the counter 13 is compared with the number of pulses recorded in the shift registers of the counter 14. From the output of the match element 15, the pulses pass through delay element 32 to the input of the trigger 16, while the circuit of the delay element 32 is blocked and does not affect the incoming pulses. The output pulses of the trigger 16 act on the interrupter 17, which in turn modulates the output voltage of the source 18 of the reference voltage. The resulting series of rectangular pulses (x-amplitude amplitude and duration corresponding to the period of the measured harmonic signal of the selected kangp is a calibration signal that is fed to switch 1 and used in-dynescence when calibrating the analyzer. In the mode of measuring the initial phases of harmonic components, functional the nodes of the circuit are in the following state: the third key 29 is open, the second key 25 is closed, the automatic switch 20 turns on the channel, the harmonic phase is equal to Secondly, the variable component of the harmonics is output from the output of the automatic switch 20 to the amplitude detector 21, where it is detected and then to the analog-to-digital converter 22 a constant component is supplied, the value of which is proportional to the amplitude of the input signal. Analog-to-digital converter 22 converts this signal to a digital code, arriving at the first reading block 23 to display a histogram of parallel analysis. At the same time, the signal goes to the digital-to-analog converter 24, then to the key 25 and the chopper 17. The chopper is controlled by trigger pulses -16. Trigger trigger pulses 16 odds a pyutc following way. The signal of the measured harmonic after the automatic switch 20 also comes to one of the inputs qi || h; ovogo phase meter 30 and on the meter 26 period. The latter ensures the arrival with frequency divider 11 of the number of pulses, detecting the period of the harmonic under study. This number of pulses is fixed in a multi-bit shift register of counter 13 and is fed to one of the inputs of the matching element 15. The other input of the matching element 15 receives pulses from the shift registers of the pulse counter 14, which, in a continuous mode of operation, captures the pulses of the pulse generator 12. When the number of pulses coming from the pulse generator 12 coincides with the number of pulses recorded in the shift registers of the pulse counter 13, the pulse output at the output of the coincidence element 15 will read the counter 14 and transfer the trigger 16 to another state.

The pulses generated after the trigger 16 are control for the chopper 17. The chopper provides modulation of the output voltage {and digital-analog converter 24. The resulting square pulses go to switch 1 to calibrate the filter path and to the second input of the digital phase meter 30, which allows you to control the operation of the digital part of the path fop in the tiller. In the absence of an error in the path of the former, a zero phase shift is indicated on the second reading unit 3J,

To measure the phase shift of the selected harmonic with respect to the first, the generated signal is assigned to the initial phase of the first harmonic as follows. The switch 8 connects the signal of the first channel to the amplifier-limiter 19. Note that the circuit of the second switch 8 allows connecting any channel of the analyzer, which provides a measurement of the phase of the selected harmonic relative to any harmonic of the complex signal. After the limiting amplifier 19, the signal enters the pulse shaper 9 and through the key 10 to the adder 27. The incoming pulse zeroes the counter 14 and resumes filling its registers with pulses from the pulse generator 12. After this begins

the earlier process of comparing and pulsing the pulse with a period corresponding to the period of the measured signal,

At this time, the delay element 32 is opened, and when the output of the coincidence element 15 is output, the pulses control the trigger 16 and a digital signal is sent to the digital phase meter 30, the initial phase of which is synchronized with the initial phase of the first harmonic signal. So for one

from the input center of the free-form ph. 11o: i-mr, 1 input sinusoidal n-th emoG phase, and on the other (goduyugsm rectangular impulses, early; on the 5th amplitude of the sinusoid with the initial phase harmonic, t., e The phase shift between these signals corresponds to the phase shift between the signal under study and the first harmonic signal.

The invention makes it possible to significantly dissipate em1 1e with a well-known function analyzer due to new possibilities of measuring the phase shift values of the harmonic components of the complex signal under study. It should also be noted that the device of a phase analyzer with a driver, in which the amplitude of the reference (calibration) signal is equal to the amplitude of the harmonic under study, differs from the known phase analyzers and phase meters in that the device eliminates the amplitude-phase error that occurs in existing analyzers and phase meters .

In addition, this device provides the ability to accurately measure the initial phases of individual harmonics relative to the initial phase of not only the first, but also any harmonic component of a complex signal.

Claims (1)

Invention Formula Frequency spectrum analyzer containing groups of series-connected analyzing filters of integrator detectors 5, whose outputs through one of two switches are connected to the indicator input, series-connected ger, interrupter, switch and input unit, series-connected pulse shaper and first key, series-connected pulse generator and frequency divider , two counters, the outputs of which are connected. to the inputs of the co-element, the inputs of the detector. are connected to the inputs of the second switch, and the source of the reference voltage, and the inputs of the second counter are connected to the outputs of the pulse generator and the element of the voltage, value, or that the purpose of expanding the functional capabilities of the device, which includes an amplifier-limiter, an automatic switch, an amplitude detector, an analog-to-digital converter, a digital-to-analog converter and a second switch, the output of which is connected to the first input of the interrupter, period meter, adder, sequentially, are connected to the amplifier inputs. connected control unit and period meter, the third key connected between the source of the reference voltage and the third input of the breaker, the first counting module connected in series with a pulse generator with a digital phase meter and second memory readout unit delay element and channel switch connected between the input unit and selective filters, automatic switch output connected to the second input of the digital phase meter and a second meter input period. 0020910 the third input of which is connected by the q output of the splitter, and the output to the input of the first counter, the output of the anapogo-digital-1 converter 5 is connected to the first reading unit, the trigger input is connected to the output of the coincidence element and to the input of the adder, the second input of which is under 10 keys to the output of the first key, and the output to the third input of the second counter, the input of the pulse driver is connected to the output of the amplifier-limiter, whose input 15 is connected to the output of the second switch, the second output of the chopper is connected to the second input of the digital phase meter, and the outputs of the control unit are connected to the control inputs of the three keys, the delay element and the adder. Sources of information taken into account in the examination I. USSR author's certificate 25 per application no. 2539072 / 18-21, cl. G 01 R 23/16, 1977.