SU1688184A1 - Spectrum analyzer - Google Patents

Abstract

The invention relates to a radio metering technique, is intended for spectral analysis of signals in a trigonometric basis and can be used to obtain amplitude and phase spectra of signals in real time by analog processing. The purpose of the invention is to expand the functionality by providing the possibility of smooth adjustment of the analysis frequency band within wide limits. This is achieved by introducing into the analyzer a one-square divider 6, an adjustable constant voltage source 7 and forming new functional connections. In addition, the analyzer contains a shaper 1 parallel samples, a converter of 2 samples into a modulated signal, a block of 3 detectors. 2 hp f-ly. 6 Il.

Description

The invention relates to a radio metering technique, is intended for spectral analysis of signals in a trigonometric basis, and can be used to obtain amplitude and phase spectrum of signals in real time by analog processing.

The purpose of the invention is to enhance the functionality by enabling smooth adjustment of the analysis frequency band over a wide range.

FIG. 1 shows a block diagram of the device; in fig. 2 - timing diagrams, explaining the principle of operation; in fig. 3 is a drawing of the electromechanical part of the device; in fig. 4 is an electrical circuit of the device; in fig. 5 - hysteresis characteristic of the process of polarization of the ferroelectric; in fig. 6 is a diagram of a compensator for nonlinear distortion.

The spectrum analyzer contains (FIG. 1) serially connected parallel sample generator 1, a sample converter 2 into a modulated signal, and a detector unit 3 consisting of an amplitude detector 4 and a phase detector 5 with closed inputs. The output of the amplitude detector 4 is connected to the first input of a one-quadrant divider 6, the second input of which is connected to the output of an adjustable source 7 of a constant voltage. The outputs of the one-quadrant divider 6 and the phase detector are connected to the output terminals of the device.

The analyzer of the complex spectrum works as follows.

About 00 | 00

00

:

316881844

The signal is input to the device. UK is a constant component.

U (t) (Fig. 2a), the spectrum of which does not contain

components with frequencies above (about. signal (4), which is easy to get rid of). According to Kotelnikov's theorem, a signal using a separating condensate U (t) is completely characterized by its subsequent 5 Sampling signals, the modulated signal (4) is detected by each other. after another with an amplitude detector interval 4 (BP) and phase detector 5 with closed

Тг / й) ь (1) inputs (contain separators horse) At the first input of one quad. During the cyclic divider 6 comes from the output

amplitude detector 4 non-negative Dg T (2) is 5 signal (m t), and to the second input is a non-negative signal ly I / T, N-number of counts 15 times the variable source 7

shaper 1 parallel voltage readout. At the output, one converts consecutive readings of a square quadrant divider connected (Fig. 2y) to the first output terminal of the device; we receive a signal (Fig. 2d)

(m2 ° v () s (,,) / (lr1 / T)

K-0, 1.2, ...; ,,

D T X UK cos K oj, t) 2 + (T Ј UK sin K t t Y

N is the reference number (3) contained

the signal U (t) 25

in parallel (same time). (8)

During the next At cycle, the converter converts 2 samples into a modulated signal. At the output of the phase detector 5, it is connected simultaneously (at time t 0). Nom with the second output terminal of the device — the UK samples received at its inputs are 30 Vac, we receive a signal (Fig. 2e a) modulated signal c (t) (Fig. 2c), where tt - D tN

  -arctg (T 2, UKX

NК 0

c (t) S UK (1 - cos t) 35

K ON

x sin Kwi t) / (T 2) UKX c0 -S (// t) costr / t + Ф (// t)

(WK ftJb + KYL. (4) 40xcosKtuit). (9)

moreover, y const is a constant coefficient. According to the Kotelnikov theorem, the complex spectrum of a signal segment U (r) of duration At is equal to

S (, t)) + (J) .U (e,) "

0 (// t) -arctg Si (// t) / S2 (/ (t) / (5)

 T I U (KT) (10)

Here about

O-u

  2 tg / At - (o / N, a, alz, (6) If in this expression replace sana

ju t we get, / At, (7)

Ola is the carrier frequency of the modulated U (j w) T 2) UK e t

signal; to °

/ g - the factor characterizing the time-ejcp ()

variable frequency scale, (/) I 1)

Thus, the signals at the outputs of the device are the amplitude and phase spectra of the signal segment in real time. Moreover, the device operates cyclically. During the time A t, parallel samples of the signal segment are formed and the amplitude and phase spectra of the previous signal segment are simultaneously formed. A regulated constant voltage source 7 produces a voltage directly proportional to the analysis bandwidth o (from O to a; b). those. inversely proportional to T or At. This voltage acts on a parallel sample former, on a sample converter into a modulated signal, and is fed to the input of a single-quadrant divider, ensuring consistent adjustment of the values of ol, T, ol, At.

With the growth of the analysis frequency band, i.e. by decreasing T, the amplitude spectrum of the signal decreases, so when tuning the analyzer, when the analysis frequency band is adjusted, it is convenient to use the auxiliary output signal taken from the output of AM 4. This signal changes less in magnitude during adjustment of the analysis frequency band. After the analyzer has been set up, it should be switched to the main output to measure the amplitude spectrum.

The electromechanical part of the device (Fig. 3) contains an executive micromotor 1 of direct current, the speed of which can be smoothly controlled over a wide range by varying the voltage of an adjustable constant voltage source (not shown) connected to the core terminals. A metal disk 3 is fixed on the shaft 2 of the micromotor, on both sides of which two parallel narrow strips of a thin-film ferroelectric information carrier 4 are applied along the diameter. On both sides, springs 5 are pressed against the metal disk by blocks of heads 6 — loose disks having a freedom plate, thanks to guides 7. Each block of heads consists of a dielectric substrate 8, a thin-film ferroelectric coating 9 and

-

deposited onto the ferroelectric of the conducting tracks 10. The tracks 10 for several microns are recessed into the ferroelectric 9. If the ferroelectric 4 is a material medium on which

5 10 15 20

25 30 35 40 45 50 55

Since the swarm is being recorded, the ferroelectric 9 on the head blocks is needed only to minimize the triboelectric effect. In order to install the necessary degree of pressing the head blocks against the rotating media, the post 11 can be moved along the base 12 with the aid of the microscrew 13. The shaft 2 and the metal disk 3 mounted on it are connected via a sliding contact 14 to the micromotor body and to the common bus.

Assembling the head blocks are arranged in parallel planes (Fig. 3). On the electrical circuit (Fig. 4), one of the head blocks is rotated 180 ° so that the blocks 1 and 2 of the heads can be drawn in the same plane. On each block of heads there are several tens of conducting tracks (in Fig. 4, 6 tracks are shown on each block). Each track includes a recording head 3 and a playback head 4. Fully shown is the playback head of the smallest radius. The rest of the playback heads show only the beginning and the end. The angular dimensions of all heads are the same 180 °. The erase head 5 is common to all tracks of the block. The erase heads are connected to the first clamp of the high-frequency voltage source b, the second clamp of which is connected to the common bus. A rotating metal disk is not shown. Narrow strips 7 of a thin-film ferroelectric, shown along the diameter of a metal disk (assembled, they are parallel) are shown. The strips 7 are the information carrier. All recording heads 3 (except for one connected to the first terminal of a source of constant voltage 8, the second terminal of which is connected to a common bus) are connected in the output non-linear distortion compensator, the input of which is connected to the input terminal of the device. All but four reproduction heads 4 are connected to the input of charge amplifier 10, the output of which is connected to the amplitude detector 11 and the first input of phase detector 12 One reproduction head that is on the same track with a recording head connected to a constant source 8 voltage connected to the input of the charge amplifier 13, the output of which is connected to the second input of the phase detector 12. The output of the amplitude detector 11, which is an auxiliary output of the device (as mentioned above), is connected to the first input ohm odnokvadrantnogo divider 14, a second input coupled to an output of a controlled source 15 a constant voltage and a first clamp actuator armature micromotor 16 DC, a second clamp which is connected to the common bus. The outputs of the one-quadrant divider 14 and the phase detector 12 are connected to the output terminals of the device.

The device uses electrostatic recording of information on ferroelectric carrier 7, the direction of polarization of the ferroelectric is perpendicular. The heads are of the capacitor type, with one head of the capacitor the head itself is, the second is the metal substrate of the carrier, the dielectric is ferroelectric 7, A narrow strip of the ferroelectric is applied along the diameter of the substrate disk and therefore consists of two radii. Moreover, during one cycle, L t (A t is the time during which the carrier makes a half turn) at one radius of the ferroelectric is recorded, and the second radius participates in reproduction. During the next cycle, the radii change roles. The path of the smallest radius of the head unit 1 is called the track of the reference signal. All the remaining tracks of block 2 will be assigned odd numbers 1, 3, 5. ...; N-1; Assign even tracks 0, 2, 3, ..., N to all tracks of block 2. Track numbers increase as their radii increase. The recording heads are equidistant. The transit time of the ferroelectric from the K-th head to (K + 1) -th is denoted by T. The total number of numbered tracks (from the 0th to the Nth) is equal to N + 1. So the cycle time Dt and the interval T are related by (2).

K-a reproductive head is bounded, on the one hand, by the semicircle of radius Gok, on the other side of the curve, whose equation in polar coordinates has the form rk r (p). (12)

Let us call (12) the equation of a head Differential of a head area as a function of the polar angle p is equal to

H5k () () - r2k

 .

The equation of the head (12) is chosen in such a way that the distribution of the head area along the coordinate /) corresponds. functions

hK (p) 1 - cos (L + KM) f

 1 -cos (o) to p / d), (14)

where K is the track number;

L and M are even numbers, and L KM; micromotor angular velocity; ОАэ + Ud, Wk Ма (15) frequencies, the values of which are stipulated by equations (4), (6), (7) (the head of the reference signal is identical to the zero track head). It means that

d S (-7jr hK (p), a const. (16)

From expressions (13), (14), (16) we find the equation of the head

10 15 20 25 30 35. 40

45

BY

55

GK (p) VroK + a h (ue)

 fee + a 1 - cos (QJk ip / w)}. (17)

The choice of a constant and depends on the width of the head (and hence the width of the track),

Electrostatic recording is similar to magnetic, so to physical processes in segs. Electroelectrics are similar to physical processes in ferromagnets. FIG. Figure 5 shows the dependence of the charge Q on the voltage U for a capacitor with a ferroelectric. The same dependence of the electric displacement D on the intensity of the electric field E.

Recording (polarization of a ferroelectric) occurs along curve 1, the initial polarization. The reproduction consists in the fact that a polarized ferroelectric carrier, the passage along the reproducing head induces on it the residual charge Qr corresponding to the short circuit mode (I) - 0).

The short circuit mode is provided by a very small input impedance of the charging amplifier 10, since its inverting input is potentially grounded. The resistor in the feedback circuit plays an auxiliary role (in an operational amplifier, a DC link between the inputs and the ground is necessary). Due to the capacitor in the feedback circuit, the output voltage of the charge amplifier with an accuracy of a constant term is proportional to the charge Q at the input of the amplifier. Prechg

rega small current resistor and toksm inverse input, we write down on the basis of the first law of Kirchhoff

(dQ / dt) -t with {hl1wyh / ach) 0. where it comes from

UBUX - -O / C + - COnSt.

We discard the insignificant constant and take into account that due to the parallel connection of reproducing heads, 0 is equal to the sum of the residual charges (Og) induced on (N + 1) reproducing heads. Then

(Og) to (Og) kL5k.

(1 / s) 1 (Og) kL8k

K 0

Ј (og) kA

where (Og) k is the residual electrical displacement of the section of the ferroelectric carrier corresponding to the Kth track, AS is the area of the Kth section of the reproducing head, which is affected by the recording at this instant.

The compensator of nonlinear distortions compensates for the nonlinear distortions of the recording-reproduction path. Then the values (Dr) x are proportional to the reference signal being analyzed

(Dr) to UK U (KT)

We also take into account that in view of the smallness of the angular size L of the ferroelectric carrier, it follows from equality (16)

L5k - | -СкО) (22)

Substituting (14), (21) and (22) into (20), we get

Willows from X UK 1 - cos (Shk r / n), (23) to 0

where const.

If we take into account that p / w t (t is the time for which a disk rotating with an angular velocity o) rotates by an angle p), then signals (4) and (23) coincide. The operation of the detectors and the single-quadrant divider is described above. Since the track of the reference signal is recorded from a constant voltage source B, and the reproducing head is identical to the head

the zero track, then the reference signal 1 h from the output of the charge amplifier 13, is the cosine wave of frequency c / s with a constant amplitude (accurate to a constant term).

The adjustment of the analysis frequency band is as follows. We change the voltage at the output of the controlled constant-voltage source 15. it

10 leads to a consistent change in the magnitudes of T, l, lL, lL, (i) o by changing the speed of the direct current micromotor 16 and changing the voltage at the second input of the one-quadrant divider 15 L 14. As a result of expression (8), ( 9), as well as (1), (2), (6) remain valid in the range of values

FIG. 6 shows a non-linear distortion compensator, made as

20 functional transducer type. It contains two specially allocated windings 1 and 2 of the same size on the head units: two amplifiers 3 and 4 charges, inverter 5,

2b is a memory device 6 and a comparison device 7. In FIG. 6 also shows the high-frequency voltage source 8 and the constant voltage source 9 included in the electric circuit of the device (FIG.

30 4, positions 6 and 8). The erasers 10 are common to all tracks of the analyzer, including tracks 1, 2 of the predistributors. The recording head 11 of the track 1 is connected to the ungrounded clamp of the constant voltage source 9, reproducing the head 12 of the track

1 is connected to the input of the charge amplifier 3, the output of which is connected via an inverter 5 to the first input of the storage device 6 and directly to the recording head 13 of the second track

2tg / L from the head 13 there is a reproducing head 14 of the second track, connected to the input of the amplifier 4 charge, output

45 of which is connected to the first input of the comparing device 7, the second input of which is connected to the input terminal of the predisk, and the output to the second input of the storage device b, the output of which

50 is connected to the output of the pre-emphasis clip. The information carrier corresponding to the track 1 is the corresponding portions of the strip 15 of the ferroelectric located on one side of the non-metallic; disk. The information carrier corresponding to track 2 is a ring 16 of a thin-film ferroelectric, the dimensions of which coincide with the dimensions of the track, on the other side of the metal disk. The metal disc in FIG. 6 is not shown.

The reproducing head of the first track is limited, on the one hand, by the semicircle of radius r0, on the other hand, by the curve

g-gf-1 - 1 -

where / 3 const.

Comparing expressions (17) and (28), we see that the area of the head is distributed according to the coordinate p according to the law

h (p) -2 (U

+ sin | L + Alr13L + (25)

The right part of expression (29) is the Fourier series of a periodic sawtooth function with a period.

Since a constant voltage is applied to the recording head 11, then at the output of the charge amplifier 3 we obtain periodic sawtooth pulses. By balancing the zero, we achieve the absence of a constant component. The charge amplifier 3 inverts the signal, therefore, at its output, the sawtooth pulses have a negative slope. From the output of the inverter 5 to the first input of the storage device receive sawtooth pulses with a positive slope.

Saw pulses with a negative slope arrive at the recording head 13, are recorded on the information carrier 16, are reproduced by the reproducing head 14 and the charge amplifier 4. At the output of the charge amplifier 4, we obtain distorted pulses with a positive slope.

Two signals arrive at the comparison device 7: the analyzed signal X and the distorted pulses F (Y) F (Kvt)

At the moment of fixation to, when these signals are equal in magnitude, the comparing device 7 outputs a short-term locking pulse to the control input of the memory 6, which stores and outputs the value of the signal Y at the moment of to, ie. Y (to) (X)

The output voltage of the prediscaler is stepped (unchanged between two adjacent fixing moments). But if

consider that the frequency of following nidopyr. pulses are many times greater than the discretization error r) but neglected.

So, at the entrance of the prequest itl

(Fig. 4) - signal X, at the output of ciitnan

 F 1 (X) -F (X).

The signal Y is fed to the recording heads of the analyzer. After playback, taking into account (24), we obtain

Z (X) - X.

Thus, the compensator for nonlinear distortion compensates for the nonlinear distortion of the recording-reproduction path.

20

Claims (3)

1. The analyzer of the complex spectrum, which contains series-connected parallel sample generator, a sample converter into a modulated signal and a detector unit, characterized in that, in order to extend the functionality by providing the possibility of smooth adjustment of the analysis frequency band within wide limits, a single-quadrant telescope and an adjustable DC voltage source are introduced into it, the first input being one nokvadrangnogo divider connected to the first output of the detector unit, and the second input with an adjustable source of direct voltage, the output of the one-quadrant divider and the second output of the detector unit are connected to the output terminals of the device. 2. The analyzer according to claim 1, characterized in that the parallel sample generator and the sample converter into a modulated signal are made on a ferroelectric in the form of a nonlinear distortion compensator, two charge amplifiers, a high-frequency voltage source, an executive micromotor of direct current smooth speed control and an adjustable constant voltage source connected to the terminals of the core fixed to the shaft of a metal disk, on both sides of which two parallel along the diameter are applied s narrow strips of a thin-film ferroelectric information carrier, and two blocks of heads in the form of fixed dielectric disks pressed against a metal disk on both sides, on the surfaces of which are erasing, recording and reproducing glasses embedded in a thin-film ferroelectric coating, each block of heads is made in the form of a group of concentric ring tracks, and each track includes a recording head in the form of a narrow radial strip and reproducing an i-edge, a cut chennuyu one hand druzhnostyu floor, on the other hand - the curve described in polar coordinates f, kt equation r (r)   + "{1 -cos (L + KM), where K is the track number; “Const; TOK - semicircle radius; L and M are even numbers, and L KM, the erasing head in the form of a narrow radial strip is one common on each block of heads, the recording heads of both blocks of heads are equidistant along the angle, while the metal disk, one of the clips of the constant voltage source, One of the terminals of the high-frequency voltage source and one of the terminals of the DC power mic micromotor are connected to a common bus, the input terminal of the device is connected to the input of a nonlinear distortion compensator, the output of which is connected to all In addition to one head, which is connected to the second clamp of a source of direct voltage, the erasing heads are connected to the second clip of a source of high-frequency voltage, the input of the first charge amplifier is connected to all reproduction heads, except one connected to the input of the second amplifier. charge located on the same track with a recording head connected to a constant voltage source, the output of the first charge amplifier is connected to the amplitude input and the first input of the phase detectors, the output of the second the charge silicon is connected to the second input of the phase detector, the output of the amplitude detector is connected to the first input of a one-quadrant divider, the second input of which is connected to an ungrounded clamp of an adjustable source of constant voltage, the output of a single-quadrant divider and phase detector of the detector is connected to output terminals devices, all detector inputs are zlokrytye. 3. The analyzer according to claim 2, that is, that the compensator for nonlinear distortion is made in the form of two specially tracks of the same size selected for it on the head blocks, two charge amplifiers, inverter, comparing and storage blocks, the recording head of the first track is connected to an ungrounded clamp of the constant voltage source, the reproducing head of the first track is limited on one side by a semi-circle of radius r0. on the other hand, the curve (Y  lf, Ј, 31 f where / const, the reproducing head of the first track is connected to the input of the first charge amplifier, the output of which is connected through an inverter to the input of the storage unit and the direct recording head of the second track, separated by an angle of 2 JT / L from the second head reproducing head, which, like the recording tracks of both tracks, is made in the form of a narrow radial strip, the reproducing head of the second track is connected to the input of the second charge amplifier, the output of which is connected to the first input of the comparing unit, the second input of which is connected to the input terminal of the nonlinear distortion compensator, and the output to the second input of the storage unit, the output of which is connected to the output terminal comp nonlinear distortion sensor, wherein the information carrier corresponding to the first track is made in the form of corresponding sections of a narrow strip of a ferroelectric on one side of the metal /. weighty disk, and the storage medium, corresponding to the second track, made in the form of a ring of a thin-film ferroelectric, whose dimensions coincide with the dimensions of the track, on the other side of the metal disk. cpus.i FIG. 2 12 Fig.Z o-e FIG 6 utE) Eri G. 5