SU1626241A1 - Oscillographical spectrum analyser - Google Patents

Abstract

The invention relates to a radio measuring technique and can be used in radiolocation and communication, where signals with combined linear frequency modulation and phase shift keying (FM chirp-FMN) are widely used. The purpose of the invention is to expand the functionality of the phase meter by visually evaluating the basic parameters of signals with combined linear frequency modulation and phase shift by manipulation. The analyzer contains a sweep generator 1, LO 2. Mixer 3, amplifier 4, often J, detector B, delay line 6, electronic ray tubes 7, 25 and 32. key 8, multipliers of U and 15 frequencies per weight, dividers 10 and 16 frequencies k-7, band-pass filters 11 and 14, block 12 p (multiplier 13 phases A detector 18, a control unit 19. frequency chutes 20 and 26, differentiating blocks 21 and 23, an amplitude detector 22, a saw voltage generator 24, rectifiers 27, a reference voltage generator 28, a phase shifter 29 of 90 ° and amplifiers 30 and 31. 5 ill. (L S

Description

about

N) O Yu 4

Ui

Schig.1

The invention relates to a radio measuring technique and can be used in radiolocation and communication, where signals with combined linear frequency modulation and phase shift keying (LFM-FMn) are used.

The aim of the invention is to enhance the functionality of the phase meter by visually assessing the main parameters of signals with combined linear frequency modulation and phase shift manipulation.

FIG. 1 is limited to the structural scheme of the proposed analyzer; in fig. 2 - detector circuitry; in fig. 3 and 4 are time diagrams that show the operation of the analyzer; in fig. 5 - view of oscillograms.

The oscillographic analyzer comprises a sequentially connected sweep generator 1, a local oscillator 2, a mixer 3, the second input of which is the analyzer input, an intermediate frequency amplifier 4 and a detector 5, the second input of which is connected to the output of the delay line 6, and the output connected to the sweep generator 1, to the input of the delay line 6, to the vertical electrode of the cathode ray tube (CRT) 7, to the input of the key 8, the horizontal electrode of the CRT is connected to the second output of the sweep generator 1. The first multiplier 9 frequencies by eight, the first frequency divider 10 by eight, the second band-pass filter 11, Г ук 12 adjustable delay, the multiplier 13, the second input of which is connected to the output of the key 8, the first band-pass filter 14, the second multiplier 15 frequencies by eight, a second divider 16 by eight frequencies, a narrowband filter 17, a phase detector 18 and a control unit 19, the output of which is connected to the second input of an adjustable delay unit 12. A second frequency detector 20, a first differentiating unit 21, a successively connected electrolyte detector 22, a second differentiating unit 23, and a sawtooth voltage generator 24 are sequentially connected to the output of the key 8. The output of differentiating unit 21 is connected to a vertical electrode of a CRT 25, a band-pass filter 14 through the first frequency detector 26 is connected to a rectifier 27, the second input of the detector 18 is connected to the output of a reference voltage generator 28. A phase shifter 29 by 90 is connected to the t / run of the latter, the first amplifier 30, the second amplifier 31 is connected to the output of the reference voltage generator 28 and the input of the vertical electrode of the CRT 32, and the modulating electrode is connected to the output of the rectifier 27.

The detector 5 (Fig. 2) consists of three channels of signal processing, each of which consists of a series-connected multiplier 33 (34, 35) frequencies, a meter 37 (38.39) spectrum width, a block 40 (41, 42) of the comparison, the second the input of which is connected to the output of the meter 36

the width of the spectrum, the threshold element 43 (44, 45), the second input of which is connected to the output of the delay line 6, and the element OR 46. Moreover, in the first channel the frequency is multiplied by two, in the second - by four, and

the third is at eight.

The analyzer works as follows.

Viewing a given frequency range Df is carried out using the generator 1

sweep, which periodically with a period of Tp, according to the sawtooth law, tunes the frequency of the local oscillator 2. Simultaneously, the sweepbench 1 sweeps the horizontal scan of the CRT 7, which is used as a frequency axis, and its length corresponds to the frequency span of the frequency span. Key 8 is in the initial state closed.

The received chirp-FMN signal, which can be described by the following expression:

IC (t) Uccos BP + lyi2 + f (t) +;

0 t Tc.

where Uc, (ik., Tc, RG. - amplitude, carrier frequency, duration and initial phase of the signal, respectively;

, &

Tr

inside the pulse;

L fd - frequency deviation;

The / () is the manipulated component of the phase, which reflects the law of phase manipulation in accordance with the modulating code M (t) (Fig. 3a), with y (t) const with k rn t (k + 1) rn and may change abruptly on Du with tk gp, t, e.

on the boundaries between the elementary premises (k 1,2N-1);

hp N is the duration and the number of elementary parcels that make up the signal with the duration of the TC (TC N gp), is fed to the first input of the mixer 3, to the second input of which the voltage of the local oscillator 2 is applied with a linearly varying frequency

Ur (t) Ur COS (fOrt -f jryrt2,),

Have

rate of change of frequency

where Ur, ov, f are the amplitude, frequency, and initial phase of the local oscillator voltage, respectively;

Df Hg Y frequency change rate

 P

heterodyne.

At the output of the mixer 3, voltage combinations are generated. The amplifier 4 is allocated the intermediate frequency voltage

Unpl (t) Unp COS f / Aipt 4-L y G2 4- + Vk (t) - y, 12 +

0 t Tc,

one

where Unp ki Uc Ur;

ki is the mixer transfer coefficient;

uAip uJt - GA- - intermediate frequency;

Pcr fk - intermediate initial phase; which enters the detector 5.

If the analyzer receives a signal with combined linear frequency modulation and single phase shift keying (chirp-OFMn), then the following oscillations form at the output of frequency multipliers 33 - 35, respectively;

ui (i) Unp cos (2 ftJnpt 4-2 lgu t2 -2 ug12 + 2 (rpr);

U2 (t) Unp cos (4 GAipt + 4 ut.2 -47ryrt2 + 4y np);

ua (t) Unp cos (8 GMpt +8 arcs2 -. -8lug12 + 8рпр);

About t TC,

Since 2pk (t) 0.2 l, 4y (t) 0.4, 8 # (t) 0.8 l, there is no phase shift in these oscillations. The width of the spectrum of the second D fa. the fourth Afi and the eighth A fa harmonics are determined by the duration of the signal Tc (

 t), whereas the width of the Afc chirp-OFMn 1s

the signal is determined by the duration of its elementary premises (Afc 7). i.e.

the width of the spectrum of these harmonics was N times smaller than the width of the input signal spectrum:

Afc

Kb

-Afc M XT N

L fa

0

five

0

0

five

0

five

Consequently, when the frequency of the LFM-OFLL is multiplied (the signal is two even-numbered.; Eight its spectrum collapses N times. This allows one to detect the LFM-OFMn signal even when it is less than the power of noise at the analyzer input.

The width of the input signal spectrum Afc is measured with a meter 36, the width of the spectrum of the second A h. the fourth Afi and the eighth Afe of the signal harmonics are measured using 37–3 ° meters. Voltages Ui, U2 and Us. proportional af2. Af4 and Affi, respectively, from the outputs of the 37-39 spectral width sensors arrive at the first inputs of the 40-40 comparison units, to the second inputs of which voltage U is applied from the output 36 of the spectrum width proportional to Afc. Because . and, then, on the inputs of the comparison blocks 40 - 42, positive pulses are generated that exceed the Unop threshold level in the threshold elements 43 - 45 and through the OR 46 element arrive at the output,

The whiteness of the analyzer input receives a signal with a combined linear frequency modulation and two-time phase shift manipulation of the chirp-DFMn pk (t) 0. TJf.

t

l, the output of the frequency multiplier 33 by two is formed by the chirp-OFMS signal y (t) 0.; T, 2 #, 3 # an output of the multipliers 34 and 35 frequencies by four and eight - oscillations U2 (t) and Ua (t) respectively, i.e., in the indicated channels, the spectrum of the input signal is convolved.

If the analyzer receives a signal with a combined linear frequency modulation and threefold phase shift manipulation, the chirp-TFMn, y (t) 0.

l: 7ГЗ „5 3 7, 4-2 4Я-Я 47Г-2; Г 47Г

then convolution

0

five

The spectrum is carried out only at the output of frequency multiplier 35 by eight. In this case, the positive voltage is generated only at the output of the comparison unit 42.

The voltage from the output of the detector 5 is fed to the control input of the sweep generator 1, stopping the rebuilding of the local oscillator 2, to the input of the delay line 6, to the control input of the key 8, opening it. and on the vertical electrode of the CRT 7. From this point in time, the viewing of the specified frequency range Df and the search for the chirp-FMN signals is stopped for the time of visual analysis of the main parameters of the detection of the chirp-FMn signal, which is determined by the delay time ge of the delay line 6. In this case, a pulse (frequency mark) is formed on the screen of the CRT 7, whose position on the horizontal scan uniquely identifies the initial carrier frequency 0) from the received chirp-FMN signal (Fig. 5a).

The Unop threshold level in detector 5 is selected such that this level does not exceed random interference.

When the tuning of the frequency a of the local oscillator 2 stops by the amplifier 4, the voltage is released (Fig. 36)

unp2 (t) UnPcos Wnpt -Lut2 + + pk (t) + 1Pr,

0 t Tc,

which, through the public key 8, enters the inputs of the frequency multiplier 9 by eight, the multiplier 13, and the frequency detector 20. The output of the frequency multiplier 9 by eight produces a voltage (Fig. 3g)

+

Unp cos 8 (Oppt + 8l2-f

About t Tc.

Since 8y (1) 0.8l- with single phase manipulation, 8y (t) 0.4, 8, 12l, - with double phase manipulation y (t) 0.2, Al, 6, 8l, Yul, 12, 14 — with threefold phase manipulation, then at the indicated voltage the phase manipulation is already absent. The voltage Unp3 (t) is fed to the input of the frequency divider 10 by eight, the output of which is the voltage (FIG, H)

Unp4 (t) Unp COS GMpt -f

+ Y12 O t Tc.

which is a chirp signal whose frequency varies linearly (Fig. 3 Sv), the voltage Unp4 (t) is extracted by a band-pass filter 11 and is fed to the input of an adjustable delay unit 12. At the output of the specified block voltage is formed

Unp5 (t) Unp COS (t - D) +

+ lu (rg) 2,

About t TC,

which is fed to the second input of the multiplier 13, to the first input of which the chirp-FMN signal of the intermediate frequency Unp (t) is applied. At the output of the multiplier 13, a beat voltage is formed (Fig. 46)

Yen (t) Uacos (wf; t -fy (t)):

0 t Tc,

1 i where Ua t; kg Unp

k - multiplier transfer coefficient;

a) (j - 1pug - beat frequency;

P (J Wnp t - the meadow is the initial phase

beat,

which is a QPSK signal at the beat frequency. Moreover, the beat frequency (/ is determined by the rate of change of the signal frequency y and the magnitude of the delay t.

The voltage u (Ji (t) is separated by a bandpass filter 14 and is fed to the input of a frequency multiplier -15 by eight, at the output of which a harmonic voltage is formed (Fig. 4c)

and 02 (t) Ua cos (8 a) r, p t + 8 y (t) + + 8 pnp) UCTCOS (8 wat h 8);

About t TC,

Voltage Ua2 (t) is fed to the input of frequency divider 16 by eight, at the output of which voltage is generated

and az (t) Uocos ((00).

which is the harmonic oscillation at the beat frequency of sod. The voltage UasW is allocated by a narrow-band filter 17 and is fed to the first input of the phase detector 18, to the second input of which voltage is supplied from the output of the generator 28 of the reference voltage:

u0 (t) U0 cos (MO t + po),

where U0, Wo, VO are the amplitude, frequency, and initial phase of the generator voltage, respectively.

If the indicated voltages differ from each other in frequency or phase, then a constant control voltage is formed at the output of the phase detector 18. Moreover, the amplitude and regularity of this voltage depends on the degree and direction of deviation of the beat frequency from the frequency (ik of the generator 28 of the reference voltage. The control voltage with the help of the equalizer unit 19 acts on the adjustable delay unit 12, changing the delay value gtak, that equality holds

  2 put (/ Lz,

To visualize the magnitude of the phase jumps Lp and the multiplicity of phase manipulation n of the received chirp-FMN signal, EPT32 is used with a circular signal, I form a i with a reference voltage generator 28, the frequency ftib of which is maintained equal to part of the beats (DQ ( c / Jb (o, with the power of the phase locked loop system. The voltage u0 (t) of the generator 28 goes through the amplifier 31 to the vertical electrode, and through the phase shifter 29 to 90 ° and the amplifier 30 to the horizontal electrode of the CRT 32.

The voltage and 7i (t) (Fig. 46) from the output of the band-pass filter 14 are simultaneously fed to the input of the frequency detector 26. At the output of which short differential pulses are formed (Fig. 4e). the temporal position of which corresponds to the moments of a jump-like change in the phase of the signal ex (g) (Fig. 46). At the output of rectifier 27 a sequence of short positive pulses is formed (Fig. 4e), which goes to the modulating ELRCT-type CRT 32 and modulates the electron beam. by brightness. On the screen of a CRT 32, an image is formed in the form of several bright points located on a circle (Fig. 5c, d, e). The number of points determines the multiplicity n of phase manipulation, and the angular distance between them is equal to the magnitude of the jumps of the phase Dy of the detected chirp-FMN signal. With the inequality of frequencies with (/ and GA, (a (j f / Jb)), the velocity labels move in a circle with the difference frequency

To obtain a stable waveform, a 3xpat CRT 32 uses a PLL system whose operation is described

For a visual assessment of the law of phase manipulation, long and rp and the number N of elementary parcels, as well as linear frequency modulation parameters, unp2 (t) (Fig. 36) from the output of the intermediate frequency amplifier 4 through the open

key 8 at the same time r p :, h-: frequency 20 and emlitude O 2 DS1 s. .- grooves At the output of the frequency detector) JO, the voltage J lr Ze), n; gp p

the national law of change in the received signal (fig n). yurtkl mi with different polarity impulses of a pumping change of the Phases r t. (Fig Z Y). This is Chopr. his

With a block 21, convert i to p-ls-carbon voltage (4lg. WL), which is fed to the vertical OJiT electrode. Gy Ampligate detector 22 PEDR / even envelope of the sigtal ig. WI} YQ. Orlch D. (. rirenziruyushchy block 3 Prepipagu gss in DIYa short times., And p / uCf (f g Zi). And polo :. | 1tol. t triggered by the pulse, and a short official impulse turns off the generator

4 pilobovz oio tense, output

the voltage of which (fig Zk) ischetch et

for f (/ g fatting horizontal DPI 25). At the same time on: paijf CRT

opj € JTCR image of a rectangular pulse with short bipolar pulses on its nepun.iu (Fig. Zj and Fig. 56) And length; The pulse is proportional to the flax length of 1G n v and Gc of the obfuchenny chirp-FMM, pulley, pulse is proportional to the rate of change of frequency y inside the signal, and the area of the pulse of proportion proportional to the frequency deviation D fo - y Gp Tj / HHMdf of the chirp -FMN signal.

The number of short opposite-polarity pulses is equal to the number of phase jumps and the reception of chirp-FMN signals. Between the number of phase jumps m and ko, n 1 the quality of elementary parcels N exists following

An analytic analysis of dependency:

N 0.5 (t + 1).

By counting the number of phase jumps m, one can determine the number of elementary premises N. By estimating Tc and TJ. you can omit the duration of the elementary parcels

Gp n

Time delay Gt line 6 s .v, LCD

It is chosen that we can visually assess the main parameters of the detected chirp-FMN signal, t about the waveforms on the EL screens of 7, 25 and 2. By

the expiration of this time, the voltage from the output of the delay line b enters the input and reset of the threshold elements 43 - cfc - resets their contents to a chubble value. In this case, the sweep generator 1 transfers the tuning mode and the key B closes, i.e. status From this point in time, the ProsMo .p 10D.1TSNOGO RATI RELATED DI iM.ilOlU Of And

The search for chirp-FMi signals continues to D service iae trace / 10 cm chirp-FMp signal analyzer operation is going on in an obvious way.

Claims (1)

Invention Formula An oscillographic spectrum analyzer containing a serial connection of a local oscillator, a messenger, a second RFID of which is connected to the input, an analysis of time, an intermediate amplifier 1 (aspta and a radiator, the second stroke of which is connected but than to the input of the line, ddgr, .ki, to the second input of the key, the first inlet f (—thatly connected by the cause of the prog / sgutot amplifier i and you, and to the vertical electrode of the first tectron-radiation bridge, the horizontal e / spectrode of which connected to the second generator diode gas screwdriver, n) a continuous generator of supports for the leg voltage, phase clamping nt first amplifiers and a horizontal circuit of the second elektronno-lumevoy tg; iG) ki, “er scale curve electrode and tO | ro p, with its amplification gel is connected by a rgod of a reference voltage generator, and a modulating electrode with a rectifier output that differs from it, in order to expand its functionality by visually assessing the main parameters of signals from a computer with a linear frequency spectrum. modulation and phase shift manipulation into which DRY frequency multipliers are introduced by eight, two dividers by eight, a multiplier, two bandwidths with | iltra, two frequency detectors, amplitude detector, two diffraction module; b) delay control unit; narrowband filter; phase detector; control unit; sawtooth voltage generator; and third tl 11 tron-beam tube, output of the key through successively intermixel, first bandpass filter, and first frequency detector underneath -1en to the rectifier input, the first multiply TR is connected in series to the key output. Frequently by eight, the first divider of the eight by eight, the second band-pass filter and an adjustable delay unit, the output of which is connected to the second input of the multiplex, are connected to the output of the first cross-section filter of an eight-second frequency divider by eight , a narrowband filter and a phase detector, the second input of which is connected to the output of the generator one of another voltage and the second to the input of the control unit, the output of which is connected to the second input of the block, adjust the delay i, to the output of the key s of the heating detector with a second frequency detector, a first differentiating unit and a vertical electrode of the third third-wave beams, each with an appropriately connected amplitude detector, a second differentiating unit and a pilot voltage generator connected to the horizontal electrode of the third electron-powered tube, the hetero- through the sweep generator is connected to the detector outlet. Otb CHOJ "3 CN Ј CM - C4 | h -5 h Fy L - o . and X 2 About J „ | g / 3,