RU2020493C1 - Spectrum analyzer - Google Patents

Abstract

FIELD: radio measurement technology. SUBSTANCE: spectrum analyzer uses input 1, calibrator 2, time-base generator 3, sweep-frequency generator 4, mixer 5, IF amplifier 6, square-law detectors 7, 17, 25, frequency discriminator 8, differentiating unit 9, rectifiers 10, 20 coincidence units 11, 21, DC amplifiers 12, 27, switches 13, 18, 22, 26, 28, 30, cathode-ray tubes 14, 23, 29, 31, multiplier 15, band-pass filters 16, 24, phase inverter 19. EFFECT: enhanced accuracy. 5 dwg

Description

 The invention relates to radio-measuring equipment and can be used in devices with which you can observe on the screens of cathode ray tubes (CRT) spectra of the studied pulse signals.

 The aim of the invention is to expand the range of spectral analysis of signals.

 In FIG. 1 shows a structural diagram of a device; in FIG. 2 is a frequency diagram explaining the formation of additional (mirror and Raman) reception channels; in FIG. 3-5 are timing diagrams explaining the operation of the device.

 The spectrum analyzer contains an input unit 1, a calibrator 2, a sweep generator 3, a sweep frequency generator 4, a mixer 5, an intermediate frequency amplifier 6, a first quadratic detector 7, a frequency detector 8, a differentiation unit 9, a first valve 10, a first matching block 11, the first DC amplifier 12, the first key 13, the first CRT 14, the multiplier 15, the first bandpass filter 16, the second quadratic detector 17, the second key 18, the phase inverter 19, the second valve 20, the second matching unit 21, the third key 22, the second CRT 23, second bandpass filter 24 , the third quadratic detector 25, the fourth key 26, the second DC amplifier 27, the fifth key 28, the third CRT 29, the sixth key 30 and the fourth CRT 31.

 The spectrum analyzer operates as follows.

 Viewing a given frequency range D is carried out using a sweep generator 3, which periodically with a period Tn, according to a sawtooth law, changes the frequency of the oscillating frequency generator 4. At the same time, the scan generator 3 forms a horizontal scan of the CRT 14, 23, 29 and 31, which is used as the frequency axis. Keys 13, 18, 22, 26, 28 and 30 in the initial state are always closed.

=

- скорость изменения частоты генератора;
Δ fg - девиация частоты.Received pulse signal
U _c (t) = V _c cos (2 πf _c t + φ _c ), 0≅t≅τ _and , where V _c , f _c , φ _c , τ _and are the amplitude, carrier frequency, initial phase and signal duration, from the output of the input unit 1 is fed to the first input of the mixer 5, the second input of which is supplied with frequency labels from the output of the calibrator 2, and the voltage of the oscillator 4 of the oscillating frequency is supplied to the third input:
U _g (t) = V _g cos (2 πf _g t + πγ ₁ t ² + φ _g ),
0 ≅t≅ T _n , where V _g , f _g , φ _g , T _n - amplitude, initial frequency, initial phase and period of repetition of the generator voltage;
γ ₁ =

=

- the rate of change of the frequency of the generator;
Δ fg is the frequency deviation.

= f_г+γ₁t-f_c= f_пр+γ₁t
f

= 2f_г+γ₂t-f_c, где первый индекс обозначает канал, по которому принимается сигнал;
второй индекс обозначает номер гармоники частоты генератора, участвующей в преобразовании несущей частоты принимаемого сигнала;
Частота настройки f_н1 и полоса пропускания Δ f₁ усилителя 6 промежуточной частоты выбраны следующим образом:
f_н1 = f_пр, Δ f₁ = 2 f_пр
Частота настройки f_н2, f_н3 и полоса пропускания Δ f₂, Δ f₃ полосовых фильтров 16 и 24 соответственно выбраны следующим образом:
f_н2 = f_г, Δ f₂ = 2 f_пр
f_н3 = 2 f_г, Δ f₃ = 2 f_пр
Однако в полосу пропускания усилителя 6 промежуточной частоты попадает только напряжение частотой (см. фиг. 4а, б)
U_пр (t) = V_пр cos (2 πf_прt+πγ₁t²+φ_пр),
0 ≅t≅τ_и где U_пр=

K₁V_cV_г;
К₁ - коэффициент передачи смесителя;
f_пр = f_г - f_c - промежуточная частота. Это напряжение представляет собой преобразованный по частоте сигнал с линейной частотной модуляцией (ЛЧМ). Напряжение с выхода усилителя 6 промежуточной частоты подается на второй вход перемножителя 15, на первый вход которого поступает принимаемый сигнал U_c(t) с выхода входного блока 1. На выходе перемножителя 15 образуется напряжение
U₁ (t) = V₁ cos (2 πf_гt+πγ₁t²+φ_г),
0 ≅t≅τ_и где V₁=

K₂V_cV_пр;
К₂ - коэффициент передачи перемножителя. которое выделяется полосовым фильтром 16, детектируется квадратичным детектором 17 и поступает на управляющий вход ключа 18, открывая его.At the output of the mixer 5, voltage of combination frequencies is formed:
f

= f _g + γ ₁ tf _c = f _ol + γ ₁ t
f

= 2f _g + γ ₂ tf _c , where the first index indicates the channel through which the signal is received;
the second index denotes the harmonic number of the frequency of the generator involved in the conversion of the carrier frequency of the received signal;
The tuning frequency f _n1 and the passband Δ f _{1 of the} intermediate frequency amplifier 6 are selected as follows:
f _H1 = f _ave, Δ f ₁ = f 2 _etc.
The tuning frequency f _n2 , f _n3 and the passband Δ f ₂ , Δ f ₃ band pass filters 16 and 24, respectively, are selected as follows:
f _n2 = f _g , Δ f ₂ = 2 f _ol
f _n3 = 2 f _g , Δ f ₃ = 2 f _ol
However, only the voltage with a frequency falls into the passband of the amplifier 6 of the intermediate frequency (see Fig. 4a, b)
U _pr (t) = V _pr cos (2 πf _pr t + πγ ₁ t ² + φ _pr ),
0 ≅t≅τ _and where U _pr =

K ₁ V _c V _g ;
To ₁ - gear ratio of the mixer;
f _CR = f _g - f _c - intermediate frequency. This voltage is a frequency-converted signal with linear frequency modulation (LFM). The voltage from the output of the intermediate frequency amplifier 6 is supplied to the second input of the multiplier 15, the first input of which receives the received signal U _c (t) from the output of the input unit 1. A voltage is generated at the output of the multiplier 15
U ₁ (t) = V ₁ cos (2 πf _g t + πγ ₁ t ² + φ _g ),
0 ≅t≅τ _and where V ₁ =

K ₂ V _c V _ol ;
K ₂ is the transmission coefficient of the multiplier. which is allocated by a band-pass filter 16, is detected by a quadratic detector 17 and is fed to the control input of the key 18, opening it.

The voltage U _pr (t) (see Fig. 4, a) from the output of the amplifier 6 of the intermediate frequency simultaneously enters the inputs of the quadratic 7 and frequency 8 detectors. Quadratic detector 7 selects the envelope of the pulse (see Fig. 4B), which is fed to the first inputs of coincidence blocks 11 and 21. From the output of the frequency detector 8, a video signal (see FIG. 4, d), the shape of which corresponds to the law of change of the pulse frequency f _c1 (see FIG. 4, b), is input to the differentiation unit 9, the input signal of which (see FIG. 4, d) is fed to the inputs of the valve 10 and the phase inverter 19. The valves 10 and 20 pass only positive pulses. The input pulse (see Fig. 4, e) of the valve 10 is supplied to the second input of the coincidence unit 11. Since the voltage (see Fig. 4, c, e) supplied to the two inputs of the coincidence unit 11 occupy the same interval on the time axis, the coincidence unit 11 is triggered. The voltage from the output of the coincidence unit 11 (see Fig. 4, g) is supplied to the control input of the key 13, opening it. In this case, the components whose frequency lies in the passband Δ f _{1 of the} intermediate-frequency amplifier 6 are amplified and, after detection in the quadratic detector 7 and amplification in the amplifier 12, are supplied through open keys 18 and 13 to the vertical-deflecting plates of the CRT 14, on the screen of which the amplitude spectrum of the signal received on the main channel at a frequency f _c (see Fig. 3, a). At the output of the phase inverter 19, a negative pulse is generated (see Fig. 4, h), which is not passed by the valve 20.

If the pulse signal is received on the mirror channel at a frequency f ₃ (see Fig. 3, b).

U ₃ (t) = V ₃ cos (2π f ₃ t + φ ₃₎ , 0 ≅ t ≅ τ _and then in mixer 5 it is converted to voltages of the following frequencies:
f ₃₁ = f ₃ -f _r -γ ₁ t = f _ave -γ ₁ t.

(t)=V

cos

2πf_прt-πγ₁t²+

, 0≅t≅τ_u, где
V

=

K₁V₃V_г,
Δ f_пр = f₃ - f_г - промежуточная частота;

= φ₃-φ_г Напряжение U_пр1(t) (см. фиг. 5,а) с выхода усилителя 6 промежуточной частоты поступает на второй вход перемножителя 15, на первый вход которого поступает принимаемый сигнал U₃(t) с выхода входного блока 1. На выходе перемножителя 15 образуется напряжение
U₂ (t) = V₂ cos (2 πf_гt+πγ₁t²+φ_г),
0 ≅t≅τ_и, где V₂=

K₂V₃V

, которое выделяется полосовым фильтром 16, детектируется квадратичным детектором 17 и поступает на управляющий вход ключа 18, открывая его.f ₃₂ = 2f _g + γ ₂ tf ₃ However, only voltage of frequency f ₃₁ falls into the passband Δ f _{1 of} amplifier 6 of intermediate frequency
U

(t) = V

cos

2πf _pr t-πγ ₁ t ² +

, 0≅t≅τ _u , where
V

=

K ₁ V ₃ V _g
Δ f _CR = f ₃ - f _g - intermediate frequency;

= φ ₃ -φ _g Voltage U _CR1 (t) (see Fig. 5, a) from the output of the intermediate frequency amplifier 6 is supplied to the second input of the multiplier 15, the first input of which receives the received signal U ₃ (t) from the output of the input unit 1. The output of the multiplier 15 is formed voltage
U ₂ (t) = V ₂ cos (2 πf _g t + πγ ₁ t ² + φ _g ),
0 ≅t≅τ _and , where V ₂ =

K ₂ V ₃ V

, which is allocated by a band-pass filter 16, is detected by a quadratic detector 17 and is fed to the control input of the key 18, opening it.

The voltage U _pr1 (t) (see Fig. 5, a) from the output of the intermediate frequency amplifier 6 simultaneously enters the inputs of the quadratic detector 7, selects the envelope of the signal (Fig. 5b), which enters the first inputs of coincidence blocks 11 and 21. From the output of the frequency detector 8, a video signal (see Fig. 5, d), the shape of which corresponds to the law of frequency change f ₃ (see Fig. 5, b), is fed to the input 9 differentiation, the output signal of which (see Fig. 5, d) is supplied to the inputs of the valve 10 and the phase inverter 19. The specified signal is not passed by the valve 10. A positive pulse is generated at the output of the phase inverter 19 (see Fig. 5, f), which is fed through the valve 20 (see Fig. 5, g) to the second input of block 21 matches. Since the voltage (see Fig. 5, c, g) supplied to the two inputs of the coincidence block 21 occupy the same interval on the time axis, the coincidence block 21 is triggered. The voltage from the output of the coincidence unit 21 (see Fig. 5, h) is supplied to the control inputs of the keys 22 and 30, opening them. In this case, the components whose frequency lies in the passband Δ f _{c of the} amplifier 6 of the intermediate frequency, are amplified and after detection in the quadratic detector 7 and amplification in the amplifier 12 through the public keys 18 and 22 are fed to the vertical-deflecting plates of the CRT 23, on the screen of which the amplitude spectrum of the signal received on the mirror channel at a frequency (see Fig. 3, c).

(t) = V

cos(2Πf

t+

), 0≅t≅τ_и принимается по первому комбинационному каналу на частоте f_к1 (см. фиг. 3,в), то в смесителе 5 он преобразуется в напряжения следующих частот:
f₁₁=f_к1-f_г-γ₁t
f₁₂=2f_г+γ₂t-f_к1=f_пр+γ₂t
Однако только напряжение частотой f₁₂ попадает в полосу пропускания Δ f₁ усилителя 6 промежуточной частоты
U

(t) = V

cos(2Πf_прt+Πγ₂t²+

, 0≅t≅τ_и где V

=

K₁V

V_г - промежуточная частота
f_пр= 2f_г-f

φ_пр=

Напряжение U_пр2 (t) (см. фиг. 4,а) с выхода усилителя 6 промежуточной частоты поступает на второй вход перемножителя 15, на первый вход которого поступает принимаемый сигнал U_к1 (t) с выхода входного блока 1. На выходе перемножителя 15 образуется напряжение
U₃ (t) = V₃ cos (4 πf_гt+πγ₂t²+φ_г),
0 ≅t≅τ_и где V₃=

K₂V

V

, которое выделяется полосовым фильтром 24, детектируется квадратичным детектором 25 и поступает на управляющий вход ключа 26, открывая его.If the pulse signal
U

(t) = V

cos (2Πf

t +

), 0≅t≅τ _{and is} received on the first combinational channel at a frequency f _к1 (see Fig. 3, c), then in the mixer 5 it is converted to voltages of the following frequencies:
f ₁₁ = f _k1 -f _g -γ ₁ t
f ₁₂ = 2f _g + γ ₂ tf _k1 = f _ol + γ ₂ t
However, only a voltage of frequency f ₁₂ falls into the passband Δ f _{1 of the} intermediate frequency amplifier 6
U

(t) = V

cos (2Πf _pr t + Πγ ₂ t ² +

, 0≅t≅τ _and where V

=

K ₁ V

V _g - intermediate frequency
f _ol = 2f _g -f

φ _CR =

The voltage U _pr2 (t) (see Fig. 4, a) from the output of the intermediate frequency amplifier 6 is supplied to the second input of the multiplier 15, the first input of which receives the received signal U _k1 (t) from the output of the input unit 1. At the output of the multiplier 15 voltage is generated
U ₃ (t) = V ₃ cos (4 πf _g t + πγ ₂ t ² + φ _g ),
0 ≅t≅τ _and where V ₃ =

K ₂ V

V

, which is allocated by a band-pass filter 24, is detected by a quadratic detector 25 and is fed to the control input of the key 26, opening it.

The voltage U _pr2 (t) (see Fig. 4, a) from the output of the intermediate frequency amplifier 6 is simultaneously supplied to the inputs of the quadratic 7 and frequency 8 of the detector. The quadratic detector 7 selects the envelope of the signal (see Fig. 4, c), which is fed to the first inputs of coincidence blocks 11 and 21. From the output of the frequency detector 8, a video signal (see Fig. 4, d), the shape of which corresponds to the law of frequency variation f (see Fig. 4, b), is input to the differentiation unit 9, the output signal of which (see Fig. 4, a ) arrives at the inputs of the valve 10 and the phase inverter 19. The output pulse (see Fig. 4, f) of the valve 10 is supplied to the second input of the coincidence unit 11. Since the voltages (see Fig. 4, c, f) applied to the two inputs of the coincidence unit 11 occupy the same interval on the time axis, the latter is triggered. The voltage from the output of the coincidence unit 11 (see Fig. 4, g) is supplied to the control inputs of the keys 13 and 28, opening them. In this case, the components whose frequency lies in the passband Δ f _{1 of the} amplifier 6 and the intermediate frequency are amplified and after detection in the quadratic detector 7 and amplification in the amplifier 27 through the public keys 26 and 28 are fed to the vertical-deflecting plates of the CRT 29, on the screen of which the amplitude spectrum of the signal received through the first Raman channel at a frequency f _k1 is observed (see Fig. 3, c). At the output of the phase inverter 19, a negative pulse is generated (see Fig. 4, h), which is not passed by the valve 20.

(t) = V

cos(2Πf

t+

), 0≅t≅τ_и, то в смесителе 5 он преобразуется в напряжения следующих частот:
f₂₂= f

-2f_г-γ₂t = f_пр-γ₂t,
f₂₁= f

-f_г-γ₁t
Однако только напряжение частотой f₂₂ попадает в полосу пропускания Δ f₁ усилителя 6 промежуточной частоты
U

(t) = V

cos(2Πf_прt-Πγ₂t²+

, 0≅t≅τ_и, где V

=

K₁V

V_г
f_пр = f_к2 - 2f_г - промежуточная частота;

=

Напряжение U_пр3 (t) (см. фиг. 5а) с выхода усилителя 6 промежуточной частоты поступает на второй вход перемножителя 15, на первый вход которого поступает принимаемый сигнал U_к2 (t) с выхода входного блока 1. На выходе перемножителя 15 образуется напряжение
U₄ (t) = V₄ cos (4 πf_гt+πγ₂t²+φ_г),
0 ≅t≅τ_и, где V₄ =

V

V

, которое выделяется полосовым фильтром 24, детектируется квадратичным детектором 25 и поступает на управляющий вход ключа 26, открывая его.If the pulse signal is received on the second Raman channel at a frequency f _k2 (see Fig. 3, g)
U

(t) = V

cos (2Πf

t +

), 0≅t≅τ _and , then in mixer 5 it is converted to voltages of the following frequencies:
f ₂₂ = f

-2f -γ _{2 z} t = f _{2 etc.} -γ t,
f ₂₁ = f

-f _g -γ ₁ t
However, only a voltage of frequency f ₂₂ falls into the passband Δ f _{1 of the} intermediate frequency amplifier 6
U

(t) = V

cos (2Πf _pr t-Πγ ₂ t ² +

, 0≅t≅τ _and , where V

=

K ₁ V

V _g
f _CR = f _K2 - 2f _g - intermediate frequency;

=

The voltage U _pr3 (t) (see Fig. 5a) from the output of the intermediate frequency amplifier 6 is supplied to the second input of the multiplier 15, the first input of which receives the received signal U _k2 (t) from the output of the input unit 1. A voltage is generated at the output of the multiplier 15
U ₄ (t) = V ₄ cos (4 πf _g t + πγ ₂ t ² + φ _g ),
0 ≅t≅τ _and , where V ₄ =

V

V

, which is allocated by a band-pass filter 24, is detected by a quadratic detector 25 and is fed to the control input of the key 26, opening it.

The voltage U _pr3 (t) (see Fig. 5, a) from the output of the intermediate frequency amplifier 6 is simultaneously supplied to the inputs of the quadratic 7 and frequency 8 detectors. The quadratic detector 7 selects the envelope of the signal (see Fig. 5, c), which is fed to the first inputs of coincidence blocks 11 and 21. From the output of the frequency detector 8, a video signal (see Fig. 5, d), the shape of which corresponds to the law of frequency change f ₂₂ (see Fig. 5, b), is fed to the input of the differentiation unit 9, the output signal of which (see Fig. 5 , e) enters the inputs of the valve 10 and the phase inverter 19. The specified signal is not passed by the valve 10. A positive pulse is generated at the output of the phase inverter 19 (see Fig. 5, f), which enters through the valve 20 (see Fig. 5, g) to the second input of block 21 matches. Since the voltage (see Fig. 5, c, g) supplied to the two inputs of the coincidence block 21 occupy the same interval on the time axis, the coincidence block 21 is triggered. The voltage from the output of the coincidence unit 21 (see Fig. 5, h) is supplied to the control inputs of the keys 22 and 30, opening them. In this case, the components whose frequency lies in the passband Δ f _{1 of the} intermediate frequency amplifier 6 are amplified and after detection in the quadratic detector 7 and amplification in the amplifier 27 through the public keys 26 and 30 are fed to the vertical deflecting plates of the CRT 31, on the screen of which the amplitude spectrum of the signal received on the second Raman channel at a frequency f _k2 (see Fig. 3, g).

Claims (1)

 A SPECTRUM ANALYZER containing consecutively connected input unit, mixer, intermediate frequency amplifier, frequency detector, differentiation unit, first gate and first matching unit, the second input of which is connected through the first quadratic detector to the output of the intermediate frequency amplifier, and the output through the first key is connected to vertically deflecting plates of the first cathode ray tube, the horizontally deflecting plates of which are connected to the first output of the sweep generator, the second output of which is through the oscillating frequency generator is connected to the second input of the mixer, a multiplier, a first band-pass filter, a second quadratic detector, a second switch and a first DC amplifier connected to the second input of the first switch in series with the third input of the mixer are connected to the output calibrator, the second input of the multiplier is connected to the output of the intermediate frequency amplifier, and the output of the first quadratic detector is connected to the second input of the second key, characterized in that, in order to broadening the range of the spectral analysis of signals, a phase-inverter, a second valve, a second coincidence unit, a third key and a second cathode ray tube, a third and fourth cathode ray tube, a second bandpass filter, a third quadratic detector, and a fourth key are connected in series, a second DC amplifier and a fifth key, as well as a sixth key, with the input of the phase inverter connected to the output of the differentiation unit, the second input of the second matching unit connected to the output of the first of the quadratic detector, the second input of the third key is connected to the output of the first DC amplifier, and the output is to the vertically-deflecting plates of the second cathode ray tube, the input of the second bandpass filter is connected to the output of the multiplier, the second input of the fourth key is connected to the output of the first quadratic detector, the output of the second DC amplifier is connected to the input of the sixth key, the second input of which is connected to the output of the second coincidence unit, and the output to the vertically-deflecting plates of the fourth a cathode ray tube, the second input of the fifth key is connected to the output of the first coincidence unit, and the output of the fifth key is connected to vertically-deflecting plates of the third cathode ray tube, and the horizontal-deflecting plates of the second, third, fourth cathode ray tubes are connected to the first output generator sweep.

Images