RU2025737C1 - Device for measuring input signal frequency of panoramic radio receiver - Google Patents

Abstract

FIELD: radiometry. SUBSTANCE: device has pickup antenna 1, input circuit 2, high-frequency amplifier 3, mixers 4,13, video amplifiers 7,27,30, intermediate-frequency amplifiers 5,15,16, amplitude detectors 6,26,29, oscillographic indicators 8,28,31, control unit 9, unit 10 for forming frequency sweep, first and second local oscillators 11 and 12, multipliers 14, 18, band-pass filters 17,19, phase inverter 20, adder 21, frequency detector 22, differentiating circuit 23, rectifier 24, switch 25. EFFECT: enhanced accuracy and reliability. 5 dwg

Description

 The invention relates to radio measurement technology and can be used in panoramic radios, spectrum analyzers and frequency meters.

 The aim of the invention is to expand the range of frequency search signals.

 The block diagram of the device shown in figure 1; a frequency diagram explaining the formation of additional (mirror) reception channels is shown in FIG. 2; timing diagrams explaining the operation of the device shown in figure 3.4 and 5.

 The device (Fig. 1) contains a receiving antenna 1, an input circuit 2, a high-frequency amplifier 3, a first mixer 4, a first intermediate-frequency amplifier 5, a first amplitude detector 6, a first video amplifier 7, a first oscillographic indicator 8, a control unit 9, block 10 the formation of the frequency sweep, the first and second local oscillators 11 and 12, the second mixer 13, the first multiplier 14, the second and third amplifiers 15 and 16 of the intermediate frequency, the first bandpass filter 17, the second multiplier 18, the second bandpass filter 19, the phase inverter 20, the adder 21, often a distinct detector 22, a differentiator circuit 23, a rectifier 24, a key 25, a second amplitude detector 26, a second video amplifier 27, a second oscilloscope indicator 28, a third amplitude detector 29, a third video amplifier 30 and a third oscilloscope indicator 31.

Separate reception of signals on the main channel at a frequency f _o , along the first mirror channel at a frequency f _s1 and along a second mirror channel at a frequency f _{s2, is} based on the use of two local oscillators 11 and 12, the frequencies of which are separated by twice the intermediate frequency: f _g2 - f _r1 = 2f and _straight symmetrical selected relative to the frequency of the main channel
f _g2 - f _o = f _o - f _g1 = fpr.

 This circumstance leads to the appearance of the second mirror channel (figure 2).

 The device operates as follows.

 Viewing the specified frequency range Df is carried out using the search unit 9, which periodically, according to a sawtooth law, changes the setting of the input circuit 2, high-frequency amplifier 3 and local oscillators 11 and 12, and also controls the horizontal sweep of the oscillographic indicators 8.28 and through the frequency sweep generation unit 10 31. In this case, the indicator scan line is used as the frequency axis, the length of which corresponds to the range of frequencies viewed.

 Received pulse signal (figa).

- скорость изменения частот гетеродинов (скорость перестройки);
Т_n - период перестройки.U _o (t) = V _o cos (2 πf _o t + φ _o ); 0 ≅t≅ τ _n , where V _o , f _o , φ _o and τ _n are the amplitude, carrier frequency, initial phase and signal duration, from the output of the receiving antenna 1 through the input circuit 2 and the high-frequency amplifier 3 is supplied to the first inputs of the mixers 4 and 13, the second inputs of which are supplied with voltage from the output of the local oscillators 11 and 12, respectively
U _g1 (t) = V _g1 cos (2π f _g1 t + πγt ² + φ _g1 );
U _r2 (t) + V _r2 cos (2π f t + πγt _r2 ² + φ _r2);
0≅t≅ T _n , where V _g1 , V _g2 , f _g1 , f _g2 and φ _g1 , φ _g2 are the amplitudes, frequencies and initial phases of the local oscillator voltages;
γ =

- rate of change of local oscillator frequencies (tuning rate);
T _n - the period of adjustment.

Moreover, the frequencies f _g1 and f _{g2 of the} local oscillators 11 and 12 are spaced at double the intermediate frequency:
f _g2 - f _g1 = 2f _pr and selected symmetrical with respect to the frequency fo of the main receiving channel
f _g2 - f _o = f _o - f _g1 = f _ol
This circumstance leads to the appearance of a second mirror channel at a frequency f _s2 ( _figure 2).

The tuning frequency f _n1 and the passband Δf _{1 of the} intermediate frequency amplifier 15 are selected as follows:
f _H1 = f _ave; Δf ₁ = f _ave .

The tuning frequency f _n2 and the passband Δf _{2 of the} bandpass filter 17 are selected as follows:
f _2n = 2f _straight; Δf ₂ = f _ave .

The tuning frequency f _n3 and the passband Δf _{3 of the} intermediate frequency amplifiers 5 and 16 and the bandpass filter 19 are selected as follows:
f = 3f _{H3 Ave;} Δf ₃ = f _ave .

In the mixers 4 and 13, the received signal is converted to the voltage of the following frequencies (figa):
f _o1 = f _o - f _r1 - γt = f _ave - γt;
f _o2 = f _r2 + γt - f _o = f _ave + γt, where the first subscript represents the channel on which the signal is received, the second index - number oscillator involved in converting the received signal frequency.

K₁V₀V_г2;
К₁ - коэффициент передачи смесителя;
f_пр = f_г2 - f_o - промежуточная частота;
φ_пр1 = φ_г2 - φ_о.However, only the voltage with a frequency f _o2 falls into the passband Δf _{1 of the} intermediate frequency amplifier 15:
U _pr1 (t) = V _pr1 cos (2πf _pr t + πγt ² + φ _pr1 );
0≅ t≅ τ _n , where V _pr1 =

K ₁ V ₀ V _g2 ;
To ₁ - gear ratio of the mixer;
f _CR = f _g2 - f _o - intermediate frequency;
_pr1 cp = φ _r2 - φ _about.

 This voltage is supplied to the first input of the multiplier 18.

K₂ V_г1V_г2;
К₂ - коэффициент передачи перемножителя;
φ_г =φ_г2 - φ_г1;
f_г2 = f_г1 = 2f_пр.Voltages U _g1 (t) and U _g2 (t) from the outputs of the local oscillators 11 and 12 simultaneously arrive at the two outputs of the multiplier 14, the output of which produces a voltage
U _g (t) = V _g cos (4 πf _pr t + φ _g ) where V _g =

K ₂ V _g1 V _g2 ;
K ₂ is the transmission coefficient of the multiplier;
φ _g = φ _g2 - φ _g1 ;
f _g2 = f _g1 = 2f _ave .

K₂ V_пр1V_г;
φ₁= φ_пр1 + φ_г, и поступает на первый вход сумматора 21.This voltage is allocated by the band-pass filter 17 and is supplied to the second input of the multiplier 18. At the output of the latter, the voltage is allocated by the band-pass filter 19
U ₁ (t) = V ₁ cos (6 πf _pr t + πγt ² + φ ₁ );
0≅ t≅ τ _n , where V ₁ =

K ₂ V _{CR 1} V _g ;
φ ₁ = φ _pr1 + φ _g , and enters the first input of the adder 21.

Since the voltage does not fall into the passband of the intermediate frequency amplifier 5, there is no voltage at the second input of the adder 21. The voltage U ₁ (t) (Fig. 4a) from the output of the adder 21 is fed to the input of the frequency detector 22, the output of which is formed by a video pulse (Fig. 4b), the shape of which corresponds to the law of variation of the frequency f _o2 (Fig. 4c). The specified video pulse is fed to the input of the differentiating link 23, the output of which forms a rectangular positive pulse (Fig.4g), which through the rectifier 24 (Fig.4d) is supplied to the control input of the key 25 and opens it. Key 25 in the initial state is always closed. The rectifier 24 passes to its output only a positive pulse. In this case, the voltage U ₁ (t) from the output of the adder 21 through the public key 25 is supplied to the input of the amplitude detector 26, which selects its envelope. The latter through the video amplifier 27 enters the vertical plates of the oscilloscope indicator 28. As a result, a frequency mark is formed on the screen of the oscilloscope indicator 28, the position of which on the horizontal scan uniquely determines the carrier frequency f _{o of the} received signal.

K₁V_з1V_г2;
3f_пр = f_г2 - f_з1; φ_пр2 =φ_г2 - φ_з1.If the input device receives a signal of the first image channel at frequency f _P1 (3b)
U _З1 (t) = V _З1 cos (2πf _З1 t + φ _З1 ); 0≅ t≅ τ _n , then in mixers 4 and 13 it is converted to voltages of the following frequencies:
f ₁₁ = f _r1 + γt - f _P1 = f _ave + γt;
f ₁₂ = f _r2 + γt - t _{P1 ave} = 3f + γt. However, only voltage with a frequency of f ₁₂ falls into the passband Δf _{3 of the} amplifier 16 of the intermediate frequency:
_Np2 U (t) = V _np2 cos (πf 6 _ave t + πγt _np2 ² + φ);
0≅ t≅ τ _n , where V _pr2 =

K ₁ V _z1 V _g2 ;
3f _{pr r2} = f - f _{P1; WP2} cp = φ _r2 - φ _P1.

This voltage is input to a pulse amplitude detector 29, where it is allocated an envelope which is supplied through a video amplifier 30 to the vertical plates oscillographic display 31. On the last formed frequency tag, the position of which on the horizontal sweep uniquely determines the carrier chastotuf _P1 received signal.

If the input of the device receives a signal through the second mirror channel at a frequency f _s2 (figv)
U _З2 (t) = V _З2 cos (2πf _З2 t + φ _З2 ); 0≅ t≅ τ _n , then in mixers 4 and 13 it is converted to voltages of the following frequencies:
f ₂₁ = f _s2 - f _r1 - γt = 3f _etc. - γt;
f ₂₂ = f _s2 - f _r2 - γt = f _ave - γt.

K₁V_з2V_г1;
3f_пр= f_з2- f_г1;

= φ_з2- φ_г1.The voltage with a frequency f ₂ falls into the passband Δf _{3 of the} intermediate frequency amplifier 5:
_PR3 U (t) = V _PR3 cos (2πf _ave t + πγt _PR3 + φ ^2);
0≅ t≅ τ _n , where V _pr3 =

K ₁ V _z2 V _g1 ;
3f _ave = f _s2 - f _d1;

= φ _z2 - φ _g1 .

This voltage is fed to the input of the amplitude detector 6, where its envelope is highlighted, which is fed through the video pulse 7 to the vertical plates of the oscilloscope indicator 8. A frequency mark is formed on the screen of the latter, the position of which on the horizontal scan uniquely determines the carrier frequency f _{s2 of the} received signal.

The voltage U _CR3 (t) is simultaneously supplied to the input of the physical inverter 20, the output of which is formed
_WP4 U (t) = V _PR3 cos (6πf _ave t + πγt _PR3 + φ ^2);
0≅ t≅ τ _n , which is fed to the second input of the adder 21.

K₁V_з2V_г2;
φ_пр5= φ_з2- φ_г2 ; f_пр= f_з2- f_г2
Это напряжение поступает на первый вход перемножителя 18, на второй вход которого подается напряжение U_г(t) с выхода полосового фильтра 17. На выходе перемножителя 18 образуется напряжение
U₂(t) = V₂cos(6πf_прt + πγt² + φ₂);
0≅ t≅ τ_n, где V₂=

K₂V_пр5V_г;
φ₂= φ_пр5+ φ_г.The voltage with a frequency f ₂₂ falls into the passband Δf _{1 of the} amplifier 15 of the intermediate frequency:
_Np5 U (t) = V _np5 cos (2πf _ave t + πγt _np5 ² + φ);
0≅ t≅ τ _n , where V _pr5 =

K ₁ V _z2 V _g2 ;
φ _pr5 = φ _z2 - φ _g2 ; f _ol = f _z2 - f _g2
This voltage is supplied to the first input of the multiplier 18, the second input of which is supplied with voltage U _g (t) from the output of the bandpass filter 17. A voltage is generated at the output of the multiplier 18
U ₂ (t) = V ₂ cos (6πf _pr t + πγt ² + φ ₂ );
0≅ t≅ τ _n , where V ₂ =

K ₂ V _{CR 5} V _g ;
φ ₂ = φ _pr5 + φ _g .

This voltage is allocated by the band-pass filter 19 and supplied to the first input of the adder 21. The voltages U ₂ (t) and U _{CR 4} (t) supplied to the two inputs of the adder form a constant voltage at its output. This voltage is supplied to the input of the frequency detector 22, at the output of which there is no voltage. Key 25 does not open. In the initial state, key 25 is always closed.

If the signals are simultaneously received on the main channel at a frequency f _o , along the first mirror channel at a frequency f _s1 and along the second mirror channel at a frequency f _s2 , then all units of the device are involved. In this case, the voltages U _CR1 (t) and U _CR5 (t), which are fed to the first input of the multiplier 18, to the second input of which the voltage U _g (t) from the output of the bandpass filter 17, fall into the passband of the amplifier 15 of the intermediate frequency The output of the multiplier 18 produces voltages U ₁ (t) and U ₂ (t), which are fed to the first input of the adder 21, the second input of which is supplied with a voltage U _CR4 (t) from the output of the phase inverter 20. A voltage U ₁ ( t) (figa), which is fed to the input of the frequency detector 22. At the output of the last o voltage is generated (Fig. 4c), the shape of which corresponds to the law of frequency variation (Fig. 4b). This voltage is supplied to the input of the differentiating link 23, the output of which forms a rectangular positive pulse (Fig. 4d), which, through the rectifier 24 (Fig. 4e), enters the control input of the key 25, opening it. Further operation of the device has already been described.

Thus, the proposed device in comparison with the prototype provides an extension of the range of frequency search for signals without expanding the range of frequency tuning of local oscillators. This is achieved by using the first and second mirror channels at frequencies f _s1 and f _s2 through the use of the first and second local oscillators 11 and 12, the frequencies of which are spaced twice the intermediate frequency:
f _r2 - f _r1 = 2f, _etc., and by symmetrical about the frequency f _o fundamental channel
f _g2 - f _o = f _o - f _g1 = f _ave .

Claims (1)

 DEVICE FOR MEASURING THE FREQUENCY OF THE INPUT SIGNAL OF A PANORAMIC RADIO RECEIVER, comprising in series a receiving antenna, an input circuit, a high-frequency amplifier, a first mixer, a first intermediate frequency amplifier, a first amplitude detector and a first video amplifier connected to the vertical plates of the first oscilloscope indicator, a series-forming block sweeps and horizontal plates of the first oscilloscope indicator, as well as sequentially connected hours a frequency detector, a differentiating link, a rectifier and a key, the outputs of the control unit are connected to the control inputs of the input circuit, a high frequency amplifier, a first local oscillator and a frequency sweep forming unit, and the second input of the first mixer is connected to the output of the first local oscillator, characterized in that, for the purpose of expanding the frequency range of the signal search, a second local oscillator, a second mixer, a second and third intermediate frequency amplifiers, a first and a second multiplier, a first and a second bandpass filter, the inverter, the adder, the second and third amplitude detectors, the second and third video amplifiers, the second and third oscilloscope indicators, the horizontal plates of the first oscillographic indicator are connected to the output of the first video amplifier, the first multiplier, the first bandpass filter, the second multiplier, and the second are connected in series to the output of the first local oscillator bandpass filter, adder, key, second amplitude detector, second video amplifier and vertical plates of the second oscilloscope indicator, g the horizontal plates of which are connected to the output of the frequency sweep unit, the second mixer, the third intermediate frequency amplifier, the third amplitude detector, the third video amplifier and the vertical plates of the third oscillographic indicator, the horizontal plates of which are connected to the output of the frequency sweep unit, are connected in series to the output of the high-frequency amplifier, the second input of the first multiplier is connected to the output of the second local oscillator, the second input of the second multiplies Curing through the second intermediate frequency amplifier is connected to the output of the second mixer, the second adder input is connected through the phase inverter to the output of the first intermediate frequency amplifier, and the second input of the second mixer is connected to the fourth output of the control unit through the second local oscillator.

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