Radio engineering training device

FIELD: radio communications.

SUBSTANCE: device has radio-location station, first high-frequency generator, modulator, first counter, scanning generator, second counter, heterodyne, first mixer, first intermediate frequency amplifier, first amplitude detector, video-amplifier, third counter, cathode-ray tube, second, third and fourth high-frequency generators, first and second adders, switches, phase-rotators and on 90°, second mixer, second intermediate frequency amplifier, multiplier, narrow-band filter, second amplitude detector, key and frequency converter.

EFFECT: broader functional capabilities.

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The invention relates to training devices and simulators for radio engineering and allows you to demonstrate the mode of the serial search pulse signals according to the frequency, the principles of education additional receiving channels in a panoramic receiver, and methods and means of their suppression.

The known device used as training devices (ed. mon. The USSR No. 1495720, 1770974; RF patents №№2003181, 2051425 and others).

Known devices closest to the proposed is a Training device for radio engineering" (patent RF №2003181, G 09 B 23/18, 1992), which is selected as a prototype.

The specified device enables you to simulate the input radar signals with different timing parameters, to demonstrate the processes of the search signal by the frequency panoramic receiver and to investigate the mode of the serial signal search.

However, the basis of the known device is a panoramic receiver, in which the same value of the intermediate frequency f_CRcan be obtained as a result of receiving signals on two frequencies f_cand f_Ci.e. f_CR=f_c-f_gand f_CR=f_g-f₃.

Therefore, if the frequency f_cto take over the main channel, along with it there is another (mirror) the receive channel frequency f₃which is located on metecno (mirrored) relative to the frequency f _glo (figure 2). Converting the image channel is the same conversion coefficient K_CRthat and the basic receive channel. Therefore, it is most significantly affect the selectivity and robustness panoramic receiver.

In addition to the mirror, there are other additional (Raman) receiving channels, the frequency of which is determined as follows:

where f_ki- frequency of the i-th Raman channel;

m, n, i is a positive integer.

The most harmful combination receiving channels are channels formed by the interaction of the frequency of the received signal with harmonics of the lo frequency of small order (second, third, and so on), because the sensitivity of the panoramic receiver through these channels close to the sensitivity of the main receive channel. For example, if m=1 and n=2 two Raman channels correspond to the following frequencies:

F_K1=2f_g-f_CRand f_K2=2_f+f_CR

The presence of false signals (interference), taken in the mirror and Raman channels, leads to lower selectivity and noise immunity panoramic receiver.

An object of the invention is to enhance the functionality of the device through demonstrations and suppress additional who's receiving channels in a panoramic receiver.

The problem is solved in that a training device for radio engineering, containing series-connected first high-frequency generator, a modulator, and the first counter, cascaded sweep generator, an oscillator, a first mixer and a first intermediate frequency amplifier, cascaded first amplitude detector, amplifier and vertical deflecting plates of the cathode ray tube, the horizontal deflecting plate which is connected to the second output of the sweep generator, while the first output of the sweep generator is connected to the second counter, the output of the amplifier connected to the third counter, supplied with a second, third and fourth high-frequency generators, five switches, two phasers on 90°, the second mixer, the second intermediate frequency amplifier, two adders, multiplier, ascocentrum filter, the second amplitude detector and the key, and to the output of the modulator is connected in series to the first switch and the first adder, the second input is via a second switch coupled to the output of the second high-frequency generator, a third input via the third switch is connected to the output of the third high-frequency generator, the fourth entrance is through a fourth switch connected to the output of Thu is REGO high-frequency generator, and the output is connected to the second input of the first mixer, the second output of the local oscillator connected in series, the first phase shifter 90°, the second mixer, a second input connected to the output of the first adder, the second intermediate frequency amplifier, a second phase shifter 90°second adder, a second input connected to the output of the first intermediate frequency amplifier, a multiplier, a second input via a fifth switch coupled to the output of the first adder, a narrow-band filter, the second amplitude detector and the key, a second input connected to the output of the second adder, and the output is connected to the first input of the amplitude detector.

A structural scheme of the device represented in figure 1 - frequency diagram illustrating the principle of formation of additional receiving channels is shown in figure 2. Frequency-time diagrams explaining the mode of the serial search pulse signals in terms of frequency, shown in figure 3 and 4.

The device contains a model of the radar 1, consistently included the first high-frequency generator 2, a modulator 3, the first switch 18, the first adder 17, the second input is through the second switch 19 is connected to the output of the second high-frequency generator 14, the third entrance is through the third switch 20 is connected to the output of the third wysokosc the frequency generator 15, the fourth input via the fourth switch 21 is connected to the output of the fourth high-frequency generator 16, the first mixer 8, a second input connected to the first output of the local oscillator 7, and the first amplifier 9 intermediate frequency, sequentially connected to the first generator 5 sweep local oscillator 7, the first phase shifter 23 90°, the second mixer 24, a second input connected to the output of the first adder 17, the second amplifier 25 intermediate frequency, a second phase shifter 26 90°the second adder 27, a second input connected to the output of the first amplifier 9 intermediate frequency multiplier 28, the second input is via the fifth switch 22 is connected to the output of the first adder 17, escapology filter 29, the second amplitude detector 30, the key 31, a second input connected to the output of the second adder 27, the first amplitude detector 10, amplifier 11 and the vertically deflecting plates of the cathode ray tube (CRT) 13, the horizontal deflecting plate which is connected to the second output of the sweep generator 5.

The device operates as follows.

The device allows you to display three modes.

In the first mode, the device allows to demonstrate the processes of the search signal by the frequency panoramic receiver and to investigate the mode of the serial signal search.

In the third mode, the device allows to demonstrate the methods and means of suppressing spurious signals (noise)received by the mirror and Raman channels.

In the first mode, the device allows to reproduce the process of discovery series of the pulse signals radar of the circular panoramic overview. When switch 18 is closed.

High-frequency signal

U_c(t)=U_ccos(2πf_ct+ϕ_c),

where U_cf_cthat ϕ_c- amplitude, carrier frequency, and initial phase high frequency signal;

from the generator 2 is supplied to the modulator 3. Model radar 1, consisting of series-connected high-frequency generator 2 and modulator 3, allows to simulate three different orbital period T₁T₂T₃Radar of the circular review and respectively three different duration of the impulse packs τ₁thatτ₂thatτ₃entering the field of view of the receiving device.

Next, the modulated signal is sent through the switch 18 and the adder 17 to the first inputs of mixers 8 and 24, the second inputs of which are served voltage of the local oscillator 7 linearly changing frequency:

U_g(t)=U_g·cos(2πf_gt+πγt²+&x003D5; _g),

U_g(t)=U_g·cos(2πf_gt+πγt²+ϕ_g+90⁰), 0≤t≤TA,

where U_gf_gthat ϕ_gthat Τ_p- amplitude, initial frequency, initial phase, and the repetition period of the voltage of the local oscillator;

the speed adjustment of the frequency of the local oscillator 7 in a predetermined frequency range D_f,

T_pthe repetition period of the voltage of the local oscillator 7 (Fig).

Changing the lo frequency is linear by using sweep generator 5, which is the generator shiroabyanga voltage. The sweep generator 5 generates a horizontal scan of the CRT 13. This voltage is fed to the counter 6 to register the number of rearrangements of the local oscillator 7.

At the outputs of mixers 8 and 22 are formed voltage Raman frequencies. Amplifiers 9 and 25 are intermediate voltage (differential) frequency:

U_PR1(t)=U_CR·cos(2πf_CRt+πγt²+ϕ_CR),

U_AC2(t)=U_CR·cos(2πf_CRt+πγt²+ϕ_CR-90°), 0≤t≤TA,

where U_CR=1/2·₁·U_c·U_g;

K₁- gain mixers;

f_CR=f_c-f_g- intermediate frequency;

ϕ_CR=ϕ_withϕ _g.

The voltage U_AC2(t) from the output of the amplifier 25 intermediate frequency is fed to the input of phase shifter 26 90°, the output of which produces a voltage

U_AC3(t)=U_CR·cos(2πf_CRt+πγt²+ϕ_CR-90°+90°)=U_CR·cos(2πf_CRt+πγt²+ϕ_CR).

Voltage U_PR1(t) and U_AC3(t) are fed to the two inputs of the adder 27, the output of which is formed by the total voltage

U_Σ(t)=U_Σ·cos(2πf_CRt+πγt²+ϕ_CR),

where UΣ=2U_CR.

This voltage is applied to the second input of multiplier 28, at the first input of which through the closed switch 22 receives the high frequency signal U_c(t) from the output of the adder 17. At the output of the multiplier 28 is formed voltage

U₁(t)=U₁·cos(2πf_gt+πγt²+ϕ_g),

where U₁=1/2·K₂·Uc·U_Σ;

To₂- transfer coefficient multiplier,

given a narrow-band filter 29, is detected by the amplitude detector 30 and is supplied to the control input key 31, opening it. In the initial state, the key 31 is always closed. The frequency f_nnarrowband filter 29 is chosen equal to the initial frequency f_glo 7(f_n=f_{g ).}

_{The voltage UΣ(t) with the output of the adder 27 via public key 31 is fed to the input of the amplitude detector 10, which is allocated a modulating signal which after amplification in the amplifier 11 is supplied to vertical deflection plates of the CRT 13 and the counter 12. In the counter 12 are fixed pulses matches the input series of pulses falling within the bandwidth of the receiver with its periodic changes with a period of Tp.}

The repetition period of T_pyou can change by changing the scan mode of the generator 5, and consequently, it is possible to change the rate of change of the frequency of the local oscillator 7.

Thus, at fixed values of T_pthat τ₁and D_fyou can demonstrate the limits of fast and slow searches. Visually these boundaries are observed at the following coincidence counters on some interval T_OBS(T_OBS≫ T_p).

Border quick search corresponds to the coincidence counters 4 and 12 (N₄=N₁₂where N₄the number recorded by the counter 4; N₁₂the number recorded by the counter 12) at T_OBS.

Border slow search corresponds to the coincidence counters 6 and 12 (N₆=N₁₂where N₆the number recorded by the counter 6; N₁₂the number recorded is Ketchikan 12) at T _OBS. Between these boundaries is the area of probabilistic search (with an average speed).

Provided in the instrument can be simulated radar signals with different timing parameters T₁that τ₁; T₂that τ₂; T₃that τ₃- allows you to demonstrate the change of borders reliable searches for a fixed search range D_fand bandwidth Δf_preceiver by passing to the analysis of the formation of pulses matches for input signals with different timing parameters.

The second mode is ensured by the fact that the switches 18 and 22 are closed, the switches 19, 20 and 21 are sequentially closed and consistently visually observed effect of false signals (interference), taken in the mirror, the first and second Raman channels for the reception of the useful signal.

At the same time on the screen of the CRT 13 (horizontal scan) are formed label frequency corresponding to the useful signal and spurious signals (noise)taken on additional channels.

The third mode provides a demonstration of methods and means of suppressing spurious signals (noise)received by the mirror and Raman channels. When the switches 18, 20 and 21 open and the switches 19 and 22 are closed. Vyskocil the private signal

U₃(t)=U₃·cos(2πf₃t+ϕ₃),

generated by the generator 14 through the closed switch 19 and the adder 17 is supplied to the input of the Converter 32 frequency. Amplifiers 9 and 25 intermediate frequency in this case there are the following voltage:

U_p(t)=U_p·cos(2πf_CRt+πγt²+ϕ_p),

U_WP5(t)=U_p·cos(2πf_CRt+πγt²+ϕ_p+90°),

where U_p=1/2·₁·U_C·U_g;

f_CR=f_g-f_C- intermediate frequency;

ϕ_CR=ϕ_g-ϕ_C.

The voltage U_WP5(t) from the output of the amplifier 25 intermediate frequency is fed to the input panoramically 26 90°, the output of which produces a voltage

U_p(t)=U_p·cos(2πf_CRt+πγt²+ϕ_p+90°+90°)=U_p·cos(2πf_CRt+πγt²+ϕ_p).

The voltage U_p(t) and U_p(t)received at the two inputs of the adder 27, at its output out. Frequency label on the screen of the CRT 13 is missing.

Therefore, a false signal (interferer)taken by the image channel at frequency f₃suppressed. To do this, use the "outer ring"consisting of a local oscillator 7, mixer 8, and 24, amplifiers 9 and 25 Prohm is filling frequency, phasers 23 and 26 90°, adder 27, and implements photocomposition method.

To demonstrate the suppression of the first Raman channel switch 19 is opened and the switch 20 is closed. When this high-frequency signal

U_K1(t)=U_K1·cos(2πf_K1t+ϕ_K1).

From the output of the generator 15 via a closed switch 20 and the adder 17 is supplied to the input of the Converter 32 frequency. In this case, the amplifiers 9 and 25 of the intermediate frequency are the following voltage:

U_p(t)=U_p·cos(2πf_CRt+πγt²+ϕ_p),

U_p(t)=U_p·cos(2πf_CRt+πγt²+ϕ_p+90°),

where U_p=1/2·₁·U_K1·U_g;

f_CR=2f_g-f_K1- intermediate frequency;

ϕ_p=ϕ_g-ϕ_K1.

The voltage U_p(t) the output of the amplifier 25 intermediate frequency is fed to the input of phase shifter 26 90°, the output of which is formed the following voltage

U_p(t)=U_p·cos(2πf_CRt+πγt²+ϕ_p+90°+90°)=-U_p·cos(2πf_CRt+πγt²+ϕ_p).

The voltage U_p(t) and U_p(t)received at the two inputs of the adder 27, at its output out. Often the Naya blip on the screen of the CRT 13 is missing.

Therefore, a false signal (interferer)taken by the first Raman channel at frequency f_K1is suppressed. It also uses the "outer ring", implementing photocomposition method.

To demonstrate the suppression of the second Raman channel switch 20 is opened and the switch 21 is closed. When this high-frequency signal

U_K2(t)=U_K2·cos(2πf_K2t+ϕ_K2)

from the output of the generator 16 through the closed switch 21 and the adder 17 is supplied to the input of the Converter 32 frequency. In this case, the amplifiers 9 and 25 are the following voltage:

U_{10% rhodium / platinum}(t)=U_{10% rhodium / platinum}·cos(2πf_CRt+πγt²+ϕ_{10% rhodium / platinum}),

U_p(t)=U_{10% rhodium / platinum}·cos(2πf_CRt+πγt²+ϕ_{10% rhodium / platinum}+90°),

where U_{10% rhodium / platinum}=1/2·₁·U_K2·U_g;

f_CR=f_K2-2f_g- intermediate frequency;

ϕ_{10% rhodium / platinum}=ϕ_g-ϕ_K2.

The voltage U_p(t) from the output of the amplifier 25 intermediate frequency is fed to the input of phase shifter 26 90°, the output of which produces a voltage

U_p(t)=U_{10% rhodium / platinum}·cos(2πf_CRt+πγt²+ϕ_{10% rhodium / platinum}-90°+90°)=U_{10% rhodium / platinum}·cos(2πf_CRt+πγt²+ϕ_{10% rhodium / platinum}).

Voltage U 10% rhodium / platinum(t) and U_p(t) are fed to the two inputs of the adder 27, the output of which is formed by the total voltage

U_Σ1(t)=U_Σ1·cos(2πf_CRt+πγt²+ϕ_{10% rhodium / platinum}),

where U_Σ1(t)=2U_{10% rhodium / platinum}.

This voltage is fed to the second input of multiplier 28, at the first entrance through the closed switch 22 receives the received signal Ck(1). At the output of the multiplier 28 is formed voltage

U₂(t)=U₂·cos(2πf₂t+πγt²+ϕ_g),

where U₂=1/2·₁·U_K2·U_Σ1;

which does not fall within the bandwidth of the narrowband filter 29. The key 31 is opened and a false signal (interferer)taken by the second Raman channel at frequency f_K2suppressed. To do this, use the "inner ring"consisting of a multiplier 28, a narrow-band filter 29, the amplitude detector 30 and the key 31 and implements the method narrowband filtering.

If closed switches 18-22, at the entrance of the panoramic receiver simultaneously receives the useful signal at frequency f_withfalse signals (interference)taken by the image channel at frequency f_Cthe first f_K1and the second f_K2Raman channels. False signals (interference), take on additional channels are suppressed, the horizontal scan of the CRT 13 is formed frequency tag, the corresponding useful signal received by the main channel at frequency f_with.

Thus, the proposed training device for comparison with the prototype allows not only to simulate the input radar signals with different timing parameters, to demonstrate the processes of the search signal by the frequency panoramic receiver and to investigate the mode of the serial search signals, but also to demonstrate the formation of additional receiving channels in a panoramic receiver, and methods and means of their suppression. Thus the functionality of the training device according to Radiotehnika expanded.

A training device for radio engineering, containing series-connected first high-frequency generator, a modulator, and the first counter, cascaded sweep generator, an oscillator, a first mixer and a first intermediate frequency amplifier, cascaded, the first amplitude detector, amplifier and vertical deflecting plates of the cathode ray tube, the horizontal deflecting plate which is connected to the second output of the sweep generator, while the first output of the sweep generator is connected to the second counter, the output of the amplifier connected to the third counter, characterized in that it is provided with a second, third and fourth high frequency the generators, five switches, two phasers 90°, the second mixer, the second intermediate frequency amplifier, two adders, multiplier, a narrow-band filter, the second amplitude detector and the key, and to the output of the modulator is connected in series to the first switch and the first adder, the second input is via a second switch coupled to the output of the second high-frequency generator, a third input via the third switch is connected to the output of the third high-frequency generator, the fourth input via the fourth switch is connected to the output of the fourth high-frequency generator, and the output connected to the second input of the first mixer to the second output of the local oscillator connected in series to the first Phaser 90°, the second mixer, a second input connected to the output of the first adder, the second intermediate frequency amplifier, a second phase shifter 90°second adder, a second input connected to the output of the first intermediate frequency amplifier, a multiplier, a second input via a fifth switch coupled to the output of the first adder, a narrow-band filter, the second amplitude detector and the key, a second input connected to the output of the second adder, and the output connected to the input of the first amplitude detector.