RU2750336C1 - Interference-free transmission system with analog selection unit and automatic matching device on discrete elements - Google Patents

Abstract

FIELD: radio communication.

SUBSTANCE: invention relates to radio communication technology and can be used in radio stations of the shortwave (SW) band, as well as in radio stations of other bands operating in conditions of concentrated interference. An interference-free transmission system with an analog selection unit and an automatic matching device on discrete elements consists of a high-frequency generator (HFG), a bidirectional coupler, a matching circuit and an antenna, as well as a tuning unit, while the HFG has a sinusoidal signal generator (SSG), a power amplifier and switch, with additionally introduced an analog selection unit, made with ability to extract the useful signal and suppress other spectral components while maintaining the phase relationships of the useful signal from both outputs of the bidirectional coupler, four analog-to-digital converters and a microprocessor device.

EFFECT: increasing the noise immunity of the transmission system to interference induced into the antenna from the signals of powerful radio transmitting devices.

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Description

The invention relates to radio communication technology and can be used in radio stations of the short-wave (HF) range, as well as in radio stations of other ranges, operating in conditions of concentrated interference.

In radio communication, the issue of matching the antenna with the transmitter plays an important role. The matching problem is relevant for different ranges and is solved for different ranges in different ways. The matching has a number of features for shortwave (HF) radio stations, which are currently actively used in civil and military communications.

Known radio transmitting devices, for example, published in Shahgildyan V.V., Karjakin V.L. Designing devices for generating and shaping signals in mobile communication systems: Textbook for universities. M: SOLON-Press, 2011 .-- 400 p. page 308 fig. 4.2, page 309 fig. 4.3. Also known is a radio transmitting device published in Sh akhgildan V.V., Shumilin V.S., Kozyrev V.B. and others, ed. V.V. Shahgildyan - 4th ed., Revised. And add. - M .: Radio and communication, 2000 - 656s. Page 377 Figure 5.6. However, these radio transmitters are designed to operate on a matched load and do not provide a matching circuit with an antenna.

The closest in technical essence to the proposed one is the device described in the article "The concept of matching radio transmitting devices with loads", T-Comm, No. 9-2013 p. 127-131, Fig. 2.

A diagram of the prototype device is shown in FIG. 1, where it is indicated:

1 - high frequency generator (HF);

2 - sinusoidal signal generator (GSS);

3 - key;

4 - power amplifier (PA);

5 - bidirectional coupler (BOT);

6 - adjustment block;

7 - matching chain (CA);

8 - load of the transmitting system Rн (antenna).

The prototype device contains a series-connected high-frequency generator 1, a bi-directional coupler 5, a matching circuit 7 and a load of the transmitting system Rн (antenna) 8. Moreover, the HF generator 1 consists of a sinusoidal signal generator 2 and an amplifier 4, the outputs of which are connected to the corresponding inputs of the key 3 , the output of which is the output of the RF generator 1. The first and second outputs of the bidirectional coupler 5 are connected to the inputs of the trimming unit 6, respectively. The four outputs of the DNO 5 are connected to the corresponding inputs of the matching circuit 7.

The prototype device operates in two modes - in the configuration mode and in the transmission mode. Since the antenna 8 acts as a load, it will have some complex impedance depending on the frequency Z (f). To ensure operation in the transmission mode of the PA 4 to the matched load in the presetting mode, DS 7 is tuned. In the tuning mode, the GSS 2 signal is used, which is fed through switch 3 to the DNO 5 and then through the DS 7 to Rn 8. In this case, the GSS 2 a harmonic signal at frequency f1, at which transmission work will be carried out in the future. Since in the initial state the transmission path is mismatched, an incident and a reflected wave is formed in it. From the DNO 5, the branch voltage of the incident power Uп and Urep - the branch voltage of the reflected power will be supplied to the adjustment unit 6. Further, the tuning unit 6, based on the values of Uп and Uref, as well as the phase between them, calculates the values of the control voltages of the DC 7. After that, the DC 7, based on the obtained control voltages, transforms the complex load resistance Rn 8 to the output of the high-frequency generator 1. This process is repeated until the tuning process comes to a steady state. In the steady state, Uref will have a small or zero value, and the power transmission path from the high-frequency generator 1 to the load 8 will be matched at the frequency f1.

In the transmission mode, switching is performed by the switch 3 of the power amplifier 4 to the DNO 5. Since the output resistances of the GSS 1 and the PA 4 are the same, the power amplifier 4 will transmit the output power to the matched load.

The antenna has a reactance that depends on the frequency Z (f). Let us consider the case in which there are 2 signals: the first is a useful signal, the source of which is in the GSS 2 tuning mode at frequency f1, the second signal is interference induced into the antenna (Rn) 8 at frequency f2. In this case, the value of the power of the useful signal in the tuning mode, as a rule, is small 0.02 ... 0.1 W. The signal strength of the interference signal from a nearby transmitter can be significantly higher. In real conditions, the isolation between nearby HF antennas can be as high as 30 dB. In the VHF range, the isolation value can be as low as 10 dB. Thus, with a power of a neighboring transmitter of 1 kW, the power induced from it into the antenna can reach 1 W. As a result, the values of the incident and reflected power in the bidirectional coupler 5 Uп and Urep will to a greater extent be determined by the interference signal acting at the frequency f2, which is more than 10 dB higher than the wanted signal acting at the frequency f1. Considering that the neighboring transmitter operates at a different frequency f2, then the DS 7 tuning process will be performed at the frequency f2. In addition, for some types of antennas, when the frequency is offset, the value of the reactance Z (f) changes greatly, therefore, when the prototype device is operating, it will be tuned to the complex resistance Z (f2) instead of Z (f1).

As a consequence, in transmission mode, power amplifier 4 will operate at frequency f1 for a mismatched load with power shedding.

When the radio transmission system is operating, the antenna may be interfered with by nearby operating powerful radio transmitting devices. In this case, the incident and reflected power is measured in the transmission path (both in the tuning mode and in the transmission mode). The presence of powerful interference from antennas, which are induced at a frequency different from the frequency of operation of the radio transmitting device (RPDU), lead to distortion of the measured values of the incident and reflected power. At the same time, due to the abnormal readings of the incident and reflected power sensors, they can reach such values at which the operation of the RPDU will be impossible.

The disadvantage of the prototype device is low noise immunity from interference to the antenna of signals from powerful radio transmitting devices.

The task of the proposed technical solution is to increase the noise immunity of the transmission system to interference induced into the antenna from the signals of powerful radio transmitting devices.

To solve the set problem, a noise-immune transmission system with an analog selection unit and an automatic matching device on discrete elements, containing a series-connected high frequency generator (HHF), a bidirectional coupler, a matching circuit and an antenna, as well as a tuning unit, while the HHF contains a sinusoidal signal generator (GSS), a power amplifier, the outputs of which are connected to the corresponding inputs of the switch, the output of which is the output of the MHF, according to the invention, an analog selection unit is introduced, made with the possibility of separating the useful signal and suppressing other spectral components while maintaining the phase relationships of the useful signal from both outputs of the bidirectional coupler connected to the inputs of the analog selection unit, as well as four analog-to-digital converters, the outputs of which are connected to the corresponding four inputs of the microprocessor device, the output of which is connected to the second input of the circuit is matched and, while the two outputs of the analog selection unit are connected to the inputs of the trimming unit, respectively.

FIG. 2 shows a diagram of the claimed device, where it is indicated:

1 - high frequency generator (HHF);

2 - sinusoidal signal generator (GSS);

3 - key;

4 - power amplifier (PA);

5 - bidirectional coupler (BOT);

6 - tuning block (BP);

7 - matching chain (CA);

8 - antenna (transmission system load);

9 - two-channel radio receiving device (RPU);

10 - block of analog selection;

11, 12, 13, 14 - from the first to the fourth analog-to-digital converters (ADC);

15 - microprocessor unit (MCU).

The inventive device contains a series-connected RF generator 1, a bi-directional coupler 5, a matching circuit 7 and an antenna 8. Moreover, the RF generator 1 consists of a sinusoidal signal generator 2 and an amplifier 4, the outputs of which are connected to the corresponding inputs of the key 3, the output of which is the output of the VS 1 generator The outputs of the bidirectional coupler 5 are connected to the corresponding inputs of the analog selection unit 10, two outputs of which are connected to the corresponding inputs of the adjustment unit 6, four outputs of which are connected to the inputs of the corresponding ADCs 11, 12, 13, 14, the outputs of which are connected to the corresponding inputs of the microprocessor device 16 , the output of which is connected to the second input of the matching circuit 7. In this case, the analog selection unit 10 is made in the form of a two-channel radio receiver 9, the inputs of which are the inputs of the analog selection unit 10, and the RPU outputs are the outputs of the unit 10.

The proposed device works as follows.

In the tuning mode, the GSS 2 signal is used, which is fed through the switch 3 to the DNO 5 and then through the DS 7 to the antenna 8. In this case, the GSS 2 generates a harmonic signal at the frequency f1, at which transmission work will be carried out in the future. Since in the initial state the transmission path is mismatched, an incident and a reflected wave is formed in it. As a result, from the DNO 5, the selection unit 10 receives Uп - the branch voltage of the incident power, and Urep - the branch voltage of the reflected power. Selection unit 10 is tuned to the frequency of receiving the useful signal f1. The two-channel radio receiver 9 passes the harmonic signal at the frequency f1 without attenuation, and attenuates the interference signals at the frequency f2 by 60 dB or more. At the output of the two-channel radio receiver 9, the induced interference signal at frequency f2 will have a power of less than 1 mW, and will not affect the operation of the tuner 6. BP 6 will receive Uп - the branch voltage of the incident power, and Uref - the branch voltage of the reflected power at frequency f1. BP 6, based on the values of Uп and Uref, as well as the phases between them, calculates the values of the control voltages. The resulting control voltages are digitized using ADC 11, 12, 13, 14 and fed to MCU 15. Microprocessor device MCU 15 determines which discrete elements need to be connected in the matching circuit to ensure the required values of inductance and capacitance of DC 7 and generates the corresponding control commands in DS 7. After that, DS 7 transforms the complex impedance of the load (antenna) 8 to the output of the high frequency generator 1. This process is repeated until the tuning process comes to a steady state.

In the transmission mode, the switch is made by the switch 3 of the power amplifier 4 to the DNO 5. Since the output resistances of the GSS 1 and the PA 4 are the same, the PA 4 will transmit the output power to the matched load.

The construction of blocks 1, 2, 3, 4, 5, 6, 7, 8 in the claimed device is well known and similar to the implementation of the corresponding blocks 1, 2, 3, 4, 5, 6, 7, 8 of the prototype device.

Analog-to-digital converters 11 - 14 can be constructed, for example, as described in the patent for utility model RU 78999 in Fig. 1. Blocks 3, 8.

The microprocessor device MCU 15 can be as described, for example, in the patent for utility model RU 78999 in Fig. 1. Block 5.

The two-channel radio receiver 9 can be made, for example, as presented in the patent RF 2225990.

The block diagram of a two-channel receiver is shown in FIG. 3, where it is indicated:

U9.1, U9.2, U9.3, U9.4, U9.5, U9.6 - from the first to the sixth amplifiers;

PF9.1.1, PF9.1.2, PF9.1.3, PF9.1.4 - from the first to the fourth band pass filters;

CM9.2.1, CM9.2.2, CM9.2.3, CM9.2.4 - from the first to the fourth analog signal mixers;

SCh9.7 - tunable frequency synthesizer;

G9.8 - generator of sinusoidal oscillations at a fixed frequency.

A two-channel analog receiver contains two channels. The first channel consists of the series-connected first amplifier U9.1, the first mixer CM9.2.1, the first PF9.1.1, the third amplifier U9.3, the third PF9.1.3 and the fifth amplifier U9.5, the output of which is the first output of the RPU 9. The second channel consists of from the series-connected second amplifier U9.2, second mixer CM9.2.2, second PF9.1.2, fourth amplifier U9.4, fourth mixer CM9.2.4, fourth PF9.1.4 and sixth amplifier U9.6, the output of which is the second output of RPU 9 In addition, the output of the tunable frequency synthesizer SCH9.7 is connected to the second inputs of the first CM9.2.1 and second CM9.2.2 mixers; The output of the sinusoidal oscillator at a fixed frequency Г9.8 is connected to the second inputs of the third CM9.2.3 and fourth CM9.2.4 mixers. The inputs of the first U9.1 and the second U9.2 amplifiers are, respectively, the first and second inputs of the RPU 9.

The two-channel analog receiver works as follows.

The signal is fed to the first and second inputs, then amplified by the first U9.1 and the second U9.2 amplifiers, after which it is fed to the first input of the first CM9.2.1 and second CM9.2.2 mixers, in which it is transferred to the intermediate frequency. At the intermediate frequency, the signal is filtered by the corresponding bandpass filters of the intermediate frequency PF9.1.1 and PF9.1.2. In this case, the same signal of the frequency synthesizer SCH9.7 is fed to the second input of both mixers CM9.2.1 and CM9.2.2 to preserve the phase difference between the signals of both channels. After the first PF9.1.1 and the second PF9.1.2 filters, the signal through the third U9.3 and fourth U9.4 amplifiers is fed to the first input of the third CM9.3 and fourth CM9.2.4 mixers, while a signal from the sinusoidal signal generator is fed to their second inputs D9.8.

The signal in the third CM9.3 and fourth CM9.2.4 mixers is transferred to the second intermediate frequency and then filtered by the third PF9.1.3 and fourth PF9.1.4 bandpass filters and then amplified by the fifth U9.5 and sixth U9.6 amplifiers. Considering that the same harmonic signal is fed to the third CM9.2.3 and fourth CM9.2.4 mixers, the phase difference of the useful signal between the channels is preserved.

Amplifiers U9.1 - U9.6 can be made, for example, as given in the book by P. Horowitz, W. Hill. The art of circuitry. Ed. 5th rev. M .: Mir. 1998 704 s. on page 181.

The implementation of bandpass filters PF1, PF2, PF3, PF4 is known and is given in the book by P. Horowitz, W. Hill. The art of circuitry. Ed. 5th rev. M .: Mir. 1998, 704 p. on page 293.

The implementation of the mixers CM1, CM2, CM3, CM4 is known, and can be carried out, for example, as given in the book by V.V. Palshkov. Radio receiving devices. Study guide - M .: Radio and communication, 1984 .-- 392 p. silt on pages 116-120.

The implementation of the G9.8 generator is known and is given in the book by P. Horowitz, W. Hill. The art of circuitry. Ed. 5th rev. M .: Mir. 1998, 704 p. on page 318.

The construction of a frequency synthesizer MF1 is known, for example, from the publication of S.K. Romanov, N.M. Tikhomirov, D.N. Rakhmanin, A.V. Grechishkin. Theory and technology of radio communication, 2013, No. 1, p. 64.

Thus, in the proposed system, an increase in the noise immunity of the transmitting system to interference induced into the antenna from the signals of powerful radio transmitting devices is achieved by introducing a two-channel receiving device, in which the operation of both receiving channels occurs at the same frequency and from one frequency synthesizer - this ensures the preservation of the difference phases between the signals of the incident Uп and reflected power Uref.

Claims (2)

1. An interference-free transmission system with an analog selection unit and an automatic matching device on discrete elements, containing a series-connected high frequency generator (HHF), a bidirectional coupler, a matching circuit and an antenna, as well as a tuning unit, while the HHF contains a sinusoidal signal generator (GSS) , a power amplifier, the outputs of which are connected to the corresponding inputs of the switch, the output of which is the output of the MHF, which differs by introducing an analog selection unit capable of separating the useful signal and suppressing other spectral components while maintaining the phase relationships of the useful signal from both outputs of the bidirectional coupler connected to the inputs of the analog selection unit, as well as four analog-to-digital converters, the outputs of which are connected to the corresponding four inputs of the microprocessor device, the output of which is connected to the second input of the matching circuit, while the two outputs of the analog selection unit are connected to the inputs of the trimming unit, respectively, the four outputs of the trimming unit are connected to the inputs of the corresponding analog-to-digital converters. 2. The transmission system according to claim 1, characterized the fact that the analog selection unit is a two-channel receiver designed to operate both channels at the same frequency and from one frequency synthesizer, the inputs of the two-channel receiver are the inputs of the analog selection unit, and the outputs are the outputs of the analog selection unit.

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