RU2748322C1 - Interference-free transmission system with a digital selection unit and an automatic matching device with continuous impedance adjustment - Google Patents

Abstract

FIELD: radio communication technology.SUBSTANCE: 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. An interference-free transmission system with a digital selection unit and an automatic matching device with continuous impedance adjustment 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 contains a sinusoidal signal generator (SSS), a power amplifier, and a key, while additionally a digital 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, and four digital-to-analog converters (DAC), and the matching circuit is made on discrete elements.EFFECT: increasing the noise immunity of the radio transmitting device to interference induced into the antenna from the signals of powerful radio transmitting devices.1 cl, 2 dwg

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 figure 4.2, page 309 figure 4.3. Also known is a radio transmitting device published in Shahgildan V.V., Shumilin V.S., Kozyrev V.B. and others, ed. V.V. Shahgildyan - 4th ed., Revised. and additional - M .: Radio and communication, 2000 - 656 p. P. 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, the DS 7 is tuned. 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 Rn 8. In this case, the GSS 2 forms 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 BOT 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 a frequency f1, the second signal is an interference induced into the antenna (Rn) 8 at a 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 reach lower values up to 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 radio transmitting device 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 a digital selection unit and an automatic matching device with continuous impedance adjustment, containing a series-connected high frequency generator (HHF), a bi-directional coupler, a matching circuit and an antenna, as well as an adjustment unit, is used. signal (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 GHF, according to the invention, a digital selection unit and four digital-to-analog converters (DAC) are introduced, the outputs of which are connected to the inputs of the matching circuit, respectively, and the matching circuit is made on discrete elements; two outputs of the bidirectional coupler are connected to the corresponding inputs of the digital selection unit, two outputs of which are connected to the corresponding inputs of the trimming unit, four outputs of which are connected to the inputs of four DACs, respectively, in addition, the digital selection unit is configured to extract the useful signal and suppress other spectral components from maintaining the phase relationships of the useful signal from both outputs of the bidirectional coupler.

Figure 2 shows the inventive 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, 10 - the first and second analog-to-digital converters (ADC);

11, 12 - the first and second digital receiving devices (CPU);

13 - digital block of selection;

14, 15, 16, 17 - from the first to the fourth digital-to-analog converters (DAC).

The proposed device contains a series-connected high-frequency generator 1, a bi-directional coupler 5, a matching circuit 7 and an 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 BC generator 1. The first and second outputs of the bidirectional coupler 5 are connected to the corresponding inputs of the digital selection unit 13, the 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 DACs 14, 15, 16, 17. The output of each DAC is connected to the corresponding the input of the matching circuit 7. The digital selection unit 13 contains two chains of the first ADC 9 and the first CPU 11 connected in series, and the second ADC 10 and the second CPU 12. Moreover, the inputs of the first 9 and the second 10 ADC are the inputs of the digital selection unit 13, the outputs of the first 11 and the second 12 TsRPU - outputs of the digital selection block 13.

The claimed device operates as follows.

To obtain analog values from digital values of control voltages, digital-to-analog converters 14, 15, 16, 17 are introduced into the device, from the outputs of which a voltage is supplied that controls the matching circuit 7.

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 branch voltage of the incident Uп and reflected power Uref is supplied to the digital selection unit 13. The digital selector unit 13 is tuned to the frequency of receiving the useful signal f1. In the selection device 13, the samples are digitized by two analog-to-digital converters 9 and 10. Then the obtained samples are fed to digital receiving devices 11, 12, respectively, the CPU 11 and 12 are tuned to the receiving frequency f1 and pass the harmonic signal at the frequency f1 without attenuation, and the signals Interference at frequency f2 is attenuated by 60 dB or more. At the output of CPUs 11 and 12, the induced interference signal at frequency f2 will have a power of less than 1 mW and will not affect the operation of the power supply unit 6. Power supply unit 6 will receive Uп - the branch voltage of the incident power, and Uref - the branch voltage of the reflected power on frequency f1 in digital form. BP 6, based on the values of Uп and Uref, as well as the phase between them, calculates the values of capacitances and inductances in DS 7. The obtained values are fed to digital-to-analog converters 14, 15, 16, 17, in which digital values of control voltages are converted into analog values. Then the DS 7 transforms the complex load impedance of the antenna 8 to the output of the RF generator 1. This process is repeated until the tuning process comes to a steady state.

In the transmission mode, the switch 3 of the power amplifier 4 is switched to the bidirectional coupler 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 (antenna).

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

The matching circuit 7, which is a set of discrete elements consisting of stores of capacitance and inductance, can be performed, for example, as described in RF patent 2282284.

Analog-to-digital converters can be made, for example, as described in utility model patent RU 78999 in Fig. 1. blocks 3, 8. Implementation of digital-to-analog converters is known and is given in the book by P. Horowitz, W. Hill. The art of circuitry. Ed. 5th rev. M .: Mir. 1998 704 s. on page 642.

Thus, in the proposed transmission system, in comparison with the prototype, an increase in the noise immunity of the radio transmitting device to interference induced into the antenna from the signals of powerful radio transmitting devices is achieved by matching the load (antenna) of the high frequency generator.

Claims (2)

1. An interference-free transmission system with a digital selection unit and an automatic matching device with continuous impedance adjustment, 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 key, the output of which is the output of the MHF, characterized in that a digital selection unit and four digital-to-analog converters (DAC) are introduced, the outputs of which are connected to the inputs of the matching circuit, respectively, and the matching circuit is made on discrete elements; two outputs of the bidirectional coupler are connected to the corresponding inputs of the digital selection unit, two outputs of which are connected to the corresponding inputs of the trimming unit, four outputs of which are connected to the inputs of four DACs, respectively, in addition, the digital selection unit is configured to extract the useful signal and suppress other spectral components from maintaining the phase relationships of the useful signal from both outputs of the bidirectional coupler. 2. The transmission system according to claim 1, characterized in that the digital selection unit is two chains of the first analog-to-digital converter (ADC), the first digital receiving device (CPU) and the second analog-to-digital converter, the second digital receiving device connected in series , and the inputs of the first and second ADC are the first and second inputs of the digital selection unit, and the outputs of the first and second CPUs are the first and second outputs of the digital selection unit.

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