RU2747575C1 - Interference-resistant transmission system with digital selection unit and automatic matching device on discrete elements - 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 (SW) range, as well as in radio stations of other ranges, operating in conditions of concentrated interference. The technical result consists in increasing the noise immunity of the transmission system to interference induced into the antenna from the signals of powerful radio transmitting devices. An interference-free transmission system with a digital selection unit and an automatic matching device on discrete elements contains 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 (SSG), a power amplifier and a switch, while additionally introduced a digital selection unit, 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 a microprocessor device.

EFFECT: noise immunity increased.

2 cl, 2 dwg

Description

The invention relates to radio communication technology and can be used in radio stations of the short-wave (HF) and ultra-short-wave (VHF) range, as well as in radio stations of other ranges operating in conditions of powerful 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 - 656 p. Page 377 fig. 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 - tuning block (BP);

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 a power amplifier 4, the outputs of which are connected to the corresponding key inputs 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 tuner 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 UM 4 to the matched load in the presetting mode, DS 7 is configured. 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 TS 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 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 DC 7. After that, 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 procedure 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 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 reach lower values up to 10 dB. Thus, when the power of the neighboring transmitter is 1 kW, the power induced from it into the antenna at the operating frequency of the neighboring transmitter f2 can reach 1 W. As a result, the values of the voltages 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 useful 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 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 this problem, a noise-immune transmission system with a digital 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 an adjustment unit, is used, 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 HHF, according to the invention, a digital selection unit and a microprocessor device are introduced, the output of which is connected to the second input of the matching circuit 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 the microprocessor device, 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 a diagram of 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 radio receivers (TsRPU);

13 - digital block of selection;

14 - microprocessor unit (MCU).

The inventive 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 microprocessor device 14, respectively. The output of the MCU 14 is connected to the second input of the DS 7. The matching circuit 7 is built on the basis of discrete elements consisting of stores of capacitances and inductances, the switching of which is provided by the microprocessor device MCU 14. The digital selection unit 13 contains two chains of the first ADC 9 and the first CPDU connected in series 11, 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 of the central control room are outputs of the digital selection block 13.

The inventive device operates in the configuration mode and in the transmission mode.

In the tuning mode, the GSS signal 2 is used, which is fed through the switch 3 to the bidirectional coupler 5 and then through the matching circuit 7 to the antenna 8. The matching circuit 7 is made on the basis of discrete elements consisting of stores of capacitances and inductances, the switching of which is provided by the microprocessor device MCU 14 In this case, the generator of the sinusoidal signal 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, a branched voltage of the incident and reflected power is supplied from the bidirectional coupler 5 to the digital selection unit 13: Uп is the branched voltage of the incident power, Uref is the branched voltage of the reflected power. The digital selector unit 13 is tuned to the frequency of receiving the useful signal f1. In the selection unit 13, the samples are digitized by two analog-to-digital converters 9, 10. Then the obtained samples are fed to the inputs of the corresponding digital radio receivers 11, 12, which are tuned to the receiving frequency f1. Digital radio receivers 11, 12 transmit the harmonic signal at frequency f1 without attenuation, and interference signals acting at frequency f2 are attenuated by 60 dB or more. At the output of digital radio receivers, the induced interference signal at the frequency f2 will have a power of less than 1 mW, with the power of the useful signal acting at the frequency f1 0.1… 0.02 mW. As a result, the action of the interference will not affect the operation of the tuning unit 6. The tuning unit 6 will receive the branch voltage of the incident power Uп, and the branch voltage of the reflected power Uref at the frequency f1 in digital form. The adjustment unit 6, based on the values of Uп and Uref, as well as the phase between them, calculates the required values of capacitances and inductances in the matching circuit 7. The obtained values are transmitted to the microprocessor device MCU 14. Microprocessor device 14 determines which discrete elements need to be switched to ensure the required values of inductance and capacitance in the matching circuit 7, and also generates the corresponding control commands in the matching circuit 7. After that, the matching circuit 7 transforms the complex impedance of the antenna 8 to the output of the high frequency generator 1. This procedure is repeated until the tuning process arrives into a steady state.

In the transmission mode, the switch is made by the switch 3 of the power amplifier 4 to the bidirectional coupler 5. Since the output resistances of the sinusoidal signal generator 2 and the power amplifier 4 are the same, the power amplifier 4 will transmit the output power to the matched load (antenna) 8.

The digital selection unit 13 is designed to extract signals at the tuning frequency of the radio transmission system and filter the remaining frequencies. When operating in an environment of intense interference, a mixture of interference at different frequencies arrives at the antenna input of the radio transmission system. The digital selection unit 13 is actually a two-channel narrow-band tunable filter, which in the tuning mode selects the useful signal and suppresses other spectral components, while maintaining the phase relationships of the useful signal from both inputs.

The construction of blocks 1, 2, 3, 4, 5, 6, 8 in the claimed device is well known and similar to the implementation of the corresponding blocks 1, 2, 3, 4, 5, 6, 8 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 in the patent for utility model RU 78999 (Fig. 1, blocks 3, 8). The microprocessor control unit MCU 14 can be built, for example, as in the patent for utility model RU 78999 (Fig. 1, block 5).

Thus, in the proposed transmission system, in comparison with the prototype, an increase in the noise immunity of the transmission system to interference induced into the antenna from the signals of powerful radio transmitting devices is achieved by filtering the interference signals in the digital selection unit.

Claims (2)

1. An interference-free transmission system with a digital 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) and 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, characterized in that a digital selection unit and a microprocessor device are introduced, the output of which is connected to the second input of the matching circuit 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 the microprocessor device, 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 contains two chains of the first analog-to-digital converter (ADC) connected in series, the first digital radio receiving device (TsRPU) and the second analog-to-digital converter, the second digital radio receiving device, moreover, 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 CPDU are the first and second outputs of the digital selection unit.

Images