RU2766573C2 - Method of generating an output signal of a super-long-wave radio station - Google Patents

Abstract

FIELD: radio engineering and communication.

SUBSTANCE: invention can be used in VLF radio transmitting equipment. This is done by generating digital signals Str and Select, wherein to generate digital signals using an internal high-speed digital-to-analogue converter, a high-frequency signal of hundreds of times higher frequency is generated, modulated with the establishment of the type of operation, and the frequency of the HF signals is selected close to 10 MHz and equal to the set VLF frequency, wherein the internal HF signal is transmitted to one comparator, which forms internal "Strobe" pulses only when the internal HF signal passes through 0 upwards, since the HF signal has a frequency N times greater than the required one, internal "Strobe" pulses are decimated to generate output "Strobe" pulses.

EFFECT: technical result consists in improvement of signal quality of VLF radio station due to significant reduction of generated pulse phase noise.

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Description

The invention relates to the field of radio engineering and communications and can be used in radio transmitting radio communication equipment with frequency modulation and telegraphy operating in the ultra-long wave (VLF) range for autonomous operation, as well as for operation as part of control systems for radio transmitting devices.

Communication on ultra-long waves for the submarine fleet is of great importance. Extra long waves can penetrate water to great depths and underwater objects can receive messages on extra long waves without surfacing.

The exciter of a modern radio transmitter is a complex and expensive device, generally consisting of a frequency synthesizer that generates one or more output coherent oscillations with specified frequencies, a shaper of the types of operation at a fixed subcarrier frequency, and a path for transferring the generated oscillations to the operating frequency range. The radio transmitter exciter is characterized by the following main parameters: frequency range of the operating oscillation, the nature of the change in the operating frequency, the total number of fixed frequencies, frequency and phase instability, the level of side spectral components, the exciter control characteristics, tuning inertia, types of work, etc.

The rapid development of microelectronics, analog and digital microprocessor and computer technology has a significant impact on the development of radio transmitting technology, both in terms of a sharp increase in functionality and in terms of improving its performance. This is achieved through the use of new principles for constructing structural diagrams of transmitters and circuit implementation of individual nodes that implement digital methods for generating, processing and converting oscillations and signals.

In modern exciters, digital signal generation methods are widely used. Known exciters for radio transmitters containing a modulator, a frequency synthesizer, an amplifying-converting unit (exciter VO-71). Technical description YAR2.209.011. TO Tambov, 1973. AN / PRC-70 radio station exciter. Collection of TsIVTI MO USSR, 1973, no. 300, book 8, pp. 38-41. Exciter GK-203C. HF SYNTHESISED DRIVER RECEIVER GK-205. 1973. Signal transmitter RU 2106061, containing a modulating signal generator, a frequency modulator, a simulated signal generator, a frequency multiplier block, and a final powerful amplifying stage with an output circuit.

Such exciters have a high level of noise and discrete side components at the output, as well as low stability of the parameters of modulated oscillations in the range of modeling and operating frequencies. Therefore, such exciters do not allow to implement the increased requirements for the quality of the generated radio signals and the suppression of parasitic side oscillations at the output.

Known multi-channel digital excitation system. Patent of the Russian Federation No. 2691757 dated 06/18/2019 Bull. No. 17, H04B 7/00. Multichannel digital exciter system, contains a control and indication unit, an Ethernet interface unit, a digital-to-analog converter module and a power supply, and the system is built on the basis of a single universal digital module (FPGA), which includes: a clock signal generation module, a digital signal processor, synchronization and common time system, global navigation satellite system, ELF-VLF, VLF-LW and MW signal generator, digital-to-analog converter module, external communications controller and code combination control module.

The closest in technical essence to the proposed method is the exciter radio transmitter "Surf", developed and commercially produced by the Omsk Research Institute. Specifications UIIAD.464117.004 TU.

The Priboy exciter provides the formation of signals of radiation classes J3E, NZE, R3E, A1B, FIB, 3K40J1BEN in the operating frequency range from 3 to 30 MHz, has an Ethernet digital input and an intermediate frequency output and is intended for use in complexes of technical means of high-speed information transmission.

The exciter is controlled remotely via one of the joints:

- at the junction of the IRPS (OST 11305.916-84);

- RS-232 in accordance with GOST 18145-81;

- RS-485;

- RS-422.

The surf exciter is made according to the superheteradin scheme with one frequency conversion of 65.128 MHz.

The main functional modules of the pathogen are:

- digital modulator of telegraph and telephone signals;

- digital-to-analog converter;

- conversion and amplification unit;

- frequency selector;

- frequency synthesis unit;

- control and indication unit;

- block interface Ethernet;

- power unit.

The disadvantage of the prototype is that the generated analog output high-frequency (HF) signal of the carrier frequency VLF range is characterized by low signal quality due to phase noise. In the exciter device, the RF signal is fed to comparators that analyze the transition of the analog RF signal through zero up and down and form pulses at these times to turn on the corresponding 24 thyratrons of the VLF radio station. In this case, phase noise that affects the quality of radio communication is not taken into account.

The analysis of the prior art made it possible to establish that analogues, characterized by a set of features identical to all the features of the claimed technical solution, are not available in known sources of information, which indicates that the claimed method complies with the patentability condition "novelty".

The results of the search for known solutions in this and related fields of technology in order to identify features that match the distinguishing features of the prototype of the claimed object showed that they do not follow explicitly from the prior art. From the prior art, the influence of the transformations provided for by the essential features of the claimed invention on the achievement of the specified technical result has not been revealed either. Therefore, the claimed invention meets the condition of patentability "inventive step".

The aim of the invention is to improve the quality of the VLF radio station signal by significantly reducing the phase noise of the generated pulse.

This goal is achieved by the fact that the proposed method for generating the output signal of an ultra-long-wave (VLF) radio station, characterized in that digital signals Str and Select are first generated, which are then fed to the switching unit, which acts as a decoder and pulse shaper on the selected optical transmitters, while for the formation of digital signals using an internal high-speed digital-to-analog converter, a high-frequency signal is formed hundreds of times higher in frequency, modulated with the establishment of the type of operation, and the frequency of the RF signals is chosen close to 10 MHz and equal to the set VLF frequency, and the internal RF signal is fed to one comparator, generating internal “Strobe” pulses only when the internal RF signal passes through 0 upwards, since the RF signal has a frequency N times greater than the required one, the internal “Strobe” pulses are thinned out to form the output “Strobe” pulses.

The proposed method for generating the output signal of a VLF radio station is as follows. In the exciter, digital signals Str (Strobe - 1 bit) and Select (selection of one of 12 pairs of optical transmitters) are generated, which are then fed to the switching unit, which acts as a decoder and pulse shaper on the selected optical transmitters. To generate digital signals in the VU, an RF signal of hundreds of times higher frequency is generated using an internal high-speed DAC, modulated in accordance with the established type of work. The frequency of the RF signal is chosen close to 10 MHz and a multiple of the set VLF frequency. For example, when forming a carrier frequency of 20 kHz, the frequency of the internal oscillator will be 10 MHz, which is 500 times higher. Similarly, to form the FT mode with a spacing of 75 Hz, an internal RF signal with a center frequency of 10 MHz and a frequency spacing of 75 × 500 = 37.5 kHz will be generated.

Further, the internal RF signal is fed to one comparator (in contrast to the pulse shaping unit), which generates internal “Strobe” pulses only when the internal RF signal passes through 0 upwards. Since the RF signal has a frequency N times the required frequency, the internal "Strobe" pulses are decimated to form the "Strobe" output pulses.

Additionally, the proposed method for generating the output signal of a VLF radio station allows using not two comparators (or one with further output inversion), but one comparator, which eliminates phase noise associated with the difference in the parts of the circuit responsible for generating pulses when the analog RF signal passes through the zero value upwards and down.

The block diagram of the exciter is shown in Fig.

It contains:

1 - switching unit;

2 - block of the device forming (1) and (2);

3 - local control panel;

4 - uninterruptible power supply;

5 - 24 V power supply devices (1) and (2);

6 - Converter A;

7 - Converter B.

The input signals of telegraph channels, MFCT channels and SEV channels are fed to the switching unit 7, which buffers them and sends them to two shaping device blocks (BUF) 2. Both shaping device blocks operate in the “hot” standby mode, in each of them the output signal is formed. pulse sequences.

When operating from telegraph and MFCT inputs, as well as in the "carrier" mode, the formation of the output pulse sequence is carried out as follows. The shaping device generates a sinusoidal signal with a frequency of about 10 MHz (the exact value of the frequency of the generated signal must be a multiple of the specified VLF frequency) fed to the FPGA clock input, which ensures the formation of pulses in accordance with the frequency multiplier and the specified type of operation.

When operating from SEB signals, the input signal is simultaneously fed to two comparators (detection of the front and fall), after which it acquires a rectangular shape of the output pulses.

The signal sequence of pulses generated in both cases from each unit of the forming device 2 returns to the switching unit 1, where the sequence of pulses from one of the block of the forming device selected as active is selected (on command from the RPDU control system) and the electrical pulses are converted into optical ones. .

Optical signals are fed to the output optical connectors for transmission to the power amplifier RPDU.

The local control panel 3, along with setting the nominal frequencies, modes and types of operation, provides the direction of the information interaction lines along the RS-485 joints coming from the RPDU control system and from the external R-787MB and Samarkand complexes through converters to both blocks of the forming device.

The power supply of the forming device 2 is provided from an external power supply network 50 Hz, 220 V through an uninterruptible power supply and two 24 V power supply devices 5.

Structurally, the forming unit 2 is a metal cabinet with overall dimensions of 600×600×1350 mm.

The block of the forming device 2 is controlled from the local control panel 3.

Forming device block 2 provides:

- formation of the types of work of the RPDU: AT, CHT, MPHT, OFT;

- transmission of information signals from the SEV equipment;

- transmission of information signals under the control of R-787MB equipment;

- transmission of information signals under the control of the Samarkand complex;

- reception and processing of TLG signals transmitted via wire channels according to GOST 22937;

- formation of rectangular pulses for controlling the valves of the power amplifier and their output to 24 optical outputs with the parameters of the output signals:

- pulse duration - (3.0±0.5) µs;

- pulse shift of two adjacent channels - 0.5 period of the carrier frequency;

- "hot" redundancy of the pulse formation device;

- information interaction with the complex of technical means of the RPDU control system at the RS-485 and "wire-command" interfaces;

- the ability to set the nominal frequencies, and types of operation both in remote control mode and from the local control panel.

The operation of the device is as follows.

When the interface connectors are correctly connected, as well as the 24 V power connector located on the back of the console, and the power is turned on, the indicator should light up and the internal software should load. In case there is no communication with the BUF, an error message will be displayed.

The main screen displays in real time:

- frequency in Hz;

- type of work at the moment (carrier, AT, TH, OFT, MPHT, SEV, Willy),

- additional parameters, depending on the established type of work (speed of manipulation, frequency spacing);

- the state of the block of the forming device (options are possible for each of the two blocks of the forming device: UNLOCKED, SERVICEABLE, TROUBLE. The currently selected CUF is indicated in green, in case of a malfunction or an accident - in orange);

- status of input signals:

- for a telegraph signal, a straight line corresponds to the absence of manipulation, the signal level at the input is indicated by the position of the line in the figure (lower position - "0", upper - "1", middle - no signal). The meander on the chart means the presence of manipulation at this input. Similarly with the first case, manipulation options are possible between "0" and no signal, "1" and no signal, "0" and "1";

- for MUF mode the current frequency position in decimal system is indicated (a number from 0 to 15) - for HF, CEB1 and CEB2 the relative signal level is displayed. A fully filled box means the maximum;

- level, completely empty - minimum;

- the currently used input has an inverted (green) background.

The control mode is selected by pressing the "LOCAL / DISTANCE" button, the current mode is displayed by indicator LEDs located to the left of the button. Switching to the local control mode can be prohibited from the control terminal of the remote control panel.

In remote control mode, all keypad buttons except "LOCAL/REMOTE" are disabled.

In the local control mode, you can set the frequency, select the type of work, enter and cancel data entry, select the shaping unit, unlock and lock the shaping unit.

Setting the frequency is done by pressing the "FREQUENCY" button and then entering an integer value of the frequency in Hz using the numeric keypad. Cancellation of the input of the last character is carried out by pressing "CANCEL". Confirmation of input - by pressing "ENTER".

The choice of the type of work is carried out by pressing the "KIND OF WORK" button, followed by the selection of the parameters of the type of work from the list. Navigation through the lists is carried out with the buttons "2", "4", "6", "8", confirmation of the entry - by pressing "ENTER", cancellation of the entry and return to the main screen - by pressing the "CANCEL" button.

The input is selected by pressing the "INPUT" button, followed by selecting the input name from the list using the numeric keypad and confirming or canceling the entry by pressing the "ENTER" and "CANCEL" buttons, respectively.

The choice of the block of the forming device is carried out by pressing the corresponding button - "BUF1" or "BUF2". If switching between blocks is currently possible (the selected block of the forming device is operational and the operation is allowed), then the changes will be displayed on the main screen by changing the background color of one of the blocks to green.

Unlocking and locking of the block of the forming device 2 is carried out by pressing the "UNLOCK" button. If the operation is currently enabled and the selected shaping device block is OK, then its status will be reversed, which will be indicated by the text "UNLOCKED" or "GOOD" under the name of the selected shaping device block. Also, the fact that one of the blocks is unlocked is indicated by the LED to the left of the "UNLOCK" button.

In the proposed method and the exciter device compared to the prototype, the signal coming to the comparators has a hundred times higher frequency. Consequently, the signal slew rate is hundreds of times higher, which leads to a multiple reduction in the phase noise of the generated pulse and a significant increase in the quality of the VLF radio station signal.

Claims (1)

A method for generating the output signal of an ultra-long-wave radio station, which consists in buffering input telegraph signals and generating an output pulse sequence, characterized in that the buffering of input telegraph signals is carried out in hot standby mode with their direction to forming devices, in each of which an output pulse sequence is formed, for which form a high-frequency sinusoidal signal that is a multiple of the specified VLF frequency close to 10 MHz to generate a clock frequency, from the input telegraph signals, rectangular pulses are formed in the shapers using a clock frequency, “strobe” and “select” pulses are formed on the local control panel, which are sent to the forming device selected as active and by means of pulses "strobe" they form "decimated" pulses of a rectangular shape in accordance with the frequency multiplicity factor, and by means of pulses "with choose an optical transmitter to convert the generated output sequence into an optical output sequence, amplify the optical output sequence and transmit it to the information exchange line, which makes it possible to drastically reduce the phase noise of the output signal during the operation of the ultra-long-wave radio station.

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