RU65320U1 - LAND ARTIFICIAL SIGNAL SIMULATOR - Google Patents

Abstract

The technical solution is intended for use as part of equipment requiring to verify an independent calibrated signal source, for example, to check the equipment of ground-based information receiving points from low-orbit, mid-orbit and geostationary artificial Earth satellites. The signal simulator of an artificial Earth satellite is built according to the scheme in which the signal is generated in the centimeter frequency range by a single spectrum transfer using a circuit based on a generator controlled by the voltage in the phase locked loop, which performs the function of integer multiplication, the reference oscillation of which is a direct frequency synthesizer signal . The technical solution will provide the required high signal stability, minimum readiness for signal emission, the possibility of generating a phase-shifted signal, with high accuracy with the possibility of tuning in level and frequency. 7 ill.

Description

The proposed technical solution relates to the field of radio engineering, namely, the equipment of ground-based information reception points from low-orbit, mid-orbit and geostationary artificial Earth satellites, as well as for ground-based tests of airborne radio complexes of geostationary, mid-orbit and low-orbit artificial Earth satellites and other equipment, for checking the operation of which , an independent calibrated signal source is required.

Known measuring equipment for general use of various types designed to generate a signal. For example, the Agilent Technologies E4438 signal generator, (see the Agilent Technologies general-purpose instrumentation catalog, April 2005, p. 15), is designed to generate a signal in the band from 9 kHz to 3 GHz with a signal level from 0, 5 to minus 157 dBW. The SML type Rohde Schwarz signal generator (see the technical description “R&S SML signal generator, August 2004, ver. 06.00, p. 2) is designed to generate a signal in the band from 9 kHz to 3.3 GHz with a level of minus 17 dBW up to minus 170 dBW. General-purpose measuring equipment cannot fully meet the requirements for a signal simulator as it is universal and has a high cost. To ensure the required accuracy of the generated signal, general-purpose measuring equipment requires periodic verification, as well as highly qualified personnel.

Known control equipment for specialized purposes - an automated information system for ground-based verification of the radio-technical satellite complex of low-orbit artificial

Earth satellite of the COSPAS-SARSAT system, designed to generate a pulsed signal of emergency beacons on three frequency channels simultaneously in the range of 406.0-406.1 MHz with a level from minus 120 dBW to minus 140 dBW. Testing equipment of this type is not designed to generate a signal in the range above 406 MHz, is not capable of generating a signal with a different type of modulating signal, and is not able to change the carrier frequency letters, in particular, to simulate the Doppler law of frequency change during the movement of an artificial Earth satellite in a circular orbit .

The closest analogue of the proposed technical solution is the signal synthesizer described in the patent for invention RU 2239940 and capable of forming a grid of stable frequencies specified by the software in the microwave range. The signal synthesizer known from RU 2239940 contains a reference generator, a microprocessor, a phase-locked loop, consisting of dividers with a variable division coefficient, a phase detector and a low-pass filter, a voltage-controlled oscillator, a frequency multiplier, a bandpass filter, an indication circuit, and a power amplifier. In the frequency synthesizer known from patent RU 2239940, it is impossible to change the generated letters of the carrier frequency according to the program recorded in the PC or by rewriting the program in the microprocessor, and it is not possible to form a phase-shifted signal with a variable modulation index. In addition, in the synthesizer circuit known from RU 2239940, there is no attenuator controlled by a microprocessor and designed to establish the level of signal attenuation.

The proposed technical solution will ensure the stability of the carrier frequency of the signal, the minimum time of readiness for radiation, the accuracy of forming the letter of the carrier frequency, the ability to switch the carrier frequency and signal power with a given step using an external control, the formation of a signal with phase shift key carrier frequency. The generated modulating signal will be continuous

a sequence of characters with encoded information, for example, a pseudo-noise sequence. It will also provide a long service life, high manufacturability in production, low cost, minimum weight, dimensions and ease of use.

The technical result expected from the use of the proposed technical solution is achieved by the fact that a simulator of the signal of an artificial Earth satellite is proposed, comprising a series-connected reference oscillator, direct frequency synthesizer, and a multiplier. The multiplier is based on a generator controlled by the voltage in the phase locked loop. The direct frequency synthesis synthesizer includes a comparator and a signal generator based on direct frequency synthesis, the inputs of which are connected to the output of the reference generator, and a primary microprocessor, the output of which is connected to the signal generator based on direct frequency synthesis. A multiplier based on a voltage-controlled oscillator in a phase-locked loop includes a series-connected bandpass filter, a comparator, a voltage-controlled oscillator in the phase-locked loop, a range attenuator with switches connected to it, an attenuator, and a secondary microprocessor. The inputs of the secondary microprocessor are connected to the PC and the external control, and the outputs are connected to the primary microprocessor, a generator controlled by voltage in the phase-locked loop and an attenuator. A reference oscillator, a signal generator based on direct frequency synthesis, a primary microprocessor, a voltage-controlled oscillator in the phase-locked loop, a secondary microprocessor and attenuator are connected to an internal power source.

Signal generation in the centimeter range, which is carried out by a single spectrum transfer using a circuit based on a generator controlled by a voltage in the phase-locked loop, with a reference signal from a direct frequency synthesizer, does not require

filtering the output signal, since it lacks sidebands and the frequency of the reference signal. When transferring the centimeter spectrum to the range using mixers, either multiple frequency conversion or the use of an output filter with a difficult to realize high quality factor is required. High-speed microprocessors that control the direct frequency synthesizer, the oscillator controlled by the voltage in the phase-locked loop and the attenuator provide the minimum signal generation time. The construction of a simulator based on microcircuits with a high degree of integration, the use of discrete elements of surface mounting and the absence of multiple shielding provides the minimum dimensions and weight of the signal simulator.

The proposed technical solution is illustrated by drawings:

Figure 1 - Scheme of the frequency formation of a signal simulator;

Figure 2 - Block diagram of a signal simulator;

Figure 3 - Structural diagram of a low-frequency line - synthesizer direct frequency synthesis;

Figure 4 - Block diagram of a high-frequency line - a signal multiplier based on a generator controlled by voltage in the phase locked loop;

Figure 5 - Frame structure of the modulating signal;

6 - The formation of a single character on the principle of biphasic L-coding at a speed of 2.5 kbit / s;

7 - The phase formation of the signal according to the Gaussian law by approximation at 5 points within 40 μs.

The artificial Earth satellite signal simulator includes a reference oscillator 1 connected in series and connected to an internal power supply 4, a low-frequency ruler — a direct frequency synthesizer 2, and a high-frequency ruler — a multiplier based on a generator controlled by the voltage in the phase-locked loop 3 connected to a personal computer and external authority 5. In quality

reference generator 1 can be used a thermostatically controlled generator, with high long-term, medium-term and short-term frequency stability. An alternating voltage power supply of ~ 220 V / 50 Hz is supplied to the input of the internal secondary power supply source 4, the power supply generates constant voltages plus 5 V, plus 12 V and minus 12 V. The output of the multiplier based on a generator controlled by the voltage in the phase-locked loop 3 can be connected to an antenna coupler of a ground-based autonomous point for receiving heliogeophysical information.

The direct frequency synthesis synthesizer 2 includes a comparator 6, a signal generator based on direct frequency synthesis 7, connected to the secondary power supply 4, and a primary microprocessor 8. The signal of the reference generator 1 is input to the comparator 6 and the signal generator based on direct frequency synthesis 7 the comparator 6 is connected to the input of the primary microprocessor 8, the output of which is connected to another input of the direct frequency synthesis generator 7.

A multiplier based on a generator controlled by a voltage in a phase-locked loop 3 includes a series-connected bandpass filter 9, a comparator 10, a generator controlled by a voltage in a phase-locked loop 11, a range attenuator 13, with switches 14 connected, an attenuator 15 controlled by a microprocessor, and also a secondary microprocessor 12. The input of the bandpass filter 9 of the multiplier based on the generator, controlled by the voltage in the phase-locked loop, is connected to the output of the generator a signal generator based on direct frequency synthesis 7. One of the outputs of the secondary microprocessor 12 is connected to the input of the primary microprocessor 8 and serves to control the frequency of the reference signal of the direct frequency synthesis synthesizer 2 via a serial control program interface. The signal generated by the simulator is changed by overwriting the programs in the primary 8 and secondary 12 microprocessors. The other two outputs of the secondary microprocessor

connected to a generator controlled by a voltage in the phase-locked loop 11 and an attenuator 15. The inputs of the secondary microprocessor are connected to an external control organ 5 and a PC, from which commands are received to switch the carrier frequency and signal level of the simulator, with manual and program control, respectively. The generator, controlled by the voltage in the phase-locked loop 11, the secondary microprocessor 12 and the attenuator 15, are connected to the internal power source 4.

During operation, the signal simulator of an artificial Earth satellite provides the formation of a continuous periodic phase-shift signal with a large dynamic range and a minimum level. The signal simulator is as follows.

After 1-2 minutes of heating after power is supplied, the reference generator 1 generates a highly stable signal supplied to the direct frequency synthesis synthesizer 2. The direct frequency synthesis 2 synthesizer instantly generates a continuous periodically repeated phase-manipulated signal with the structure of the modulating signal recorded in memory from the instructions of the primary microprocessor 8 primary microprocessor 8. Clocking of the primary microprocessor 8 and the signal generator based on direct synthesis of frequency 7 from high stability The signal of the reference oscillator 1 is carried out using a comparator 6, which converts the sinusoidal signal into a signal of the TTL type (transistor-transistor logic), and provides high stability of the frequency, modulation, and temporal characteristics of the signal of the direct frequency synthesizer 2. The parallel control interface of the primary microprocessor 8 and the generator direct synthesis of frequency 7 provides the rise and fall times of the signal phase according to the Gausus law. Upon receipt of a signal from the secondary microprocessor 12, the primary microprocessor 8 changes the letter of the carrier frequency to minimum or maximum.

When changing the program in the primary microprocessor 8, a signal generator based on direct frequency synthesis 7 is able to generate a signal in the specified range with the required accuracy, with any modulation index. The rise and fall of the modulating signal can be approximated by a linear, quadratic, bell-shaped and other law, and the minimum rise and fall times of the signal phase are several μs without changing the hardware design of the direct frequency synthesizer 2. It is also possible to approximate the Doppler law of frequency variation, for example, when moving low- or medium-orbit artificial Earth satellite in a circular orbit with a linearly-broken function without changing the program of the primary microprocessor 8. Personnel truktura baseband signal, namely, the frame synchronization bytes sequence of digital data bytes embedded in the baseband signal, checking bytes generated by the primary microprocessor 8 can be changed by rewriting the program in the primary microprocessor 8 without changing the hardware construction of the frequency synthesizer of the direct synthesis 2.

From the output of the direct frequency synthesizer 2, the reference oscillation is fed to the input of the multiplier based on a generator controlled by the voltage in the phase-locked loop 3, where it is multiplied by an integer coefficient, minimizing phase noise in the output signal of the signal simulator. In the input band-pass filter 9, the clock frequency and the combination components of the direct synthesis generator are filtered. Next, in the comparator 10, the sinusoidal reference signal of the direct frequency synthesizer 2 is converted into a TTL type signal, which is necessary for the generator to operate, controlled by the voltage in the phase-locked loop 11.

The generator controlled by the voltage in the phase-locked loop 11 is a microcircuit controlled by a secondary microprocessor 12 and multiplying the signal from the direct frequency synthesis synthesizer 2 by an integer coefficient. Generator control

controlled voltage in the phase-locked loop 11, the secondary microprocessor 12 is the formation of codes for obtaining coefficients, multiplying and dividing the signals of the voltage-controlled generator, and the reference oscillation for generating the output signal in the centimeter range according to the formula: F _ex = F _gun = N · R · F _fd = (B · P + A) · R · F _fd , where F _o - the output signal of the simulator; F _gun - voltage controlled oscillator signal; F _fd is the comparison frequency formed by dividing the signal of the generator controlled by voltage by the coefficient M and the reference oscillation divided by the coefficient R of the phase detector in the microcircuit of the generator controlled by the voltage in the phase-locked loop; R, B, P, A are integer coefficients the codes of which are generated by the secondary microprocessor 12. The serial program interface for controlling the secondary microprocessor 12 of the generator controlled by the voltage in the phase-locked loop 11 provides the establishment of a phase-shifted signal for any milliseconds on any of the carrier letters with the necessary modulation index and the required accuracy with accuracy. The generator controlled by the voltage in the phase-locked loop 11 allows, depending on the program embedded in the secondary microprocessor 12, to generate a signal without changing the hardware construction of the multiplier based on the generator controlled by the voltage in the phase-locked loop 3.

The average signal level in the required range is formed by the range attenuator 13, the attenuation value of which is set by the switches 14. The attenuator 15 attenuation value is changed according to the program embedded in the secondary microprocessor 12. When turned on, the secondary microprocessor 12 sets the maximum attenuator attenuation. Subsequently, when controlling the signal simulator using a PC program or external control unit 5, it is possible to increase or decrease the attenuation value, indicating the amount of attenuation, and the LEDs on / off on the dashboard of the signal simulator.

To change the letter of the generated signal when controlling the simulator from a PC or external control unit 5, the secondary microprocessor 12 transmits a signal frequency control code to the primary microprocessor 8, which generates a frequency code for the direct frequency synthesis generator 7.

Thus, the proposed technical solution will provide the required high signal stability, the minimum time for signal emission, the ability to generate a phase-shifted signal with the necessary modulation index, symbol rate, frequency range, signal level, with high accuracy and with the possibility of tuning in level and frequency. Rewriting programs in the primary and secondary microprocessors allows you to generate a signal with a different modulating function, symbol rate, carrier frequency and signal level. The proposed technical solution can be used as a part of ground stations for receiving and processing information from geostationary, mid-orbit and low-orbit artificial Earth satellites (data acquisition and transmission systems, the COSPAS-SARSAT space search and rescue system) as a signal simulator. The most probable is the use of the proposed technical solution as a signal simulator of the heliogeophysical information channel of the airborne radio complex of the geostationary artificial Earth satellite to verify the operability of the receiving path of the ground-based autonomous receiving station of heliogeophysical information. In addition, the proposed technical solution can be used for ground-based testing of airborne radio complexes of geostationary, mid-orbit, and low-orbit artificial Earth satellites and other equipment, the verification of which requires an independent calibrated signal source.

Claims (1)

An artificial Earth satellite signal simulator comprising a reference oscillator, a direct frequency synthesis synthesizer and a multiplier based on a generator controlled by a voltage in the phase locked loop, characterized in that the direct frequency synthesis synthesizer includes a comparator and a signal generator based on direct frequency synthesis, inputs which are connected to the output of the reference generator, and a primary microprocessor, the output of which is connected to a signal generator based on direct frequency synthesis wherein the multiplier based on the generator controlled by the voltage in the phase-locked loop includes a series-connected bandpass filter, a comparator, a generator controlled by voltage in the phase-locked loop, a range attenuator with switches connected to it, an attenuator, and also a secondary microprocessor, inputs which are connected to a PC and an external control body, and the outputs are connected to a primary microprocessor, a generator controlled by voltage in the ring Royko frequency and the attenuator, and the reference oscillator, the oscillator signal based on a direct frequency synthesis, the primary microprocessor, a voltage controlled oscillator in the phase-locked loop ring, a secondary microprocessor and an attenuator connected to the internal power source.