RU187912U1 - Interference signal transmitter for GSM communication systems - Google Patents

Abstract

The proposed device relates to electronics and can be used in electronic warfare and electronic suppression. The technical result is to increase the efficiency of signal suppression of communication systems of the GSM standard. To obtain this result, a reference generator (1) and a modulated signal generating unit (3) are introduced into the proposed device while the output of the reference generator (1) is connected to the input of the local oscillator (2) and to the input of the modulated signal generating unit (3), which is connected to the second input at a balanced mixer (4).

Description

The proposed device relates to electronics and can be used in electronic warfare and electronic suppression.

A known method and device for creating intentional interference according to US Pat. RF 2543078, H04K 3/00, used to interfere with the global navigation satellite system (GNSS). When using the described method to suppress communication systems of the GSM standard, high hardware costs are required, moreover, such a device is not possible to place in small-sized and portable mobile complexes.

There is also known a method (options) and a device (options) for creating intentional interference according to US Pat. RF 2583159, Н04К 3/00, which provides for the creation of interference with communication systems with pseudo-random tuning of the operating frequency (MFC). This method involves receiving signals from radiation sources, determining the frequency and structural parameters of these signals, and generating an appropriate interfering signal. This method is complicated in execution, and also implies that the parameters of the suppressed signal are unknown. In communication systems of the GSM standard, the main characteristics of the signal are known a priori, therefore, in this case, the method described in the patent is technically complex and does not imply the possibility of placement in mobile and small-sized devices.

The closest analogue in technical essence to the proposed one is the transmitter of direct noise interference with a skew spectrum, given in the book [Fundamentals of the theory of electronic warfare, ed. Nikolenko N.F., Moscow: Military Publishing House, 1987. 351 s].

The circuit of the prototype device is shown in FIG. 1, where indicated:

2 - tunable local oscillator;

4 - balanced mixer;

5 - tunable, filter;

6 - power amplifier;

7 - transmitting antenna;

8 - source of noise;

9 - correction filter;

10 - control unit.

The prototype device contains a serially connected noise source 8, a correction filter 9, a balanced mixer 4, a tunable filter 5, a power amplifier 6, the output of which is connected to a transmitting antenna 7. In addition, the output of the control unit 10 is connected to the second input of the tunable filter 5 and, through tunable local oscillator 2, with the second input of the balanced mixer 4.

The prototype device operates as follows.

Relatively low-frequency noise u _W (t) having an uneven spectral density (Fig. 3, a) comes from the noise source 8 to the correction filter 9. The amplitude-frequency characteristic (AFC) of the filter is selected from the condition of equalizing the spectrum of the signal of the primary source 8 in the interval from 0 to F _max , which allows you to "whiten" the noise of the primary source (Fig. 3, b). Next, the “bleached” noise enters the first input of the balanced mixer 4. Sine waves from the tunable local oscillator 2, controlled by the control unit 10, are fed to the second input of the balanced mixer 4. Commands for tuning can be controlled, for example, by a reconnaissance receiver. In the balanced mixer 4, a multiplication operation takes place. As a result of this conversion, two bands of the high-frequency spectrum are allocated at the output of the mixer 4. From the spectrum of the signal at the output of the balanced mixer 4, a frequency band Δƒ _P (Fig. 3, c) is allocated by a tunable resonant filter 5. The signal from the input of the tunable filter 5, after passing through the power amplifier 6, is emitted into the space by the transmitting antenna 7.

The disadvantages of the prototype device are the lack of the ability to quickly adjust the operating frequency, the lack of modulation of the interfering signal, as well as the high power consumption.

The objective of the proposed device is to increase the suppression efficiency at the same output power of the amplifier, modulation of the interfering signal and the ability to quickly tune the operating frequency.

To solve this problem, an interfering signal transmitter to a GSM communication system containing a serial oscillator, a balanced mixer, a bandpass filter, a power amplifier and an antenna, according to a utility model, a reference oscillator is introduced, the output of which is connected to the inputs of the local oscillator and the modulated signal generating unit, output which is connected to the other input of the mixer, while the local oscillator consists of a series-connected first phase locked loop (PLL), the first PLL filter , the first amplifier and the first voltage-controlled oscillator (VCO), one output of which is connected to the second input, and the other output is the output of the local oscillator; the modulated signal generating unit contains a second PLL, a second PLL filter, an adder, a second amplifier and a second VCO, one output of which is connected to the second input of the second PLL, the other is the output of the modulated signal generating unit, in addition, the output is a modulating signal generator connected to the second input of the adder.

In FIG. 2 presents a diagram of the proposed device, where it is indicated:

1 - reference generator;

2 - local oscillator;

2.1 - the first block, phase-locked loop (PLL);

2.2 - the first PLL filter;

2.3 - the first amplifier;

2.4 - the first generator controlled by voltage (VCO);

3 - block modulated signal generation (BFMS);

3.1 - the second block of the PLL;

3.2 - second PLL filter;

3.3 - adder;

3.4 - second amplifier;

3.5 - the second VCO;

3.6 - modulating signal driver;

4 - balanced mixer;

5 - band-pass filter;

6 - power amplifier;

7 - transmitting antenna.

The proposed interference signal transmitter for communication systems of the CSM standard contains a reference oscillator 1, the output of which is connected to the inputs of the local oscillator 2 and the modulated signal generating unit 3. The local oscillator 2 consists of series-connected PLLs 2.1, the first PLL 2.2 filter, the first amplifier 2.3, the first VCO 2.4, the second output of which is connected to the second input of the first PLL 2.1 block to create negative feedback. The modulated signal generating unit (BFMS) 3 contains a second PLL 3.1, a second PLL filter 3.2, an adder 3.3, a second amplifier 3.4, a second VCO 3.5, the second output of which is connected to the second input of the second PLL 3.1, in series to create negative feedback. In addition, the output of the driver of the modulating signal 3. 6 is connected to the second input of the adder 3.3. The first input of the first PLL block 2.1 and the second PLL block 3.1 are inputs of the local oscillator 2 and BFMS 3 and are connected to the output of the reference oscillator 1. The first output of the first VCO 2.4 is the output of the local oscillator 2 and is connected to the first input of the balanced mixer 4. The first output of the second VCO 3.5 is the output of the BFMS 3 and is connected to the second input of the balanced mixer 4, the output of which through a series-connected bandpass filter 5 and power amplifier 6 is connected to the transmitting antenna 7.

The proposed device operates as follows.

где N кратно четырем (фиг. 4, а).The signal from the output of the reference oscillator 1 enters the local oscillator 2. In the local oscillator 2, the signal passes through the first block. PLL 2.1, in which phase comparison is performed. The error signal obtained after phase comparison passes through the first PLL 2.2 filter with a small time constant, then the filtered signal, amplifying in 2.3, is fed to the VCO 2.4 input as a control signal. The signal from the output of the VCO 2.4 is fed to the input of the first PLL 2.1, providing negative feedback in the local oscillator unit 2, and to the first input of the balanced mixer 4. Thus, a reference frequency is formed at the output of the local oscillator 2, the values of which vary within the values

where N is a multiple of four (Fig. 4, a).

Also, from the output of the reference generator 1, the signal enters the block for generating the modulated signal 3. Phase conversion occurs in the second PLL 3.1 unit, after which the control signal is fed to the second PLL 3.2 filter, which has a large time constant. Due to the fact that the cut-off frequency of the PLL filter 3.2 is an order of magnitude lower than the frequency of the modulating signal, it becomes possible to add the signal from the output of the PLL filter 3.2 and the shaper of the modulating signal 3.6 in adder 3.3. The summed signal is amplified by the second amplifier 3.4 and fed to the second VCO 3.5 as a control signal. The signal from the output of the VCO 2.5 is fed to the input of the second PLL 3.1, providing negative feedback in the block for generating the modulated signal 3, and to the second input of the balanced mixer 4 (Fig. 4, b).

(фиг. 4, в). После прохождения через полосовой фильтр 5 и усилитель мощности 6, на вход передающей антенны 7 поступает только один модулированный сигнал, излучаемый в пространство.At the output of the mixer 4, two modulated interfering signals are generated, while the central frequency of the received signals

(Fig. 4, c). After passing through a band-pass filter 5 and a power amplifier 6, only one modulated signal is emitted to the input of the transmitting antenna 7.

Due to the possibility of fast tuning of local oscillator 2, during the duration of one GSM packet, the proposed interference signal transmitter sends N modulated interference signals, each of which covers only part of the spectrum of the suppressed signal. Since the GSM standard uses time division of channels, in one frame with a duration of 577 μs, time-separated information packets for eight subscribers are sent. Each of the N interference signals provides suppression of the order of 20-25 of 175 channels in a packet for a period of time equal to 1/8 of the frame duration. Therefore, when N interference signals are emitted at different central frequencies during the duration of one frame, effective suppression is achieved (Fig. 4, g).

Thus, thanks to the ability to quickly adjust the frequency, it is possible to send up to 8 interfering signals at different central frequencies during the duration of one frame. Modulation allows the generation of an interfering signal having the desired frequency spectrum close to rectangular. This technique allows us to provide several times greater suppression efficiency at the same output power of the amplifier as that of the prototype.

Claims (1)

Interference signal transmitter for GSM communication systems containing a serially connected local oscillator, a balanced mixer, a bandpass filter, a power amplifier and an antenna, characterized in that a reference oscillator is introduced, the output of which is connected to the inputs of the local oscillator and the modulated signal generating unit, the output of which is connected to another input mixer, while the local oscillator consists of a series-connected first phase locked loop (PLL), the first PLL filter, the first amplifier and the first generator ra, the voltage controlled oscillator (VCO), one output of which is connected to the second input and the other output is the output of the local oscillator; the modulated signal generating unit contains a second PLL, a second PLL filter, an adder, a second amplifier and a second VCO, one output of which is connected to the second input of the second PLL, the other is the output of the modulated signal generation unit, in addition, the output of the modulating signal generator is connected with the second input of the adder.

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