RU216552U1 - MODIFIED INVARIANT AMPLITUDE MODULATOR WITH TWO REFERENCE SIGNALS - Google Patents

Abstract

The proposed utility model relates to the field of systems, networks and devices of telecommunications and radio engineering and can be used in radio transmitting devices, telecommunication systems and devices where an amplitude-modulated transmitted signal is required for transmission to a communication channel.

The achieved technical result of the utility model is aimed at the possibility of generating an amplitude-modulated transmitted signal with increased noise immunity characteristics to a specific type of interference, as well as for the secrecy of transmitted messages in comparison with the prototype and analogues.

This is achieved by the fact that the modified invariant amplitude modulator uses two reference signals, from which an amplitude-modulated transmitted (information) signal is formed, which allows the use of a greater variety of signals in the communication system, and not just signals of a similar shape, as in the well-known invariant amplitude modulation . And in the vector representation, the line of location of the ends of the vectors of the reference and information signals can occupy an arbitrary position relative to the origin of the coordinate system of the signal space. 2 ill.

Description

The proposed utility model relates to the field of systems, networks and devices of telecommunications and radio engineering and can be used in radio transmitting devices, telecommunication systems and devices where an amplitude-modulated transmitted signal is required for transmission to a communication channel.

The achieved technical result of the utility model is aimed at the possibility of generating an amplitude-modulated transmitted signal with increased noise immunity characteristics to a specific type of interference, as well as for the secrecy of transmitted messages in comparison with the prototype and analogues [1, 2].

This is achieved by the fact that the modified invariant amplitude modulator uses two reference signals, from which an amplitude-modulated transmitted (information) signal is formed, which allows the use of a greater variety of signals in the communication system, and not just signals of a similar shape, as in the well-known invariant amplitude modulation . And in the vector representation, the line of location of the ends of the vectors of the reference and information signals can occupy an arbitrary position relative to the origin of the coordinate system of the signal space (Fig. 1).

The utility model proposes a modification of the well-known invariant amplitude modulation that conveys the values of information elements by the ratio of the lengths of the signal vectors lying on the same straight line passing through the origin of the signal space coordinate system [3]. Modification of such modulation allows using signals, the ends of vectors of which lie on a straight line, not necessarily passing through the origin of the signal space coordinate system.

Synthesis of modified invariant amplitude modulation.

In order to provide greater clarity of the procedure for synthesizing the modified invariant amplitude modulation, a two-dimensional signal space is used, the coordinate axes of which correspond to some orthonormal basis functions of time, for example, the Kotelnikov functions ϕ ₁ (t) and ϕ ₂ (t), which differ in a time shift that ensures their orthogonality. In this case, the signals can be represented by two time samples, the values of which specify the coordinates of the ends of the signal vectors in the two-dimensional signal space (Fig. 1).

In FIG. 1 on the left shows a straight line that occupies a general position and does not pass through the origin of the signal space coordinate systems. Points A, B, and C define the ends of the three vectors of input signals

Одна из возможных форм записи инварианта аффинного преобразования в форме «отношения трех точек» в данном примере имеет следующий видAs already mentioned [1, 2], the transformation of input signals into output signals is described by an affine group of transformations. In FIG. 1 dotted lines represent the scheme of affine transformation of the ends of the vectors of the input signals into the ends of the vectors of the corresponding output signals

One of the possible forms of writing the invariant of an affine transformation in the form of a “three-point relation” in this example has the following form

It is also possible to write the invariant

We assume that in (1) S ₁ (t) and S ₂ (t) play the role of the so-called "reference signals", and S ₃ (t) - information S _i (t). In this case, from (1) it is possible to obtain the modified invariant amplitude modulation algorithm [1, 2]:

алгоритм модуляции,

modulation algorithm,

where J _i is the value of the transmitted information element;

- вектор информационного сигнала S_i(t), который совместно с опорными сигналами S₁(t) и S₂(t) передает значение информационного элемента J_i;

- the vector of the information signal S _i (t), which together with the reference signals S ₁ (t) and S ₂ (t) conveys the value of the information element J _i ;

- вектор первого опорного сигнала S₁(t);

- vector of the first reference signal S ₁ (t);

- вектор второго опорного сигнала S₂(t);

- vector of the second reference signal S ₂ (t);

i - number of the time interval during which the value of the information element J _i is transmitted.

From expression (2) one can obtain the second algorithm of the modified invariant amplitude modulation [1,2]:

алгоритм модуляции.

modulation algorithm.

Block diagram of a modified invariant amplitude modulator with two reference signals.

The block diagram of the modulator is shown in Fig. 2. The scheme consists of:

IIE - generator of information elements;

GPOS - generator of the first reference signal;

GVOS - generator of the second reference signal;

BVRV - block for calculating the difference of vectors;

BOAMILM - block for determining the modified amplitude modulation algorithm;

BGS and U - block of group synchronization and control;

multiplier;

adder;

Multiplexer.

The work of the modulator begins with the formation of two reference signals of different forms to the generators of the first and second reference signal (GPOS, GVOS). The reference signals from the outputs of the generators are fed to the block for calculating the difference of vectors (BVRV), then the result obtained from the BVRV is fed to the multiplier. At the same time, the multiplier receives information elements from the generator of information elements, which must be transferred to the communication channel. In parallel with the receipt of the reference signals to the BVR, the reference signals are fed to the input of the block for determining the algorithm of the modified invariant amplitude modulator (BOAMIAM). In BOAMILM, an algorithm is defined by which modulation will be performed according to expression (1) or (2). If modulation algorithm 1 is selected, then the second reference signal will be sent from the BOAMIAM output, if modulation algorithm 2 is selected, then the first reference signal will be sent from the BOAMIAM output. The selected reference signal from BOAMIAM and the result from the multiplier are fed to the adder, at the output of which we obtain an information signal for transmission to the communication channel. A multiplexer is used for sequential transmission of the first and second reference signal, as well as the information signal, into the communication channel.

The coordinated operation of all blocks of the modified invariant amplitude modulator is provided by the block of group synchronization and control. For clarity, in Fig. 2 from BGS and U to all blocks of the modified invariant amplitude modulator, connecting lines are not shown.

Conclusion:

Modified invariant amplitude modulator with two reference signals for a communication system with modified invariant modulation is a further generalization of the known system with invariant amplitude modulation [3].

The advantage of this utility model is that there is no need to ensure the similarity of the shapes of the signals used, as is the case with the prototype. The line of location of the ends of the vectors of the transmitted signals can occupy an arbitrary position in the coordinate system of the signal space. This circumstance can be used to increase the degree of secrecy of transmitted messages similarly to the known method of carrier frequency tuning [1, 2].

In addition, when changing the sequence of transmission of reference signals, taking into account the lengths of their vectors, it becomes possible to transmit a sign of the positive or negative values of information elements. For example, a sign of being positive may be that the temporally first reference signal has a shorter vector length compared to the vector length of the second temporally reference signal. The sign of negativity is transmitted by the reverse order of the reference signals.

Thus, the proposed modified invariant modulation makes it possible to double the volume of the alphabet of information elements in comparison with the prototype.

In the modified invariant amplitude modulation, in contrast to the invariant amplitude modulation, signals are used not of one form, but of three different forms - two different reference signals and an information signal, which also differs in shape from the reference ones. This means that in order to intercept messages transmitted by a communication system with a modified invariant amplitude modulation, the enemy's task becomes three times more difficult. To calculate the value of the transmitted information element, it needs to detect and evaluate the parameters of three previously unknown signals of different shapes, and not one shape, as in the case of a transmission system with invariant amplitude modulation. Thus, it can be argued about three times the computational cost of intercepting messages in a communication system with a modified invariant amplitude modulation compared to the prototype system or, in other words, about a threefold increase in the information security (stealth) of transmission.

Bibliography.

1. I.I. Pavlov Estimation of noise immunity of the communication system with MIAM // Vestnik svyazi. - 2020. - No. 5 p. 5.

2. Modified invariant amplitude modulation / V.V. Lebedyantsev, S.S. Abramov, I.I. Pavlov, E.V. Morozov, E.S. Abramova, M.S. Pavlova // T - Comm. Telecommunications and transport. 2020. Vol. 14, No. 6. pp. 13-19.

3. Lebedyantsev V.V. Development and research of methods for analysis and synthesis of invariant communication systems. Dissertation for the degree of Doctor of Technical Sciences. Novosibirsk, 1995

Claims (1)

A modified invariant amplitude modulator with two reference signals, characterized in that it contains two reference signal generators configured to generate reference signals of different shapes in parallel in time, also consisting of a vector difference calculation unit (VVRV), configured to receive the first and the second reference signal, the output of the BVR is connected to the multiplier, configured to receive a signal from the BVR to its first input, and to the second input - information elements from the information element generator (IEG), configured to form sequential information elements that must be transmitted through communication channel to the recipient, simultaneously from the reference signal generators, the first and second reference signals are sent to the block for determining the modified invariant amplitude modulation algorithm (BOAMIAM), which is configured to determine the algorithm by which the mod will be produced modulation, if modulation algorithm 1 is selected, then the second reference signal will be sent from the BOAMIAM output, if modulation algorithm 2 is selected, then the first reference signal will be sent from the BOAMIAM output, the BOAMIAM output and the output of the multiplier are connected to the adder with the possibility of forming an amplitude-modulated of the transmitted (information) signal, the received amplitude-modulated transmitted (information) signal and two reference signals are fed to the inputs of the multiplexer with the possibility of sequential transmission of the information signal, the first and second reference signals, also consisting of a group synchronization and control unit with the possibility of providing coordinated operation of all blocks of the modified invariant amplitude modulator.

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