RU2276467C1 - Device for receiving signals with minimal frequency modulation - Google Patents

Abstract

FIELD: digital radio communications, engineering of systems for transferring discontinuous information for receiving signals with minimal frequency modulation.

SUBSTANCE: device for receiving signals with minimal frequency modulation contains synchronization device, first and second correlators, comparator, first and second devices for selection and storage and adder by module two.

EFFECT: increased trustworthiness of receipt.

5 dwg

Description

The invention relates to telecommunications, namely to digital radio communications, and can be used in signal transmission systems with minimum frequency modulation (MFM) without phase discontinuity.

A device for receiving frequency-manipulated signals (Fink L. M. Theory of discrete message transmission. M., Sov. Radio, 1970, p. 155-156), containing a synchronizer, the first and second correlators, the first and second blocks of the calculation of the signal module , a subtraction unit, a comparator, the clock input of which is connected to the clock output of the synchronizer and to the clock inputs of the first and second correlators, the information inputs of which are connected to the input of the device, and the reference inputs, respectively, with the first and second reference outputs of the synchronizer, at The trigger output is the output of the device.

A disadvantage of the known device for receiving frequency-manipulated signals is the lack of fidelity of demodulated signals, because when receiving, the correlation between the elementary signals (symbols) of the received signals with the MFM without phase discontinuity is not taken into account.

Closest to the proposed is a device for receiving signals with minimal angular modulation (RF patent No. 2234198 C1, CL H 04 L 27/14, 2004), containing a synchronizer, first and second correlators, first and second adders, first, second, third and a fourth sample / storage device, a comparator, multiplier and relative decoder, the clock input of which is connected to the clock output of the synchronizer and to the clock inputs of the first and second correlators, the information inputs of which are connected to the input of the device and the input of the synchronizer and the reference inputs, respectively, with the first and second reference outputs of the synchronizer, with the output of the first adder connected to the direct input of the comparator, the output of the multiplier to the inverse input of the comparator, the first input of the multiplier to the output of the second adder, the second input of the multiplier to the control inputs of the first and the second sampling / storage devices and to the direct control output of the synchronizer, the inverse control output of which is connected to the control inputs of the third and fourth sampling / storage devices, the outputs of which s are connected to the first inputs of the first and second adders, respectively, the second inputs of which are connected to the outputs of the first and second sampling / storage devices, the information inputs of which are connected to the outputs of the first and second correlators and to the information inputs of the third and fourth sampling / storage devices, moreover, the first information output of the device is the output of the comparator, which is connected to the information input of the relative decoder, the output of which is orym data output device which sinhrovyhod connected to the clock output of the synchronizer.

The known device when operating in the mode of receiving signals with MFM without phase disruption provides a higher accuracy of the prima of such signals by taking into account the correlation between their elementary signals (symbols).

However, the disadvantage of the known device when receiving signals from the MFM is also the lack of fidelity of demodulated signals, because receiving signals from the MFM without breaking the phase is carried out in two stages: first, the signal from the MFM is received as a signal with minimal phase modulation, then relative decoding of this signal is performed. As a result of applying relative decoding, the number of errors in the recognition of elementary signals (symbols) in the received signal from the MFM is doubled.

To eliminate this drawback, it is necessary to provide direct optimal correlation reception of signals with MFM.

The objective of the invention is to increase the fidelity of receiving signals from the MFM.

The problem is achieved by the fact that in the device for receiving signals with minimum frequency modulation, containing a synchronizer, a comparator, the first and second sampling / storage devices, the control inputs of which are connected respectively to the direct and inverse control outputs of the synchronizer, the first and second correlators, clock inputs which are connected to the clock output of the device and to the clock output of the synchronizer, the first and second reference outputs of which are connected to the reference inputs of the first and second, respectively about correlators whose information inputs are connected to the input of the device and to the input of the synchronizer, an adder modulo two is introduced, the output of which is the output of the device, and the first and second inputs are connected to the outputs of the first and second sampling / storage devices, the inputs of which are connected to the output of the comparator , the first and second inputs of which are connected to the outputs of the first and second correlators, respectively.

The proposed device for receiving signals with MFM directly implements their optimal correlation reception and provides increased fidelity of reception of such signals.

A comparative analysis with the prototype showed that the proposed device for receiving signals with MFM includes new significant features set forth in the claims. Therefore, the technical solution meets the criterion of "novelty."

Since the required technical result is achieved by the entire newly introduced set of essential features that are not found in the well-known patent and scientific literature at the filing date, the proposed technical solution meets the criterion of "inventive step".

Figure 1 shows the electrical block diagram of the proposed device for receiving signals with MFM, figure 2 is a timing diagram explaining its operation, figure 3, 4 are trellis diagrams of the received signal with MFM at three symbol intervals, and in Fig. 5 is an electrical block diagram of a prototype.

A device for receiving signals from the MFM (see Fig. 1) comprises a synchronizer 1, first and second correlators 2 and 3, a comparator 4, first and second sampling / storage devices 5 and 6, and an adder modulo two 7. An input is connected to the input of the device synchronizer 1 and the information inputs of the first and second correlators 2 and 3. The clock output of the synchronizer 1 is connected to the clock inputs of the first and second correlators 2 and 3 and is the clock output of the device, and its direct and inverse control outputs are connected respectively to the control inputs of the first and second th devices 5 and 6, the sample / storage. The first and second reference outputs of the synchronizer 1 are connected to the reference inputs of the first and second correlators 2 and 3. The outputs of the first and second correlators 2 and 3 are connected respectively to the first and second inputs of the comparator 4, the output of which is connected to the inputs of the first and second devices 5 and 6 sampling / storage. The outputs of the first and second sampling / storage devices 5 and 6 are connected respectively to the first and second inputs of the adder 7 modulo two, the output of which is the output of the device.

The device for receiving signals from the MFM operates as follows. The received signal with the MFM, the value of the transmitted logical symbol "0" or "1" in which is embedded in the frequency of the corresponding elementary signal (symbol), in the absence of noise on any kth symbol interval of duration T can be represented by one of four elementary signals

where A is the signal amplitude;

- начальная фаза сигнала на границе к-го символьного интервала,

- the initial phase of the signal at the border of the k-th character interval,

ω ₁ and ω ₀ are the circular frequencies of elementary signals corresponding to the transmitted logical symbols "1" and "0", and their difference is ω ₁ -ω ₀ = 2π / 2Т = π / Т.

Any two consecutive elementary signals are correlated with each other, which reflects the trellis diagram of the signal with the MFM (see figure 3).

The nodes of the indicated trellis diagram correspond to elementary signals S ₁ , S ₂ , S ₃ or S ₄ transmitted in the corresponding (k = 0, 1, 2, 3, ...) symbol intervals of duration T, and the edges are allowed instantaneous transitions between the indicated elementary signals transmitted in adjacent symbol intervals.

The edges shown in dashed lines entering the nodes on the left correspond to the transmitted logical symbols “1” (elementary signals S ₂ or S ₃ ), and the edges shown in solid lines correspond to the transmitted logical symbols “0” (elementary signals S ₁ or S ₄ ).

The allowed sequences of elementary signals of the MFM signal are determined by the allowed paths on the trellis diagram.

In order to determine the logical symbol received at the kth symbol interval, it is necessary to determine which of the allowed sequences of elementary signals the implementation of the received signal with the MFM at the kth and (k + 1) symbol intervals is most correlated with.

To this end, the received signal from the MFM is fed to the information inputs of the first and second correlators 2 and 3 (Fig. 2, a), while the clock pulses are fed to the clock inputs of the first and second correlators 2 and 3 from the clock output of the synchronizer 1 (Fig. 2, b) with a repetition period T, and the basic elementary signals are supplied to the reference inputs of the first and second correlators 2 and 3 from the corresponding outputs of the synchronizer 1 at the kth symbol interval (FIG. 2, c and 2, d)

- амплитуда и начальная фаза опорных элементарных сигналов.where A ₀ and

- the amplitude and initial phase of the reference elementary signals.

The values of the signals (Fig.2, d and Fig.2, f) at the outputs of the first and second correlators 2 and 3 at the end of the _kth symbol interval are equal to the values of correlation metrics (values of the correlation integrals between the received signal and elementary reference signals S _op1 And S _op3 ) nodes S ₁ and S ₃ .

The value of the difference signal (figure 2, g), equal to the difference of the output signals (see figure 2, d and figure 2, e) of the correlators 2 and 3, at the end of the kth symbol interval corresponds to the difference in the values of the correlation metrics of nodes S ₁ and S ₃ and determines the signal value (Fig. 2, h) at the output of the comparator 4, which at the end of the kth character interval is equal to "1" if the difference in the values of the correlation metrics of the nodes S ₁ and S _{3 is} greater than zero, and is equal to "0" otherwise.

The values of the output signals (Fig. 2, and; Fig. 2, k) of the first and second sampling / storage devices 5 and 6 are constant for two consecutive (k + 1) -, (k + 2) - and (k + 2, respectively ) - and (k + 3) th symbol intervals and are equal to the signal values (see Fig. 2, h) at the output of comparator 4 at the end of the previous kth and (k + 1) th symbol intervals, i.e. . at times corresponding to the arrival at the control inputs of the first and second devices 5 and 6 of the sample / store from the direct and inverse control outputs of the synchronizer 1 of the positive edges of the corresponding control signals (Fig. 2, l; Fig. 2, m), which are mutually inverse meanders with a frequency of 1 / (2T), the levels of which change at the end of symbol intervals.

The output signals (see Fig. 2, and; Fig. 2, k) of the first and second sampling / storage devices 5 and 6 are respectively supplied to the first and second inputs of the adder 7 modulo two.

At the output of the adder 7 modulo two, an output signal is obtained (Fig. 2, n), the value of which is constant during any (k + 2) th symbol interval and is equal to the value of the symbol estimate of the signal with the MFM received at the kth symbol interval.

The clock output of the device from the clock output of the synchronizer 1 serves clock pulses (see figure 2, b) with a repetition period T.

A device for receiving signals from the MFM implements the following algorithm.

1. Sequentially on each current (k = 0, 1, 2, 3, ...) symbol interval of duration T, corresponding to the next four vertically located nodes S ₁ (k), S ₂ (k), S ₃ (k) and S ₄ (k) trellis diagrams (see FIG. 3) calculate and compare two correlation metrics a ₁ (k) and a ₂ (k) nodes S ₁ (k) and S ₂ (k) (two correlation integrals between the input signal and reference elementary signals S _op1 and S _op3 ). At the end of each (k = 0, 1, 2, 3, 4, ...) symbol interval, two surviving nodes S ₁ (k) and S ₂ (k) or S ₃ (k) and S ₄ (k ) of the four possible nodes S ₁ (k), S ₂ (k), S ₃ (k) or S ₄ (k) according to the following rule: if the correlation metric a ₁ (k) of the node S ₁ (k) is greater than the correlation metric a ₃ (k) of the node S ₃ (k), then the nodes S ₁ (k) and S ₂ (k) are selected, otherwise the nodes S ₃ (k) and S ₄ (k) are selected (Fig. 4, a and Fig. .4, b).

2. The pair of nodes S ₁ (k), S ₂ (k) or S ₃ (k), S ₄ (k) (the result of comparing correlation metrics) is sequentially remembered for a time equal to the duration of the next two ( k + 1 = 1, 2, 3, 4, ... and k + 2 = 2, 3, 4, 5 ...) symbol intervals.

3. In sequence at each (k + 2) -th symbol interval, compare two pairs of surviving nodes selected at the previous k-th and (k + 1) -th symbol intervals and determine the adopted logical symbol according to the rule: if identical pairs of nodes S consistently survived ₁ (k), S ₂ (k) and S ₁ (k + 1), S ₂ (k + 1) or S ₃ (k), S ₄ (k) and S ₃ (k + 1), S ₄ ( k + 1), then the logical symbol "0" is accepted, otherwise the logical symbol "1" is accepted.

The proposed algorithm allows, in accordance with the transitions allowed by the trellis diagram and the list of surviving nodes at two consecutive clock intervals, to determine the only surviving node on the first clock interval and the value of the corresponding logical symbol, since each node of the trellis diagram corresponds to one possible elementary signal.

For example, in Fig. 4, the results of the first and second steps of the algorithm are shown, as a result of which the nodes S ₃ (k) and S ₄ (k) are selected _{on the} kth character interval (see Fig. 4, a), and on (k + 1) -th symbol spacing (see Fig. 4, b) nodes S ₃ (k + 1) and S ₄ (k + 1) are also selected. At the third step of the algorithm, a decision is made to accept the logical symbol c (k) = 0, because the pairs of surviving nodes S ₃ (k), S ₄ (k) and S ₃ (k + 1), S ₄ (k + 1) are the same.

A device for receiving signals with MFM can be implemented on known functional elements.

A possible example of the execution of the synchronizer 1 is known from the prototype, other components of the proposed device can be implemented on standard functional elements.

The above information indicates the fulfillment of the following set of conditions when using the claimed technical solution:

- the proposed device is intended for use in industry, namely in communication technology, in particular, in digital signal transmission systems with MFM,

- for the claimed device in the form described in the independent clause of the claims, the possibility of its implementation using the means and methods described in the application or known prior to the priority date is confirmed.

Therefore, the claimed technical solution meets the criterion of "industrial applicability".

When using the proposed device for receiving signals with MFM, the implementation of the optimal coherent reception of these signals is provided taking into account the correlation between their symbols, which ensures an increase in fidelity of reception.

Claims (1)

A device for receiving signals with minimum frequency modulation, comprising a synchronizer, a comparator, first and second sampling / storage devices, the control inputs of which are connected respectively to the direct and inverse control outputs of the synchronizer, the first and second correlators, the clock inputs of which are connected to the clock output of the device and to the clock the synchronizer output, the first and second reference outputs of which are connected to the reference inputs of the first and second correlators, respectively, the information inputs of which are are connected to the input of the device and to the input of the synchronizer, characterized in that an adder modulo two is introduced, the output of which is the output of the device, and the first and second inputs are connected to the outputs of the first and second sampling / storage devices, the inputs of which are connected to the output of the comparator, the first and the second inputs of which are connected to the outputs of the first and second correlators, respectively.

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