RU1837344C - Method for determination of frequency of digital information transmission and device for implementation of said method - Google Patents

Description

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The alleged invention relates to the field of transmission of digital information and may find application in devices for receiving telemetric information arriving in the form of a continuous data stream with relative phase shift keying. .

The purpose of the invention is to improve the accuracy of determining the frequency of transmission of digital information,

Fig. 1 is a functional diagram of a device for implementing the proposed method; Fig. 2 is a timing diagram illustrating its operation.

A device for determining the transmission frequency of digital information (figure 1) contains the first, second and third elements 1, 2 and 3 And, the first, second, third and fourth one-shots 4, 5, 6, 7, the first and second delay elements 8 and 9 , first, second, and third elements 10, 11, and 12, OR, shaper 13 of the original base code N, shaper 14 of the threshold code P, generator 15 clock pulses, trigger 16, counter 17, duration 18, switch 18, first register 19, second register 20, first, second and third digital comparators 21, 22 and 23, match number counter 24 S, memory block 25.

The proposed method for determining the transmission frequency of digital information with relative phase shift keying is as follows.

In a data stream with relative phase manipulation, the phase transitions coincide with the clock rate of the data before their phase manipulation. The appearance of a combination of type 00 in the data stream causes the appearance of two phase transitions in the output signal, the time interval between which unambiguously corresponds to the period of the data clock frequency. In other words, in the data stream at any of the possible frequencies of its transmission there are several phase transitions caused by the appearance of a combination of the form 00, the interval between which contains information about the frequency of the transmitted data. The proposed method is based on the described regularity and is a set of operations allowing one to find the intervals between phase transitions characteristic of the desired frequency and to identify the obtained value from one of the possible data transmission frequencies from a predefined set.

To this end, phase transitions are determined in the input phase-manipulated signal (Fig. 2, c) by forming at

and

10

fifteen

twenty

25

thirty

35

40

45

fifty

55

each change in the level of the input signal (for example, from logical level 1 to logic level O, and vice versa) of a single short pulse with a duration

T "imin ..

where rmin is the duration of the time interval between phase transitions in the sequence of elements of the input data stream of type 00 at the maximum frequency.

In this case, a pulse sequence is formed consisting of short pulses unevenly located on the time axis (see Fig. 2, d).

In the obtained pulse sequence, the time interval between each two adjacent pulses is measured by counting the number of clock pulses (Fig. 2, b) located between the pulses fronts of sequence d), Fig. 2. Thus, essentially, the measured time interval is converted into binary code T |. In this case, the frequency of clock pulses (see Fig. 2, b) is selected from the condition:

ft fmax f

where fmax is the frequency of characters following the maximum data rate.

Immediately before starting the determination of the transmission frequency, the binary code T is stored as the basic code, where Gmax is the duration of the time interval between phase transitions and sequences of elements of the input stream of type 00 at the minimum frequency, and gmax is measured using Fr.

Storing the original base code T ensures the correct determination of any of the possible transmission frequencies.

The resulting binary Ti code is compared with the stored base code T. The following relationships are possible:

Tj - T

In the first case, the measured value of Ti is discarded, since a time interval of such a duration is not characteristic even of the lowest possible frequency.

If T) T, then the number of matches Si for the TI code is summed to avoid false determination of frequency.

And finally, if, then the obtained Ti code is now stored as the base code and all subsequent operations of comparison with the obtained Tj are carried out with respect to the new base code.

The number of matches Si binary TI code. with the base code T is compared with a certain threshold value P sufficient to prevent a false conclusion about the true data rate. In the General case, the threshold value of P is chosen equal to

p p7TiW (1)

where Pi is the probability of occurrence in the input data stream of a sequence of elements of type 00 characterizing the static properties of the transmitted stream;

2 - the probability of distortion of the sequence of elements of type 00 in the input data stream due to the influence of interference in the communication channel;

The probability Pi is determined a priori based on an analysis of system parameters providing data transmission (mainly from analysis of the structure of the transmitted data stream). Taking into account the fact that without determining the transmission frequency it is impossible to establish the clock, as well as cyclic synchronization (with time division of channels), data in many systems are not transmitted until these types of synchronization are established. This means that zeros of information are transmitted into the line in a continuous stream, and P) is equal to 1. However, the proposed method provides the determination of the information transfer rate even when a non-zero data stream is transmitted along the line. However, in this case as well, there are always some basic characteristics of the data stream that make it possible to determine Pi. For example, the sync pattern, which should be selected to provide the appearance of several combinations of elements of type 00.

The probability g is a system parameter that determines the quality of the communication channel; therefore, using its specific value does not cause any difficulties.

An analysis of relation (1) shows that the expression enclosed in brackets is always almost 1, taking into account the real characteristics of communication channels (less commonly. It follows that the threshold value P is determined by the value Pi, which is equal to 1 at zero data flow Thus, taking into account the real characteristics and algorithms of operation of the data transmission channels P 2. For other values of Pi and P2, R. will also change, for example, for P1-0.5 and RaYu.B.

R

1

D3TT4I5)

P 4 etc.

Thus, if the co-division number of the Si code is with the base code T pat to it. fie exceeds the threshold value mn P, the process of determining the frequency of data transmission continued.

As soon as for any binary code TJ, the number of its collisions is S; It turned out to be the threshold threshold value P, this means that the time interval characteristic of a given transmission frequency is determined. By the value of the specified code T | (or, which is the same, according to the last basic code T), the data transmission frequency is identified, since the correspondence between the values of the TJ codes and the information transmission rates has been established in advance.

Graphically illustrate the proposed method as follows (see table 1).

As follows from the table. 1, the code Tj corresponding to the data transmission frequency U reached the threshold value for the number of matches. At the same time, during the analysis of the value of the basic code, it changed three times, even a certain number of matches of the code T | with Oasis (for transmission frequency f2). Upon reaching the threshold value PM-, the desired transmission frequency if, was identified.

To eliminate the situation where, despite the received new value of the base code T, it is not possible to reach the threshold value for the number of matches, a certain analysis time interval can be introduced, after which, if the threshold value is not reached, the determination of the transmission frequency starts with. the very beginning. The specified time interval, for example, can be selected based on possible transmission frequencies, or, based on specific, real characteristics of the data transmission systems mentioned above (in the absence of data synchronization are not transmitted), it can be about: - limited by several periods of the clock frequency for the lowest transmission frequency. However, such an operation is not essential, since it does not communicate any additional benefits to the proposed method, although it can be used if necessary.

Figure 1 shows a diagram of a device that implements the above method. Elements of the device can be performed using standard microcircuits, for example, the K564 series. (see. Analog and digital integrated circuits. Handbook edited by S.V. Yakubovsky, M .. 1985,). Elements 1,2,3 11 - K554LA7 with the inclusion of ng output of each element AND-NOT of the measurer 564LN1; single vibrators 4 ... 7 - 564AG1 with time chains connected to them from resistors of type 2-23 and capacitors of type B-18 (condenser assemblies).

Delay elements 8, 9 can be performed on several elements sequentially connected K564LA7 (or K564LB5. K564LN1) with an even number of elements in the connection;

elements 10. “12 OR - K564LE5 with switching on the output of the inverter K564LN1;

The shaper of the initial base ode 13 can be made either in the form of a connection, connected at the edge of the board, of the inputs of the switch 18 with contacts whose signal level corresponds to 0 or 1, or in the form of a set of switches for two positions;

Shaper 14 can be performed similarly to shaper 13;

the clock generator can be performed as a multivibrator, or as a series connection of two elements of the type K564AG1 with the output of the second element connected to the start input of the first;

trigger 16-K564TR1;

counter 17 -K564IE10;

switch 18 - K564LS2;

registers 19 and 20-K564IR9;

digital comparators 21 ... 23 - K564IP2;

counter 24- K564IE10;

memory block 25 - K573RF20,

In the initial state, the trigger 16 is in a position in which there is a zero potential at its output, closing the element 1I, the duration counter is removed from the counting mode of the clock pulses of the signals from the output of its highest order, the registers 19 and 20 are reset, the counter 24 matches number is reset , at the outputs of one-shots 4 ... 7 there are zero potentials, at the outputs of digital comparators there are zero potentials, at the outputs of elements 1, 2, 3 And; 10,11,12 OR there are zero potentials, a threshold code is present at the outputs of the driver 13. A number of matches, a zero code is present at the address inputs of the memory block 25, according to which a code does not correspond to any of the outputs of the memory 25 data transmission frequency code; the remaining addresses of the memory block 25 store transmission frequency codes, the addresses of which correspond to codes proportional to the length of the period of the information clock transmission frequency.

A device for determining the transmission frequency of digital information operates as follows.

When the Start signal is applied to the start input of the one-shot 6, a single pulse is formed at its output, switching the output of trigger 16 to the log state. 1 and installing the switch 18 in a position that provides

. connecting the outputs of the generator 13 of the initial basic code to the inputs of the parallel recording of the register 19. The same pulse delayed by the element 9 of the time delay passes through the element 11 OR to the clock input of the register 19. writing to it the original basic code. On the decline of the pulse from the output of the one-shot 6, the switch 18 is switched to the position that provides the connection output

counters 17 to the inputs of the register 19.

When a 1 A element appears at the second input, a high (low) potential of the input phase-manipulated (FM)

signal, at its output there also appears a high (low) potential, triggering single-vibrators 4 or 5 (single-vibrator 4 is triggered by the front of the pulse, single-vibrator 5 by the decay of the pulse).

. However, the single vibrators 4 and 5 do not start as long as a pulse is present at the output of the single vibrator b, i.e. until the initial installation of the device is completed. Single vibrators 4 and 5 form

pulses at the moments of phase transitions in the input FM signal with a duration

t

where Zmin is the duration of the time interval between phase transitions and the sequence of elements of the input data stream of type 00 at the maximum frequency.

These pulses through the element 10 OR are fed to the input of the delay element 8 and to the first inputs of the elements 2 and 3 I. On

the second inputs of elements 2 and 3 And the signals from the outputs of the digital comparators 21 and 22 are received, respectively. At the output of the comparator 21, a high potential appears if the code. received at the outputs of counter 17 is less than the code stored in register 19. At the output of comparator 22, a high potential appears if the code received at the outputs of counter 17 is equal to the code stored

in register 19. Thus, using the digital comparators 21 and 22, the measured duration between the phase transitions in the input FM signal is compared with a base value.

The delayed pulse from the output of the delay element 8 affects the input of the eros counter 17 of the duration, which after each reset pulse begins to accumulate pulses from the output of the generator 5 clock pulses (Fig.2,6). At each phase transition in the input FM signal (fi2, c), the output of the delay element 8 contains a pulse (Fig.2d), after which the counter 17 duration accumulates a certain number of clock pulses (Fig .2, d). If, by the time the next transition occurs, the code at the output of the duration counter 7 is less than the one stored in the register 19, then at the output of the omparator 21 a high potential arises, allowing the output pulse of the element 10 OR to pass through element 2

1 (figure 2, e). In this case, at the time of the phase transition, a code is written to the register 19 from the output of the duration counter 17, i.e. code, basic. (Fig.2.z). The contents of the counter 24 are reset to zero (Fig. 2, i), i.e., the result of accumulation of the number of mastery for the previous basic code is zeroed.

If, by the time the base transition occurs, the binary code at the output of the duration counter 7 will be equal to the code. Since the register is 19, then a high potential appears at the output of the digital omparator 22, disrupting the passage of the pulse from the output of the OR element 10 through the 3 AND element (Fig. 2. g). This pulse will arrive at the clock input of the counter 24, changing the contents in the direction of accumulation of the number of acquisitions of the measured duration between the two neighboring phase transitions of the base value.

The output code of the counter 24 goes to the outputs of the digital comparator 23, where it is equal to the code of the threshold number of messages coming from the output of the shaper 14. When the compared values are equal, the output of the digital comparator 23 has a high potential, which triggers one vibrator 7. The output pulse of the single-oscillator 7 (Fig. 2, k), passing through the OR element 12, resets the counter 24 and affects the clock input of the register 20, writing in it a binary code proportional to the minimum duration between phase transitions into input M-signal (figure 2, ). At the same time, the code corresponding to the binary code of the desired frequency appears on the outputs of the memory lock 25, which is the output signal of the device (Fig. 2 m).

The pulse from the output of one-shot 7 affects the input of the installation of the trigger 16 in

zero state, i.e. brings the device to its original state.

The output of the single-vibrator signal 7 (pulse decay) can be used to start the single-vibrator 5, i.e. to organize the cyclic operation of the device. In this case, the output of the one-shot 7 must be connected to the start input by the recession of the one-shot 6,

0 The start-up input of one-shot 6 can be used to periodically set the device to its initial state in time, after which a START pulse is generated. Timer can be executed

5 in the form of a ring counter, one of the bits of which is connected to the start input of one-shot b, and an additional clock generator, the frequency of which is less, is connected to the clock input of the counter

0 repetition rate of information symbols at the lowest information rate.

The technical and economic advantages of the proposed invention as compared with the prototype are to increase the accuracy of determining the transmission frequency of digital information.

Improving the accuracy of determining the speed due to the fact that it is excluded by

Compared with the prototype, the possibility of a false determination of speed with various combinations of binary elements in the input information stream.

Claims (2)

The claims 5 1. A method for determining the transmission frequency of digital information, which consists in converting digital information into phase-manipulated signals, extracting phase transitions in a phase-manipulated signal, and identifying the transmission frequency from the analysis results, characterized in that, in order to increase the accuracy of determination, the phase transitions are stored before as 5 basic code binary code gmax, where Tmex is the duration of the time interval between phase transitions in the sequence of elements of the input data stream of the form 00 at the minimum frequency, 0 phase transitions in the input phase-manipulated signal are distinguished by generating a pulse at each change in the level of the input signal WITH DURATION T Cumin. WHERE Gmin GDL5 tel-jHOCTb of the time interval between phase transitions in the sequence of elements of the input data stream of type 00 at the maximum frequency, the time interval between each two adjacent pulses is measured, the measured time interval is converted to binary code Ti. compare the binary code P with the base code T, store the binary code TV as the base code T under the condition Ti T, summarize the number of matches Si of the binary: code Ti provided, compare the number of matches Si of the binary code Tt with the threshold value P, the identification of the transmission rate data is carried out according to the code Ti, for which, moreover, the threshold value P is chosen equal to p, 1. Pl (1-P2) where Pi is the probability of occurrence in the input data stream of a sequence of elements of the form 00, characterizing the statistical properties of the transmitted stream, Pr is the probability of distortion of the sequence of elements of type 00 in the input data stream due to interference or the occurrence of failures. 2. A device for determining the transmission frequency of digital information, comprising a clock. Duration counter, first register and memory unit, characterized in that, in order to increase the accuracy of determining the transmission rate, the first, second and third AND elements, a switch, the first, second, third and fourth one-shots, the first and second delay elements are introduced into it , first, second and third elements OR, generator of the initial base code, generator of the threshold code, trigger, second register, first, second and third digital comparators and a counter of the number of matches, while the inputs of the start of the first and second of the radiators are combined and connected to the output of the first element I. The first input of which is the input of the entire device, and the second input is connected to the output of the trigger, the S-input of which is connected to the inputs for inhibiting the start of the first and second single vibrators and connected to the output of the third single vibrator, the start input of which is the start input of the entire device, the outputs of the first and the second one-shot are connected to the corresponding inputs of the first OR element, the output of which through the first delay element is connected to the reset input of the duration counter, the clock input of which is connected to the output of the clock generator, the overflow output of the duration counter is connected to its resolution input, information outputs of the counter durations are connected to the first groups of inputs of the switch, the first and second digital comparators, the outputs of the generator of the initial basic code are connected to the second group of inputs of the switch, the outputs of which are connected to the information inputs of the parallel recording of the first register, the information outputs of which are connected to the second groups of inputs of the first and second digital comparators and the information inputs of the parallel recording of the second register, the information outputs of the memory block connected to the address inputs, the outputs of which are the output of all devices, the output of the third one-shot is connected to the control input of the switch and through the second delay element to the first input of the second OR element, the output connected to the clock input of the first register, the outputs of the first and second digital comparators are connected to the first inputs of the second and third elements AND, the second inputs of which combined and connected to the output of the first OR element, the output of the second AND element is connected to the second input of the second OR element and to the first input of the third OR element, the output of the number of matches connected to the reset input counter, clock input which is connected to the output of the third element VI, and the information outputs are connected to the first group of inputs of the third digital comparator, the second group of inputs of which is connected to the outputs of the threshold code generator, and the output through the fourth one-shot is connected to the trigger R input, the second input of the third OR element, and clock input of the second register.