The method of transmission and reception of code combinations
(57) Abstract:The invention relates to electrical engineering, in particular to telecommunications, and can be used in digital telephony, alarm systems and telecontrol systems, namely the systems of transmission and reception of binary information. The task of the invention is to simplify the method of transmission and reception of code combinations. This object is achieved in that you use the following property: period complex frequency signal uniquely associated with frequencies fiand fjthat form a recognizable signal, and hence with the transmitted code combination. At the receiving side determines the period of the complex frequency signal TC is uniquely associated with frequencies fiand fj. On the found period TC judge adopted a combination of frequencies, which carry information about the code combination. Found a way to transfer and recognition of digital frequency signals eliminates the necessity of recognition of each of the frequencies that make up a recognizable signal. 1 table, 3 Il. The invention relates to electrical engineering, in particular to telecommunications, and can be used in digital telephony, signalizaciyi networks around the world are widely used alarm system, in which to transfer numbers are used multifrequency signals. Widely used signaling system in which numbers are transmitted using multi-frequency code 2 of 8. Multifrequency signals in this case are formed by addition of two harmonic oscillations. To control the switching equipment of automatic telephone stations, in which applied alarm system, automatic telephone exchange must be device, receiving and recognizing signals using multi-frequency code. Therefore, the recognition of multi-frequency signals with high reliability is an important task.A device for receiving multi-frequency signals. C. SU 1663784, IPC H 04 Q 1/46, 1991). This device contains a first amplitude corrector, the first threshold unit, the first counter, a decoder, the first, second and third memory blocks, comparator, the second amplitude corrector, the second threshold unit, the second counter, the delay unit, the pulse generator. The amplitude corrector constructed in such a way that the first has a linearly increasing, and the second linearly decreasing amplitude-frequency characteristic.eat the number of intersections with the zero time multiple of periods of all the received frequency depends only on the frequency of the signal of greatest amplitude. This number is calculated by counters. The received signal is processed by the decoder. The signal at the output of the device is issued if the value matched for the two periods of analysis of the received signal. The analysis period is set by a pulse generator. This device is built on the principle of high-frequency and low-frequency components, the components of the transmitted signal, which complicates the recognition process of the received code.The known method of reception of code combinations that are transmitted over digital communication channels (M. Y. Evsikov. Recognition of multi-frequency signals transmitted via digital channels of communications/ telecommunications. 1998. 11. C. 19-21.) using the Fourier transform (PF), selected as a prototype, which gives the best result (in terms of noise immunity and simplicity) when determining the frequency of harmonic oscillations, the components of multi-frequency signals. The described method of transmitting and receiving code combinations may be represented by the block diagram shown in Fig.1. A signal formed by adding the two harmonic number of the calling PF determine the frequency of this signal and the corresponding frequency is judged on the number of code combinations. For discrete-time periodic signals, the process of integration in the expression for PF is replaced by a summation:
< / BR>where is the twiddle factor.
x(n) - nth count of the received digital signal;
N - number of samples in the array of signal being analyzed;
< / BR>However, the application of PF when the detection frequency signals requires knowledge of the period of these signals. To recognize a particular code combination transmitted frequencies fiand fjuse PF to determine these frequencies, pre-calculating the period of the considered signal. The result is complicated by the recognition process of the received code.The task of the invention is to simplify the method of transmission and reception of code combinations.This object is achieved in that in the method of transmission and reception of code combinations, as in the prototype, on the transmission side form code combination by adding two harmonically oscillations with frequencies fiand fjpass it over the communication channel in the form of a dual-frequency digital signal and recognize her on the receiving side.According to the invention, unlike the prototype, recognize koji these frequencies.In this case we use the following property: period complex frequency signal uniquely associated with frequencies fiand fjthat form a recognizable signal, and hence a transmitted code combination. This eliminates the need for the recognition of each of the components of frequencies.Thus, as a result of refusal of recognition of each of the components of frequencies is provided by the simplification of the process of recognition code combination transmitted by the dual-frequency signal, as is the fact that difficult period double-frequency signal uniquely associated with frequencies fiand fjand means and transmitted by a combination of frequencies.In Fig. 1 shows a block diagram illustrating the method for recognition of a digital frequency signals using PF.In Fig. 2 shows a block diagram of the proposed method of transmitting and receiving code combinations.In Fig. 3 shows a block diagram of the device determine the period of the analyzed signal.The table shows the possible combinations of frequency fiand fjuniquely associated with a period of complex signal TC.
rmiranda using the composition of two harmonic oscillations (frequency generators fiand fj), is transmitted over the communication channel, which may be a telephone line connection. For detection of the received code calculates the period of a received frequency signal uniquely associated with the frequency fiand fjand thus with the code combination.As the generator frequency fiand fjcan be applied to generators series HA-117, GZ-105 or GZ-106.To determine the period of the frequency signal, you can apply one of the known methods of determining the period of a complex periodic oscillations (after the consumer Century A. Calculation of parameters of periodic components of discrete data with limited observation interval // Measurement techniques. 1999. 2. C. 10-12; Measurements in electronics: a Handbook. Ed. Kuznetsov A. C. - M.: Energoatomizdat. 1987. 512; Popov, B. C., Shumarov E. C. Measurement period of the electrical signals, in digital form, / / Measurement techniques. 1995. 1. C. 50-54; Popov, B. C., Shumarov E. C. a method of measuring the period of the electrical signals with a DC component and a non-sinusoidal shape of the curve // Measurement techniques. 1998. 7. S. 34-39). In this case, the method was applied to calculate the period of a complex signal COI is level and looks for a second. Found time interval between two zero crossings is checked for frequency
If the condition is false periodicity of the second zero crossing is discarded from consideration, is searched for the next signal transition through the zero level, and these operations are repeated until then, until you find the true period of the analyzed signal.The structural scheme of the device determine the period of the frequency signal is illustrated in Fig.3. The device determination period double-frequency signal includes a filter 1, a comparator 2, a pulse counter 3, a comparator 4, a square-wave generator 5, the delay unit 6, and a storage device 7.To the input of filter 1 is the received signal X(k). The output of filter 1 is connected to the inputs of the comparator 2, the delay unit 6, and a storage device 7. The first output of the comparator 2 is connected to the input of the pulser 5, and the second to the first input of the pulse counter 3. The output of the square-wave generator 5 is connected to a second input of the pulse counter 3. The output of the pulse counter 3 is connected to the first input of the comparator 4, and the outputs of the delay unit 6 and the memory is I 4 is given the value of TC.Coming from the telephone line signal X(k) is filtered from the noise filter 1, which can be used to filter KPA or CRP. The filtered signal is applied to the comparator 2, the delay unit 6, and a storage device 7. The delay unit 6, and a storage device 7 can be implemented on the chip CAP and CRA respectively. From the output of the comparator 2 to the first input of the pulse counter 3 (chip CIA or equivalent) are rectangular pulses characterizing positive and negative half-wave. At the first transition of the analyzed signal through the zero level comparator 2 sends a pulse to the pulser 5 (chip CGH) to run it. To the second input of the pulse counter 3 start enter the rectangular pulses from the pulser 5. The pulse counter 3 counts the number of pulses generated by the pulser 5. The comparator 4 allows to reveal the true period of the signal using inspections at the intervals of several points, memorized storage device 7, and the current signal delayed through the delay unit 6 at the time, neobhodimo implemented on the chip CSA or CSS.In the table as example 29 possible combinations of frequency fiand fjwe received the result of the experiment. These tabular data illustrate the relation of the above combinations of frequencies with a period of complex signal TC.Thus, the proposed method of transmitting and receiving code combinations allows you to refuse the recognition of each of the frequency components of the received signal, which simplifies the recognition process the received code combination. The method of transmission and reception of code combinations, namely, that on the transmission side form code combination using the composition of two harmonic oscillations with frequencies fiand fjpass it over the communication channel in the form of a dual-frequency digital signal and recognize her on the receiving side, wherein recognize the code combination of the determination of the period of dual frequency digital signal TC is uniquely associated with the combination of these frequencies.