RU1815806C - Method for generation of digital delta-flow of pulses for group transmitter of control and interaction signals - Google Patents

Abstract

Usage: methods for generating a digital delta pulse stream. The inventive device for implementing the method includes a generator 1, a switch-multiplexer 2, read-only memory 3, switch 4, shift register 5, switch-demultiplexer 6, channel random access memory 7, delta decoder 8. 1-2 -3-4-5-6-7-8. 1 ill.

Description

ate

00

about (

The invention relates to telecommunication technology and is intended, in particular, for generating control and interaction signals in a group M-channel delta stream for the purpose of interfacing digital electronic exchanges with adaptive delta modulation (EATS-CA) with analog coordinate exchanges.

The aim of the invention is to increase the accuracy of the formation of a digital delta pulse stream,

The drawing shows a functional diagram that implements the proposed method.

The digital group transmitter of control and interaction signals with adaptive delta modulation contains generator equipment 1, a multiplexer switch 2 combination numbers, a read-only memory (ROM) 3 delta streams, a switch 4 quadruples of delta samples, a shift register 5, a switch a demultiplexer of 6 channels, a group of 7 channel RAM and a group of 8 delta decoders according to the number of N transmission channels, in the ROM 3 of the delta stream, segments of control signals and interactions are recorded while maintaining transients during growth a quantization step and with amplitude pre-emphasis in favor of the low-frequency component of the two-frequency signal, while the first input of the generator equipment 1 receives a sequence of pulses of cyclic synchronization Pts 8 kHz, the second input of the generator equipment 1. combined with the clock input of the shift register 5, a pulse sequence is supplied FT 8 (N) kHz clock synchronization, the first logaN outputs of the generator equipment 1 are fed to the combined control inputs of the multiplexer switch of the same name 2 combination numbers and demultiplexer switch b channels, data outputs of the multiplexer switch 2 combination numbers are fed to the first group of address inputs of ROM 3 delta stream, the second group of address inputs of which are connected to the same address inputs of group 7 channel RAM and connected to the second the outputs of the generator equipment 1. its third and fourth outputs are each connected to the inputs of the switch of the same name 4 quadruples of delta samples, its first and second quadruples of inputs are connected to the outputs of the same name ROM 3 cases there is a stream, the code outputs of the switch of four four delta samples are fed to the same inputs of the shift register 5, its output is connected to the data input of the switch-demultiplexer of 6 channels, the outputs of which are each fed to the data inputs of the same channel RAM as part of group 7, their inputs write / read and

the samples are separately combined and connected respectively to the fifth and sixth outputs of the generator equipment 1, the outputs of each channel RAM of group 7 are fed to the input of the same delta decoder of group 8, the outputs of group 8 delta decoders according to the number N of transmission channels are the outputs of the device, and N groups of codes (Di-Dm) at the data inputs of the switch-multiplexer 2 combination numbers

are the information inputs of the device.

Consider the essence of the proposed method for generating a digital delta pulse stream in a group transmitter

control and interaction signals using an example of a device implementing it.

To the data inputs of the switch-multiplexer 2, the combination numbers are N-rpynn of m-digit binary codes (Di-Dm),

each of which displays the number of one of 2 combinations of control and interaction signals. For example, the code combination (00000) corresponds to the silent mode (pause) - not a single one is transmitted

of the frequency components, the delta stream has the form: 101010 ... Combinations (00001) correspond to digit 1 of the dialing number, a pair of frequencies 700-900 Hz; combination 00010 (2) corresponds to a pair of frequencies 700 + 1100 Hz and

etc., combinations 01001 (9) - a pair of frequencies 1100 + 1500 Hz, 01010 (0) -1300 + 1500 Hz. Combinations 01011 (11) - 700 + 1700 Hz; 01100 (12) - 900 + 1700 Hz; 01101 (13) - 1100 + 1700 Hz; 01110 (14) - 1300 + 1700 Hz; 01111 (15) 1500 + 1700 Hz are auxiliary and standby.

The remaining sixteen combinations are assigned to single-frequency signals

a five-digit binary code, namely, combinations from 1000 (16) to 10011 (19) corresponds to a buzzer signal of 425 Hz; combinations from 10100 (20) to 10111 (23) - 500 Hz ANI signal; combinations from 11000 (24) to

1Y11 (27) - network monitoring at a frequency of 700 Hz; combinations from 11100 (28) to 11111 (31) - network monitoring at a frequency of 1100 Hz. Four-way redundancy for single-frequency signals provides

transmission of longer single-frequency bursts (up to TI 256 ms), while dual-frequency dialing digits will be transmitted with a duration of not more than T2 64 ms and the same pause (00000 combination) at a nominal value of T2nom 50 ms.

To the control inputs of the switch-multiplexer 2, the combination numbers are received from the first logaN outputs of the generator equipment 1 pulse sequences of changing the channel numbers from the 1st to the Nth. The drawing shows an example of N 8, the three control inputs of the switch - multiplexer 2 receive the sequence of f - 32.16 and 8 kHz channel change for the 8-channel group of control signals and interaction with adaptive delta modulation and quantization frequency in each fKe channel 32 kHz.

During the existence of the data address 1

go channel DT

 15.6 μs in

2 32 10

32N group delta stream - 256 kBit / s transmits one four delta samples

channel, once during the cycle TC

125 μs.

When the data outputs of the switch-multiplexer (2) are read over time Ac, the combination number is sent to the first group of five address inputs of the ROM (3) delta stream; a five-digit binary code of the number of the control and interaction signal transmitted in this channel is received.

In the ROM (3) of the delta stream, 20 variants of the delta stream are recorded corresponding to the above signals - silent mode, 15 dual-frequency signals and 4 single-frequency ones.

Programming the ROM (3) of the delta stream was carried out by modeling on a microcomputer an adaptive delta encoder, the input of which, starting from the silent mode, received one of 15 dual-frequency signal implementations during a T2 time of 64 ms or one of 4 single-frequency signal implementations over a time of 256 ms.

In the process of modeling the adaptive delta encoder on the microcomputer, the characteristics of the real integrated delta encoder used in the digital EATS-CA equipment were taken into account.

The law of variation of the adaptive quantization step H (n) at the nth step in a real delta encoder and in its model is determined by the algorithm:

H (p) H (p-1) -H (p-1) + D (p), (1) where H (p-1) is the step on the previous (l-1) -th beat; A

H (p-1) - the higher 8 bits corresponding to the integer part of the 17-bit code H (p-1);

D (p) is the increment of the pitch H (p). If there is a stream (train) of delta samples of the same sign with a length of I 4 (for example 1111 or 0000), D (n) 2 and a quantization step

H (p) increases by 2 relative units compared to the previous step H (p-1), otherwise at I 4, D (p) 0. At the same time, regardless of the presence or absence of flow I 4, with each beat, With an IKB quantization frequency of 32 kHz, the step H (n) decreases by about 2

- th part of the previous value of H (p-t /.

1). With increasing signal level at the input

of the real delta encoder (and its model), the step code H (n) grows from the minimum relative value Nmin (0) 1 to a certain steady state. Nust 2av values. The step-up law and the settling time are determined by Algorithm 1 and depend on the peak slope of the signal (its first derivative module) and the type of signal (single-frequency, two-frequency, complex shape). In any case, during the rise

step in the delta encoder, a transition process takes place, which develops as follows: at the beginning, at Nmin (0) 1, the delta encoder is heavily overloaded and at its output long trains of delta counts of the same sign appear, causing a rapid increase in step with each successive step T HQ by value of D 2. As the step H (n) increases, the flux density of the quadruples of delta samples of the same sign begins to decrease,

step growth is gradually slowing. Finally, a dynamic equilibrium occurs, in which the growth and decrease of the step gain equal intensity and are mutually compensated. The transition process of increasing the quantization step in the adaptive deletion encoder is completed, with this step the steady-state step Nust and the settling time are directly proportional to the peak slope

input signal.

The decay of the quantization step after the loss of the signal is performed in accordance with algorithm 1 exponentially with a constant of 29

ts-16 ms, while the step increases by an order of magnitude faster and for signals of average steepness it practically ends within a time of ((1 + 2) ms.

When a delta stream, including a step establishment transient, is supplied to the delta decoder, & the latter begins to develop similar transients, ending in achieving the same steady-state quantization step of HomSt as in the encoder.

Consequently, the information about the NSDL decoder is completely contained in the duration of the transient in the delta stream, and the higher this duration, the greater the value of Empty. Loss of transient information results in a loss of the true Nous value in the decoder, usually located at the other end of the digital communication channel.

In this way. The ROM 3 of the delta stream must be programmed taking into account the transient process, which for each of the 20 types of control and interaction signals develops after the silent mode in different ways.

In order to compensate for the suppression of low frequencies against high because of the nonlinearity of the delta encoder, it is necessary to take measures to equalize the steepness of each of the two frequency components of the signal at the encoder input when transmitting two-frequency dialing digits with a 2 out of 6 code. Because for a sinusoidal signal U (t) A sinon its derivative (steepness) has an amplitude of A А (о, equality A2 (02 leads to a distortion of the amplitudes (A1 / A2) at the input of the delta encoder according to the law ((02 / coi), i.e., vice versa - in proportion to frequencies.

Submitting to the input of the model of the delta encoder two-frequency dialing signals with pre-emphasis according to the law (wz / toj) and recording the received delta streams at the time T2 of 64 ms on the microcomputer floppy then it is possible to program ROM 3 delta streams according to the law. Similarly, the programming of the RAM (3) of the delta stream in the single-frequency mode is carried out, only with Ti 4T2 256 ms. The silent mode corresponds to a stream of the form 101010 ...

The amplitude is A single-frequency signals, and

also low frequencies in each dual frequency

Alternatively, choose from the condition that the transmission level of Pper is -7.3 dB, or A 473 mV. When modeling the delta encoder, it was taken into account that the minimum step in the silent mode is NMin (0) 0.5 mV, in the operating mode Nmin "ImV, Nmzks" 255 mV, A. Depending on the combination number at the first five address inputs of the ROM (3) of the delta stream, one of the 20 possible memory areas of the ROM is selected 3. Continuously changes the codes on the second group of 8 address inputs of the ROM 3 from the second outputs of the generator equipment 1 provides the appearance at the outputs of the ROM 3 fours

0

5

0 5 0

fifty

5

0 5

delta samples of the next channel. Thanks to the 8-bit organization of the output word of the ROM 3 of the delta stream, it is possible to program two four delta samples, even and odd, respectively, at the same ROM address. This allows you to halve the frequency of address change in the second group of 8 address inputs of ROM 3 and provide in one housing chip ROM type K573RF4 and provide in one housing chip ROM type K573RF4 record the full volume of all 20 segments of the delta stream of the desired duration . The change of codes of the number of samples on the second group of address inputs of the ROM 3 of the delta stream occurs with a frequency of F2 2 kHz, the existence time of the address of two successive fours of information (even and odd) in all N 8 channels is T 1 / 2F2 250 μs, according to TC 125 μs for every four. At the same time, the change of codes on the first group of address inputs of the ROM 3 of the delta stream is performed with a frequency of FI 32 kHz of changing the channel numbers on the control inputs of the switch-multiplexer 2 combination numbers, information about which exists during the time T 1 / 2Fi 15.6 μs of the passage of the four delta samples of a given channel. Switching the even and odd quadruples of the delta samples from the outputs of the ROM 3 of the delta stream is performed with a frequency of 2Pr 4 kHz at the inverse control inputs 3 and 4 of the switch 4 of the four quadruplets of the delta samples.

Shift register 5, advanced at its clock input with a frequency of FT NF4, converts the four delta samples at its parallel information inputs into a serial group delta stream at the output (MRC) of kbit / s.

Using a switch-demultiplexer of 6 channels, controlled by its address inputs from the first outputs of the generator equipment 1, group information is distributed over each of the M-channels. At the data input of each channel RAM of group 7, it is received during recording in a sequential code once during a cycle TC 125 µs of four delta samples of this channel during an AT time of 15.6 µs. The memory addresses of RAM 7 for recording and reading information are set by codes from the second outputs of the generator equipment 1. In this case, reading the four information from the moment of recording in each of RAM 7 is stretched uniformly for the cycle time TC -125 μs with a frequency fKe 32 kHz, those. with that

at the same speed as in the one-shot delta encoder.

The write / read and sample modes of RAM 7 are provided respectively from the fifth and sixth outputs of the generator equipment 1.

From the outputs of a group of 7 channel RAMs, individual delta streams are each delivered to the corresponding delta decoder as part of a group of 8 delta decoders according to the number of N-receive channels. At the output of each decoder, a low-frequency analog control and interaction signal transmitted on a given channel appears. Duration T | the output signals of the 1st delta decoder is determined by the time that information exists on the number of a particular combination on a given channel from the 20 possible combination numbers on the data inputs (D1i + D5t) of the switch-multiplexer 2. As already mentioned, normal operation devices are provided at Ta 64 ms for dual-frequency signals, as well as at Ti 256 ms for single-frequency signals. If these conditions are not met with respect to the durations of Ti and T3, phase jumps occur in the output analog signals Ti T1nom and T2 T2nom due to a jump-like change in the memory areas used in the ROM 3 of the delta stream at times multiple of TIHOM or Tan. It should be noted, however, that the receivers of the analogue control and interaction signals as part of the switching equipment of the analogue coordinate exchanges react mainly to the envelope of the signal and rare phase jumps practically do not affect the noise immunity of the reception.

The outputs of group 8 of delta decoders in terms of the number N of transmission channels are the analog outputs of the device, which are in turn fed to the inputs of N analog receivers of control and interaction signals as part of the coordinate exchange. Thus, the digital EAGS-CA and the analog ATSC are coupled during the transmission of control signals and interaction from the EATS CA to the ATSC, while the interface equipment is located on the ATSC.

Claims (1)

The proposed digital group transmitter of control and interaction signals is built on digital integrated circuits, mainly CMOS structures. The 8-channel transmitter is made on one printed circuit board and contains 20 cases of microchips of the K561, K537 and K573 series, as well as 8 cases of specialized LSI delta decoders designed for EATS-CA. Current consumption from power supply,. ± 5% does not exceed h 100 mA, from the power supply of the LSI of the delta decoders Ea + 9V + 5% - not more than 50 mA. SUMMARY OF THE INVENTION A method for generating a digital delta stream of pulses in a group transmitter of control and interaction signals, which consists in generating two-frequency control and interaction signals, adaptively delta modulating them, storing the resulting delta modulation pulses, and then reproducing one of them, characterized in that, in order to increase accuracy, before the adaptive delta modulation, the amplitudes of the two-frequency control signals and the feedback but in proportion to their frequencies, and when storing the resulting delta-modulation pulses, the duration of the adaptation interval for the quantization step of the two-frequency control and interaction signals is simultaneously memorized.