SU972568A1 - Cycle synchronization method in digital data recording and reproducing - Google Patents

Description

The invention relates to a pulse technique, namely, to the technique of recording audio information signals in binary form and reproducing this information, and can be used in digital sound players and tape recorders.

Known methods for direct recording and recording with channel coding.

In direct digital recording of random analog signals, they are converted into a digital signal with a certain frequency, called a cyclic one, as a result of which the information is expressed by n-bit ¹ binary numbers (code words or cycles). In this case, between the end of one and the beginning of the next cycle (or blocks consisting of several cycles), identification signals of the section of cycles (clock signals) are introduced. The information stream of binary symbols with the input sync signals2 is applied to the medium, i.e., the recording itself is carried out directly.

When a record is played back, the synchronization signals are found in the digital stream, i.e., they perform an operation called cyclic synchronization, and thus code words are separated. After that, the code words are sent to the decoder, where the original random analog signal is restored.

When recording with channel coding, all operations are performed in the same order, but after the introduction of the clock signal, channel 15 is additionally encoded using the MPM method or some other method, and during playback, the signal is decoded back from the channel to digital until the clock signals are searched. At ²⁰ to assure correct operation of the device for generating -dekodirovanie, it is fed-clock frequency, the phase position

972568 characters must (block) ·>

with 50% in the previous synchronization method.

However, the obtained recording density is insufficient for digital audio recording on magnetic tape and disk media.

In addition, the method is characterized by the complexity of the equipment that implements it. For example, a device ι intended for detecting a concentrated sync group necessarily includes a register, a shift (in beats) of at least equal to the length of the sync group or the length of the digital i stream on which the distributed sync group is distributed ..

Since, when recording with channel coding, the playback device contains a channel signal decoder, it is necessary to provide signals with a clock frequency, the phase position of which relative to the boundaries of the symbols 25 of the original digital signal, is strictly determined, i.e., setting information on which the boundaries of the original digital signal to be strictly defined.

A known method of cyclic synchronization in the direct recording-playback of digital information, in which between the end of one and the beginning of the next cycle (block) enter the clock signal in the form of a single clock pulse, physically different from the pulses of the digital stream of useful information, for example, in the form of a round spot (for photographic recording ), the diameter of which is approximately two times larger than the diameter of the spots corresponding to units of useful information, G1].

The disadvantages of the method are that the recording density of useful information, compared with recording without sync pulses, is reduced by as many times as the diameter of the sync pulse is larger than the diameter of a single pulse of useful information (since the recording tracks in this case are located less frequently).

In addition, a device that implements the method is rather complicated, since it includes an optical readout circuit ₃₀ , which should include an analyzer of the diameter of the readout spot.

Closest to the invention in technical essence is a method of cyclic (block) synchronization during recording-reproduction of digital information, in which the clock signal is generated in the form of a group of pulses called a sync group. A sync group can be either concentrated or dispersed. In the first case, a constant code combination is introduced at the border of information cycles (blocks), the probability of occurrence of which in a continuous digital stream is minimal. In the second case, only a part of the synchronization group is introduced at the border of cycles (blocks), the next part is introduced at the next border of cycles (blocks) and t d. C 2].

The synchronization method provides a more dense record of information. So, · in this case, synchro-groups usually have a length of 15 ~ 40 cycles, which with a total cycle (block) length; 3 records of 128 cycles (most often used in digital sound recording systems) is about 10-30% compared to the device phase;

in case of using us35

However, the tanning group there is a need to highlight it in a continuous stream of useful information, in other words, interrupt the information stream to record the installation group and mark the group accordingly. And this leads to a significant complication of the circuit of the device for setting the phase of the synchronizer.

The aim of the invention is to increase the recording density and simplification of the device for implementing the method of cyclic synchronization when recording and reproducing audio information in digital form.

This goal is achieved by the fact that according to the method of cyclic synchronization in the recording-playback of digital information, which consists in introducing at the boundaries of the code words of sync groups in channel coding, cyclic synchronization is carried out in the process of converting the information signal into a channel by introducing sync intervals at the borders of cycles, the duration of which exceeds the maximum interval of the channel code by half the clock interval for one binary binary following it • 55 information values ion signal and a whole clock interval for a different value, and during playback, the selection of the clock intervals is performed by selecting them by duration. ₅

In FIG. 1 is a timing chart in the case of introducing a sync interval, subject to channel coding, for example, using the IMF method; in FIG. 2 is a block diagram of a device for setting the phase of the synchronizer during decoding; in FIG. 3 timelines of his work.

• The method is as follows. ,5

The original digital signal with <(Fig. 1) enters the coding device with cycles (blocks) of, for example, 13 clock cycles. In addition, _Μ δ clock pulses with a duration of three cycles, the following time between cycles, arrive at the encoding device. As a result, the conversion channel signal 8 will have sinhrointervaly starting at the beginning of clock pulse 5, wherein the length sinhrointervala is ST (T _B = T _m and _COP + T) if the first stroke following the sinhrointervalom cycle (in this sluchae_. '' K) - unit and 2.5 T (T _si = T _max + zo + 0.5 T). If the first clock cycle of the next `` cycle '' (K + 1) is zero, T _ms4hc for channel coding by the _MPM method is 2T.

Thus, the proposed method, in which the operations of introducing a clock signal and channel coding are combined, as well as the operations of channel decoding and cycle synchronization, allows for a more dense recording of information. The proposed method is also characterized by the simplification of the installation unit phase synchronizer when decoding a channel signal.

The phase setting device (Fig. 2) contains a block 1 for extracting a double clock frequency from a channel signal, three | - a frequency divider 2, a decoder 3 for a channel signal and a block for selecting clock pulses, and one input of the block for selecting 4 clock pulses is connected to the input phase setting device, the other input of block 4 is connected to the output of block 1. allocating twice the clock frequency from the channel signal, and the output of block 4 is connected to the second input of trigger 2.

The device operates as follows.

The channel signal δ, (Fig. 3)> corresponding to the original digital signal O, is fed to the double frequency extraction unit 1, which in the trigger divider 2 is divided into two and forms the clock frequency g. The signals δ and g are fed to decoder 3, by the output of which signal d is the reconstructed original digital signal o. Until the sync pulse is separated into the phase of signal g, it is inverse and does not provide the correct signal recovery q. Correct restoration is provided from the moment the clock pulse arrives at the second input of trigger 2. The clock pulse e at the output of block 4 appears when a clock interval appears in signal b.

The advantage of the proposed method when using the described device in comparison with the known consists in the following.

It is not necessary to transmit a special group of characters intended to perform only the required installation operation. Due to this, the operational qualities of the device are improved (maintenance is simplified) and the circuitry of the decoder is simplified, as well as the recording density is increased, since there is no need to allocate an additional time interval and, accordingly, the track section for recording this installation group.

In addition, a special unit for isolating the installation pulse is not required, since a cyclic clock is used for this purpose, and the decoder phase is set up with a pulse extracted from the clock intervals.

Claims (2)

The invention relates to a pulse technique, namely, to a technique of recording audio information signals in binary form and reproducing this information, and can be used in digital sound players and tape recorders. Methods of direct recording and recording with channel coding are known. With direct digital recording of random analog signals, they are converted into a digital signal at a certain frequency, called a cycle signal, with the result that the information is expressed as n-bit binary numbers (code layers or cycles). In this case, between the end of one cycle and the beginning of the next cycle (or blocks consisting of several cycles), the identification signals of the cycle section (sync signal) are introduced. The information stream of binary symbols with the inputted sync signals is plotted on the carrier, i.e. the recording itself is carried out. When playing a recording in the digital stream, the sync signals are found, i.e., an operation called frame alignment is performed, and thus the code words are separated. After that, the codewords are sent to a decoder, where the original random analog signal is restored. When recording with channel coding, all operations are performed in the same order, but after the input of the sync signal, channel coding is additionally performed using the MFM method or some other method, and during playback, prior to searching for the sync signals, the signal is reversed from channel to digital. At the same time, in order to ensure the correct functioning of the device producing -decoding, it is supplied with a clock frequency, the phase position of which relative to the character boundaries of the source digital signal must be strictly defined. A known method of cyclic (bloom) synchronization with direct recording and reproduction of digital information, in which a sync signal is inserted between the end of one and the beginning of the next cycle (block) in the form of a single sync pulse physically different from the pulses of the digital payload, for example, tn (for photographic recordings), the diameter of which is approximately two times larger than the diameter of the spots corresponding to units of useful information 1. The disadvantages of the method are that the recording density of useful information, as compared to recording without sync pulses, decreases by as many times as the diameter of the sync pulse is larger than the diameter of a single pulse of useful information (since the recording tracks are in this case less often). In addition, the device that implements the method is quite difficult, since it includes an optical readout circuit, which must include an analyzer for the diameter of the spot readable. The closest to the invention according to the technical nature is the method of cyclic (block) synchronization during the recording-reproduction of digital information, in which a sync signal is inserted as a group of pulses, called a sync group. A sync group can be both concentrated and dispersed. In the first case, on the border of the cycles (blocks) of information, a constant code combination is entered, the probability of occurrence of which in a continuous digital stream is minimal. In the second case, on the border of the cycles (blocks), only a part of the synchro group is entered, the next part is entered on the next border of the cycles (blocks), etc. From 2. The synchronization method provides a more dense recording of information. So in this case, sync groups usually have a cycle length, which, with a total cycle length (block). Records of 128 cycles (most often used in digital audio recording systems) are about 10-30% compared to 9 84 with 50% in the previous way to sync. However, the resulting recording density is not sufficient for digital audio recording on magnetic tape and disc media. In addition, the method is characterized by the complexity of the equipment implementing it. For example, a device for detecting a lumped synchro group necessarily includes a register. shift 1 and length (in cycles) at least equal to the length of the sync group or the length of the digital stream on which the concentrated sync group is distributed. Since during recording with channel coding, the playback device contains a decoder of the channel signal, it is necessary to feed it to ensure correct functioning of the decoder signals with a clock frequency, whose phase position relative to the character boundaries of the original digital signal is strictly defined, i.e. the playback device must include a phase setting device; However, in the case of using a setup group, it is necessary to allocate it in a continuous stream of useful information, in other words, interrupt the information flow in order to record the setup group and label the group accordingly. And this leads to a significant complication of the device circuit installation phase synchronizer. The aim of the invention is to increase the recording density and simplify the device for implementing the method of frame synchronization when recording and playing audio information in digital form. This goal is achieved by the fact that according to the frame synchronization method when recording and reproducing digital information, involving the introduction of sync groups in channel coding at the boundaries of the code words, cycle synchronization is performed during the process of converting the information signal into a channel signal by introducing synchrointervals at the boundaries of cycles, the duration of which exceeds the maximum interval of the channel code is half the clock interval for the one binary value 59 that follows it th signal and a clock interval of values for another, and the playback selection sinhrointervalov t derivatives by selection of their length. FIG. 1 shows a timing diagram in the case of the introduction of sync intervals P | ei under the condition of the implementation of channel coding, for example, by the IMF method; in fig. 2 is a block diagram of a device for setting the phase of the synchronizer during decoding; in fig. 3 time diagrams of his work. The method is carried out as follows. The original digital-c signal (Fig. Arrives at the encoding, equipment cycles (blocks) with a length of, for example, 13 cycles. In addition, the coding device receives sync pulses 5 of three clocks duration, which are in time between cycles). As a result of the conversion, the channel signal 8 will have synchrointervals, starting at the moment of the start of the sync pulse 5, and the synchrointer + T length, the evalval is equal to ST (T is the first clock cycle following the sync interval (in this case, K) - one and 2.5 T (T (.and + Oj5 T). If the first beat of the next after The inter-frame loop (K + 1), when channel coding by the method of the MPM, is 2T. Thus, the proposed method combining the sync signal input and channel coding, as well as the channel decoding and frame synchronization operations, allows for a more dense recording of information. The method also differs in simplifying the synchronizer phase setting block when decoding a channel signal. The phase setting device (Fig. 2) contains a doubled clock frequency selection unit 1 from a channel signal, three | - frequency divider 2, an analog signal decoder 3, and a sync pulse allocation unit k, with one input of the sync pulse allocation unit connected to the device input phase setting, another input of the block C is connected to the output of the block 1. extracting the doubled clock frequency from the channel signal, and the output of the block k is connected to the second input of the trigger 2. 8 The device operates as follows. The channel signal 6, (fig. 3) corresponding to the original digital signal d, is fed to the double frequency selection block 1, which is divided into two in the splitter divider 2 and forms the clock frequency r. The signals 5 and d are fed to the decoder 3, at the output which signal d is a reconstructed original digital signal and. Until the release of the sync pulse e, the phase of the signal r is inverse and does not ensure the correct recovery of the signal. Ever recovery is provided from the moment the sync pulse arrives at the second trigger input. 2. A sync pulse at the output of the C block appears when a syncinterval appears in the signal b. The advantage of the proposed method when using the described device in comparison with the known is as follows. There is no need to transmit a special group of characters intended to perform only the required installation operation. This improves the performance of the device (simplifies maintenance) and simplifies the circuit design of the decoder, and also increases the recording density, since there is no need to allocate an additional time interval and, accordingly, the track section to record this setting group. In addition, a special setup pulse separation unit is not required, since a cyclic clock pulse is used for this purpose; The phase setting of the decoder is made by a pulse emitted from the sync intervals. Claims The method of frame synchronization in recording-reproducing digital information, which consists in introducing sync groups at channel coding boundaries in channel coding, characterized in that in order to increase the recording density, frame synchronization is performed in the process of converting the information signal into the channel by introducing on the boundaries of the cycles of synchrointervals, the duration of which exceeds the maxi79725688 the maximum interval of the channel code on the sources of information half of the clock interval for one taken into account during the examination of the binary sign that follows it. 1. US Patent No. 3,795,902, information signal and at the center. 3 0/173, publ. 19b5. second clock interval for another zn-5 2. Shlepobersky B, I. The basics of technical reproduction of discrete message allocations, synchrointerval is produced by selek-m., bond, 1973, p. 296-298 (prototsii them for the duration.type); l t // f / ,, a 1 i J L 7I71g.7 | 7171ff | 7 | g 7 7 71, o..o   W. P GL CLfHJ (pO f / 3Cf / 77 (p / / c f g //./ PGGL 1 g FIG. f O // € lf, S / fff / Cf / a S USH z j li finiL s, o..ff.o.  I I / fOf / ff / fO / fO / rff f m0. (P ffV ff0WV ffW ff.