DE2661093C2 - - Google Patents

Description

The invention relates to a device for playback a binary recorded input signal after the upper Concept of claim 1.

In the Journal of the Audio Engineering Society, September 1973, Vol. 21, No. 7, pages 535 to 548, is a device described using the PCM-digitized audio signals recorded intermittently on a recording medium be net.

According to AD converters, there is a continuous input signal current of digital information of a given bit Rate ahead as the audio signals are processed in real time will. This continuous stream of digital information NEN is divided into sections with gaps. Because in the Gaps between sections no information be drawn, the processing of digitized Audio signals must be done in real time, however Compress sections. This happens because the digital information from a memory with a ver larger, predetermined bit rate can be read out like this from US-PS 37 89 137 and US-PS 38 60 760 prinzi is known piell. Then on the playback page in reverse order the compressed recorded Continuous output recovery signal audio signals expanded.

In US-PS 37 63 328 a device is described the gaps in a scanned record under Ver application of the principles of time compression and time expansion sion closes. In this device, a switch divides a continuous stream of data in two from each other separated channels. The two channels get alternating one section of the data stream each. In every channel there is a delay line that goes through everyone delayed section passing through it.  

The delay of each section of the data stream changes along its length, making it uneven moderate compression of the sections gives: The delay each section takes from its beginning to its End from. So the compression is greatest at the beginning and then becomes less, so that at the end of each Section no longer occurs. The from the ver delay lines emerging compressed sections are combined in an adder, so that a sequence kompri sections. The sections are through Gaps are separated from one another and are traces of one Recording medium recorded.

When reading the recorded compressed section The read information is divided and two channels fed through a switch so that each Channel alternating a section of the read data receives electricity. These two channels are delayed provided lines that the sections to their original length reversed analogously as before recording expand so that the gaps in the data stream are closed will be. The expanded sections are then in an adder to form a continuous data streams united.

In US-PS 37 89 137 is one device at the time compression of audio signals described. This device device contains a low-pass filter to which an audio signal to be led. The filtered signal arrives in a Analog-to-digital converter. The digitized signal is fed to a shift register at a first clock rate and from the shift register at a second clock rate read to compress the digitized signals. The compressed digital signal is then converted into an audio signal converted using a digital-to-analog converter. The analog output signal of the digital-analog converter arrives through a low-pass filter to an FM oscillator. The modulated analog signal is compressed in on a  Recording medium recorded.

If the recorded information from the recording medium to be read, this is done in similar to how it was recorded. That of the up Analog signal read from the drawing medium passes through a low-pass filter in an analog-to-digital converter. The first read from the recording medium, vice versa converted digital information gets into a slide register and are saved there. The record medium is moved before a subsequent digital information is fed to the shift register. This ent there are gaps in the digital information. The digital information with the dividing them into sections Gaps are covered by a digital-to-analog converter and a Low pass filter output.

The gaps between the sections have a length of time which a recording or reading head needs in order to the correct recording or reading position for opening drawing or reading of a next data section to get. The device according to US-PS 37 89 137 therefore leads to gaps in the information read as planned one.

The object of the invention is a device according to the The preamble of claim 1 specify the simpler How to write and read the memory allowed tet without the memory being overfilled.

The solution to this problem is the hallmark of the claim 1 specified.

Advantageous embodiments of the invention are in the Un specified claims.

The invention is illustrated below in one embodiment  game with reference to the attached drawings wrote. It shows:

Fig. 1 is a block diagram of an electronic circuit for binary recording of input signals,

Fig. 2 is a block diagram of an electronic circuit for reproducing the recorded signals,

Fig. 3 is a diagram of a typical course of the recorded signals,

Fig. 4 is a plan view of a recording medium with recorded signals.

In Figs. 1 and 2 are block diagrams are shown of electronic circuits which receive a continuous sequence of binary input signals, divide this sequence into segments and the segments write time-compressed in tracks on a recording medium, said small blanking intervals remain between the segments. The blanking gaps result from the temporal compression of the segments. When the segments are read out, the segments are stretched over time, so that the blanking gaps disappear.

FIG. 3 shows a time course of television signals, a complete horizontal line 264 having a segment and a horizontal blanking pulse 266 . There are sample gaps 268 between sequences of horizontal lines 64 , which can form vertical blanking pulses.

A plurality of horizontal lines 264 may be recorded in a given track 284 on tape 14 in FIG . The band 14 , apart from the signals recorded in tracks 284 , is transparent. The recorded signals can be in the form of digital points, the spacing of which in a line 264 is very narrow. The tracks 284 are very close apart. The tracks 284 run diagonally over the belt 14 and can be successively scanned by lenses in a grid-like manner while the belt 14 is moved in its longitudinal direction. The beginning of each track 284 is therefore almost at the same level as the end of the immediately preceding track 284 . The sampling gaps 268 correspond to the short times between the end of one track 284 and the beginning of the next track 284 .

In the arrangement of Fig. 1 binary input signals and an input clock U in a read-write memory 234 are fed. The memory 234 is reset by an AND gate 238 when this gate 238 holds a horizontal synchronizing pulse, a vertical synchronizing pulse and a scan start indication signal from a control stage, thereby indicating that a scanning beam is at the beginning of a line to be scanned 264 is located, thereby resetting an up-down counter 236 . The signals of a line 264 are then fed into the memory 234 at a repetition frequency determined by the input clock U. At the same time, the up-down counter 236 , which is controlled by the input clock U and an output clock D, counts up. However, no signals are read out from the memory 234 until a full condition of the memory 234 is fulfilled. If this is the case, the counter 236 triggers a flip-flop 240 in such a way that an AND gate 244 is activated.

The output clock D then fed from a clock generator 242 via the gate 244 into the memory 234 effects the reading of the signals from the memory 234 for recording on the tape 14 . The speed of a recording rotary head is controlled so that a recording beam from a lens array generates the tracks 284 on the tape 14 . The scan start indication signal for gate 238 is conveniently obtained from a detector responsive to marks on the head to drive gate 238 to the start of a track 284 when the scan beam is in a position in which the signals have no timing Compression would start. This location corresponds to the end of each track 284 . The speed of the head determines the input clock U.

During the recording of the signals in a track 284 , the output clock D of the clock generator 242 is also fed via the gate 244 into the up-down counter 236 , whereby this counts down until an empty condition of the memory 234 is fulfilled. If this is the case, flip-flop 240 is switched over and gate 244 is thereby blocked. A new gap 268 now occurs. The output clock D of the clock generator 242 is also fed via a gate 248 into a counter 250 dividing by a factor N. N is the number of clock bits per track 284 . N is therefore also the number of bits in a sequence of lines 264 delimited by sampling gaps 268 . The counter 250 delivers an output signal to a phase detector 246 at the end of a track 284 and switches off its own input via a lock input of the gate 248 . At the same time, the up-down counter 236 also provides an empty signal to the phase detector 246 at the end of a track 284 . If the pulse edges of the input signals from the two counters 236 , 250 to the phase detector 246 do not coincide, the phase detector 246 provides an analog signal for adjusting the clock generator 242 to the correct frequency, so that the correct phase is set at the end of each track 284 , whereby a desired gap 268 and a desired data flow are ensured. The counter 250 is reset by a "full" output of the up-down counter 236 , which indicates the start of a track 284 .

Fig. 2 shows a block diagram of an electronic circuit for generating a continuous output signal from the signals recorded in the tracks 284 , as is necessary, for example, for sound and video purposes. The signals are supplied as input data, for example from a playback detector, and are synchronized with an input clock U of a clock generator 272 . An output clock D, which is fed into a memory 252 and into an up-down counter 280 , is expediently obtained from a reference standard, for example from the color reference standard of a color television receiver.

The memory 252 is expediently a read-write memory corresponding to the memory 234 in FIG. 1. The input data coming from the playback detector are fed into the memory 252 and into a data start detector. The data start detector is formed by a diode 254 coupled to an input of an amplifier 262 coupled to an integrating parallel RC element from a capacitor 256 and a resistor 258 to ground. A second input of amplifier 262 is connected to a tap of a potentiometer 260 , the end terminals of which are connected to voltages that are suitable for adjusting a threshold value. The cathode of diode 254 is on amplifier 262 and provides amplifier 262 with a positive signal at the end of each sample gap 268 , which resets flip-flop 270 . The input and output of amplifier 262 remain "high" for the duration of scanning a track 284 until the next sampling gap 268 is detected, whereupon amplifier 362 is then reset according to the setting of potentiometer 260 . The charge on capacitance 256 is discharged through resistor 258 , after which the data start detector is ready to generate the next positive signal at the end of a sampling gap 268 .

At the beginning of the input data, the output signal of the amplifier 262 resets the memory 252 , a counter 278 dividing by the factor N, the counter 280 and the flip-flop 270 . The flip-flop 270 then turns on an AND gate 274 , which then inputs the input clock U from the clock generator 272 into the memory 252 , so that the input data are stored in the memory 252 . While scanning a track 284 , signals are input into memory 252 faster than read out. The counter 280 , which records the input clock U and the output clock D for the memory 252 , is used to determine when the memory 252 is full. If this is the case, an output signal is fed into a comparator 282 . During the scanning of tracks 284, counter 278 , which receives signals from clock generator 272 via a gate 276, counts the number of clock bits per track 284 and supplies an output signal to comparator 282 at the end of each track 284 , which also transmits its own input a blocking input of gate 276 blocks. When the pulse edges of the output signals of both the comparator 282 supplying counters 278, 280 do not coincide provides the Compa rator 282, an analog voltage for setting the speed of a Abtastrotationskopfes a Wiedergabevorrich tung, so that a continuous output signal is generated.

The duration of a scanning gap 268 can be chosen so that 14 indexing marks can be attached to the edge of the tape, which are scanned by a detector. If such indexing marks are to be scanned by a light beam, the detector contains a light source, for example a laser, and a photo detector.

Claims (5)

1. A device for reproducing a binary recorded input signal which is recorded in segments ( 265 ) on tracks ( 284 ) of a recording medium ( 14 ) compressed at a first bit rate and as a continuous binary output signal at a second bit rate, which is smaller than the first bit rate, is reproduced ge, with a memory ( 252 ) in which, controlled by an input clock (U), the binary input signals recorded at the first bit rate are written and from which controlled by an Output clock (D) the output signal is read at the second bit rate, characterized in that a comparator ( 282 ) the number of bits written into the memory ( 252 ) in a predetermined time period corresponding to the number of clocks of the input clock (U) with the Number of bits read from the memory ( 252 ) in the same time period corresponding to the number of clocks of the output clock (D) in the same time pe period compared to a predetermined relationship and controls the speed of a drive device of a reproducing device according to the result of the comparison. 2. Device according to claim 1, characterized in that the comparator ( 282 ) compares the bits since the beginning of the respective segments ( 265 ). 3. Apparatus according to claim 1 or 2, characterized in that it has a counter ( 280 ) controlled with the input clock (U) and the output clock (U, D). 4. Device according to one of the preceding claims, characterized in that the comparator ( 282 ) determines the difference from the written bits and the read bits. 5. Device according to one of the preceding claims, characterized in that the comparator ( 282 ) controls a motor via a servo mechanism that determines the Ge speed of the drive device of the playback device.