GB2117549A - Security marking video tape recordings - Google Patents
Security marking video tape recordings Download PDFInfo
- Publication number
- GB2117549A GB2117549A GB08208156A GB8208156A GB2117549A GB 2117549 A GB2117549 A GB 2117549A GB 08208156 A GB08208156 A GB 08208156A GB 8208156 A GB8208156 A GB 8208156A GB 2117549 A GB2117549 A GB 2117549A
- Authority
- GB
- United Kingdom
- Prior art keywords
- control
- recording
- tape
- security
- video
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 238000000034 method Methods 0.000 claims description 20
- 230000000694 effects Effects 0.000 claims description 5
- 238000012544 monitoring process Methods 0.000 claims description 2
- 230000001419 dependent effect Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 5
- 230000007246 mechanism Effects 0.000 description 4
- 238000000926 separation method Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000002789 length control Methods 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 230000005236 sound signal Effects 0.000 description 1
- 238000003079 width control Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
- G11B23/28—Indicating or preventing prior or unauthorised use, e.g. cassettes with sealing or locking means, write-protect devices for discs
- G11B23/283—Security features, e.g. digital codes
- G11B23/284—Security features, e.g. digital codes on the record carrier
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
- G11B20/00094—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy involving measures which result in a restriction to authorised record carriers
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
- G11B20/00086—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy
- G11B20/00876—Circuits for prevention of unauthorised reproduction or copying, e.g. piracy wherein physical copy protection means are attached to the medium, e.g. holograms, sensors, or additional semiconductor circuitry
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
- G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
- G11B27/19—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
- G11B27/28—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
- G11B27/32—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on separate auxiliary tracks of the same or an auxiliary record carrier
Landscapes
- Engineering & Computer Science (AREA)
- Computer Security & Cryptography (AREA)
- Signal Processing (AREA)
- Signal Processing For Digital Recording And Reproducing (AREA)
- Indexing, Searching, Synchronizing, And The Amount Of Synchronization Travel Of Record Carriers (AREA)
- Management Or Editing Of Information On Record Carriers (AREA)
Abstract
A video tape recorder is adapted to record security code markings on a tape when recording. The markings are produced in the control track of the tape and do not affect normal playback. Control pulses from a sync separator (13) which are normally stretched to, say, 28 mS for recording on the control track are fed to a further switchable pulse stretcher (17) controlled by a modulator control (18). The pulse stretcher (17) selectively alters the width of control pulses from 28 mS to, say, 18 mS in accordance with code from the control (18) to pulse width modulate the pulses. Leading edges of the pulses which are employed for timing during playback are not affected.
Description
SPECIFICATION
Security marking video tape recordings
The present invention relates to security marking video tape recordings.
With the increasing popularity of video tape recorders and the growing market for prerecorded video tapes, increasing attention is being paid to the problem of illegal copying of video tape recordings. So called "piracy" of copyright video tape recordings is becoming increasingly prevalent resulting in significant financial losses to the owners of the copyright in the recorded material.
As a result, considerable effort is being made at the present time to develop systems for defeating illegal copying or piracy, or at least making it substantially more difficult.
At present, it is only necessary for an intending illegal copier to acquire the necessary video tape recording apparatus and buy or rent a single copy of a copyright pre-recorded tape. It is then straightforward for duplicates of the original tape to be made which the pirate can then sell.
Hitherto, considerable effort has been put into devising a system for 'doctoring" the original copyright pre-recorded video tapes to make them impossible or difficult to copy.
However no satisfactory method of doctoring the recording has been found which does not cause an unsatisfactory degree of interference to the video recording on normal playback.
The present invention is concerned with a method of security marking an original copyright video tape recording which can enable any tampering with the original recording to be detected subsequently and also allows original copyright recordings to be distinguished from illegal copies.
It will be understood that substantially all video tape recording methods presently available include a system of recording control pulses in a separate control track on the tape.
Both the well known V.H.S. and the Betamax systems record control pulses in a separate control track in this way. The control pulses are derived from the original video sync pulses but comprise a single pulse per T.V.
field of the video signal. The control pulses are picked up and used on playback of the video tape to servo control the tape transport and head drive mechanisms of the replay machine to ensure proper synchronisation with the recorded video signals on the tape.
According to one aspect of the present invention there is provided a method of security marking a video tape recording of a kind having control pulses recorded in a separate control track on the tape, the method comprising recording a predetermined security code signal on said control track, the security code signal being selected and arranged not to interfere with the normal effect of the control pulses recorded on the control track during playback.
By recording the predetermined security code on the control track of the tape recording, the security code is not reproduced by a normal playback machine in a form in which it can be again recorded onto a slaved recorder.
Thus, if an original copyright tape is marked in accordance with the method of the invention, any illegal copies made from the marked recording will not have the security marking.
As a result it will be possible to detect illegal copies subsequently. It is believed this will have an important deterent effect on illegal copying and will also enable illegal copies more easily to be tracked down so that prosecutions can be launched against the copiers.
For example, it has been a practice hitherto for illegal copiers to rent a copyright version of a new video recording in the normal way from a legitimate source. The copier then makes a first set of illegal copies on his equipment and sometimes goes to the length of removing the original copyright recording tape from the original cassette holder and replacing the contents with one of his illegal copies, so that he retains the original legal tape to use as a master for future copying.
This practice will be detectable immediately on return of the copy tape in the original cassette to the rental establishment since the copy will not include the original security marking. It is believed that this will have an important effect on video recording piracy.
Furthermore, it can be seen that there is a considerable advantage in easily being able to check video recordings on sale in various stores to see that they are indeed correctly security marked and therefore proper copyright versions.
Preferably, the security code signal is recorded when recording video on said tape by applying a coded modulation to the control pulses recorded on the control track. Conveniently the coded modulation is width modulation effected without altering the timing of the edges of the control pulses responsible for synchronising control of the video playing apparatus during playback. It will be understood that only usually the leading edges of the control pulses recorded on the control track of a video recording are used on playback to synchronise the transport and head drive mechanisms of the playback machine.
Thus, the trailing edge of the control pulse can be altered, effectively altering the width of the control pulse, without affecting the usefulness of the control pulses for their normal synchronising task.
In a preferred example, the security code signal has a predetermined duration, during recording and/or playback, and is located only at a selected position along the length of the tape. This would make much more difficult and impracticable the task of locating the security marking on an original copyright tape recording and providing an equivalent marking on all illegal copies. The location of the security marking on any particular original recording or batch of recordings could be predetermined, e.g. by means of a computer generated random number, such that only appropriate detecting apparatus in the hands of the legal purveyors of recording could locate the position of the security marking and check that a particular recording is indeed an original legal version.
The present invention also envisages the provision of video tape recording apparatus which records control pulses in a separate control track during video recording on the tape, and being adapted to security mark the recording, the apparatus including a pulse width modulator arranged for selectively modulating the width of the control pulses being recorded on the control track without altering the timing of the edges of the control pulses responsible for synchronising control of the video playing apparatus during playback, and an encoder to control the modulator to apply a coded modulation. Conveniently, the apparatus may include location control means arranged to control the modulator to apply said modulation only at a selected location along the length of the tape.
Further, the invention envisages apparatus for detecting security markings on video tape recordings as produced by the above described method and apparatus, the detecting apparatus including a playback head arranged to pick up control pulses recorded in the control track of a recording, pulse width detecting means providing an indication of the width of the control pulses from the head, and demodulator means responsive to detecting said coded modulation of the width of the control pulses to provide an output indication that a security marking is present.Preferably, the detecting apparatus includes store means containing data defining the correct selected location along the tape of the coded modulation for the respective recording and location monitoring means responsive to provide said output indication that a security mark is present only if the actual location of any detected coded modulation coincides with the stored correct location.
The invention still further envisages a method of marking a video tape recording, of the kind having control pulses recorded in a separate control track on the tape, to provide a security marking or a control function during playback, the method comprising pulse width modulating in a predetermined fashion the control pulses recorded on the control track without altering the timing of the edges of the control pulses responsible for synchronising control of the video playing apparatus during playback.
Examples and embodiments of the present invention will now be described in more detail with reference to the accompanying drawings in which:
Figure 1 is a block schematic diagram of a video tape recorder incorporating a simple form of security marking apparatus;
Figure 2 is a block schematic diagram illustrating modifications to a video playback machine which enable the presence of a security marking to be indicated;
Figure 3 is a schematic illustration of a portion of recorded video tape illustrating the distribution of recorded tracks on the tape;
Figure 4 is a block schematic diagram of a practicable system for security marking video tape recordings as they are produced in batches; and
Figure 5 is a block schematic diagram of a security marking detecting system for detecting encoded security markings applied by the system of Fig. 4.
With reference to Fig. 1, a simplified block diagram of a typical video recording system is illustrated. Complete raw video from the desired source is supplied on a line 10 and fed to an F.M. modulator 11 for modulation to a suitable carrier for recording on the magnetic recording tape by means of a recording head 12. At the same time, the raw video 10 is supplied to a sync separation unit 13 in which the sync pulses contained in the video signal are separated out and employed to produce a vertical sync reference pulse on an output line 14. The vertical sync reference pulse is used as a control pulse in the recording process.
The control pulse generated on line 14 may be a short duration pulse which is coincident with alternate vertical sync periods of the video sync pulse stream. The output on line 14 from the sync separation unit 13 is supplied to a monostable 15 which simply stretches the sync pulse to a standard pulse width for ease of recording the control pulses on the control track of the tape. The monostable 15 is a standard part of video tape recorders and the typical width of the control pulses produced by the monostable 15 is about 28 milliseconds. It will be appreciated that only the leading edges of the stretched pulses from the monostable 15 have a critical timing relationship to the original video sync pulses. In a normal video tape recorder, the stretched control pulses from the monostable 15 are fed directly (via appropriate buffer amplifiers if necessary) to a control track head 16 which records the control pulses in the control track on the magnetic tape during the recording process.
In Fig. 1, the usual video tape recorder is modified by the inclusion of a further monostable device 17 between the normal monostable 15 and the control track head 16. When activated, the monostable 17 is arranged to produce a relatively shorter width pulse, typically of 18 milliseconds and feed this to the control track head 16 instead of the usual 28 milliseconds control pulse. The leading edge of the pulses are unaltered by the monostable 17 so that the control effect on playback of the recorded control pulses is also unaffected.
The activation of the monostable 17 is controlled by a modulator controlled unit 18 so as to shorten the control pulses recorded by the head 16 selectively in accordance with a desired code. It will be understood that when not activated, the monostable 17 permits the control pulses generated by the monostable 15 to pass directly to the head 16.
In the present example, the original monostable 15 of a video tape recorder has been retained to simplify modification. It will be appreciated, however, that a single variable monostable may be included between the sync separation unit 13 and the control track head 16. The single monostable could then be controlled by the control unit 18 to supply control pulses of selected varied widths in accordance with desired coding.
The coding provided by the modulator control 18 can apply various selected data to the tape during recording. In the simplest form, the coding simply applies one or a succession of relatively shortened (or lengthened) control pulses; so that the presence or absence of the different length control pulses act as a security marking on the tape recording. However, the encoding of the modulation may be arranged to encode data, such as the date, time, batch number, etc. of the respective tape recording. At the same time of course the absence or presence of the encoded data provides the security marking.
Still further, the pulse width modulation of the control pulses could be used to control additional accessory equipment during replay of the video recording, for example editing operation, lighting, or sound track control.
It will be appreciated that the coded modulation of the control pulses may be applied to the video recording only at a particular location along the length of the tape. The location itself can provide an extra security feature.
The modulator control 18 is then arranged to apply the coded modulation only at a predetermined selected location along the tape and to store the location against the serial or batch number for the particular recording. The security value of the modulation is then enhanced because the location of any coded modulation on a particular tape recording can be compared against the stored selected location for that recording.
Fig. 2 illustrates a simple system for detecting width modulation of control pulses during playback of a video tape recording. The usual control track head 20 of the playback machine picks up the control pulses recorded in the control track on the tape recording and supplies corresponding pulse signals on a line 21 to the usual servo control 22 of the machine. It will be appreciated that the square wave control pulses originally applied to a control track head during recording of the tape are picked up by the head 20 during playback as positive and negative going impulses corresponding to the leading and trailing edges of the original square wave pulse.
Normally, the servo control unit 22 is responsive only to the timing of the leading edge impulses of the detected signal to control the transport and head rotation mechanisms of the playback machine. The detected control pulse signal is supplied in the illustrated example also to a pulse shaper 23 which amplifies the detected signal and restores the square wave shape of the original recorded control pulses. The square wave output of the pulse shaper 23 is then supplied to an integrator 24 which is arranged to integrate the control pulses and provide a DC output signal on a line 25 having a DC level corresponding to the mark/space ratio of the square wave pulses from the shaper 23. It can be seen therefore that the DC level on line 25 varies in accordance with variations in the width of the original control pulses recorded on the tape.
The DC level output from the integrator 24 is supplied to a level detector 26 which is itself arranged to supply energising voltage to a light emitting diode 27 only if the DC level on line 25 falls below a predetermined threshold indicating a succession of relatively short control pulses.
Thus, this simple system enables a security marking comprising a succession of reduced width control pulses on the control track to be detected and provide indication by illuminating the LED 27.
Fig. 3 illustrates a typical track format on a length of magnetic video recording tape 30.
The video signal itself is recorded in successive sweeps 31 diagonally across the width of tape. The diagonal sweeps are produced by the usual helical scanning system of video tape recorders commonly available. However, at a top edge 32 of the tape, a longitudinal track 33 is left and used for recording the audio signal associated with the particular video recording. Also at a bottom edge 34 of the tape, a further longitudinal track 35 is left and used as the control track. The control pulses are recorded in the control track 35 and picked up by the control track head of the playback machine as described above. Thus, the coded modulation providing the security marking of a video recording as described in the present specification is physically recorded in the control track 35.The material recorded in the control track 35 is not reproduced in the usual output signal from a video playback machine and thus it can not normally be reproduced by an ordinary duplicating operation between machines in playback and recording modes.
Fig. 4 illustrates a more comprehensive system for encoding security markings on mass produced video recordings. When mass producing video recordings, a master playback machine 40 is used to playback a master video tape recording of the desired programme. The video signal from the master playback machine 40 is supplied on a line 41 via a distribution amplifier 42 to each of a number of slave recording machines 43. Only three slave recorders are illustrated in Fig. 4, but as many as 500 to 1000 such machines may in fact be operated simultaneously to record signals from a single master playback machine.
In this example, the sync pulses for the master playback machine are generated by a separate sync pulse generator 44 interconnected with the machine. The servo within the master playback machine 40 is locked to the sync pulses from generator 44.
Field pulses from the generator 44 are then fed also to a control pulse generator 45 arranged to produce control pulses for supply via a distribution amplifier 46 to each of the slave recorders 43. In this example of the present invention, the control pulse generator 45 can itself be controlled to alter the width of the control pulses produced to provide the desired coded modulation for security marking the batch of recordings being produced. Thus, the control pulse generator 45 is controlled from an encoder control unit 47 to apply the desired pulse width modulation code to the control pulses at a desired location along the tape. The signal encoded by the unit 47 may include data representing the batch number, programme identification and any other desired material.Furthermore, the location of the encoded modulation along the tape may be automatically predetermined by a computer to be distinct for the particular batch of recordings being produced. The location of the encoding for the batch is logged by the computer against the batch number. Then, the recordings produced can subsequently be checked for the presence of the security markings by ensuring that the markings occur along the length of the tape at the position corresponding to the particular batch number.
Normally, the batch number of the recording is marked on the housing of the cassette containing the tape recording. The cassette housing may be so marked in a computer readable fashion, e.g. bar code to be read by a light pen.
Fig. 5 illustrates a more generalised system for detecting security markings on recordings.
Again, control pulses from the control track head 50 are supplied as usual to the servo mechanism 51 of the playback machine. The control pulses are however also supplied to a demodulator 52 which detects and decodes any pulse width modulation of the pulses and provides any relevant data encoded thereby on an appropriate display 53. The demodulator 52 may include an input device whereby data identifying the batch number, for example, of the recording being tested can be entered into the demodulator 52. The demodulator 52 may be then arranged to access a computer store logging the predetermined locations of security markings against batch numbers for various tape batches. Then, the appropriate data of a security marking detected by the system is identified as genuine only if located on the tape recording at the correct position along the tape.
Claims (14)
1. A method of security marking a video tape recording of the kind having control pulses recorded in a separate control track on the tape, the method comprising recording a predetermined security code signal on said control track, the security code signal being selected and arranged not to interfere with the normal effect of the control pulses recorded on the control track during playback.
2. A method as claimed in Claim 1 wherein the security code signal is recorded when recording video on said tape by applying a coded modulation to the control pulses recorded on the control track.
3. A method as claimed in Claim 2 wherein the coded modulation is width modulation effected without altering the timing of the edges of the control pulses responsible for synchronising control of the video playing apparatus during playback.
4. A method as claimed in any preceding claim wherein the security code signal has a predetermined duration, during recording and/or playback, and is located only at a selected position along the length of the tape.
5. A video tape recording security marked in accordance with the method of any preceding claim.
6. Video tape recording apparatus which records control pulses in a separate control track during video recording on the tape, the apparatus being adapted to security mark the recording and including a pulse width modulator arranged for selectively modulating the width of the control pulses being recorded on the control track without altering the timing of the edges of the control pulses responsible for synchronising control of the video playing apparatus during playback, and an encoder to control the modulator to apply a coded modulation.
7. Apparatus as claimed in Claim 6 and including location control means arranged to control the modulator to apply said modulation only at a selected location along the length of the tape.
8. A video tape recording security marked by the apparatus of Claim 6 or Claim 7.
9. Apparatus for detecting security markings on video tape recordings in accordance with Claim 8, or Claim 5 as dependent from
Claim 3, the apparatus including a playback head arranged to pick up control pulses recorded in the control track of a recording, pulse width detecting means providing an indication of the width of the control pulses from the head, and demodulator means responsive to detecting said coded modulation of the width of the control pulses to provide an output indication that a security marking is present.
10. Apparatus as claimed in Claim 9 and including store means containing data defining the correct selected location along the tape of the coded modulation for the respective recording, and location monitoring means responsive to provide said output indication that a security mark is present only if the actual location of any detected coded modulation coincides with the stored correct loaction.
11. A method of security marking a video tape recording substantially as hereinbefore described.
12. Video tape recording apparatus adapted for security marking recordings, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
13. Apparatus for detecting security markings on video tape recordings substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.
14. A method of marking a video tape recording, of the kind having control pulses recorded in a separate control track on the tape, to provide a security marking or a control function during playback, the method comprising pulse width modulating in a predetermined fashion the control pulses recorded on the control track without altering the timing of the edges of the control pulses responsible for synchronising control of the video playing apparatus during playback.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08208156A GB2117549A (en) | 1982-03-19 | 1982-03-19 | Security marking video tape recordings |
| PCT/GB1983/000082 WO1983003321A1 (en) | 1982-03-19 | 1983-03-18 | Security marking video tape recordings |
| EP19830900949 EP0102998A1 (en) | 1982-03-19 | 1983-03-18 | Security marking video tape recordings |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08208156A GB2117549A (en) | 1982-03-19 | 1982-03-19 | Security marking video tape recordings |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2117549A true GB2117549A (en) | 1983-10-12 |
Family
ID=10529144
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08208156A Withdrawn GB2117549A (en) | 1982-03-19 | 1982-03-19 | Security marking video tape recordings |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0102998A1 (en) |
| GB (1) | GB2117549A (en) |
| WO (1) | WO1983003321A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0130843A2 (en) * | 1983-07-04 | 1985-01-09 | John William Hawkins | Recording information on magnetic recording means |
| WO1986000745A1 (en) * | 1984-07-16 | 1986-01-30 | Mcwhirter Holdings Pty. Limited | Recorded information verification system |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA1214268A (en) * | 1982-11-11 | 1986-11-18 | Akihisa Osawa | Video cassette designed for video theater use |
| DE3619359A1 (en) * | 1986-06-09 | 1987-12-10 | Gen Service Electronics Gmbh | METHOD FOR TRANSMITTING AN INFORMATION CODE ON THE SYNCHRONOUS TRACK OF A VIDEO TAPE, DEVICE FOR CARRYING OUT THE METHOD AND VIDEO TAPE PRODUCED BY THE METHOD |
| DE3806413C2 (en) * | 1988-02-29 | 1997-12-04 | Thomson Brandt Gmbh | Recorder with copy protection |
| ES2048102B1 (en) * | 1992-06-09 | 1997-02-16 | Duplico S A | VIDEO TAPE CODING SYSTEM. |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2892882A (en) * | 1955-02-21 | 1959-06-30 | Paramount Pictures Corp | Television secrecy system with width modulated synchronizing pulses |
| DE2503264A1 (en) * | 1975-01-28 | 1976-07-29 | Bosch Gmbh Robert | Application of control pulses to data track - is especially for video signals and has frequency bands for data records and time markers |
| JPS52112311A (en) * | 1976-03-18 | 1977-09-20 | Sony Corp | Demodulating circuit |
| JPS6052625B2 (en) * | 1976-03-22 | 1985-11-20 | ソニー株式会社 | Recorded recording medium and its production method |
| GB1571386A (en) * | 1977-03-09 | 1980-07-16 | Ivs Ltd | Video tape recording apparatus |
| AU5706180A (en) * | 1979-04-11 | 1980-10-16 | John Anthony Dimmers | Video copying inhibitor |
-
1982
- 1982-03-19 GB GB08208156A patent/GB2117549A/en not_active Withdrawn
-
1983
- 1983-03-18 WO PCT/GB1983/000082 patent/WO1983003321A1/en unknown
- 1983-03-18 EP EP19830900949 patent/EP0102998A1/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0130843A2 (en) * | 1983-07-04 | 1985-01-09 | John William Hawkins | Recording information on magnetic recording means |
| EP0130843A3 (en) * | 1983-07-04 | 1985-08-28 | John William Hawkins | Recording information on magnetic recording means |
| WO1986000745A1 (en) * | 1984-07-16 | 1986-01-30 | Mcwhirter Holdings Pty. Limited | Recorded information verification system |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0102998A1 (en) | 1984-03-21 |
| WO1983003321A1 (en) | 1983-09-29 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |