GB2082365A - Recording three-channel playback on compact cassette tapes - Google Patents
Recording three-channel playback on compact cassette tapes Download PDFInfo
- Publication number
- GB2082365A GB2082365A GB8025762A GB8025762A GB2082365A GB 2082365 A GB2082365 A GB 2082365A GB 8025762 A GB8025762 A GB 8025762A GB 8025762 A GB8025762 A GB 8025762A GB 2082365 A GB2082365 A GB 2082365A
- Authority
- GB
- United Kingdom
- Prior art keywords
- playback
- signal
- tape
- recording
- winding
- 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- Withdrawn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
- 238000004804 winding Methods 0.000 claims abstract description 69
- 239000003990 capacitor Substances 0.000 claims abstract description 5
- 230000008878 coupling Effects 0.000 claims abstract description 4
- 238000010168 coupling process Methods 0.000 claims abstract description 4
- 238000005859 coupling reaction Methods 0.000 claims abstract description 4
- 230000005236 sound signal Effects 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 8
- 230000000694 effects Effects 0.000 claims description 5
- 230000007246 mechanism Effects 0.000 claims description 5
- 230000000007 visual effect Effects 0.000 claims description 3
- 230000001052 transient effect Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 3
- 239000004020 conductor Substances 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000000994 depressogenic effect Effects 0.000 description 1
- 230000004069 differentiation Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B15/00—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function
- G11B15/02—Control of operating function, e.g. switching from recording to reproducing
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B15/00—Driving, starting or stopping record carriers of filamentary or web form; Driving both such record carriers and heads; Guiding such record carriers or containers therefor; Control thereof; Control of operating function
- G11B15/02—Control of operating function, e.g. switching from recording to reproducing
- G11B15/12—Masking of heads; circuits for Selecting or switching of heads between operative and inoperative functions or between different operative functions or for selection between operative heads; Masking of beams, e.g. of light beams
-
- 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
- G11B23/0007—Circuits or methods for reducing noise, for correction of distortion, or for changing density of recorded information
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/008—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires
- G11B5/00813—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires magnetic tapes
Landscapes
- Signal Processing Not Specific To The Method Of Recording And Reproducing (AREA)
Abstract
Recording/playback apparatus for use with a standard compact cassette stereo tape has a playback unit including a playback/recording head with three in-line windings (12, 16, 18) in a single can for cooperation with three respective tracks of the tape, and circuit means are provided to enable the three windings respectively to handle an analogue (audio) signal, a tone burst (slide cue) signal and a digital (VDU data) signal. A tape can be recorded by coupling a recording unit to the playback unit. The apparatus enables any combination of simultaneous recording, erasing and playback on the three channels. To avoid or minimise crosstalk between the channels, the analogue and digital signal windings 12, 18 are assigned to respective edge tracks, and the tone burst signal winding 16 is assigned to the track next to the digital track. In addition, digital signal winding 18 and a capacitor 46 form a tuned circuit to reject crosstalk signals from the other windings, and diodes 49 in the digital, playback channel remove residual crosstalk and noise by slicing out the centre portion of the playback signal from winding 18 between predetermined positive and negative thresholds. A similar pair of diodes are included in the digital signal recording channel. <IMAGE>
Description
SPECIFICATION
Improvements in or relating to recording and playback on cassette Tapes
This invention relates generally to apparatus for and a method of recording and playback on cassette tapes, especially compact cassette multitrack tapes such as twin sided compact cassette stereo tapes.
In the field of advanced tuition, to quote one application by way of example, there is need for apparatus which can playback a tape simultaneously to generate an audio (analogue) signal, a data (digital) signal for generation of information on a visual display unit (VDU) and a cueing (tone burst) signal for controlling actuation of a slide projector.
A standard compact cassette stereo tape has four parallel tracks, but is twin sided with the intention that a standad playback unit (cassette player) with twin windings will sense two tracks when one side of the cassette is uppermost and the other two tracks when the cassette is reversed in its holder to position the other side uppermost.
It is an object of this invention to provide apparatus and method enabling simultaneous playback of an analogue signal, a digital signal and a tone burst signal from a compact cassette multitrack tape.
According to one aspect of the present invention, there is provided recording and playback apparatus comprising a recording/ playback head, a holder for a compact cassette multitrack tape and a tape drive mechanism, said head having at least three independent windings for respective cooperation simultaneously with at least three separate tape tracks, and circuit means whereby simultaneously one winding can handle an analogue signal, one winding can handle a digital signal and one winding can handle a tone burst signal, each to record or playback its corresponding signal on or from its associated track.
The holder is preferably for a twin-sided compact cassette stereo-tape, the analogue signal, digital signal and tone burst signal windings being arranged for cooperation simultaneously with three of the four tape tracks.
Conveniently, said windings are arranged for cooperation with two adjacent tracks nearer one edge of the tape and the track most remote from said edge, and the winding arranged for cooperation with the last-mentioned remote track is the analogue signal winding. In this connection, it is to be appreciated that the problem with three windings handling differing types of signal, when said windings are incorporated in a single small head (as is necessary for cooperation with a compact cassette tape), is that interference by induction can occur between one winding and another. Risk of this type of crosstalk is reduced by making the analogue signal winding physically more remote from the other two windings.It is also advantageous for the same reason for the digital signal winding (which handles the signal most sensitive to crosstalk) to be located on the remote side of the tone burst signal winding from the analogue signal winding.
The apparatus will have an analogue signal channel, a digital signal channel and a tone burst signal channel, and switching means is preferably provided in each channel enabling any combination of simultaneous recording, playback and erase at the respective tape tracks. Thus, by the use of three three-position switches one in each channel, it is possible, when recording, to record the tone burst (cueing) signal and/or digital (VDU data) signal while playing back the analogue (audio) signal, thereby to ensure proper synchronism of the recordings on the three tape tracks.
Also, corrections involving erasure can be effected on any one track independently of the others. When playing back, it is possible to replay any one or two tracks in isolation or, of course, to replay all three tracks simultaneously.
As previously mentioned, crosstalk is a major problem to be solved in handling differing types of signals in a physically confined apparatus. Preferably, therefore, the circuit means includes one or more circuit devices for minimising crosstalk between the said channels.
Specific such circuit devices will be referred to later.
The apparatus preferably has separate recording and playback units, the two units being used in combination to effect recording and the playback unit being operable without the recording unit to effect playback. Thus when, for example, the apparatus is used for tuition purposes, the student requires only the playback unit and a copy of the tape which has previously been recorded by a lecturer using a playback unit and recording unit in combination. It is self-evident that the playback unit will contain the cassette holder, tape drive and the recording/playback head. The playback unit will also have conventional switch controls for play, rewind etc. analogue to those provided on a conventional cassette player.The recording unit will comprise the signal generators and processing circuitry including the above-mentioned switching means necessary to provide the required analogue, digital and tone burst signals to be recorded, these being fed out on output conductors from said recording unit which can be plugged into the playback unit to apply such signals to the appropriate windings in the recording/playback head when the switches on the recording unit are set to "record".
Thus, according to another aspect of the invention, there is provided tape playback apparatus comprising a playback head, a holder for a compact cassette multitrack tape and a tape drive mechanism, said head having at least three independent windings for respective cooperation simultaneously with at least three separate tape tracks, and circuit means whereby simultaneously one winding can handle an analogue signal for playback, one winding can handle a digital signal for playback and one winding can handle a tone burst signal for playback, each from its associated tape track.
According to a still further aspect of the invention, there is provided a method of recording and playback on a compact cassette multitrack tape, wherein one tape track is employed to carry an analogue signal, one tape track is employed to carry a digital signal, and one tape track is employed to carry a tone burst signal, and a recording/playback head including three windings respectively cooperating with said three tracks is employed at least to enable simultaneous playback from all three tracks. In a preferred example, the said analogue signal is an audio signal, the said digital signal is a data signal for generating information on a visual display unit and the said tone burst signal is a cueing signal controlling actuation of a slide projector.
Further features of the apparatus of the invention will be apparent from the following description referring to a preferred practical embodiment, in which:~
Figure 1 is a block diagram of the playback unit of the apparatus;
Figure 2 shows the front control panel of the recording unit of the apparatus; and
Figure 3 is a block diagram of the recording unit.
The playback unit of Fig. 1 has a recording/playback head or can 10 containing four in-line windings 12, 14, 16. 18. The unit also has a holder for a standard compact cassette stereo tape and a tape drive mechanism.
These items are of conventional nature and not shown in the drawing. The four in-line windings 12 to 18 are arranged to cooperate with the four tracks of a stereo tape cassette fitted in the holder; however, in the embodiment illustrated the winding 14 for cooperating with the second tape track is not used.
The three operative windings 12, 16. 18 are respectively connected in three signal channels, namely an analogue signal channel 20, a tone burst signal channel 22 and a digital signal channel 24. Having regard to the preferred use of the apparatus referred to herein, these channels are respectively termed an audio signal channel 20, a cueing signal channel 22 and a data signal channel 24 in the ensuing description.
The audio signal channel 20 in the replay unit primarily comprises an amplifier 26 provided with an output to a loudspeaker 28.
However, it is also convenient to show in Fig.
1 a block 30 comprising audio signal mixer and bias control circuitry, which is of conventional nature. This circuitry in fact forms part of the recording unit (Fig. 3), but is illustrated in Fig. 1 to indicate the connection to a bias erase conductor 32, which leads to a separate head having a winding 34 which cooperates with the audio signal track (the first track) on the tape for erasing a recorded audio sgnal.
Erasing of cueing and data signals on the third and fourth tracks of the tape is performed through the windings 16, 18.
The cueing signal channel 22 in the replay unit primarily comprises an amplifier 36 providing an output for actuating a relay 38 operative to index the slide carousel of a projector.
The data signal channel 24 includes two d.c. coupled amplifiers 40, 42 providing an output to a data integrator 44 which provides an input to a VDU (not shown) for character generation and the like.
The circuit blocks thus far referred to are of, conventional nature and will not be described in detail. However, the data signal channel 24 in the replay unit also includes two circuit devices for reducing crosstalk. A tendency to crosstalk necessarily arises when signals of differing types are being handled in spatially confined apparatus, especially when closely proximate windings such as the windings 12, 16, 18 are involved. A degree of crosstalk is not significant in a conventional stereo cassette player, because the division of sound between the right-hand and left-hand loudspeakers is not critical. Clearly, however, in the apparatus of the invention the audio, cueing and data signal outputs can be disturbed by crosstalk, and in the case of the data signal channel can lead to improper operation of the VDU.In the recording head 10, the separation of the audio signal winding 12 from the other two operative windings 16, 18 contributes to the reduction of crosstalk, and risk of disturbance in the data signal channel is lessened by making this channel winding 18 the fourth channel winding most remote from the audio signal channel winding 12.
In addition, however, the above-mentioned two crosstalk reducing devices are included in the data signal channel 24. The first said device is a capacitor 46 shunted across the data signal winding 18. This capacitor 46 with the inductance of the winding 18 in effect constitutes a tuned circuit enabling frequency selection to reject unwanted signals transformed from the other windings. The second said device is a slicing circuit 48 incorporated in the d.c. coupling between the amplifiers 40, 42. This slicing circuit 48 consists of two semi-conductor diodes 49 connected in opposition in parallel circuit paths.
The action of this circuit 48 is twofold: firstly to avoid differentiation of the data pulses being amplified, since a small offset voltage from the first amplifier 40 would be amplified by the second amplifier 42 to prevent proper operation both of the latter amplifier and also of the data integrator 44; second to slice out the centre portion of the incoming signal, thus removing residual crosstalk and noise. For both purposes, the slicing circuit 48 is operative with positive and negative thresholds, which in practice may be between zero and + 0 7 volts.
The playback unit will have conventional switches for play, rewind etc. analogous to those provided on a conventional portable cassette player.
The front control panel of the recording unit is shown in Fig. 2, which serves to indicate various features of the apparatus for which conventional circuitry is incorporated.
In Fig. 2, the references 50, 52 and 54 denote three three-position switches, one 50 for the audio signal channel, one 52 for the cueing signal channel and one 54 for the data signal channel. The three positions of each switch correspond to "record", "play" and "erase" respectively, and each switch is operable entirely independently of the other two so that any chosen combination of recording, playback and erasing is possible as between the three operative tape tracks. Indicators 56, 58 and 60 respectively light to show when recording or erasing is being effected on any of the three channels. Adjacent the audio switch control 50 is an audio-level meter 62.
Three signal level controls 64, 66, 68, one for each channel, are also provided, and below these controls two microphone inputs 70, 72 on either side of the DIN input 74 (say feeding 0~7V r.m.s. into 10k ohms) for copying. Associated with the cueing channel switch 52 is a push-button 76 for cue signal (tone burst) generation, with a cue light indicator 78, whilst associated with the data channel switch 54 is control switch bank 80 for on-line, copy, off line and half/full duplex.
Turning now to the block diagram of the recording unit (Fig. 3), the data signal channel 90 includes a data switching block 92 (operative by switch bank 80 in Fig. 2), an amplifier 94, and a rejection circuit 96 similar to the slicing circuit of Fig. 1. The rejection circuit 96 comprises two opposed semi-conductor diodes 98 connected in parallel to reject noise which otherwise would be amplified by the d.c. coupled amplifiers in the data channel in the replay unit.
The audio signal channel 100 comprises a mixer 101 feeding an amplifier 102, associated with an audio bias/ernse oscillator 104, generating a sine wave of a frequency about 50,000 c/s. The circuit blocks 101 and 104 together correspond to the single circuit block 30 of Fig. 1.
The cueing signal channel 106 comprises a tone burst generator 108.
When the recording unit is coupled to the playback unit, the outputs of the respective three signal channels 90, 100, 106 are fed to the recording head in the playback unit when the respective switches 50, 52, 54 on the recording unit are set to record. However, especially for the protection of master tapes, it is desirable to arrange that the usual "record" control provided on the playback unit (cassette player) must be depressed to enable recording through the said switches 50, 52, 54 on the recording unit.
In use, recording (requiring use of the recording unit and playback unit in combination) may require six passes of the tape as follows:
1) data erase
2) data record
3) data check
4) data playback and record audio
5) playback data and audio and record cues
6) playback data, audio and cues as check.
Each tape pass can involve the following initial procedure: a) depress "pause" "record" and "playback" on playback unit, b) select functions (three channels) on recording unit, c) set levels on recording unit, d) release pause on playback unit.
In use for playback, with the recording unit disconnected, the conventional cassette player controls on the playback unit are operable in a conventional manner.
Thereafter, a prepared tape can be copied as many times as necessary using two playback units in combination with a recording unit.
As previously mentioned, the above-described apparatus of the invention has especial applicability to advanced tuition techniques, enabling a lecturer with access to both playback and recording unit to record a lecture involving speech, slide projection and
VDU display, and a student having access to a playback unit and a recorded tape to attend the lecture with the aid of a slide projector and VDU. However, various other applications of the apparatus are readily envisaged, and various modifications of the above-described embodiment are possible, to suit the various purposes to which the apparatus may be put, within the scope of the invention as defined in the appended claims.
Claims (24)
1. Recording and playback apparatus comprising a recording/playback head, a holder for a compact cassette multitrack tape and a tape drive mechanism, said head having at least three independent windings for respective cooperation simultaneously with at least three separate tape tracks, and circuit means whereby simultaneously one winding can handle an analogue signal, one winding can handle a digital signal and one winding can handle a tone burst signal, each to record or playback its corresponding signal on or from its associated track.
2. Apparatus according to claim 1, having a holder for a twin-sided compct cassette stereo tape, the analogue signal, digital signal and tone burst signal windings being arranged for cooperation simultaneously with three of the four tape tracks.
3. Apparatus according to claim 2, wherein said windings are arranged for cooperation with two adjacent tracks nearer one edge of the tape and the track most remote from said edge.
4. Apparatus according to claim 3, wherein the winding arranged for cooperation with the last-mentioned remote track is the analogue signal winding.
5. Apparatus according to any of claims 1 to 4, having a separate head for analogue signal erase.
6. Apparatus according to claim 5, having an analogue signal channel, a digital signal channel and a tone burst signal channel, and switching means in each channel enabling any combination of simultaneous recording, playback and erase at the respective tape tracks.
7. Apparatus according to claim 5, including in the circuit means one or more circuit devices for minimising crosstalk between the said channels.
8. Apparatus according to claim 7, wherein one said circuit device comprises a capacitor connected across the digital signal winding to form with said winding a tuned circuit adapted to reject signals transformed from other windings.
9. Apparatus according to claim 7 or claim 8, wherein one said circuit device comprises a slicing circuit in the playback output path of the digital signal channel for slicing out the centre portion of the signal between predetermined positive and negative thresholds.
10. Apparatus according to claim 9, wherein said slicing circuit is connected in a
D.C. coupling circuit between two amplifiers so as also to act to remove any d.c. input to the second amplifier below a predetermined voltage level.
11. Apparatus according to any of claims 7 to 10, wherein one said circuit device comprises a slicing circuit in the recording input path of the digital signal channel for slicing out transient signals between predetermined positive and negative thresholds.
12. Apparatus according to any of claims I to 11, having separate recording and playback units, the two units being used in combination to effect recording and the playback unit being operable without the recording unit to effect playback.
13. Tape playback apparatus comprising a playback head, a holder for a compact cassette rnljltttrack tape and a tape drive mechanism, said head having at least three independent windings for respective cooperation simultaneously with at least three separate tape tracks, and circuit means whereby simultaneously one winding can handle an analogue signal for playback, one winding can handle a digital signal for playback and one winding can handle a tone burst signal for playback, each from its associated tape track.
14. Apparatus according to claim 13, having a holder for a twin-sided compact cassette stereo tape, the analogue signal, digital signal and tone burst signal windings being arranged for cooperation simutaneously with three of the four tape tracks.
15. Apparatus according to claim 14, wherein said windings are arranged for cooperation with two adjacent tracks nearer one edge of the tape and the track most remote from said edge.
16. Apparatus according to claim 15, wherein the winding arranged for cooperation with the last-mentioned remote track is the analogue signal winding.
17. Apparatus according to any of claims 13 to 16, including an analogue signal channel, a digital signal channel and a tone burst signal channel, and in the circuit means one or more circuit devices for minimising crosstalk between the said channels.
18. Apparatus according to claim 17, wherein one said circuit device comprises a capacitor connected across the digital signal winding to form with said winding a tuned circuit adapted to reject signals transformed from other windings.
19. Apparatus according to claim 17 or claim 18, wherein one said circuit device comprises a slicing circuit in the playback output path of the digital signal channel for slicing out the centre portion of the signal between predetermined positive and negative thresholds.
20. Apparatus according to claim 19.
wherein said slicing circuit is connected in a d.c. coupling circuit between two amplifiers so as also to act to remove any d.c. input to the second amplifier below a predetermined voltage level.
21. A method of recording and playback on a compact cassette multitrack tape, wherein one tape track is employed to carry an analogue signal, one tape track is employed to carry a digital signal, and one tape track is employed to carry a tone burst signal, and a recording/playback head including three windings respectively cooperating with said three tracks is employed at least to enable simultaneous playback from all three tracks.
22. A method according to claim 21, wherein said analogue signal is an audio signal, said digital signal is a data signal for generating information on a visual display unit and said tone burst signal is a cueing signal controlling actuation of a slide projector.
23. Recording and/or playback apparatus substantially as hereinbefore described with reference to the accompanying drawings.
24. A method of recording and playback
as claimed in claim 21 and substantially as
hereinbefore described.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8025762A GB2082365A (en) | 1980-08-07 | 1980-08-07 | Recording three-channel playback on compact cassette tapes |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8025762A GB2082365A (en) | 1980-08-07 | 1980-08-07 | Recording three-channel playback on compact cassette tapes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2082365A true GB2082365A (en) | 1982-03-03 |
Family
ID=10515295
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8025762A Withdrawn GB2082365A (en) | 1980-08-07 | 1980-08-07 | Recording three-channel playback on compact cassette tapes |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2082365A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0535300A1 (en) * | 1991-09-30 | 1993-04-07 | Pioneer Electronic Corporation | Digital recording and reproducing method |
| EP0585628A1 (en) * | 1992-09-03 | 1994-03-09 | BÄSSGEN AV - TECHNIK GmbH | Apparatus for storing and reproducing audio records with synchronous driving of the additional apparatus, by the accompanying audio reproduction |
-
1980
- 1980-08-07 GB GB8025762A patent/GB2082365A/en not_active Withdrawn
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0535300A1 (en) * | 1991-09-30 | 1993-04-07 | Pioneer Electronic Corporation | Digital recording and reproducing method |
| US5296977A (en) * | 1991-09-30 | 1994-03-22 | Pioneer Electronic Corporation | Digital recording/reproducing method in which digital control codes are simultaneously recorded/reproduced with analog info to enhance analog recording/reproduction |
| EP0585628A1 (en) * | 1992-09-03 | 1994-03-09 | BÄSSGEN AV - TECHNIK GmbH | Apparatus for storing and reproducing audio records with synchronous driving of the additional apparatus, by the accompanying audio reproduction |
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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) |