GB2231758A - DPSK demodulation - Google Patents
DPSK demodulation Download PDFInfo
- Publication number
- GB2231758A GB2231758A GB9006685A GB9006685A GB2231758A GB 2231758 A GB2231758 A GB 2231758A GB 9006685 A GB9006685 A GB 9006685A GB 9006685 A GB9006685 A GB 9006685A GB 2231758 A GB2231758 A GB 2231758A
- Authority
- GB
- United Kingdom
- Prior art keywords
- data signal
- reproducing apparatus
- envelope
- change
- detecting
- 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.)
- Granted
Links
Classifications
-
- 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
- G11B27/30—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 the same track as the main recording
- G11B27/3027—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 the same track as the main recording used signal is digitally coded
-
- 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
- G11B20/10—Digital recording or reproducing
- G11B20/10009—Improvement or modification of read or write signals
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B2220/00—Record carriers by type
- G11B2220/20—Disc-shaped record carriers
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
- H04N2201/32—Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
- H04N2201/3201—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
- H04N2201/3225—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title of data relating to an image, a page or a document
- H04N2201/3243—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title of data relating to an image, a page or a document of type information, e.g. handwritten or text document
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
- H04N2201/32—Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
- H04N2201/3201—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
- H04N2201/3225—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title of data relating to an image, a page or a document
- H04N2201/3254—Orientation, e.g. landscape or portrait; Location or order of the image data, e.g. in memory
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N2201/00—Indexing scheme relating to scanning, transmission or reproduction of documents or the like, and to details thereof
- H04N2201/32—Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
- H04N2201/3201—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
- H04N2201/3274—Storage or retrieval of prestored additional information
- H04N2201/3277—The additional information being stored in the same storage device as the image data
Landscapes
- Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Television Signal Processing For Recording (AREA)
- Digital Magnetic Recording (AREA)
- Signal Processing Not Specific To The Method Of Recording And Reproducing (AREA)
Description
t DATA SIGNAL REPRODUCING APPARATUS
Background of the Invention 1. Field of the Invention
The present invention relates to a still video and, more particularly, to an apparatus for reproducing a data signal recorded together with a picture signal in the form of a multiplex recording signal.
2. Description of Related Art
A typical conventional still video camera has heretofore been arranged such that the image of an object is photoelectrically converted by means of an image pickup device to catch hold of the object image in the form of a luminance signal (Y) and a color signal (C) and these signals are combined together by frequency modulation and recorded on a magnetic disc in the form of a multiplex picture signal. According to a recent unified standard for still video cameras, a data signal which indicates whether a particular record is a field record or frame record and which also carries other information, for example, the ordinal number of a track on which a particular record has been stored, is recorded on a magnetic disc while being superposed upon the above-described picture signal by a frequency multiplexing method.
To modulate the data signal, DPSK (Differential Phase Shift Keying) modulation is adopted. Accordingly, the data signal is subjected to DPSK modulation and recorded on a magnetic disc while being superposed upon the picture signal. To reproduce the recorded data, the data signal is extracted from the frequency-modulated signal read out from the magnetic disc and subjected to DPSK demodulation after waveform shaping. Various apparatuses for reproducing the data signal have been developed [for example, Japanese Patent Application Laid-Open (KOKAI) No. 62-223855 (1987)1.
However, the conventional data signal reproducing circuit has a complicated circuit configuration, and the scale of the circuit is large.
Accordingly, the production cost is raised, and the circuit control is complicated.
Summary of the Invention
In view of the above-described problems of the conventional data reproducing apparatus, it is an object of the present invention to provide a data reproducing apparatus having a simplified circuit configuration.
The present invention, which was made by noting that the DPSK carrier wave changes in the phase when the state of the non-carrier wave changes, comprises: an envelope detecting means for detecting a DPSK-modulated data lo signal, a change point detecting means for detecting a point of change of the detected envelope, and a latch means for inverting and holding the output signal every time said change point detecting means detects a point of change of said envelope.
By virtue of the above-described arrangement, the data signal is demodulated by the envelope detecting means-and the change point detecting means arxi the circuit configuration is therefore simplified.
In addition, it is possible to reproduce each bit of the data signal by providing the latch means that inverts and holds the output signal every time the change point detecting means detects a point of change of the envelope.
According to another aspect of the present invention,there is provided a read means for reading a picture signal and a DPSK-modulated data signal which have been recorded on a recording medium in the form of a multiplex recording signal, a data signal extracting means for extracting the DPSK-modulated data signal from the multiplex recording signal read by said read means, an envelope detecting means for detecting the DPSK-modulated data signal outputted from said data signal extracting means, a change point detecting means for detecting a point of change of the detected envelope, and a latch means for inverting and holding the output signal every time said change point detecting means detects a point of change of said envelope.
Brief Description of the Drawings
Figure 1 is a block diagram schematically showing a still video reproducing apparatus to which the data signal reproducing apparatus of the present invention is applied; Fig. 2 is a diagram showing even more specific circuits of the data signal tuned amplifier, envelope detecting circuit, change point detecting circuit and flip-flop of the embodiment shown in Fig. 1; Figs. 3A and 3B are circuit diagrams each showing a portion where the demodulated data signal is inputted to the microcomputer; and Fig. 4 is a timing chart regarding various circuits in the embodiment.
Description of Preferred Embodiments
The present invention will be described below by way of one embodiment illustrated in the drawings. Fig. 1 is a block diagram showing the circuit configuration of a still video reproducing apparatus to which the present invention is applied.
A magnetic disc 10 has, as is generally known, a picture signal comprising a luminance signal and a chrominance(color) signal, together with a data signal, recorded thereon in the form of a multiplex recording signal.
The luminance and chrominance signals are frequency-modulated in high and low frequency bands, respectively, and the data signal is DPSK-modulated in a frequency band which is lower than that for the chrominance signal.
The magnetic disc 10, which serves as a recording medium, is driven to rotate by a servomotor 14 which is controlled by a microcomputer 12. The multiplex signal recorded on the magnetic disc 10 is read by a magnetic head 16 which serves as a read means. It should be noted that the magnetic head 16 is moved so as to follow a given track by the action of a head tracking mechanism (not shown) which is controlled by the microcomputer 12.
The multiplex recording signal that is read by the magnetic head 16 is amplified in a pre-amplifier 20 and then outputted to a high-pass filter MPF) 22, a low-pass filter (LPF) 24 and a data signal tuned amplifier 26 which serves as a data signal extracting means. The high-pass filter 22 passes only signals in the high-frequency band which are related to the luminance signal, while the low-pass filter 24 passes only signals in the low-frequency band which are related to the chrominance signal, and the data signal tuned amplifier 26 amplifies and passes only the data signal carrier wave.
The luminance signal having passed through the high-pass filter 22 is subjected to a predetermined processing in a luminance signal processing circuit 28 and then outputted to an encoder 32. Similarly, the chrominance signal having passed through the low-pass filter 24 is subjected to a predetermined processing in a chrominance signal processing circuit 30 and then outputted to the encoder 32. The encoder 32 demodulates the frequency-modulated luminance and chrominance signals and outputs them to a video terminal 34 in the form of a composite picture signal (video signal). - Meantime, the data signal tuned amplifier 26 extracts and amplifies only the data signal and outputs it to an envelope detecting circuit 36. It should be noted that the data signal read out from the magnetic disc 10 is synchronous with the horizontal synchronizing signal H. More specifically, the following pieces of information have been synchronously recorded: a 1- bit initial bit which is assigned 4H from 28H; 2-bit information indicating whether a particular record is a field record or a frame record, which is assigned 8H from 32H; and 7-bit track number information which is assigned 28H from 40H. 25 The data signal that is extracted and amplified in the data signal tuned amplifier 26 is subjected to envelope detection in the envelope detecting circuit 36, and the enveloped signal is outputted to a change point detecting circuit 38. The change point detecting circuit 38 detects a point (valley) of change of the envelope and shapes it into a pulse signal and then outputs it to a -5flip-flop 40 which serves as a latch means.
The flip-flop 40, every time it receives the pulse signal, inverts the output level to form a DPSK-demodulated data signal and outputs it to a data signal output terminal 42.
Fig. 2 exemplarily shows specific circuit configurations of the data signal tuned amplifier 26, the envelope detecting circuit 36, the change point detecting circuit 38 and the flip-flop 40.
The multiplex signal that is inputted to the data signal tuned amplifier 26 passes through a capacitor Cl where the DC component is removed and then passes through a base of a transistor Trl. Thereafter, only the data signal MPSK carrier wave) is amplified in a parallel resonant circuit LC1 connected to the collector of a second-stage transistor Tr2 and a series resonant circuit LC2 connected to the emitter of the transistor Tr2. After the DC component has been removed in a capacitor C3, the data signal is subjected to band limited amplification by a transistor Tr3 having a parallel resonant circuit LC3 connected to its collector and then outputted to the envelope detecting circuit 36.
Fig. 4W shows the output waveform of the data signal tuned amplifier 26.
The data signal that is inputted to the envelope detecting circuit 36 is subjected to envelope detection by transistors Tr4 and Tr5, the emitter of the transistor Tr4 being grounded through a capacitor C4, and then outputted to the change point detecting circuit 38. Fig. 4(B) shows the output, waveform of the envelope detecting circuit 36. More specifically, a portion of the carrier wave which represents the same data signal bit has a fixed amplitude and therefore shows a fixed potential, whereas, a portion of the carrier wave where the frequency changes, that is, a boundary portion where the data signal bit is inverted, shows a potential changing in the shape of a V.
After the DC component has been removed through a capacitor C5 in the 30 change point detecting circuit 38, the enveloped data signal is amplified by -6a transistor Tr6 and then inputted to a monostable multivibrator (M 39. Since the monostable multivibrator-39 outputs an M" pulse every time the input rises, the data signal is shaped into a pulse signal wave in which each V portion is shaped into a rectangular wave, as shown in Fig. 4(C). The data signal thus shaped is outputted to the flip-flop 40.
The flip-flop 40 comprises a D flip-flop 41 in which the above-described enveloped pulse signal is inputted to the input CL. The output Z1 of the D flip-f lop 41 is fed back to the input D, while the output Q is delivered to the data signal output terminal 42. Accordingly, every time an W pulse is lo inputted to the input CL, the level of the output Q is inverted and the output Q is latched at the inverted level, resulting in the waveform shown in Fig. 4M1) or 4 (D2).
The output from the data signal output terminal 42, that is, the output Q of the D flip-flop 41, is read bitwise by the microcomputer 12 through a logical circuit, for example, an exclusive-OR gate 44 shown in Fig. 3A.. One input terminal of the exclusive-OR gate 44 is supplied with the output Q of the flip-flop 40, while the other input terminal of the gate 44 is supplied with the output Q of the exclusive-OR gate 44 a predetermined time (corresponding to 4H of the horizontal synchronizing signal) before, which is outputted from the microcomputer 12 at a predetermined timing based on the horizontal synchronizing signal, thereby reproducing the data signal on a bitwise basis.
The reproduced data signal that is outputted from the exclusive-OR gate 44 is decoded in the microcomputer 12 and stored therein as well as subjected to a predetermined processing. In this embodiment, the field/frame information bits are "10 and the track number bits are 01101(01)" and the data signal is therefore decoded as being a frame recorded the outer 35th track. Then, the track number "35" is displayed on a given display.
It should be noted that the arrangement may be such that the exclusive -OR gate 44 is not provided but exclusive-ORing is executed in the -7microcomputer 12 instead, as shown in Fig. 3B.
According to the foregoing embodiment, it is possible to demodulate the data signal by detecting changes of the data signal bits by use of the data signal carrier envelope detecting circuit and the change point detecting circuit. Accordingly, the arrangement of the data signal reproducing circuit is simplified.
Although the present invention has been described aboveon the basis of the embodiment illustrated in the drawings, it should be noted that the present invention is not necessarily limitative to the described embodiment and that the essential thing is to provide a circuit configuration which enables envelope detection of a modulated data signal and detection of a point of change of the envelope resulting from the envelope detection.
In addition, the data reproducing apparatus of the present invention may also be applied to still video cameras having reproducing equipment.
is As will be clear from the foregoing description, the data signal reproducing apparatus of the present invention is capable of demodulating the data signal by envelope-detecting the carrier wave of the DPSKmodulated data signal and detecting a point of change of the detected envelope. it is therefore possible to simplify the circuit configuration and hence reduce the size of the circuit and lower the production cost.
Claims (14)
1. A data signal reproducing apparatus comprising:
an envelope detecting means for detecting a DPSK-modulated data signal; a change point detecting means for detecting a point of change of the detected envelope; and a latch means for inverting and holding the output signal every time said change point detecting means detects a point of change of said envelope.
2. A data signal reproducing apparatus according to Claim 1, wherein said the change point detecting means includes a monostable multivibrator which outputs a pulse when a phase of said envelope is changed.
3. A data signal reproducing apparatus according to Claim 2, wherein said latch means included a flip-flop circuit which reverses and holds a output signal when said monostable multivibrator outputs the pulse.
4. A data signal reproducing apparatus comprising: a read means for reading a DPSK-modulated data signal which have been recorded on a recording medium; an envelope detecting means for detecting the DPSK-modulated data signal outputted from said read means; a change point detecting means for detecting a point of change of the detected envelope; and a latch means for inverting and holding the output signal every time said change point detecting means detects a point of change of said envelope.
5. A data signal reproducing apparatus according to Claim 4, wherein said recording medium is a magnetic disc.
Z1
6. A data signal reproducing apparatus according to Claim 5, wherein said read means is a magnetic head.
7. A data signal reproducing apparatus according to Claim 4, wherein said the change point detecting includes a monostable multivibrator which outputs a pulse when a phase of said envelope is changed.
8. A data signal reproducing apparatus according to Claim 7, wherein said latch means includes a flip-flop circuit which reverses and holds an output signal when said monostable multivibrator outputs the pulse.
9. A data signal reproducing apparatus comprising:
a read means for reading a picture signal and a DPSK-modulated data signal which have been recorded on a recording medium in the form of a multiplex recording signal; a data signal extracting means for extracting the DPSK-modulated data signal from the multiplex recording signal read by said read means; an envelope detecting means for detecting the DPSK-modulated data signal outputted from said data signal extracting mans; a change point detecting means for detecting a point of change of the detected envelope; and a latch means for inverting and holding the output signal every time said change point detecting means detects a point of change of said envelope.
10. A data signal reproducing apparatus according to Claim 9, wherein said recording medium is a magnetic disc.
11. A data signal reproducing apparatus according to Claim 10, wherein said read means is a magnetic head.
f
12. A data signal reproducing apparatus according to Claim 9, wherein said data signal extracting means is a data signal tuned amplifier.
13. A data signal reproducing apparatus according to Claim 9, wherein said the change point detecting means includes a monostable multivibrator which outputted a pulse when a phase of said envelope is changed.
14. A data signal reproducing apparatus according to Claim 13, wherein said latch means includes a flip-flop circuit which reverse a output signal 10 when said monostable multivibrator outputs the pulse.
is Published 1990 at The Patent Office. Stats'llrouse. 66; '71 High Holborn. London WC1R 4TP. Further copies maybe obtained from The Patent Office.
Sales Branch, St Mary Gray. Orpington. Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent. Con. 1187
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1076324A JP2808301B2 (en) | 1989-03-28 | 1989-03-28 | Data signal reproduction device |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9006685D0 GB9006685D0 (en) | 1990-05-23 |
| GB2231758A true GB2231758A (en) | 1990-11-21 |
| GB2231758B GB2231758B (en) | 1993-06-09 |
Family
ID=13602184
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9006685A Expired - Fee Related GB2231758B (en) | 1989-03-28 | 1990-03-26 | Data signal reproducing apparatus |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JP2808301B2 (en) |
| DE (1) | DE4009952A1 (en) |
| FR (1) | FR2645382B1 (en) |
| GB (1) | GB2231758B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5287197A (en) * | 1990-04-20 | 1994-02-15 | Asahi Kogaku Kogyo Kabushiki Kaisha | Signal demodulation device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1560107A (en) * | 1975-10-29 | 1980-01-30 | Western Electric Co | Timing recovery circuit for a differentially coherent phase modulated data transmission system |
| US4628271A (en) * | 1983-11-02 | 1986-12-09 | Canon Kabushiki Kaisha | Differential phase shift keying demodulator |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3924186A (en) * | 1974-02-07 | 1975-12-02 | Ncr Co | Staggered quadriphase differential encoder and decoder |
| JPS58129864A (en) * | 1982-01-27 | 1983-08-03 | Hitachi Ltd | Demodulator for phase modulated signal |
| JPS59164918U (en) * | 1983-04-21 | 1984-11-05 | ソニー株式会社 | Video signal and digital signal reproducing device |
| JPS60223259A (en) * | 1984-04-19 | 1985-11-07 | Nippon Kogaku Kk <Nikon> | Psk or dpsk demodulating circuit |
| JPH0722403B2 (en) * | 1986-05-24 | 1995-03-08 | 富士写真フイルム株式会社 | Video signal recording medium duplication device |
-
1989
- 1989-03-28 JP JP1076324A patent/JP2808301B2/en not_active Expired - Fee Related
-
1990
- 1990-03-26 GB GB9006685A patent/GB2231758B/en not_active Expired - Fee Related
- 1990-03-27 FR FR9003904A patent/FR2645382B1/en not_active Expired - Fee Related
- 1990-03-28 DE DE19904009952 patent/DE4009952A1/en active Granted
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1560107A (en) * | 1975-10-29 | 1980-01-30 | Western Electric Co | Timing recovery circuit for a differentially coherent phase modulated data transmission system |
| US4628271A (en) * | 1983-11-02 | 1986-12-09 | Canon Kabushiki Kaisha | Differential phase shift keying demodulator |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2808301B2 (en) | 1998-10-08 |
| GB2231758B (en) | 1993-06-09 |
| JPH02254674A (en) | 1990-10-15 |
| FR2645382B1 (en) | 1997-04-18 |
| DE4009952C2 (en) | 1992-11-26 |
| FR2645382A1 (en) | 1990-10-05 |
| GB9006685D0 (en) | 1990-05-23 |
| DE4009952A1 (en) | 1990-10-04 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4347619A (en) | Digital formatting system | |
| JPH0473677B2 (en) | ||
| US4746992A (en) | Apparatus for reproducing video signals | |
| US5245484A (en) | DPSK-demodulating apparatus | |
| GB2231758A (en) | DPSK demodulation | |
| JPS59164918U (en) | Video signal and digital signal reproducing device | |
| US3715474A (en) | Color video recording and playback system | |
| US3230306A (en) | Magnetic recording and reproducing system | |
| US5706387A (en) | Movie video camera, apparatus for reproducing movie video signal, method of recording movie video signal, and method of reproducing same | |
| JPS6316078B2 (en) | ||
| KR880012097A (en) | Video signal recorder | |
| US3764731A (en) | Color signal recording and decoding apparatus | |
| GB2249451A (en) | A circuit for folding the high frequency component of a luminance signal | |
| JP2675817B2 (en) | Image signal processing device | |
| JP2576115B2 (en) | High-resolution video disc player | |
| JPS62154886A (en) | Demodulating device | |
| JPS59101009A (en) | Magnetic recording and reproducing device | |
| JP2787462B2 (en) | Data signal reproduction circuit of still video device | |
| JPS62159997A (en) | Serial component video signal transmission system | |
| JPS6339154B2 (en) | ||
| JP2625051B2 (en) | Magnetic playback device | |
| JPS58100573A (en) | Facsimile device | |
| JPS5981989A (en) | Video signal regenerating device | |
| KR930003017A (en) | Magnetic regeneration device | |
| JPH0380462A (en) | Signal recording device and signal reproducing device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20050326 |