GB1307959A - Decoder for television signals - Google Patents
Decoder for television signalsInfo
- Publication number
- GB1307959A GB1307959A GB5237871A GB5237871A GB1307959A GB 1307959 A GB1307959 A GB 1307959A GB 5237871 A GB5237871 A GB 5237871A GB 5237871 A GB5237871 A GB 5237871A GB 1307959 A GB1307959 A GB 1307959A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signal
- phase
- signals
- pal
- output
- 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.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N11/00—Colour television systems
- H04N11/06—Transmission systems characterised by the manner in which the individual colour picture signal components are combined
- H04N11/12—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only
- H04N11/14—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only in which one signal, modulated in phase and amplitude, conveys colour information and a second signal conveys brightness information, e.g. NTSC-system
- H04N11/16—Transmission systems characterised by the manner in which the individual colour picture signal components are combined using simultaneous signals only in which one signal, modulated in phase and amplitude, conveys colour information and a second signal conveys brightness information, e.g. NTSC-system the chrominance signal alternating in phase, e.g. PAL-system
- H04N11/165—Decoding means therefor
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Processing Of Color Television Signals (AREA)
Abstract
1307959 Television INTERNATIONAL STANDARD ELECTRIC CORP 11 Nov 1971 [17 Nov 1970] 52378/71 Addition to 1307566 Heading H4F In a decoder for a PAL type chrominance signal 1, circuits 25 and 3-10 separately amplitude and phase demodulate the signal 1, the phase representative signal 18 (U#) is converted directly and after a one line delay 11 by respective halves of a phase coder 13 to pairs of signals 14, 15 and 17, 16 derived from triangular functions approximating the functions sin U# and cos U#, Figs. 2a and 2b (not shown), and after averaging the undelayed and delayed signals at 19, 20 and conversion to the sinusoidal or cosinusoidal function at 21, 22, they are fed together with the output of demodulator 25 to mixers 23, 24 to provide colour difference video signals 26, 27. It is said that in this way saturation errors resulting from the normal PAL averaging process are avoided, although some error in the average phase angle (hue) may arise near to 0 and 180 degrees or 90 and 270 degrees for the cosine and sine functions, respectively. As shown, in the phase demodulator, the signal 1 is limited, 4, and activates a Schmitt trigger 6. The output pulses are differentiated, 7, and applied, together with differentiated pulses similarly derived from a reference subcarrier frequency input 2 to a bi-stable 8 to produce a pulse width modulated phase representative signal. A PAL switch 9 alternately transmits positive and negative versions of this signal to a filter 10 providing the D.C. signal U#. A circuit suitable for converting the signal 18 to signals 14, 15 is described with respect to Fig. 4 (not shown). In variants of the embodiment shown, (a) the shaping circuits 21, 22 may occur before the respective adders 19, 20, or (b) the signal U# may be obtained by synchronously demodulating the output oflimiter 4 and passing the demodulated signal through a PAL switch.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE2056583A DE2056583C3 (en) | 1970-11-17 | 1970-11-17 | Method and circuit arrangement for recovering the video or carrier frequency color difference signals from a PAL chrominance signal |
Publications (1)
Publication Number | Publication Date |
---|---|
GB1307959A true GB1307959A (en) | 1973-02-21 |
Family
ID=5788384
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB5237871A Expired GB1307959A (en) | 1970-11-17 | 1971-11-11 | Decoder for television signals |
Country Status (10)
Country | Link |
---|---|
AT (1) | AT328005B (en) |
AU (1) | AU468126B2 (en) |
BE (1) | BE775423R (en) |
DE (1) | DE2056583C3 (en) |
ES (1) | ES397061A2 (en) |
GB (1) | GB1307959A (en) |
IT (1) | IT976370B (en) |
NO (1) | NO139196C (en) |
SE (1) | SE378498B (en) |
ZA (1) | ZA717566B (en) |
-
1970
- 1970-11-17 DE DE2056583A patent/DE2056583C3/en not_active Expired
-
1971
- 1971-11-09 AT AT962971A patent/AT328005B/en not_active IP Right Cessation
- 1971-11-10 NO NO4142/71A patent/NO139196C/en unknown
- 1971-11-10 ZA ZA717566A patent/ZA717566B/en unknown
- 1971-11-11 GB GB5237871A patent/GB1307959A/en not_active Expired
- 1971-11-11 SE SE7114397A patent/SE378498B/xx unknown
- 1971-11-12 AU AU35657/71A patent/AU468126B2/en not_active Expired
- 1971-11-16 ES ES397061A patent/ES397061A2/en not_active Expired
- 1971-11-16 IT IT31124/71A patent/IT976370B/en active
- 1971-11-17 BE BE775423A patent/BE775423R/en active
Also Published As
Publication number | Publication date |
---|---|
NO139196C (en) | 1979-01-17 |
AU468126B2 (en) | 1976-01-08 |
DE2056583A1 (en) | 1972-05-25 |
ZA717566B (en) | 1972-08-30 |
NO139196B (en) | 1978-10-09 |
AU3565771A (en) | 1973-05-17 |
SE378498B (en) | 1975-09-01 |
ATA962971A (en) | 1975-05-15 |
IT976370B (en) | 1974-08-20 |
BE775423R (en) | 1972-05-17 |
DE2056583C3 (en) | 1979-05-17 |
DE2056583B2 (en) | 1978-09-14 |
AT328005B (en) | 1976-02-25 |
ES397061A2 (en) | 1975-04-01 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PS | Patent sealed | ||
435 | Patent endorsed 'licences of right' on the date specified (sect. 35/1949) | ||
PCNP | Patent ceased through non-payment of renewal fee |