EP0705518A1 - Derivation de filtre pour la transmission d'un signal supplementaire avec un signal video - Google Patents
Derivation de filtre pour la transmission d'un signal supplementaire avec un signal videoInfo
- Publication number
- EP0705518A1 EP0705518A1 EP94920725A EP94920725A EP0705518A1 EP 0705518 A1 EP0705518 A1 EP 0705518A1 EP 94920725 A EP94920725 A EP 94920725A EP 94920725 A EP94920725 A EP 94920725A EP 0705518 A1 EP0705518 A1 EP 0705518A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- signal
- filter
- processor
- video
- during
- 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- Withdrawn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
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/08—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division
- H04N7/081—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division the additional information signals being transmitted by means of a subcarrier
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N7/00—Television systems
- H04N7/08—Systems for the simultaneous or sequential transmission of more than one television signal, e.g. additional information signals, the signals occupying wholly or partially the same frequency band, e.g. by time division
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
- H04N5/445—Receiver circuitry for the reception of television signals according to analogue transmission standards for displaying additional information
Definitions
- This invention relates to transmitting a second signal with a video signal and more particularly to transmitting two signals with a video signal.
- a drawback of such approaches is that the phase and delay distortion of the filtering may adversely effect the blanking interval and the data transmitted during those intervals such as close caption data.
- the comb filter described in U.S. Patent No. 4,958,230 may cause intersymbol interference or the like, thereby adversely affecting reception of close captioned data.
- such filtering may also adversely effect the beginning and ending of the vertical and horizontal blanking intervals. Although these effects may not cause a perceptible degradation of the received signal, the delays and phase distortion may be perceptible during the transmission of test patterns. Still further, such effects may result in an adverse impact on testing of the transmitted signal.
- Such adverse effects can be particularly adverse in testing the quality of various transmission links used for transmitting video signals such as coaxial and fiber optic cable links, microwave relay links, and satellite links.
- the presence of such delays and phase distortion makes it difficult for test equipment and technicians to discern whether the effects are caused by the filters used for transmitting the additional signal or by the transmission link.
- the bypassing operation may be controlled by either a controllable high impedance attenuator in series with a bypass around the filters, by a voltage controlled filter or by a controllable double throw, single pole switch forming a bypass around the filters.
- the control lead of the switch or the attenuator or the control node of the voltage controlled filter is coupled to a control signal generated by a blanking detector.
- the blanking detector provides a control signal that causes the attenuator or switch to effectively remove the filter from the circuit during the blanking interval.
- FIG. 1 is a block diagram of an embodiment of the invention. Detailed Description of the Embodiments
- Figure 1 shows an embodiment of the signal processor 10 of the transmitter that may be used for transmitting a tertiary digital data signal 49 through a transmitter with a primary NTSC color video signal 12 also containing a secondary data signal comprised of, for example, closed captioned data.
- Other embodiments of the invention may be used for transmitting an additional third analog signal with closed captioned data combined with an NTSC signal, for transmitting a second signal with an NTSC video signal lacking closed captioned data and for transmitting a second signal with another video format signal such as SECAM or PAL.
- FIG. 1 The embodiment of Figure 1 is virtually identical to the embodiment in Figure 3 of U.S. Patent Application No. 07/947,134 to Montgomery et al. filed on September 18, 1992 and assigned to WavePhore, Inc with the notch filter omitted.
- a second signal 49 is rasterized and modulated by the data section 50 for injection at the adder 70 into the output of the video section 20.
- the low pass filter 27 substantially attenuates the video signal above the chroma subcarrier and in particular above 3.7 megahertz. That filter 27 like the comb filter referred to above for U.S. Patent No. 4,958,230 may cause phase distortion and different delays to the input signal.
- the filter 27 also causes frequency distortion to test signals that may be transmitted in lieu of ordinary television programming.
- the instant embodiment differs from the embodiment of Figure 3 of U.S. Patent Application No. 07/947134 to Montgomery et al. filed on September 18, 1992 in that a filter bypass circuit 100 is included.
- the filter by ⁇ pass circuit 100 includes a delay element (not shown) that equals the time duration of the delay of the filter 27 and includes a lead 112 coupled to the input of the filter 27 and a lead 115 coupled to a first throw of a single pole double throw analog switch 110.
- the output of the filter 27 is also coupled to a lead 113 for a second throw of the double throw switch 110.
- a control terminal 114 of the switch 110 is coupled to the output of the OR gate 116.
- the pole of the switch is coupled to a lead 119 connected to the adder 70.
- the switch is a high speed analog semiconductor switch such as is available from a variety of different semiconductor manufacturers.
- the switch 110 may also be a controllable attenuator as described below.
- a delayed composite blanking signal 117 provided as one of the timing signals 54 is coupled through the OR gate 116 to the control electrode 115 of the switch 110.
- the delayed composite blanking signal 117 causes the switch 110 to select the by-pass element 100 instead of the filter 27 during the horizontal and vertical blanking intervals. Therefore, the filter 27 is by-passed during the blanking intervals. Hence, there is no phase distortion or frequency distortion of the video signal occurring during the horizontal or vertical blanking intervals.
- the filter 27 attenuates a portion of the video spectrum above 3.7 Megahertz during active video lines and does not attenuate the same portion of the spectrum during the blanking intervals.
- control signal 118 is also supplied to the OR gate 116 to control the filter. This allows system operators to bypass the filter so that during transmission link testing, test engineers can observe an unfiltered test pattern or verify performance with an unfiltered video signal when the subscriber cannot observe the video program.
- a still further input may be coupled to an input of the OR gate 116 so that the filtering may be by-passed when there is no data present to transmit.
- the IEEE 449 interface/rasterizer 51 generates the further control signal (not shown) coupled to the OR gate 116.
- the control signal is generated and the filter 27 is by-passed. The by-passing of the filter 27 continues until data is present at the output of the modulator 56 for transmission.
- a controllable high impedance attenuator (not shown) may be substituted therefore.
- the impedance of the attenuator causes the filter 27 output to be supplied during the active video intervals to the adder 27 and the output of the filter bypass circuit 100 to be provided during the blanking intervals.
- the low pass filter 27 may be replaced with a voltage controlled filter, thereby eliminating the need for the switch 110 and leads 112 and 115.
- the output of the OR gate 116 may be coupled directly to the voltage control node of the filter so that the filter characteristics change to avoid phase distortion and filtering during the horizontal and video blanking intervals.
- the OR gate 116 is not coupled to the delayed, composite sync signal. Rather circuitry (not shown) determines the appropriate time for data to be added to the video signal is used to bypass the filter 27 whenever data is not being sent. During the vertical blanking intervals and the intervals when data is not being sent, a control signal will be generated so that the OR gate 116 will cause the filter 27 to be by ⁇ passed.
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Television Systems (AREA)
- Picture Signal Circuits (AREA)
- Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
Abstract
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US7588893A | 1993-06-14 | 1993-06-14 | |
US75888 | 1993-06-14 | ||
PCT/US1994/006627 WO1994030011A2 (fr) | 1993-06-14 | 1994-06-10 | Derivation de filtre pour la transmission d'un signal supplementaire avec un signal video |
Publications (1)
Publication Number | Publication Date |
---|---|
EP0705518A1 true EP0705518A1 (fr) | 1996-04-10 |
Family
ID=22128582
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94920725A Withdrawn EP0705518A1 (fr) | 1993-06-14 | 1994-06-10 | Derivation de filtre pour la transmission d'un signal supplementaire avec un signal video |
Country Status (9)
Country | Link |
---|---|
EP (1) | EP0705518A1 (fr) |
JP (1) | JPH08511669A (fr) |
KR (1) | KR960703306A (fr) |
CN (1) | CN1125501A (fr) |
AU (1) | AU7172394A (fr) |
BR (1) | BR9406817A (fr) |
CA (1) | CA2164830A1 (fr) |
FI (1) | FI955972A (fr) |
WO (1) | WO1994030011A2 (fr) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100716290B1 (ko) | 2005-07-04 | 2007-05-09 | 삼성전자주식회사 | 영상처리장치, 부가정보처리장치 및 영상처리방법 |
Family Cites Families (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5327237A (en) * | 1991-06-14 | 1994-07-05 | Wavephore, Inc. | Transmitting data with video |
JP3141963B2 (ja) * | 1991-09-06 | 2001-03-07 | 日本テレビ放送網株式会社 | 情報信号のエンコーダおよびデコーダ |
-
1994
- 1994-06-10 KR KR1019950705657A patent/KR960703306A/ko not_active Application Discontinuation
- 1994-06-10 EP EP94920725A patent/EP0705518A1/fr not_active Withdrawn
- 1994-06-10 CN CN94192433A patent/CN1125501A/zh active Pending
- 1994-06-10 BR BR9406817A patent/BR9406817A/pt not_active Application Discontinuation
- 1994-06-10 JP JP7502148A patent/JPH08511669A/ja active Pending
- 1994-06-10 WO PCT/US1994/006627 patent/WO1994030011A2/fr not_active Application Discontinuation
- 1994-06-10 AU AU71723/94A patent/AU7172394A/en not_active Abandoned
- 1994-06-10 CA CA002164830A patent/CA2164830A1/fr not_active Abandoned
-
1995
- 1995-12-13 FI FI955972A patent/FI955972A/fi not_active Application Discontinuation
Non-Patent Citations (1)
Title |
---|
See references of WO9430011A2 * |
Also Published As
Publication number | Publication date |
---|---|
JPH08511669A (ja) | 1996-12-03 |
CN1125501A (zh) | 1996-06-26 |
AU7172394A (en) | 1995-01-03 |
BR9406817A (pt) | 1996-07-23 |
FI955972A (fi) | 1996-02-08 |
WO1994030011A3 (fr) | 1994-12-22 |
CA2164830A1 (fr) | 1994-12-22 |
WO1994030011A2 (fr) | 1994-12-22 |
FI955972A0 (fi) | 1995-12-13 |
KR960703306A (ko) | 1996-06-19 |
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