Television – Diverse device controlled by information embedded in video...
Reexamination Certificate
1996-03-21
2001-02-13
Flynn, Nathan (Department: 2711)
Television
Diverse device controlled by information embedded in video...
C348S555000, C348S705000, C348S706000
Reexamination Certificate
active
06188438
ABSTRACT:
BACKGROUND OF THE INVENTION
The SMPTE 259M has hitherto been known as the standard for serial digital interface (hereinafter simply referred to as a “SDI”) of video signal used in professional and broadcasting station video equipments. This SMPTE 259M standard describes a serial digital interface for 525/60 and 625/50 digital television equipment operating with either 4:2:2 component signals or 4f
sc
composite digital signals.
FIG. 1
of the accompanying drawings shows the SDI format.
As shown in
FIG. 1
, the SDI format comprises an EAV (end of active video)
131
provided at the starting portion, an ancillary signal area
132
provided next to the EAV
131
, and a SAV (start of active video)
133
provided next to the ancillary signal area
132
. The EAV
131
and SAV
133
comprise words (3FF, 000, 000, XYZ)
h
each word of which is a hexadecimal signal. The EAV
131
, the ancillary signal area
132
, and the SAV
133
are composed of 276 words for the 525/60 television receiver, and composed of 288 words for the 625/50 the television receiver.
The SDI format further includes an effective image signal area
134
provided next to the SAV
133
, and the effective image signal area
134
is used to transmit an image signal. The effective image signal area
134
is followed by a timing reference signal EAV
135
. The image signal comprises a luminance signal Y and blue and red color difference signals Cb, Cr each of which is a 10-bit digitized signal, and the luminance signal Y and the blue and red color difference signals are arranged in the sequential order of Cb, Y, Cr and Y. The effective image signal area
134
is composed of 1440 words for both the 525/60 television receiver and the 625/50 television receiver. Therefore, an area which results from adding the effective image signal area
134
to the EAV
131
, the ancillary signal area
132
and the SAV
133
is composed of 1716 words for the 525/60 television receiver, and composed of 1728 words for the 625/50 television receiver.
The effective image signal area
134
is followed by the timing reference signal EAV
135
. The timing reference signal EAV
135
is composed of words (3FF, 000, 000, XYZ)
h
each word of which is a hexadecimal signal. The SAV
133
, and the EAV
131
,
135
are inserted into the horizontal blanking period.
A parallel signal according to the SDI format is converted in the form of parallel to serial signal, and in this case, the LSB (least significant bit) of any data word shall be transmitted first. Then, the serial signal is converted into a scrambled NRZI (nonreturn-to-zero inverted) signal, channel-coded, and thereby transmitted as serial digital video signal of 270 Mbit/sec.
In the SDI format signal transmission system, the serial digital video signal is transmitted with a word synchronization of word unit. However, in this SDI format signal transmission system, it is frequently demanded that a plurality of signals are switched by a signal switching device. This signal switching device switches and outputs the inputted signal in the form of the serial signal. Before or after the signal is switched by the signal switching device, a word synchronization of signal becomes discontinuous, and a synchronization of switched signal is not achieved, thereby causing a transmission error. The transmission error continuously occurs until a word synchronization of signal is established by the next EAV.
For this reason, according to the SDI format, a signal is switched during a vertical blanking period, whereby a signal error that occurred due to a discontinuous word synchronization of signal generated when the signal is switched can be prevented from becoming conspicuous on a picture screen of a television receiver on the reception side.
As described above, in the SDI format signal transmission system, before or after a plurality of signals are switched by the signal switching device, a word synchronization of signal becomes discontinuous, and a synchronization of switched signal cannot be established, resulting in a transmission error. In order to avoid the occurrence of transmission error, a signal has to be switched during the vertical blanking period.
SUMMARY OF THE INVENTION
In view of the aforesaid aspect, it is an object of the present invention to provide method of and apparatus for identifying a signal transmitting source in which the reception side detects a switching of a signal thereby to prevent a transmission error from occurring when signals are switched.
According to an aspect of the present invention, there is provided a receiving apparatus for receiving a transmitted signal with a transmitting source identifying code added thereto at a transmission end of a transmission line as a received signal. This receiving apparatus comprises transmitting source identifying code extracting means for extracting the transmitting source identifying code from the received signal, transmitting source identifying code change detecting means for detecting a change of the transmitting source identifying code extracted from the received signal by the transmitting source identifying code extracting means, and transmitted signal switching detecting means for detecting a switching of the transmitted signal based on the transmitting source identifying code whose change was detected by the transmitting source identifying code detecting means.
According to another aspect of the present invention, there is provided a method of switching a transmitted signal which is comprised of the steps of adding a transmitting source identifying code to a transmitted signal at a transmitting end of a transmission line, extracting the transmitting source identifying code at a receiving end of the transmission line, detecting a change of the transmitting source identifying code extracted at the receiving end, and detecting a switching of the transmitted signal based on the transmitting source identifying code this changed.
REFERENCES:
patent: 4613904 (1986-09-01), Lurie
patent: 4723302 (1988-02-01), Fulmer et al.
patent: 4945412 (1990-07-01), Kramer
patent: 5187575 (1993-02-01), Lim
patent: 5339111 (1994-08-01), Park
patent: 5444491 (1995-08-01), Lim
patent: 5457499 (1995-10-01), Lim
patent: 5485462 (1996-01-01), Helm et al.
patent: 5526427 (1996-06-01), Thomas et al.
patent: 5532732 (1996-07-01), Yuen et al.
patent: 5630203 (1997-05-01), Weinblatt
patent: 5646675 (1997-07-01), Copriviza et al.
Proposed SMPTE Standard for Television—Serial Data Transport Interface, Aug. 24, 1998.
Flynn Nathan
Frommer William S.
Frommer & Lawrence & Haug LLP
Kessler Gordon
Sony Corporation
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