Pulse or digital communications – Systems using alternating or pulsating current
Reexamination Certificate
1997-12-19
2001-04-03
Chin, Stephen (Department: 2734)
Pulse or digital communications
Systems using alternating or pulsating current
C375S216000, C375S244000, C375S245000, C348S446000, C348S394100
Reexamination Certificate
active
06212238
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to digital-to-analog and analog-to-digital devices; in particular, to systems which utilize the analog form as a common intermediary form between such devices. This invention is particularly applicable to devices such as Digital Video Disks (DVDs), High Definition Televisions (HDTVs), and the like, which utilize a digital form for processing, storing, or displaying the information, and utilize a common intermediary analogy form, such as NTSC or PAL, for communicating the information to each other.
2. Description of Related Art
FIG. 1
shows a system comprised of multiple components, with switching and selection means. Such a system may represent a home electronics center, a recording studio, a multi-media center, etc. The names of the components in the system of
FIG. 1
are presented for illustrative purposes only. The components
101
through
108
are interconnected to each other via interconnections
111
through
119
. Communications among the components via these interconnections will have a form and format such that each device can accurately receive the information content of these communications. Consider interconnection
115
and switch
105
. Interconnection
115
may carry information from either component
106
or
107
, via interconnections
116
or
117
respectively, in dependence upon the state of switch
105
. Conventionally, to assure that device
104
is able to accurately transmit or receive information to or from the selected component, both components
106
and
107
operate using the same information format. The common information format also allows devices
106
and
107
to communicate with each other, also via switch
105
.
Conventionally, commonly accepted formats are employed for the information exchange, so that the components may communicate independent of the particular vendors of the components, and independent of the form of the information utilized within the components. Because newer components must be compatible with legacy components to be marketable, the common formats are often those used before the advent of digital products. For example, if component
106
is a video recorder, component
107
is a video disk, and component
104
is a television, the format of the communications on interconnections
116
and
117
will be NTSC, PAL, or other common analog format. In this manner, via switch
105
, components
104
,
106
, and
107
may communicate to each other as desired.
To effect a conversion to and from analog and digital form, standard digital encoders (DENCs) and decoders (DMSDs) have been developed. The digital encoders convert standard digital signals, such as MPEG encoded video, into standard analog signals, such as NTSC and PAL. The digital decoders, or video input processors, convert standard analog input, such as NTSC and PAL, into standard digital signals, such as MPEG encoded video. By incorporating such a digital encoder and digital decoder into a digital product, compatibility, via the analog standard, can be achieved with another component which conforms to the analog standard, independent of whether the other component is analog or digital. Similar interface components are available for converting audio signals to and from a standard digital form, such as AC-3 (a.k.a. “Dolby Digital”), DTS, S/PDIF, AES/EBU, ADAT, etc.
Digital components are often characterized as having higher quality than their analog counterparts. For example, CDs have the potential for much higher audio quality than cassettes; digitally recorded cassettes have the potential for higher quality than conventional analog cassettes. Similarly, DVDs and HDTVs have the potential for higher quality than VCRs and conventional televisions. These digital components may utilize newer digital formats, such as MPEG, CCIR 601 serial-D1, AC-3, S/PDIF, etc., for communicating digital data directly. Such direct communication minimizes the degradation caused by the conventional conversion of the digital signals to analog, and back to digital, between such digital devices. For example, if component
107
is a video disk, and component
104
is an MPEG-compatible television, the connection
118
could be an MPEG, digital, connection. Note, however, that even with a digital connection
108
for improved quality, components
104
and
107
must also contain an analog interconnection
115
,
117
to maintain compatibility with legacy systems. If a device contains both an analog and digital interconnection capability, the selection between the format to be utilized is also required, typically requiring the user to manually select the specific source of the input to and output from each device.
SUMMARY OF THE INVENTION
It is an object of this invention to provide alternative formats for communications between components, and to provide an automatic selection of the preferred format between components.
In accordance with this invention, a supplemental signal is appended to a conventional analog intermediary signal by the transmitting component. This supplemental signal conveys information regarding the alternative formats available from that component. In response to this supplemental signal, the receiving component signals the transmitting component to switch to an alternative format. Thereafter, the transmitting and receiving components communicate via the selected format, bypassing the degradation caused by conversions to and from the analog intermediary format.
In another preferred embodiment, the supplemental format signalling is effected by the receiving component only. Upon detection of this signalling, the transmitting component switches to the alternative format, and the receiving component switches thereafter, upon detection of this alternative format.
In the preferred embodiment, the supplemental signal is appended to the conventional analog formatted signal in a substantially non-interfering manner. In this way, compatibility with a conventional receiving component is maintained. By switching to an alternative format only upon command of the receiving component, the communication from a transmitting component in accordance with this invention is compatible with conventional receiving components as well as receiving components designed in accordance with this invention.
In the preferred embodiment, also, communications in the selected format is via the same interconnection used to communicate the analog intermediary signal. In this manner, no additional interconnections, compared to the conventional interconnections, are required.
REFERENCES:
patent: 3781686 (1973-12-01), Ching
patent: 3913016 (1975-10-01), Candy
patent: 5353119 (1994-10-01), Dorricott et al.
patent: 5592508 (1997-01-01), Cooper
Chin Stephen
Liu Shuwang
Philips Electronics North America Corporation
Piotrowski Daniel J.
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