Error detection/correction and fault detection/recovery – Pulse or data error handling – Error count or rate
Reexamination Certificate
1997-06-30
2002-05-07
Decady, Albert (Department: 2133)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Error count or rate
C360S013000, C714S798000
Reexamination Certificate
active
06385745
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to receiver/decoders generally and, more particularly, to a receiver/decoder for use with otherwise incompatible systems.
BACKGROUND OF THE INVENTION
The Society of Motion Picture and Television Engineers (SMPTE) has created a serial interface standard (the SMPTE-259M) for sending non-compressed component and composite digital video streams between various pieces of studio grade equipment. There is a large installed base of SMPTE-259M compliant equipment. The interface uses a phase independent form of signaling called NRZI (Non-Return-To-Zero, Invert on ones). The interface may present both true and complement data. One common form of SMPTE equipment is a serial switch that is used to route these video streams between other pieces of equipment.
Another common serial interface, the DVB-ASI (Digital Video Broadcast—Asynchronous Serial Interface) also makes use of a serial interface to route MPEG
2
encoded video streams between pieces of equipment. The DVB-ASI interface makes use of an 8B/10B encoded data stream that, unlike SMPTE-259M, is sensitive to the phase of the data stream. Other than this one characteristic, both the DVB-ASI and SMPTE-259M physical interfaces are essentially identical. Both operate at or handle 270 Mbaud serial data, use 75 Ohm studio grade coax (e.g., Belden Type 8281), have the same launch amplitude (800 mV), connectors, etc. The physical similarity between the interfaces has led some video production studios to use standard SMPTE serial switches to route DVB-ASI data streams. Unfortunately, the configuration of such a system requires significant trial and error in connections (for proper operation) to find out which inputs/outputs do not introduce an inversion in the data stream.
FIG. 1
illustrates a conventional approach for interconnecting SMPTE and DVB devices.
FIG. 1
comprises a number of SMPTE transmit devices
12
a
,
12
b
and
12
n
, a number of DVB transmit devices
14
a
,
14
b
and
14
n
, a number of SMPTE receive devices
16
a
,
16
b
and
16
n
, a number of DVB receive devices
18
a
,
18
b
and
18
n
, a SMPTE switch
20
, a SMPTE switch
22
and a DVB switch
24
. Since the SMPTE transmit devices
12
a
-
12
n
and the SMPTE receive devices
16
a
-
16
n
are base and dependent devices, the SMPTE switches
20
and
22
may present signals at either the true (+) or complement (−) outputs. However, the DVB transmit devices
14
a
-
14
n
and the DVB receive devices
18
a
-
18
n
are phase dependent devices. When connected through the DVB switch
24
, a true phase is maintained between the DVB transmit devices
14
a
-
14
n
and the DVB receive devices
18
a
-
18
n
. The DVB transmit device
14
a
is shown connected through the SMPTE switch
22
. In such a configuration, it is important to maintain the positive phase at the output of the SMPTE switch
22
prior to presenting it to the DVB receive device
18
b
. Conventional approaches require the implementation of either DVB-ASI specific equipment, or identification of ports on SMPTE equipment that do not introduce an inversion in the data stream.
Referring to
FIG. 2
, a block diagram of a conventional circuit
30
is shown. The circuit
30
generally comprises data cable
32
, a receive equalization circuit
34
and a logic circuit
36
. A logic circuit
36
generally presents a framed and decoded data signal at an output
38
and an error detected signal RVS at an output
40
. The logic
36
generally comprises a differential amplifier
42
and a decoder framer
44
. The signal received by the circuit
30
must have a proper phase relationship in order for the decoder framer
44
to provide a proper functioning at the output
38
. See, for example, U.S. patent application Ser. No. 08/658,760, now U.S. Pat. No. 5,754,011 filed Jun. 5, 1996, the appropriate sections which are hereby incorporated by reference.
The existing methods all have significant drawbacks for video studios implementing DVB-ASI. Such studios must either abandon their existing SMPTE switches when they add on DVB-ASI compliant equipment, duplicate and segregate their existing switches into SMPTE and DVB cable plants, or reduce the usable port capacity of their SMPTE equipment by a factor of two. The costs and logistics of any of these techniques could significantly slow the adoption of DVB-ASI.
SUMMARY OF THE INVENTION
The present invention concerns a circuit comprising a receiver configured to receive a first signal having a first phase, a second signal having a second phase opposite the first phase and an output configured to present either the first or second signals. A state machine may be configured to receive the output of the receiver circuit and to provide a control signal configured to select the first or second signal.
The objects, features and advantages of the present invention include providing a phase independent transmit and/or receive device that may be implemented using switches that may invert the polarity of the signal and may independently and/or automatically compensates for phase inversions.
REFERENCES:
patent: 3644683 (1972-02-01), Braun
patent: 3961269 (1976-06-01), Alvarez, Jr.
patent: 5185722 (1993-02-01), Ota et al.
patent: 5260906 (1993-11-01), Mizukami
patent: 5724007 (1998-03-01), Mar
patent: 5754254 (1998-05-01), Kobayashi et al.
patent: 5844849 (1998-12-01), Furutani
patent: 5923663 (1999-07-01), Bontemps et al.
Cypress Semiconductor Corp.
De'cady Albert
Lamarre Guy J.
Maiorana P.C. Christopher P.
LandOfFree
Phase independent receiver and/or decoder does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Phase independent receiver and/or decoder, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Phase independent receiver and/or decoder will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2857588