Error detection/correction and fault detection/recovery – Pulse or data error handling – Error/fault detection technique
Reexamination Certificate
2000-03-21
2003-02-04
Chung, Phung M. (Department: 2784)
Error detection/correction and fault detection/recovery
Pulse or data error handling
Error/fault detection technique
C714S799000
Reexamination Certificate
active
06516445
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to data reception, processing and transmission of digital signals between a cable distributor and an end user. More particularly, the present invention relates to the failure detection of a point-of-deployment (POD) module inserted into a digital receiver of the end user.
BACKGROUND OF THE INVENTION
A cable distributor provides various services to a customer, for example multiple television programs. The television programs are transmitted from the distributor's headend to the customer (end user) by way of cable and satellite. The end user typically receives the television programs through a digital receiver.
Depending on the type of services requested by the end user, a point-of-deployment (POD) module may be required. For example, a POD module is required, when the end user wishes to view a pay-per-view program. Typically, the POD module is a PC card given to the end user by the cable distributor. The end user inserts the POD module into the digital receiver.
In operation, the television program is scrambled and transmitted-by the headend to the end user's receiver. The receiver sends the scrambled signal to the POD module, the latter descrambling the signal. The descrambled signal is then sent from the POD module to the receiver for further processing and eventual display.
One example of a POD module (which is not a PC card but a credit card) is the National Renewable Security Systems (NRSS) Smart Card used for decrypting an encoded MPEG-2 format data stream, described in. U.S. Pat. No. 5,675,654. It is noted that the NRSS Smart Card includes a resident, programmable microprocessor and decryption engine.
The syntax for the MPEG-2 standard received by the NRSS Smart Card defines several layers of data records which are used to convey both audio and video data. To transmit information, a digital data stream representing, for example, multiple video sequences, is divided into several smaller units and each of these units is encapsulated into a respective packetized elementary stream (PES) packet. For transmission, each PES packet is divided, in turn, among a plurality of fixed-length transport packets. Each transport packet contains data relating to only one PES packet. The transport packet also includes a header, which holds control information sometimes including an adaptation field to be used in decoding the transport packet.
When decryption is necessary, valid data beginning with a predetermined synchronization byte is sent to the NRSS Smart Card. The Smart Card recognizes this predetermined synchronization byte (i.e., distal pattern), synchronizes to it and begins decrypting, for example, the next 188 bytes.
The interface between the POD module and the digital receiver is defined in Society for Cable Television Engineers (SCTE) DVS131, POD Module Interface, which is incorporated herein for its teachings of physical, hardware and software interfaces existing between the POD module and the digital receiver.
POD modules are built by several manufacturers and given to end users by the cable distributor. Quality control typically varies from one manufacturer to another, resulting in reliability differences between one POD module and another POD module. One POD module may be functional, while another may be inoperative and a third may be marginally functional.
Presently, when an end user inserts a POD module into the receiver, and does not see a viewable program, the end user has no way of knowing whether the fault is in the transmission, the receiver or the POD module.
The present invention addresses this problem.
SUMMARY OF THE INVENTION
To meet this and other needs, and in view of its purposes, the present invention provides a method for detecting failure in a point-of-deployment (POD) module. The POD module interfaces with a digital receiver and receives a first data stream with a first predetermined pattern. The method includes receiving the first data stream; forwarding the first data stream to the POD module; receiving a second data stream with a second predetermined pattern from the POD module; monitoring validity of the first and second data streams; and if the first data stream is valid and the second data stream is invalid, providing a failure alert regarding the POD module.
The method includes monitoring each of the first and second data streams for a predetermined synchronization byte. The method also includes monitoring each of the first and second data streams for a packet start and an end-of-packet; and monitoring each of the first and second data streams for a clocking signal. The method further includes synchronizing and comparing each of the respective clocking signals to an internal clocking signal. The communications between the digital receiver and the POD module are also monitored.
It is understood that the foregoing general description and the following detailed description are exemplary, but are not restrictive of the invention.
REFERENCES:
patent: 5613001 (1997-03-01), Bakhoum
patent: 5675654 (1997-10-01), Ryan
patent: 6298400 (2001-10-01), Candelore
Conditional Access System for Terrestrial Broadcast, ATSC, pp. 1-27 (Jul. 17, 1999).
Digital Video Broadcasting (DVB),European Telecommunications Standards Institute, 13 pgs. (Oct. 1996).
Chung Phung M.
Matsushita Electric - Industrial Co., Ltd.
RatnerPrestia
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