Broadcast Receiver Switching Unit for CI Slot Decryption
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Solution Overview
Problem
In set-top boxes with two tuners and two CI slots, users cannot watch paid broadcasting if they insert the CAM into the wrong CI slot, as each tuner and CI slot are associated on a one-on-one basis, leading to decryption failures.
Innovation Solution
A broadcast receiver with a switching unit that can redirect the input destination of transport stream signals between two modules, each equipped with a decryption circuit, allowing the system to decrypt signals even if the CAM is inserted into the wrong CI slot by controlling the switching process to ensure successful decryption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the tuner and CI slot are associated on a one-on-one basis, then the system structure is simple and clear, but the user cannot watch paid broadcasting if the CAM is inserted into the wrong CI slot
Solution Approach 1:
The patent implements dynamic switching capability that allows the system to change the association between tuners and CI slots at runtime. The switching unit can dynamically redirect transport stream signals from any tuner to any CI slot based on decryption success, making the system adaptable rather than fixed. This resolves the contradiction by maintaining simple physical structure while achieving flexible operational behavior through dynamic signal routing.
Solution Approach 2:
The patent separates the tuner-CI slot association into independent functional modules: a switching unit that can independently route signals from any tuner to any CI slot, and a decoder that independently tests decryption success. This segmentation allows the system to try different tuner-CI slot combinations without requiring complex reconfiguration of the entire system, resolving the contradiction between simple structure and flexible operation.
2Ease of operation
If the user inserts the CAM into the wrong CI slot, then the decryption fails and paid broadcasting cannot be watched, but adding switching capability increases device complexity
Solution Approach 1:
The system performs self-diagnosis and self-correction by automatically testing decryption success and switching to alternative tuner-CI slot combinations when needed. The controlling unit monitors decoder output and autonomously controls the switching unit without user intervention. This self-service approach achieves CAM insertion flexibility while minimizing the complexity burden on the user, as the system handles the complexity internally through automated trial-and-error decryption testing.
Solution Approach 2:
The patent changes the operational parameters of the system by allowing multiple tuner-CI slot associations to be tested rather than maintaining a single fixed association. The system varies the signal routing parameters dynamically based on decryption success feedback, achieving flexibility without permanently increasing hardware complexity. The switching capability is activated only when needed, based on parameter changes in signal routing rather than structural changes.
3Reliability
If multiple tuner-CI slot combinations are tested for decryption, then the probability of successful decryption increases, but the time required for signal processing increases
Solution Approach 1:
The system performs decryption testing with multiple tuner-CI slot combinations only when necessary, rather than always testing all combinations. The switching unit attempts decryption with the default or first available CI slot, and only activates the trial-and-error process with alternative combinations when initial decryption fails. This partial action approach achieves sufficient decryption reliability while minimizing time loss by avoiding unnecessary testing in cases where the first attempt succeeds.
Solution Approach 2:
The system implements a feedback loop where the decoder's decryption success or failure signal immediately feeds back to the controlling unit, which then decides whether to switch to alternative tuner-CI slot combinations. This feedback mechanism allows the system to quickly terminate the testing process when decryption succeeds, minimizing time loss. The feedback-driven approach ensures that multiple combinations are tested only when the feedback indicates failure, optimizing the balance between reliability and processing time.
Data Source
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AI summary
A broadcast receiver includes: a first receiving unit and a second receiving unit each of which is configured to receive a broadcast wave and outputs a TS signal; a first CI slot and a second CI slot each of which is connected to a card module including therein a decryption circuit, decrypts, using the decryption circuit, an inputted TS signal, and outputs the decrypted TS signal; a decoder which decodes a signal outputted from the first CI slot or the second CI slot, and determines whether or not the signal is successfully decrypted; a switching unit configured to switch an input destination of the TS signal between the first CI slot and the second CI slot; and a controlling unit configured to control the switching by the switching unit.