| 主权项 |
1. A security module comprising:
a processor configured to process at least one audio/video data stream; an interface comprising a plurality of contacts including a power supply contact and a clock contact configured to receive a clock signal; a frequency divider configured to divide a frequency of the clock signal to generate a divided clock signal, a frequency multiplier configured to multiply the frequency of the clock signal to generate a multiplied clock signal, or both; a voltage detector configured to measure a voltage on the power supply contact and to categorize the measured voltage as pertaining to one from a plurality of predetermined voltage ranges; and a multiplexer configured to select between the received clock signal or divided clock signal or multiplied clock signal for operating the security module; wherein said security module is configured to function according to any one from a plurality of predetermined operation modes, each of the predetermined operation modes having a frequency of operation corresponding to a frequency of one of the received clock signal, divided clock signal, or multiplied clock signal, the predetermined operation modes including any communication protocol from a plurality of different communication protocols or any class from a plurality of classes of a communication protocol; and wherein the security module is configured to monitor for a change in a category of the measured voltage from the voltage detector following power-on and, when the security module detects the change in the category, to switch to a different one from the plurality of operating modes and to cause the multiplexer to select between the received clock signal or divided clock signal or multiplied clock signal corresponding to the different one from the plurality of operation modes. |
