Importance

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Abstract

Different digital radio transceiver front panel escutcheon plate modules are provided for different optional transceiver configurations. A security circuit is provided in each module in addition to user controls and associated circuitry. The security circuit is connected to communicate serial data signals to and from a digital signal controller which is part of the main transceiver circuitry. The controller is capable of performing any of various basic and option functions under control of program control instructions stored in an associated non-volatile memory. Upon initial application of power to the transceiver, the controller transmits a sequence of digital signals to the security circuit. The security circuit permutes the sequence of signals into a different sequence, the specific permutation used being arbitrarily complex--and dependent on transceiver 'option' features to be enabled. The security circuit communicates the permuted signal sequence back to the controller. The controller enables (executes) portions of the program control instructions stored in its associated non-volatile memory and disables (does not execute) other portions of the stored program control instructions in response to the sequence received from the security circuit.

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First Claim