Motorola Corporation

Michael J McClaughry

John Paul Byrns

Larry C Puhl

Ezzat A Dabbish

Michael W Bright

Daniel P Brown

Eric F Ziolko

A cryptographic apparatus for encrypting and decrypting digital words includes a mechanism that permits a cipher algorithm to be electronically stored after the manufacture of the apparatus. The storing mechanism includes at least one electrically erasable, programmable gate array containing a portion of the cipher algorithm and at least one random access memory device coupled to the array for storing digital data generated by the algorithm. A mechanism which is coupled to the gate array and memory device controls the execution of the algorithm for each digital word thereby decrypting encrypted digital words and encrypting non-encrypted digital words.

Cryptographic method and apparatus with electronically redefinable

A demodulator is described for demodulating phase-encoded data signals transmitted on a noisy communication channel, such as, for example, radio communication channels of a radio communication system. The demodulator includes a digital phase-locked loop for phase-locking to the mid-bit transitions of the phase-encoded data signal, which, in the preferred embodiment is encoded according to the well known Manchester coding format, and further includes demodulating circuitry for sampling the phase-encoded data signal a predetermind number of times, weighting the samples according to predetermined weighting factors, totalizing the weighted samples for each bit interval and comparing the totalized samples to a predetermined threshold value for ascertaining the logical state of each bit of the phase-encoded data signal. For example, if the magnitude of the totalized samples is greater than or equal to the threshold value, a logical one state may be provided for the decoded data signal, and, if the magnitude of the totalized samples is less than the threshold value, a logical zero state may be provided for the decoded data signal. In preferred embodiments of the present invention, the weighting factors assigned to each sample may be either binary weighted or sine weighted, although any suitable weighting factors may be utilized depending on the characteristics of the phase-encoded data signal. The phase-encoded data signal demodulator embodying the present invention is particularly well adapted for demodulating high speed, phase-encoded data signals transmitted over radio channels to mobile and portable stations of a radio communication system.

Phase-encoded data signal demodulator

Growing community of inventors

Cary, IL, United States of America

Michael J McClaughry