Abstract: An apparatus is disclosed which accurately measures, over a wide ambient temperature range, the average power derived from an electrical signal. Furthermore, embodiments of the present invention can be fabricated with inexpensive, off-the-shelf components and can have excellent circuit characteristics at RF frequencies. These results are obtained in an illustrative embodiment of the present invention that comprises a first thermal detector, a second thermal detector, an error amplifier and a summer. The first thermal detector provides a reference signal, which varies with the ambient temperature, to the error amplifier. The summer receives the signal to be measured and the signal output from the error amplifier, and outputs to the second thermal detector a composite signal, which is indicative of the sum of the power derived from input signal and the output signal from the error amplifier.

Abstract: A digital system in which an integrated circuit complements the signaling protocol of non-standard devices so that the non-standard devices can operate and communicate with other devices as if the non-standard device were able to support the signaling protocol of the other devices. Embodiments of the invention are taught which reduce the overall power consumption in the system, which enhance the functionality of the system, and which reduce the overall package count in the system.

Abstract: A method for synthesizing gateways from formal specifications. We present an efficient procedure that computes protocol converters from formal specifications. This procedure has a polynomial number of computation steps. The method involves computation of a common subset of services. This common subset is used to compute the converter. Conditions under which the converter can be stateless are also described.

Abstract: A method and apparatus are disclosed for imparting a linear, but sloped, frequency response signal to a narrowband signal having a sinusoidal component at .omega..sub.0 radians per second. An illustrative embodiment comprises: a first signal divider, a first signal combiner and three signal paths between them. The first signal path advantageously comprises a first bi-phase attenuator; the second signal path advantageously comprises a first delay element; and the third signal path advantageously comprises both a second bi-phase attenuator and a second delay element. The first delay element preferably makes the second signal path substantially close to ##EQU1## seconds longer than the first signal path, where N is an integer. The second delay element preferably makes the third signal path substantially close to ##EQU2## seconds longer than the first signal path.

Abstract: A low-distortion, high-power, feed-forward amplifier is disclosed which is particularly well-suited for cellular radio applications. An illustrative embodiment comprises a main amplifier and a pair of correction amplifiers, which each are used to eliminate different distortion products introduced by the main amplifier into the amplified signal.

Abstract: A method and apparatus for imparting a positive phase slope (i.e., a negative group delay) to a narrowband signals is disclosed which adjusts the phases of the various frequency components of a signal in a manner opposite to that of a delay line. The invention also permits the amount of phase slope to be adjusted, electronically, without the need for electro-mechanical apparatus or the interchange of cables. Furthermore, embodiments of the present invention are advantageous in that at the center of the operating band they maintain the phase of the delayed signal. These results are obtained in an illustrative embodiment of the present invention which divides the signal to be delayed into two signals which traverse different signal paths and are recombined in a signal combiner. The first signal path advantageously comprises a gain control block. The second signal path advantageously comprises a second gain control block and a fixed line delay which is not found in the first signal path.

Abstract: A decoder for a modified and improved MPEG signal syntax includes a subtractor responsive to an input signal, a frame buffer responsive to the subtractor, a motion compensator responsive to the buffer and to applied motion vector signals, and a multiplier responsive to frame leak signals and to a modified prediction signal for developing an output signal applied to the subtractor. Furthermore, the decoder includes a processor responsive to the motion compensator and to applied adaptive macroblock leak signals for developing the modified prediction signal. The processor comprises a transform circuit responsive to the motion compensator, a gating template responsive to the transform circuit and the adaptive macroblock leak signals, and an inverse transform circuit responsive to the gating template. The transform circuit operates on 2.times.2 blocks of pixels to form 2.times.2 blocks of transform elements. The gating template is responsive to signals that specify a treatment for 2.times.

Abstract: A cryptographic communication system. The system, which employs a novel combination of public and private key cryptography, allows two parties, who share only a relatively insecure password, to bootstrap a computationally secure cryptographic system over an insecure network. The system is secure against active and passive attacks, and has the property that the password is protected against offline "dictionary" attacks. If Alice and Bob are two parties who share the password P one embodiment of the system involves the following steps: (1) Alice generates a random public key E, encrypts it with P and sends P(E) to Bob; (2) Bob decrypts to get E, encrypts a random secret key R with E and sends E(R) to Alice; (3) Alice decrypts to get R, generates a random challenge C.sub.A and sends R(C.sub.A) to Bob; (4) Bob decrypts to get C.sub.A, generates a random challenge C.sub.B and sends R(C.sub.A, C.sub.B) to Alice; (5) Alice decrypts to get (C.sub.A, C.sub.B), compares the first against the challenge and sends R(C.