Abstract: Coding gain is improved by employing an N-dimensional trellis encoder incorporating an N'-dimensional convolutional encoder where N' is less than N. The additional coding gain is realized as a shaping gain. This unique modulator encodes a digital signal by generating a sequence of N-dimensional symbols as a function of the digital signal using an N'-dimensional convolutional encoder within the trellis encoder more than once (integer N/N' times) during each N-dimensional symbol interval. This allows the trellis encoder to produce an output of higher dimensionality than would normally be expected from the lower dimensionality convolutional encoder. The trellis encoder is applicable to television transmission.

Abstract: A method of coding a speech signal is described. In accordance with the method, a plurality of sets of indexed parameters are generated based on samples of the speech signal. Each set of indexed parameters corresponds to a waveform characterizing the speech signal at a discrete point in time. Parameters of the plurality of sets are grouped based on index value to form a first set of signals which represents the evolution of characterizing waveform shape; the signals of the first set are filtered to remove low frequency components and thereby produce a second set of signals which represents relatively high rates of evolution of characterizing waveform shape. The speech signal is then coded based on the second set of signals representing high rates of characterizing waveform shape evolution. Coding of the speech signal may further be based on a set of smoothed first signals.

Abstract: A moisture-collecting hood assembly (10) for a vapor-generating machine (12) includes a hood (14) having an open bottom (15)and upwardly tapering sides (16) and ends (18). On the inside of the hood is a gutter (24) for collecting moisture in the vapor condensing on the hood interior. Vapors from the machine that enter the hood are exhausted through a horizontally-oriented, moisture-collecting sleeve that has a central portion (46) whose cross-sectional area is larger than that of an inlet (43) in communication with the hood, and an outlet (48) in communication with a negatively pressurized exhaust line (49). The central portion of the sleeve serves to collect moisture in its lower portion that condenses from the vapor exhausted from the hood.

Abstract: A process for making a MOS device on a silicon substrate includes the step of forming a buried layer of germanium-silicon alloy in the substrate, or, alternatively, a buried layer of silicon enclosed between thin, germanium-rich layers. This buried layer is doped with boron, and tends to confine the boron during annealing and oxidation steps. The process includes a step of exposing the substrate to an oxidizing atmosphere such that an oxide layer 10 .ANG.-500 .ANG. thick is grown on the substrate.

Abstract: Testing of a sequential circuit (10) containing at least one embedded RAM (16) is accomplished by first generating a set of sequential vectors and then applying the vectors in sequence to a set of primary circuit inputs (PO.sub.o -PO.sub.j). The vectors are generated such that upon application to the circuit, the vectors excite potential faults at nodes (A) upstream of the RAM and propagate the effects of the faults through the RAM to the primary circuit outputs (PO.sub.o -PO.sub.j). Also, the test vectors serve to excite faults downstream of the RAM by propagating values through the RAM needed to excite the downstream faults. The fault effects (if any) that propagate to the circuit primary outputs are compared to a set of reference values to determine if any faults are present.

Abstract: An access control system stores two codes for each user that is authorized to access a resource, a primary code and a secondary code. When a user desiring access inputs the primary code to the system, the code is compared with the stored code for that user. If the primary code is valid, the user is allowed to access the resource. However, if the primary code is entered incorrectly, a count of the number of invalid attempts for that user is incremented, and if the count does not exceed a first threshold, the user can try again. When the number of invalid access attempts for the user exceeds the first threshold, the system requires the user to correctly input both the primary and secondary codes, before access to the resource is allowed. A second count is also maintained of the number of failed attempts in providing both codes. When the number of failed attempts exceeds a second threshold, the user is "locked out", i.

Abstract: At least one new video signal is created by using portions taken from each signal of a plurality of original video signals to create at least one new video signal, with the sequencing of the assignments of the particular portions from any of the original video signals to any particular ones of the new video signals, or the positions therein, being the output of a cryptographic function. A cryptographic function is a function that employs a cryptographic algorithm to supply as an output an enciphered version of the values of at least one of its inputs. Because the portion assignment sequence is the output of a cryptographic function, the resulting arrangements of the portions from the original video signals within the new video signals appear random to a viewer of the new video signals. Thus, the information content of the original video signals is not intelligible when viewing the new video signals, either individually or in any combination.

Abstract: In a communications system, a generalized partial response signaling (GPRS) technique is employed to compensate for intersymbol interference. To this end, signal points representative of data to be transmitted are selected from a signal constellation. This signal constellation includes a multiplicity of signal points which are regularly spaced within a polygonal region having more than four sides. The selected signal points are precoded in the transmitter in accordance with the GPRS technique. Because of the particular choice of the signal constellation used, the precoded signal points for transmission occupies a region identical to the polygonal region.

Abstract: Digital signals, such as digitized television signals, are subjected to a source coding step followed by a channel mapping step. The source coding step causes the television signal to be represented by two or more data streams while, in the channel mapping step, the mapping is such that the data elements of the various data streams have differing probabilities of being erroneously detected at the receiver. In preferred embodiments, a first one of the aforementioned data streams carries components of the overall television signal which are regarded as the most important--for example the audio, the framing information, and the vital portions of the video information, such as motion compensation information--and that data stream is mapped such that its data elements have the lowest probability of error.

Abstract: A phase-lock loop includes a scaling element whose scale factor is adaptively adjusted as a function of the value of a state variable in the loop--illustratively, the magnitude thereof. That function is such that, after the adjustment has been made, the value taken on by the state variable is within a predetermined range. In particular embodiments, the scale factor and the state variable are simultaneously adjusted reciprocally, rather than simply adjusting only the scale factor and waiting for the normal operation of the loop to change the state variable, advantageously minimizing any transient degradation in loop performance that may occur as a result of the adjustment.

Abstract: A modem which represents the transmitted primary data stream using signal points selected via a trellis code is provided with the further capability of transmitting secondary data. In particular, a standard constellation of signal points is expanded to include a number of signal points which is greater than that needed to transmit the primary data. Particular primary data word values are representable by either of a predetermined pair of signal points associated with that value--one signal point of the pair being a standard signal point and the other being an expanded signal point. The specific one of the two signal points of the pair that is transmitted at any given time is chosen as a function of whether the value of the next bit in the secondary data stream waiting to be transmitted is a "0" or "1".

Abstract: An echo canceller for passband data signals is comprised of a pair of real passband filters which generate samples of the echo replica in response to respective streams of rotated data symbol components.