Harris Corporation

Norman C Seiler

George A Waschka, Jr

Thomas J Nixon

Stephen S Walker

Paul W Casper

Peter H Halpern

James W Toy

Fred J Orlando

J Richard Jones

Charles R Patisaul

Willie T Burton, Jr

Harold Iley

Ronald R Giri

W B Ashley

A coding scheme which uses Shannon-Fano coding for data headers to identify the type of command signal, uses a first set of formant data in the command signal to generate second sets of formant data for sound class initialization, and uses delta modulation to update the initialized sound class and for sound type transitions. The header indicates initialization of sound classes, repeat of the previous command, updating the previous command or end of word. Given types of command signals and sound classes have the same header and the data portion of the command signal defines which type of command signal is present. A unique delta modulation scheme is used wherein an increment, decrement or no change is indicated by a 11, a 00 or a 10 or 01 wherein each pair represents the delta modulation bit for a parameter, one in the present frame and one in the previous frame for that parameter. A repeat code with no data is used when the delta modulation bit for all parameters change from the previous frame.

Speech data encoding scheme

A Gray code digital to analog converter having an inherently monotonic and an not inherently monotonic embodiments. The inherently monotonic embodiment connects a first end terminal of a ladder stage to the intermediate terminal of a previous stage and switches the second end terminal between the end terminal of the previous stage. In the not inherently monotonic embodiment, the ladder is an R-2R ladder wherein the end terminals of the stage are switched by a double pole, single throw switch between an end terminal and an intermediate terminal of the previous stage.

Gray code DAC ladder

A formant-based multi-path speech synthesizer is reconfigurable to use common elements for different types of sounds. A pitch generator or a noise generator is connected to a glottal signal path for vowel or aspirate sound, respectively. The pole and zero filters normally part of the fricative signal path which produces fricative or stop sounds are used in the glottal signal path for nasal sounds. The output of a spectral filter in the glottal signal path bypasses the cascaded formant filters and is connected directly to the glottal path attenuator for voice bar sounds. The output of the first formant filter is rectified and modulates the noise signal in the fricative path and the glottal and fricative signal paths are summed for voiced fricative sounds. To minimize spectral tilt, the third and fourth formant filters and the pole filter are peak filters. The glottal path attenuator is at the end of the glottal signal path to maximize the signal-to-noise ratio.

Formant-based speech synthesizer

A digital to analog signal converter having a resistor ladder and switching network of the R-2R type is provided with the 2R resistor legs divided into two parallel 4R resistors, the most significant bit stage replaced with a switchable terminating 4R resistor stage, and logic means provided for each remaining bit stage responsive to its own bit stage input signal as well as the MSB stage signal such that, at the mid scale, the added 4R terminating resistor is switchable in and there is no switching at the other 4R resistor legs. By reducing the switching noise at the lowest input signal level, the system signal to noise ratio is substantially increased. To further reduce switching noise, additional bit stages may be replaced by terminating resistors and the 2R resistor legs appropriately modified.

Binarily weighted D to a converter ladder with inherently reduced ladder

A repeatered, multichannel fiber optic communication network includes a plurality of full duplex fiber optic channels and one or more auxiliary channels. In order to supervise and control the operation of the network, for both data transmission and fault/maintenance actions, each terminal station contains a processor-based subsystem capable of network monitoring, first level maintenance action, fault isolation, and remote network control and status reporting. This processor-based subsystem interfaces with each fiber optic channel, with an orderwire communication link, and with external input/output devices and surveillance equipment. Three substantially autonomous processor-based sections which are dedicated to performing specific functions within the overall network operation are employed for carrying out these separate interfacing tasks. Each section of the processor-based subsystem in a terminal station contains its own CPU and associated memory and is programmed to carry out specific functions identified with that section. Each section is interconnected with the other two so that, internally, the subsystem is fully integrated.

Repeatered, multi-channel fiber optic communication network having fault

An orderwire scheme for a multichannel repeated communication network contains an auxiliary communication link that is coupled to communication sites along the network and is configured of a pair of orderwire links each formed of a conventional interstitial copper wire pair. To carry out supervisory functions with respect to each of the stations along the communication link, messages are conveyed from a control facility coupled to or as part of the network to respective stations along the link in the form of command instructions. These messages may contain a request for information from the addressed site as to equipment conditions at the site or a directive that the equipment at the site perform a particular task. In reply to the command message sent to it the addressed site returns a response message back to the control facility representative of the action taken including any data requested by the instructions. In addition to providing a distributed communication link over which supervisory command and response messages can be transmitted among the stations along the orderwire link, a further facility for conveying voice communications over the same orderwire link is provided. In order to implement the exchange of command and response messages among the various sites of the network, supervisory signals are transmitted using digitally encoded ON/OFF keying of frequency tone signals.

Orderwire communication system

A privacy communication system in which increased security is provided in the scrambling of speech signals. Input speech is separated into a high frequency band and a low frequency band, and each band is time scrambled independently and recombined prior to transmission. Additional security is obtained with randomly selected segments of the scrambled speech being reversed in time. Further randomizing of the pseudorandom sequence which controls the scrambling operation is also provided, as well as simplified computing of delay times for the descrambling operation.

Growing community of inventors

West Melbourne, FL, United States of America

Norman C Seiler