Centralized data communications system incorporating a plurality of remote stations (11), each having a plurality of information channels (10) associated therewith. A selected remote station and its associated information channels are tone addressed by a central station (23) communicating with a group of remote stations over a respective communications channel (12). The remote stations (11) may have a current sensor (210) connected to one of the information channels for sending data corresponding to the amount of current sensed in an electrical path (212) back to the central station (23) upon being properly addressed. This data, together with data representative of the voltage on the monitored electrical path, is used by the central station to calculate energy consuption. The calculated energy consumption is retained at the central station (23) and used for information and billing purposes. The central station may also send data to an addressed information channel (10) at a remote station for controlling an operation thereat. The central station (23) can also receive data from various parameter measuring sensors (47) at a remote station, e.g. sensors measuring temperature, humidity, fluid flow, etc. which may be connected to other information channels (10) and thus the system may be used as a general purpose data gathering or distributing communications system.

Computer controlled energy monitoring system

An isolation system is provided that is suitable for use in telephony, medical instrumentation, industrial process control and other applications. Preferred embodiments of the invention comprise a capacitive isolation barrier across which a digital signal is communicated. The system provides a means of communication across the isolation barrier that is highly immune to amplitude and phase noise interference. Clock recovery circuitry may be employed on one side of the isolation barrier to extract timing information from the digital signal communicated across the barrier, and to filter the effects of phase noise introduced at the barrier. Delta-sigma converters may be disposed on both sides of the isolation barrier to convert signals between analog and digital domains. An isolated power supply may also be provided on the isolated side of the barrier, whereby direct current is generated in response to the digital data received across the isolation barrier. Finally, a bidirectional isolation system is provided whereby bidirectional communication of digital signals is accomplished using a single pair of isolation capacitors. In preferred embodiments, the digital data communicated across the barrier consists of digital delta-sigma data signals multiplexed in time with other digital control, signaling and framing information.

Isolation system with digital communication across a capacitive barrier

A system for control of a video storage device by a programmed processor. A preferred implementation illustrates a tutorial system including a personal computer as the programmed processor, a video cassette recorder as the video storage device, a video monitor, and an interface and control circuit for communication and control among the system elements. Under control of the personal computer audio, video, and digital data can be read from or written to any location on a video tape of the video cassette recorder. The system uses this capability to store a plurality of video segments and audio segments on the video tape relating to a story board. Additionally stored on the tape is a programmed index in digital form indicating the storyboard sequence of the video segments and their locations on the tape. An interactive teaching program run on the personal computer reads the index and plays the video segments in the story board sequence. The teaching program interacts with a student via prompts and questions and is adapted to change the display sequence of the video segments in response to his answers.

System for control of a video storage means by a programmed processor

A data storage medium comprises a plurality of data regions, and a plurality of servo regions configured to provide positioning information to a reading device. Each of the plurality of data regions corresponds to more than one of the plurality of servo regions. The more than one of the plurality of servo regions are configured to provide positioning information to the reading device at discrete times corresponding to a data operation of a corresponding data region.

Servo design in data storage media

A method for recording and reproducing a video format signal on and from a recording medium. A two-dimensional screen is divided based on the video format signal into a plurality of blocks with one of them being divided into a plurality of subblocks, and video information or information compressed on a time basis is inserted into each of the subblocks. Video information and control information are inserted in the remaining blocks while recording the information on the recording medium. The information in at least one of the subblocks is written into memory in a reproduction mode, and thereafter the information in the at least one subblock is read out of the memory while expanding the information on a time basis, and simultaneously writing the information next to the information in the at least one subblock into the memory, whereby the information in the at least one subblock and the next information can successively be reproduced.

Method for recording and reproducing video format signal

At least one channel of digitized information is recorded in a selected number of data tracks by a record medium. The digitized information is encoded, modulated and then recorded in a predetermined number of tracks. For example, if n channels of digitized information are to be recorded in m data tracks, then each channel is recorded in m/n data tracks (m≧n). A control signal is generated to include control data representing at least one of the following: (a) the number of data tracks in which each channel of digitized information is recorded, (b) the encoding scheme used to encode the information, (c) the type of modulation used to modulate the encoded information and (d) the relative speed of movement of the record medium. The control signal is recorded in a separate control track. Thus, the control signal represents the particular format in which the digitized information is recorded.

Method and apparatus for recording digitized information on a record medium

An apparatus for recording and/or reproducing a serial digitized analog signal controls the transport speed of a recording medium according to the sampling rate employed in digitizing the analog signal to produce a constant data density on the recording medium regardless of the sampling rate selected. The frequency of a fundamental clock signal establishes the sampling frequency during recording. A coded timing signal also recorded on the recording medium includes both a sync signal and a coded identity of the sampling frequency in use. During reproduction, the coded identity of the sampling frequency is used to select the same fundamental clock signal as was used during recording and the reproduced sync signal is phase compared with a reference signal derived from the fundamental clock signal to correspondingly control the speed and phase of transport of the recording medium. The fundamental clock signal may be manually varied during reproduction for pitch control of the reproduced analog signal.

Apparatus for recording and/or reproducing digital signal

An amplitude adjustment circuit transmits an analog signal to an analog-to-digital converter. If the resulting digital signal reaches the maximum permissible digital value, a monostable control circuit is triggered to cause the amplitude adjustment circuit to reduce the level of the analog signal a certain amount. If the digital signal again reaches the maximum permissible digital value before the control circuit returns to its stable condition a second monostable circuit is triggered (and the first one is retriggered) to cause the amplitude adjustment circuit to reduce the level of the analog signal another amount. The unstable interval for the second monostable circuit is shorter than for the first, and, in the absence of further triggering, both such circuits return to their stable states in succession. The digital signals are used to reconstruct the analog signal in apparatus similar to the encoding apparatus and including amplitude adjustment apparatus controlled by the amplitude compression signals.

Signal transmitting apparatus using A/D converter and monostable control circuit

In dynamic modulation (D.M.) of non-return-to-zero pulse signals, the only condition under which the D.M. signal would remain in the same state, either 1 or 0, for two consecutive pulse intervals is when the NRZ signal includes the sequence 101. Two sampling signals at the proper clock repetition rate are generated from the D.M. signal by the decoder and are successively used to sample the D.M. signal and to sample the signal resulting from the first sampling. Information of the state of the D.M. signal at the time of the first sampling is retained to be compared with the state of the D.M. signal at a later time, and the state of one of the compared signals is separately compared with the state of a signal between the first-compared signals. If the wrong clock pulses midway between the correct clock pulses are used in making the comparisons, a correction signal will be generated in the last half of the second consecutive pulse interval in which the D.M. signal remains in the same state. This correction signal is used to adjust the clock pulse selector to select the correct pulses.

Circuit for automatically correcting the timing of clock pulse in self-clocked pulse signal decoders

A signal conversion system in which an analog signal of a certain magnitude can be encoded as a digital signal making full use of the available number of bits of an A/D converter. The system includes amplitude adjustment apparatus with an up-down counter actuated by the maximum available binary value of the digital signal to count UP one step and set an amplitude selection circuit to effectively attenuate the amplitude of the analog signal by a predetermined amount. The counter may have more than one memorizable count level to control a corresponding number of amplitude selection levels. The counter counts DOWN when the most significant bit of the digital signal drops from 1 to 0. The invention includes a corresponding analog signal reconstruction circuit except that it includes a D/A converter that produces an analog signal at maximum value that must be attenuated for low-amplitude values.

Takenori Sonoda

Papers

Method and apparatus for recording digitized information on a record medium

Apparatus for recording and/or reproducing digital signal

Signal transmitting apparatus using A/D converter and monostable control circuit

Circuit for automatically correcting the timing of clock pulse in self-clocked pulse signal decoders

Transmitting apparatus using A/D converter and analog signal compression and expansion