International Business Machines Corporation

British Columbia Telephone Co.

Microtel Limited

Ibm Canada Limited - Ibm Canada Limitee

Belwinder Singh Barn

Joe Geofroy

Piyush Bhupatrai Kothary

Christopher Michael Look

A network of terminals and a server linked by a communications medium, comprising a device for assigning a selected one of a plurality of downstream frequency channels for transferring information from the server to the terminals and a selected one of a plurality of upstream frequency channels for transferring information from each of the terminals and the server.

Multiple channel terminal server communications network

A broad band broadcasting transmission system for sending broad band downstream data and telephone signals from a central office to a number subscriber set top terminal. Each frame of data is marked to indicate the set top terminals it is to be received by. A downstream light fiber is located between the head office and a curbside box. A transmitter transmits the frames along a light fiber to a SAC box. A converter converts the light signals from the light fiber to electrical signals. A distribution line coupled to the curbside box carries the electrical signals to a plurality of drop line twisted pair conductors connected to the distribution line. The drop lines are coupled via a residential units to the set top terminals. The downstream data is transmitted in a single broad frequency band in a frequency range starting sufficiently greater than zero so that distinct frequency bands are available between zero and the starting frequency for the transmission of ordinary telephone service and upstream signals from the set top terminals to the central office.

Broad band transmission system

A full-fluxed, single-ended, DC converter is disclosed. The converter includes a transformer having primary and secondary windings magnetically coupled and wound about a common core. A regulation switch is connected in series with the primary winding and allows the primary current to be interrupted in a time-controlled fashion, causing the desired output characteristics to be achieved. The series combination of a storage capacitor and reset switch are provided in parallel with the regulation switch to initiate bidirectional magnetizing current flow in the primary winding and, hence, bidirectional flux excursions in the transformer core. As a result, power transfer characteristics are improved. In the preferred embodiment, the regulation and reset switches are complementary field effect transistors (FETs) whose sources and gates are tied together allowing their gates to be coupled to a single bipolar drive signal. The resulting configuration allows full-fluxed operation to be achieved in a simple manner ensuring complementary operation of the switches.

Full-fluxed, single-ended DC converter

In a DC switching regulator circuit, a circuit to demagnetize the transformer during OFF periods to extend the duty cycle range of the regulator. The regulator uses a transformer in series with an FET switch device to cause the primary transformer current to be switched ON and OFF in response to the power needs of an electrical load connected to the secondary circuit. A first diode, connected to the junction of the primary winding and a series switch, conducts the demagnetizing energy out of the primary circuit into a shunt connected storage capacitor. A second FET switch, operating out of phase with the first switch, allows the storage capacitor to discharge through an inductor back to the unregulated input source. A shunt diode between the inductor and the second FET switch provides a path for the inductor to discharge through when the second switch opens the path between the storage capacitor and the inductor.

Growing community of inventors

Burnaby, Canada

Belwinder Singh Barn