Universal Data Systems, Inc.

O Leon Pierce

Mark C Smith

R Byron Driver

A synchronous receiver for receiving a phase shift modulated signal having binary data at a clock rate occurring within a baud interval. The synchronous receiver provides multiple estimates of the signal phase during selected portions of the baud interval, wherein the resulting phase values are averaged to provide a data output of low error rate and high reliability. The synchronous receiver of the present invention independently recovers the carrier and clock signals by separate digital phase-locked loops, wherein the resulting signals are used by the synchronous detector portion to recover the digital data. Moreover, the data acquisition time is improved by variable bandwidth characteristics of the phase locked loops.

Synchronous receiver

A modem for coupling a data terminal or other apparatus to a telephone line and deriving its operating power for both transmitting and receiving operation from the telephone line, and providing electrical isolation between the telephone line and the data terminal. The modem is switchable to provide orginate or answer operation in either of two operating frequency bands.

Switchable line powered modem

An electro-optical isolator circuit especially adapted for operation in a modem which is powered solely from the telephone line and employed to isolate the line from utilization equipment. The isolator includes a guard circuit which substantially improves low current operating speed such that an inexpensive electro-optical component can be utilized at very low drive levels to achieve response times less than 10 microseconds.

Electro-optical isolator circuit for line powered modem

A modem for coupling a data terminal or other apparatus to a telephone line and deriving its operating power for both transmitting and receiving operation from the telephone line, and providing electrical isolation between the telephone line and the data terminal.

Line powered modem

A DC to DC converter circuit for use in a telephone line powered modem and operative to convert a voltage derived from the telephone line to operating voltages required for modem operation.

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Huntsville, AL, United States of America

O Leon Pierce