David L Worthington

US Patent:

43026290, Nov 24, 1981

Filed:

Aug 1, 1979

Appl. No.:

6/062720

Inventors:

John D. Foulkes - Kirkland WA
David K. Worthington - Bellevue WA
John E. Trombly - Winchester MA

Assignee:

Teltone Corporation - Kirkland WA

International Classification:

H04M 1100

US Classification:

179 2DP

Abstract:

Simultaneous conventional telephone signaling and audio communication, plus digital data transmission, on nonloaded telephone wires is disclosed. Modems (21) connect a telephone (23) and a digital data terminal (25) to one end of the telephone wires. A data transmitter (59) in each modem (21) converts digital data from binary to FSK form and a receiver (57) converts digital data from FSK to binary form. Each transmitter includes a frequency synthesizer that produces one of two FSK signals (F1, F2) depending upon the binary nature (0 or 1) of a particular data bit; and, the receivers include frequency detectors that detect two other FSK signals (F3, F4) and produce a corresponding binary data bit (0 or 1). Voice filters (51) prevent the FSK data signals from reaching the telephones and spurious telephone high frequency signals from reaching the telephone wires. A CO or PABX subsystem (37) is connected to the other end of the telephone wires and includes modems comprising receivers (97) that convert the F1/F2 FSK signals into binary digital data.

US Patent:

43306870, May 18, 1982

Filed:

Mar 14, 1979

Appl. No.:

6/020252

Inventors:

John D. Foulkes - Kirkland WA
David K. Worthington - Bellevue WA
John E. Trombly - Winchester MA

Assignee:

Teltone Corporation - Kirkland WA

International Classification:

H04M 1106
H04H 108

US Classification:

179 2DP

Abstract:

A subscriber data carrier system for simultaneously carrying both base band telephone signals and full duplex digital data transmissions on a single pair of nonloaded telephone wires is disclosed. That is, the system provides for simultaneous conventional telephone signaling and audio communication and full duplex digital data communication between a pair of subscribers, each connected to the same main distribution frame of a central office by a single pair of nonloaded telephone wires. The system includes a modem (21) located at each subscriber's premises. The modems are connected to the subscriber's telephone (23) and digital data terminal (25). The modems include data transmitters (47) and receivers (49) that convert digital data from binary form into FSK form for transmission and from FSK form into binary form upon reception. More specifically, the transmitters include a frequency synthesizer (59) that produces one or the other of two FSK signals (F1 or F2) depending upon the binary nature (0 or 1) of a particular data bit to be transmitted; and, the receivers include frequency detectors (67) that detect two other FSK signals (F3 and F4) and, depending upon the frequency of the detected signal produce a corresponding binary data bit (0 or 1). F1 and F2 are produced in a manner that maintains phase coherency during shifts between F1 and F2 and in a manner such that the waveforms of F1 and F2 are substantially free of harmonics at the frequencies of F3 and F4.