Ronald S Maxwell

US Patent:

41258720, Nov 14, 1978

Filed:

Mar 31, 1977

Appl. No.:

5/783144

Inventors:

Ronald K. Maxwell - Palo Alto CA

Assignee:

Racal-Vadic, Inc. - Sunnyvale CA

International Classification:

G06F 728

US Classification:

364900

Abstract:

Apparatus for controlling an automatic dialer which, in response to dial digits, automatically establishes communication paths over a plurality of telephone lines. The apparatus includes interface logic connected to a computer port for receiving serial digital data from the computer. The data includes control characters and dial digits. The serial data is stored in parallel word format in a random access memory (RAM) buffer. The RAM is operated in three modes, a write mode in which addresses and digits are stored in the RAM, a read mode in which the addresses and digits are presented to the dialer and an abort mode in which a call in progress is interdicted and resumed later, or completely aborted. Control logic responds to the serial interface and stores successive digits in successive RAM address locations, the final word being a buffer empty character to signify the end of the stored data. The control logic then signals the dialer and, under control of a demand/response hand shake procedure, transfers the stored words in parallel to the dialer.

US Patent:

41018338, Jul 18, 1978

Filed:

Mar 7, 1977

Appl. No.:

5/775104

Inventors:

John A. C. Bingham - Palo Alto CA
Ronald K. Maxwell - Palo Alto CA

Assignee:

The Vadic Corporation - Sunnyvale CA

International Classification:

H04L 2700

US Classification:

325 30

Abstract:

A full duplex communication system including a pair of full duplex modems. Each modem has both a call originate mode of operation and a call answer mode of operation. In the call originate mode outgoing data is transmitted by modulation of a carrier frequency F2 and incoming data is received by demodulation of a data modulating carrier of frequency F1. When in the answer mode of operation, the data is received on frequency F2 and transmitted on frequency F1. Means are provided for injecting a carrier frequency F6 in the outgoing data transmission path. The frequency F6 is near the midpoint between F1 and F2. The amplitude is such that the distribution of power within the transmission band is balanced so that the power in the frequency band set aside for single frequency signaling systems does not exceed the power in the remainder of the transmission band. This prevents the false operation of signal frequency systems triggered by the transmission of certain bit patterns, which could result in improper billing, intermittent transmission interruptions, insertion of a band elimination filter in the transmission path or the complete disconnection of a call.

US Patent:

47714174, Sep 13, 1988

Filed:

Sep 18, 1986

Appl. No.:

6/909012

Inventors:

Ronald K. Maxwell - Palo Alto CA
Karl J. Zorzi - Pleasanton CA
Harunori Yoshikawa - Cupertino CA
Venkat Prasad - San Jose CA
Fred G. Smith - Longwood FL

Assignee:

Racal Data Communications, Inc. - Milpitas CA

International Classification:

H04B 312
H04J 1500

US Classification:

370 31

Abstract:

A modem is disclosed having a data transmission protocol involving lower-speed, full-duplex operation during the connect sequence with a remote modem and an automatic switch to higher-speed, half-duplex operation for data transfer. Further, the modem data transmission involves transparently changing between lower-speed, interactive operation and higher-speed operation based upon transmission demands. The operation is controlled by a processor monitoring the contents of a transmit data buffer and providing a mode control command to the modem transmitter. The modem also adapts its speed to the quality of the telephone line by fallback or fallforward to a different speed based upon predetermined data frame retransmission criteria.

US Patent:

49244566, May 8, 1990

Filed:

Aug 29, 1988

Appl. No.:

7/197128

Inventors:

Ronald K. Maxwell - Palo Alto CA
Karl J. Zorzi - Pleasanton CA
Harunori Yoshikawa - Cupertino CA
Venkat S. Prasad - San Jose CA
Fred G. Smith - Longwood FL
Ming-Chih Hsieh - San Jose CA

Assignee:

Racal Data Communications, Inc. - Sunrise FL

International Classification:

H04J 1500

US Classification:

370 32

Abstract:

A modem is disclosed having a data transmission protocol involving lower-speed, full-duplex operation during the connect sequence with a remote modem and an automatic switch to higher-speed, half-duplex operation for data transfer. Further, the modem data transmission involves transparently changing between lower-speed, interactive operation and higher-speed operation based upon data transmission demands. The operation is controlled by a processor monitoring the contents of a transmit data buffer and providing a mode control command to the modem transmitter. The modem also adapts its speed to the quality of the telephone line by fallback or fallforward to a different speed based upon predetermined data frame retransmission criteria.

US Patent:

42152437, Jul 29, 1980

Filed:

Nov 17, 1978

Appl. No.:

5/961849

Inventors:

Ronald K. Maxwell - Palo Alto CA

Assignee:

Racal-Vadic Inc. - Sunnyvale CA

International Classification:

H04M 1100

US Classification:

179 2DP

Abstract:

Apparatus for communicating between a number of remote use terminals and a central computer. The apparatus initially answers an incoming call under concentrator control, and transmits an answer tone to the calling terminal. The terminal user places the modem at the terminal in data mode. The apparatus detects which modem type called, conditions the concentrator port interface and connects an answering modem of the same type into the circuit between the telephone line and the concentrator port. The port automatically detects speed and code, and conditions the computer adapter clock and software appropriately to be compatible. The user experiences no change in existing connection sequences and only one telephone number is necessary for servicing a number of different modem types having common access to the computer.