Telecommunications – Radiotelephone system – Zoned or cellular telephone system
Reexamination Certificate
1998-08-31
2001-05-08
Shankar, Vijay (Department: 2673)
Telecommunications
Radiotelephone system
Zoned or cellular telephone system
Reexamination Certificate
active
06230010
ABSTRACT:
DESCRIPTION
1. Technical Field
The present invention relates in general to the control, transmission and reception of standard data, fax data and voice signals. More particularly, but not by way of limitation, it relates to a distinct method and apparatus for the auto-selecting and auto-routing of either standard data, fax data or voice communication over a cellular telephone system, a radio frequency (RF) network, a satellite system or telephone line service or a combination of communication services.
2. Background Art
In recent years, with the increased emphasis on and use of portable or laptop computers and the availability of the cellular telephone system, radio frequency networks and satellite systems, more and more people are finding the need for, and the desirability of combining the portable or laptop computer with radio frequency networks, cellular telephone systems, satellite systems and conventional telephone line service to not only send and receive voice signals but to send and receive digital standard data and fax data between remote sites.
It is well known to send digital standard data or information over telephone lines from one to another by the use of conventional telephone line type modems. The conventional telephone line type modem is not reliable over cellular telephone systems, radio frequency networks or satellite systems.
There are other error-correcting modems able to send and receive standard data over cellular telephone systems, and other modems able to send and receive standard data over radio frequency networks, and other modems able to send and receive standard data over satellite systems, but none have the capabilities to work with all four; telephone line service, radio frequency networks, satellite systems and cellular telephone systems.
One modem that connects to a computer and a cellular phone is able to send and receive standard data over cellular and land line telephone systems; the Bridge modem. It will not communicate to a conventional telephone line type of modem, but using the Bridge's host modem; the Span modem, connected to a computer and a telephone line, the Bridge modem is able to achieve error-free standard data communication over cellular telephone systems. It is rated at 1200 bps, but with the overhead of it's proprietary error correcting scheme, the throughput of the Bridge is no more than 80%. The Span modem, if it is manually switched to non-cellular mode, will work with a conventional telephone line type of modem via telephone line; but the Span modem, connected to a computer and a telephone line, is unable to distinguish or auto switch from a cellular incoming Bridge call or an incoming conventional telephone line type of modem call. This makes the Span modem unsuitable as a host type of modem where you have incoming cellular and conventional telephone line type modem calls. Two separate modems, a Span modem and a conventional telephone line type of modem on two separate telephone lines would have to be used to handle this situation. The Bridge or Span modems do not support voice or fax communication over wireless radio frequency telemetry modules, packet radios, satellite systems or telephone line communications.
The standard data communications discussed above is the serial type of standard data communications which has two different forms, namely synchronous and asynchronous.
Synchronous communication requires the use of a common clock between the communication systems. Compared to asynchronous communication, synchronous communication is faster, but is also requires more complex controlling software as well as hardware for it to properly transmit and receive standard data. One of the primary applications of synchronous communication is in high-speed computer-to-computer or DTE to DTE communications.
Asynchronous communication does not require a common clock between the two communication systems; thus, the two systems are not synchronized with each other. Instead of sharing a common clock, each system has its own clock, which, in order to communicate properly, must be very close to the clock rate of the other system. Because there is no common synchronizing clock between asynchronous systems, they are limited to slower speeds. Modems used by the personal computer owner are typically asynchronous.
During the transfer or sending of large amounts of digital data (such as a standard file transfer or fax), it is important that errors do not occur and if they do occur it is important to discover and correct any such errors in the data.
The solution to the problem is to have communications software monitor the accuracy of the transferred standard or fax data and request that standard or fax data be sent again when errors are detected. Software techniques for doing this are called protocols. The error detection and correction procedure allows for the detection of and orderly recovery from errors caused by factors outside the control of the computer at either end. Signal quality deterioration, interference or noise, hand-off, and loss of carrier are some of the primary problems in the transfer of standard or fax data over rural telephone lines, cellular telephone systems, satellite systems and radio frequency networks.
There is a need to be able to have voice communication and error-free transmission of digital standard and fax data over cellular telephone systems, telephone line service, satellite systems and radio frequency networks from a remote type of DTE to a host type DTE connected to a telephone line type of modem-controller capable of distinguishing and auto switching from an incoming cellular call, conventional telephone line call, satellite system call, or radio frequency call and to transmit and receive at a rate higher than 1200 baud.
U.S. Pat. No. 4,456,793 to Baker et al. shows a computer with an optical link and an optical transceiver mounted in a ceiling or other high place.
DISCLOSURE OF THE INVENTION
A method and apparatus (modem-controller) for auto switching and controlling the transmission and receiving of voice and error-free transmission of standard data signals, fax data signals and voice communications over telephone line service, radio frequency networks, satellite systems, as well as cellular telephone systems is provided and is operatively connected to computers or other types of DTE, a method to select a data access arrangement (DAA) which either connects to a telephone line, satellite system or a cellular telephone, and another method to bypass the DAA and select and control radio frequency telemetry modules or packet radios. The apparatus includes analog switches that receive control signals from the micro-controller for controlling and switching the audio or data path of the internal voice board and the analog signals from the data pump to and from a radio frequency transceiver via the radio frequency transceiver interface/logic board, a cellular telephone transceiver via the cellular telephone transceiver interface, a telephone landline via a data DAA, a satellite system via a telephone landline through the DAA. Therefore, voice signals from the voice board, standard data or fax data from a computer or other type of DTE device can be sent over telephone landlines, wireless radio frequency networks, satellite system networks, cellular telephone system networks and infrared transmission.
With reference to the software implementation, the operation of modem-controller is divided into three modes; comprising a command mode, a data mode and an escape mode. Therefore, the software is based upon the three modes of operation.
In order to eliminate standard or fax data errors that may occur during signal quality deterioration, interference, noise, hand-off, and loss of carrier using dirty or poor quality conventional telephone line service, radio frequency networks, satellite systems and cellular telephone systems, the ITC-RM was developed. The ITC Reliable Mode (ITC-RM) enhances and fine tunes Microcom Networking Protocol (MNP) levels 2, 3, 4 and 5. ITC-RM is programmed in the modem BIOS in an
Shankar Vijay
Timmons W. Thomas
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