Pulse or digital communications – Transceivers
Reexamination Certificate
1997-03-11
2002-04-16
Trost, William (Department: 2683)
Pulse or digital communications
Transceivers
C375S220000, C370S474000, C370S465000
Reexamination Certificate
active
06373884
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to the transmission data, and more particularly to a method and apparatus for transmitting data between communication devices.
BACKGROUND OF THE INVENTION
Data communication schemes have been developed and used to transmit data between devices, such as electronic devices, according to the type of data being transmitted. In a synchronous communication system, transmission is accomplished by sending bit streams and character streams which are slaved to accurately synchronized clocks at the transmitting and receiving stations. Because a constant time interval is established between successive bits, characters, or events, beginning and end pulses are not required with each character. That is, synchronous transmission associated with a clock signal keeps the transmitter and receiver in phase. In contrast, in an asynchronous communication system, the transmission of data is independently controlled by beginning and end pulses in each frame of data. Although the data may be partitioned into frames of a predetermined number of bits and control bytes must be transmitted, the transmission of the bits or frames are not dependent upon a clock signal.
In order to transmit data in either mode, control signals or bytes are transmitted to provide the receiver with information to help decode the data. For example, control bytes representing the beginning of a frame (BOF) of data and an end of frame (EOF) of data are transmitted to provide an indication to the receiver that the data frame has been sent when sending asynchronous data. Particularly, the control bytes are particular bit arrangements which would be recognized by the receiver as having a particular meaning, such as that the data is being started or ended.
However, a problem occurs when the control signals are present in the data to be transmitted. That is, a receiver may decode the bits of data as being a control signal, and incorrectly receive the remaining data of the frame. In order to avoid sending data which could be interpreted as a control signal, the data could be assigned bit patterns such that the data could not include the bit patterns of the control signals. For example, when transmitting ASCII bit patterns representing alphanumeric characters, the ASCII bit patterns could be chosen to insure that they do not correspond to control signal bit patterns. However, such systems for transmitting asynchronous data are limited to the transmission of predefined bit patterns representing certain characters, such as letters.
According to another scheme for transmitting asynchronous data, the data is modified prior to transmitting to insure that the data does not include a control signal. For example, if the control signal represents six “one” bits in row, the transmitter will insert a “zero” bit whenever a five “one” bits are detected in the data. Accordingly, when the receiver detects five data bits, the receiver will remove the following “zero” and decode the next bit as either a “one” or “zero”. If the following bit is a “one” bit, representing six “one” bits of data, the receiver will not detect the six “one” bits as a control byte, but as data. In contrast, when the receiver detects six “one” bits in a row (without removing a “zero” bit), the receiver will detect the control signal. Such a scheme for transmitting data is described in the advanced data communication control procedures (ADCCP), published by the American Nationals Standards Institute, Inc., on Jan. 9, 1979. However, such bit “stuffing” require the transmission of additional data, which lowers the speed and efficiency of the data transmission system.
Finally, according to another scheme for transmitting asynchronous data, a control byte, called an escape (“ESC”) byte is transmitted prior to sending a byte of data which corresponds to a control byte. In addition to sending the control bit, the data byte itself could be altered, such by an “exclusive or” Boolean operation. Upon receiving an escape byte, the receiver would know that the following byte is not a control signal and should be decoded. However, such methods require the transmission of an escape byte for each byte which corresponds to a control byte, and also lowers the speed and efficiency of the data transmission system. Such a system also creates inconsistency in data efficiency. For example, if one frame coincidentially had a number of data bytes which coincided with control bits, the system would be particularly inefficient for that frame because it would have to send an escape byte for each such data byte
Accordingly, there is a need for an improved method and apparatus for transmitting data.
REFERENCES:
patent: 4574362 (1986-03-01), Spindel et al.
patent: 4949333 (1990-08-01), Gulick et al.
patent: 5204768 (1993-04-01), Tsakiris et al.
patent: 5206851 (1993-04-01), Cho
patent: 5420809 (1995-05-01), Read et al.
patent: 5502696 (1996-03-01), Yoon et al.
patent: 5521921 (1996-05-01), Murai
patent: 5550829 (1996-08-01), Wang
patent: 5553067 (1996-09-01), Walker et al.
patent: 5621720 (1997-04-01), Bronte et al.
patent: 5717760 (1998-02-01), Satterfield
patent: 5748681 (1998-05-01), Comino et al.
patent: 5842113 (1998-11-01), Nanda et al.
patent: 6038436 (2000-03-01), Priest
patent: 6070140 (2000-05-01), Tran
Infrared Data Association, “Serial Infrared Link Access Protocol (IrLAP)”, Version 1.1, Jun. 16, 1996.
American National Standards Institute, Inc., “American National Standard for Advanced Data Communication Control Procedures (ADCCP)”, Jan. 9, 1979, pp. 19-22.
Collopy Daniel R.
King John J.
Motorola Inc.
Tran Congvan
LandOfFree
Method and apparatus for transmitting data does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for transmitting data, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for transmitting data will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2915886