Browse Prior Art Database

Channelized Modem

IP.com Disclosure Number: IPCOM000079810D
Original Publication Date: 1973-Sep-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 30K

Publishing Venue

IBM

Related People

Costes, M: AUTHOR

Abstract

An arrangement is described which enables a transmitting modem to transmit to a receiving modem, digital data fed to the transmitting modem via a plurality of input lines, when the speed of some of them is lower than the speed at which data must be sent over the transmission channel in the form of information elements.

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Channelized Modem

An arrangement is described which enables a transmitting modem to transmit to a receiving modem, digital data fed to the transmitting modem via a plurality of input lines, when the speed of some of them is lower than the speed at which data must be sent over the transmission channel in the form of information elements.

This result is achieved by incorporating into the transmitting modem an auxiliary clock which is used in conjunction with its main clock, and supplies timing signals at the various rates required to process the digital data signals traveling on those input lines, whose respective speeds are lower than the speed at which the information elements are sent over the channel The receiving modem is provided with a similar auxiliary clock. A sync tone is generated by the transmitting modem to synchronize the two auxiliary clocks, and the receiving modem includes circuits which compensate for distortions of the sync tone due to phase or frequency shift.

As shown in the figure, a number K of input lines L from a computer or other data-processing machine are connected within the transmitting modem to a set of buffers 1, whose contents are sequentially sampled and applied to a coder 2 which generates the information elements to be sent over the transmission channel TN to the receiving modem. The sampling of the contents of buffers 1 and the operation of coder 2 are controlled by the timing signals generated by a main clock 3, which is of a conventional type, and by an auxiliary clock 4 connected to clock 3. These timing signals travel along lines A. Clocks 3 and 4 also generate, in any suitable form, the sync tone which is sent to coder 2 and then transmitted to the receivi...