# US RE32,327 E · Multiple channel data communication system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US RE32,327 E - Document ID: USRE32327E - Status: Granted - Kind: E - Application number: 06/645,566 - Filed: 1984-08-30 - Granted: 1987-01-06 - Earliest claimed: 1980-07-07 - Assignees: Sytek, Inc. - Inventors: Kenneth J. Biba; Jose J. Picazo, Jr. - Web page: https://patentgrep.com/patent/USRE32327E ## Abstract A multiple channel communications system and method for communication among multiple channels using a channel selectable MODEM. The system is comprised of a coaxial cable, a variety of interface units with attached communicating devices and a channel bridge. The interface units include a MODEM and a microprocessor based support element adapted for the attached communicating device. The channel bridge includes two or more [MODEM's] MODEMs and a microprocessor based computer for receiving data from one MODEM and transmitting the data on another MODEM. ## Claims ### Claim 1 A data communication system comprising: a coaxial cable; a plurality of [MODEM's] MODEMs connected to the cable including means for selecting the transmit and receive [frequency bandwidths] frequencies of each of the [MODEM's] MODEMs ; means connected to the [MODEM's] MODEMS for supplying data to and receiving data from each of the [MODEM's] MODEMs ; a central retransmission facility connected at the head end of the cable [whereby] such that a signal transmitted by at least one of the [MODEM's] MODEMs is received by the central retransmission facility and translated to the receive frequency [bandwidth] of the MODEM which transmitted said signal; and a channel bridge connected to the cable including two or more [MODEM's] MODEMs each of said [MODEM's] MODEMs having different [transmit frequency bandwidths] transmitting frequencies and different [receive frequency bandwidths] receiving frequencies than the other of said MODEMs in said channel bridge and including means for transferring [a signal] signals received by one of said MODEM's to another of said [MODEM's whereby the MODEM's] MODEMs in the channel bridge such that the MODEMs connected to the cable which are transmitting and receiving [in] at different [frequency bandwidths] frequencies may receive signals from and transmit signals to each other via the channel bridge . ### Claim 2 (depends on 1) The data communication system of claim 1, wherein; the coaxial cable comprises a broadband coaxial cable. ### Claim 3 (depends on 1) The data communication system of claim 1, wherein[;] : the means connected to some of the [MODEM's] MODEMS for supplying data to and receiving data from the [MODEM's] MODEMS include means for supplying data to and receiving data from a terminal. ### Claim 4 (depends on 1) The data communication system of claim 1, wherein[;] : the means connected to some of the [MODEM's] MODEMS for supplying data to and receiving data from the [MODEM's] MODEMS include means for supplying data to and receiving data from a plurality of terminals. ### Claim 5 (depends on 1) The data communication system of claim 1, wherein[;] : the means connected to some of the [MODEM's] MODEMS for supplying data to and receiving data from the [MODEM's] MODEMS include means for supplying data to and receiving data from a host computer. ### Claim 6 (depends on 1) The data communication system of claim 1, wherein[;] : the [MODEM's] MODEMS include means for detecting the presence of a signal on the cable. ### Claim 7 (depends on 1) The data communication system of claim 1, wherein[;] : the means connected to the [MODEM's] MODEMS for supplying data to and receiving data from each of the [MODEM's] MODEMS includes means for comparing a plurality of the first bits of data received to the corresponding bits of data transmitted by one of the [MODEM's] MODEMS attempting to transmit a signal whereby data collisions may be detected. ### Claim 8 (depends on 7) The data communication system of claim 7, wherein; said means for comparing data are included in a universal synchronous receiver/transmitter. ### Claim 9 (depends on 1) The data communication system of claim 1, further comprising[;] : encryption means coupled with the means for supplying data to and from the [MODEM's] MODEMS whereby data transmitted over the cable is encrypted by the transmission source and decrypted by the transmission destination. ### Claim 10 (depends on 9) The data communication sytem of claim 9, wherein; the encryption means includes an interchangeable encryption key. ### Claim 11 (depends on 10) The data communication system of claim 10, wherein; said encryption key comprises an erasable programmable read only memory. ### Claim 12 (depends on 1) The data communication system of claim 1, wherein[;] : said means for transferring a signal included in the channel bridge comprises : a universal synchronous receiver/transmitter connected to said [MODEM's] MODEMS , data and address buses connected to each of said universal synchronous receiver/transmitters, a central processing unit connected to said data and address buses , and memory connected to said data and address buses. ### Claim 13 A method of collision detection for data communication comprising the steps of: formating digital data by a transmitting node whereby a flag is inserted at the beginning of a transmission frame; broadcasting said transmission frame onto a cable; receiving said transmission frame by a central transmission facility; translating said transmission frame by said central retransmission facility to a receive frequency bandwidth; rebroadcasting said transmission frame in said receive frequency bandwidth onto said cable; receiving said flag of said transmission frame by said transmitting node; comparing said flag as received to said flag as transmitted to detect a collision of data; aborting the broadcasting of said transmission frame when a collision of data is detected; waiting a random time after detecting a collision of data; and rebroadcasting said transmission frame after waiting a random time.