External synchronizing method and apparatus for information transmission system

Claim 1

A method of synchronizing a plurality of transmitters (12a, 12b, 12c) which are included in an information transmission system (10) in combination with at least one receiver (14) and a transmission line (16) for transmitting information signals (30) output from the respective transmitters (12a, 12b, 12c) to the receiver (14), said method comprising the steps of: transmitting a pulse signal (42) having a voltage level higher than a maximum voltage level of said information signals (30) or lower than a minimum voltage level of said information signals (30) to the respective transmitters (12a, 12b, 12c) over the transmission line (16) as an external sync signal by using blanking level portions of the information signals (30); Separating said pulse signal (42) transmitted over the transmission line (16) from said information signals (30) on the basis of a level difference of said pulse signal (42) from said information signals (30); and applying said separated pulse signal (42) to the respective transmitters (12a, 12b, 12c).

Claim 2

A method of synchronizing a plurality of transmitters (12a, 12b, 12c) which are included in an information transmission system (10) in combination with at least one receiver (14) and a transmission line (16) for transmitting information signals (30) output from the respective transmitters (12a, 12b, 12c) to the receiver (14), said method comprising the steps of: transmitting a pulse signal (42) having a voltage level higher than a maximum voltage level of said information signals (30) or lower than a minimum voltage level of said information signals (30) to the respective transmitters (12a, 12b, 12c) over the transmission line (16) as an external sync signal by using blanking level portions of the information signals (30); Separating said pulse signal (42) transmitted over the transmission line (16) from said information signals (30) on the basis of a level difference of said pulse signal (42) from said information signals (30); and applying said separated pulse signal (42) to the respective transmitters (12a, 12b, 12c).

Claim 4

A device for synchronizing a plurality of transmitters (12a, 12b, 12c) which are included in an information transmission system (10) in combination with at least one receiver (14), a transmission line (16) extending from the receiver (14) and having branch lines (22a, 22b, 22c) connecting respectively to the transmitters (12a, 12b, 12c) transmit information signals (30) output from the transmitters (12a, 12b, 12c) to the receiver (14), and amplifier circuit means (35, 36, 38) associated respectively with the branch lines (22a, 22b, 22c) of the transmission line (16) for blocking propagation of signals toward the transmitters (12a, 12b, 12c), said device comprising: external sync signal generator circuit means (40) connected to the respective branch lines (22a, 22b, 22c) of the transmission line (16) at that said of each of the amplifier circuit means (35, 36, 38) associated with the branch lines (22a, 22b, 22c) which is adjacent to the receiver (14), for generating a pulse signal (42) having a voltage level higher than a maximum voltage level of said information signals (30) output from the respective transmitters (12a, 12b, 12c) or lower than a minimum voltage level of said information signals (30); bypass passages consisting of comparator circuit means (46) connected respectively to the branch lines (22a, 22b, 22c) in parallel to the amplifier circuit means (35, 36, 38) for allowing only said pulse signal (42) to be transmitted toward the transmitters (12a, 12b, 12c) on the basis of a signal voltage level; and comparator circuit means (44) associated respectively with the transmitters (12a, 12b, 12c) for separating said pulse signal (42) transmitted over the branch lines (22a, 22b, 22c) from said information signals (30) on the basis of a level different of said pulse signal (42) from said information signals (30), and applying said separated pulse signal (42) to the transmitters (12a, 12b, 12c) associated with said comparator circuit means (44), thereby synchronizing the transmitters (12a. 12b, 12c) to each other.

Claim 5

A device for synchronizing a plurality of transmitters (12a, 12b, 12c) which are included in an information transmission system (10) in combination with at least one receiver (14), a transmission line (16) extending from the receiver (14) and having branch lines (22a, 22b, 22c) connecting respectively to the transmitters (12a, 12b, 12c) transmit information signals (30) output from the transmitters (12a, 12b, 12c) to the receiver (14), and amplifier circuit means (35, 36, 38) associated respectively with the branch lines (22a, 22b, 22c) of the transmission line (16) for blocking propagation of signals toward the transmitters (12a, 12b, 12c), said device comprising: external sync signal generator circuit means (40) connected to the respective branch lines (22a, 22b, 22c) of the transmission line (16) at that said of each of the amplifier circuit means (35, 36, 38) associated with the branch lines (22a, 22b, 22c) which is adjacent to the receiver (14), for generating a pulse signal (42) having a voltage level higher than a maximum voltage level of said information signals (30) output from the respective transmitters (12a, 12b, 12c) or lower than a minimum voltage level of said information signals (30); bypass passages consisting of comparator circuit means (46) connected respectively to the branch lines (22a, 22b, 22c) in parallel to the amplifier circuit means (35, 36, 38) for allowing only said pulse signal (42) to be transmitted toward the transmitters (12a, 12b, 12c) on the basis of a signal voltage level; and comparator circuit means (44) associated respectively with the transmitters (12a, 12b, 12c) for separating said pulse signal (42) transmitted over the branch lines (22a, 22b, 22c) from said information signals (30) on the basis of a level different of said pulse signal (42) from said information signals (30), and applying said separated pulse signal (42) to the transmitters (12a, 12b, 12c) associated with said comparator circuit means (44), thereby synchronizing the transmitters (12a. 12b, 12c) to each other.