Communication circuit loopback test apparatus

Claim 3

The method as claimed in claim 1 comprising the additional step of: acknowledging receipt of the loopback signal at the receiver stage receiving only two pulses by returning a single pulse to the transmitter on the return path of said communication link.

Claim 8

Apparatus for testing a communication link including at least an end terminal transmitter, a remote end terminal receiver and a plurality of intermediate repeater stages for localizing the section of the communication link having transmission problems comprising, in combination: communication link end terminal transmitter first means for interrupting the flow of information from transmitter to remote receiver with a "null" signal for a time sufficient to cause all intermediate receiver stages to reset to an initialized condition; second means, comprising a part of said first means, for transmitting N+1 pulses of predetermined length and of a frequency distinguishable from that used in data transmission; a plurality of repeater stations connected in series in said communication between end terminals, each repeater station including; "null" signal detection means for reinitializing each repeater station upon reception and detection of the "null" signal and for setting said repeater station to a test or a data condition in accordance with the frequency of the next received signal; third means for receiving transmitted pulses at each intermediate receiver stage in succession and for transmitting one less pulse than received when more than two pulses are received; and fourth means for altering the signal path condition, in the intermediate repeater stage receiving only two pulses, to a loopback configuration; fifth means, comprising a part of said end terminal means, for transmitting a test signal through said looped communication link; sixth means, comprising a part of said end terminal means, for clearing the communication link by transmitting a null signal for initializing each intermediate receiver and returning same to normal signal transmission conditions between the transmitter of said end terminal and a remote end terminal receiver at the other end of said communication link, if no faults are detected; and seventh means for providing an indication that no faults were detected in a given N+1 pulse transmission test.

Claim 9

Apparatus for testing a communication link including at least an end terminal transmitter, a remote end terminal receiver and a plurality of intermediate repeater stages for localizing the section of the communication link having transmission problems comprising, in combination: communication link end terminal transmitter first means for interrupting the flow of information from transmitter to remote receiver with a "null" signal for a time sufficient to cause all intermediate receiver stages to reset to an initialized condition; second means, comprising a part of said first means, for transmitting N+1 pulses of predetermined length and of a frequency distinguishable from that used in data transmission; a plurality of repeater stations connected in series in said communication between end terminals, each repeater station including; "null" signal detection means for reinitializing each repeater station upon reception and detection of the "null" signal and for setting said repeater station to a test or a data condition in accordance with the frequency of the next received signal; third means for receiving transmitted pulses at each intermediate receiver stage in succession and for transmitting one less pulse than received when more than two pulses are received; and fourth means for altering the signal path condition, in the intermediate repeater stage receiving only two pulses, to a loopback configuration; fifth means, comprising a part of said end terminal means, for transmitting a test signal through said looped communication link; sixth means, comprising a part of said end terminal means, for clearing the communication link by transmitting a null signal for initializing each intermediate receiver and returning same to normal signal transmission conditions between the transmitter of said end terminal and a remote end terminal receiver at the other end of said communication link, if no faults are detected; and seventh means for providing an indication that no faults were detected in a given N+1 pulse transmission test.

Claim 10

Apparatus as claimed in claim 5 comprising, in addition: eighth means for returning an acknowledgement pulse to said end terminal transmitter over the return path of said communication link by the looped back intermediate repeater stage thereby indicating that the link is ready to be tested.

Claim 11

Apparatus for remotely localizing the area of failure in a multiple repeater station communication link between two end terminals comprising, in combination: end terminal first means for interrupting the transmission of data signals long enough for detection of an initializing "null" signal by receiving equipment in the repeater stations; end terminal second means for transmitting N+1 pulses of a predetermined frequency and length with predetermined "null" signal times between the transmitted pulses from one of said end terminals; a plurality of repeater station third means connected in series in the communication link between end terminals, each of said third means including retransmitting fourth means, reconnecting fifth means, "null" signal detecting and initializing sixth means and further means to set the station to test or data transmission modes in accordance with signals first received after receipt of an initializing "null" signal; said fourth means portion of each of said third means retransmitting one less pulse than received to the following repeater station in the communication link wherein the retransmitted pulses have the same timing characteristics as the originally transmitted pulses; said fifth means reconnecting the repeater station that receives only two pulses in a loopback configuration; and end terminal seventh means for transmitting a test signal from said end terminal and checking for receipt of same by said end terminal due to the loopback connection at said remote repeater station.

Claim 12

Apparatus for remotely localizing the area of failure in a multiple repeater station communication link between two end terminals comprising, in combination: end terminal first means for interrupting the transmission of data signals long enough for detection of an initializing "null" signal by receiving equipment in the repeater stations; end terminal second means for transmitting N+1 pulses of a predetermined frequency and length with predetermined "null" signal times between the transmitted pulses from one of said end terminals; a plurality of repeater station third means connected in series in the communication link between end terminals, each of said third means including retransmitting fourth means, reconnecting fifth means, "null" signal detecting and initializing sixth means and further means to set the station to test or data transmission modes in accordance with signals first received after receipt of an initializing "null" signal; said fourth means portion of each of said third means retransmitting one less pulse than received to the following repeater station in the communication link wherein the retransmitted pulses have the same timing characteristics as the originally transmitted pulses; said fifth means reconnecting the repeater station that receives only two pulses in a loopback configuration; and end terminal seventh means for transmitting a test signal from said end terminal and checking for receipt of same by said end terminal due to the loopback connection at said remote repeater station.

Claim 15

Repeater station apparatus for use in a communication link sending data at a first frequency between end terminals comprising, in combination: a pair of signal detection receiver means for receiving signals from the east and the west; a pair of signal transmission means for transmitting, to both the east and the west, amplified versions of signals received by a connected receiver means; signal detection first means for resetting the circuitry to an initialized condition where the east receiver is connected to the west transmitter and the west receiver is connected to the east transmitter whenever a null signal is received; and signal detection second means for reconnecting a given receiver means in a loopback condition to the complementary transmitter means whenever a predetermined signal of a second frequency, where said second frequency is distinguishable from said first frequency, is received immediately after a null signal has been detected and the circuitry has been reset to an initialized condition.

Claim 16

Repeater station apparatus for use in a communication link sending data at a first frequency between end terminals comprising, in combination: a pair of signal detection receiver means for receiving signals from the east and the west; a pair of signal transmission means for transmitting, to both the east and the west, amplified versions of signals received by a connected receiver means; signal detection first means for resetting the circuitry to an initialized condition where the east receiver is connected to the west transmitter and the west receiver is connected to the east transmitter whenever a null signal is received; and signal detection second means for reconnecting a given receiver means in a loopback condition to the complementary transmitter means whenever a predetermined signal of a second frequency, where said second frequency is distinguishable from said first frequency, is received immediately after a null signal has been detected and the circuitry has been reset to an initialized condition.

Claim 17

Apparatus as claimed in claim 9 wherein said signal detection second means maintains said loopback condition until said first means detects receipt of a further null signal.