Methods and equipment for testing reflection points of transmission lines

Claim 3

An equipment for locating and/or measuring the distance of a point of reflection in a transmission line and/or measuring the level or coefficient of reflection at said point, said equipment comprising: means for producing, at an output terminal for connection to a line to be tested, repetitions of a digital word which is a predetermined number of digital bits in length and for progressively delaying the repetitions of said words in steps each of which occurs after a predetermined number of repetitions and corresponds with a length of line to be tested; means for effecting multiplication of separated reflected words by the progressively step delayed word repetitions; means for integrating the results of multiplication produced during each step of delay of the progressively step delayed word repetitions to produce a series of output values from said integrating means; and means for utilizing the peak value of said series of values to indicate the location or distance of the point of reflection in a transmission line connected to said output terminal and/or the level or coefficient of reflection at said point by noting the number of steps of progressive delay at which said peak value occurs to determine the location or distance of said point and/or by noting the amplitude of said peak value relative to that of the repetition of the digital word produced at said output terminal to determine the level or coefficient of reflection at said point.

Claim 4

An equipment for locating and/or measuring the distance of a point of reflection in a transmission line and/or measuring the level or coefficient of reflection at said point, said equipment comprising: means for producing, at an output terminal for connection to a line to be tested, repetitions of a digital word which is a predetermined number of digital bits in length and for progressively delaying the repetitions of said words in steps each of which occurs after a predetermined number of repetitions and corresponds with a length of line to be tested; means for effecting multiplication of separated reflected words by the progressively step delayed word repetitions; means for integrating the results of multiplication produced during each step of delay of the progressively step delayed word repetitions to produce a series of output values from said integrating means; and means for utilizing the peak value of said series of values to indicate the location or distance of the point of reflection in a transmission line connected to said output terminal and/or the level or coefficient of reflection at said point by noting the number of steps of progressive delay at which said peak value occurs to determine the location or distance of said point and/or by noting the amplitude of said peak value relative to that of the repetition of the digital word produced at said output terminal to determine the level or coefficient of reflection at said point.

Claim 5

An equipment as claimed in claim 2 wherein the means for producing at said output terminal repeated repetitions of a digital word is a binary chain code generator.

Claim 6

An equipment as claimed in claim 3 wherein the binary chain code generator comprises a shift register and a feedback path connected across said shift register, comprising at least one exclusive OR-gate, said gate being connected to receive an input each from a stage in said shift register.

Claim 7

An equipment as claimed in claim 2 wherein words reflected back to said output terminal are separated out by means including an inverter means for inverting said repeated repetitions of said words, and a differential amplifier having one input supplied from said output terminal and the other supplied with the inverted repeated repetitions of the digital words.

Claim 8

An equipment as claimed in claim 2 wherein the correlation function between separated reflected words and progressively delayed word repetitions is determined by a multiplier having one input supplied with the separated reflected words and the other supplied with the progressively delayed word repetitions; and an integrator supplied with the output from said multiplier.

Claim 9

An equipment as claimed in claim 2 wherein said utilization means include a display or recording device.

Claim 10

An equipment as claimed in claim 2 wherein the means for producing the progressively step-delayed word repetitions comprise: a ring counter, means for supplying periodic pulses thereto, a selector having a plurality of stages each connected to receive the output from a different stage of said counter, and means controlling said selector to select, cyclically and in turn, a different one of the ring counter stages and to pass the selected output to the means for generating said similar words.

Claim 11

An equipment as claimed in claim 8 wherein the said means for supplying periodic pulses comprise a clock pulse source and a frequency divider fed from said source.

Claim 12

An equipment as claimed in claim 8 wherein the frequency divider is of adjustable ratio.

Claim 13

An equipment as claimed in claim 2 wherein the means for producing the repetitions of the digital word include a shift register and wherein there is provided a selector controlled by a multi-stage binary counter to which input is supplied from a multiple input AND gate having its multiple inputs supplied each from a different stage in said shift register, said binary counter having a plurality of its end stages connected to control said selector.

Claim 14

An equipment as claimed in claim 11 wherein the binary counter is adjustable as to the number of its stages in operation at any time.

Claim 15

An equipment as claimed in claim 2 further comprising means, including an exclusive OR gate and change over switch means for automatically cancelling drifts and offsets, said exclusive OR gate being driven by a wave which also drives the change over switch.