Technique and apparatus for testing a time division multiplexed transmission system using selective signal bit extraction

Claim 2

Apparatus for testing a time division multiplexed transmission system comprising a time division multiplexed transmission channel having a digital data signal transmitted thereon, said signal including recurrent intervals of bits in time sequence positions of different binary significance means for splitting said digital data signal into first and second parts with said first part remaining in said transmission channel without interruption of signal continuity, means for selectively extracting a group of digital data bits from said second signal part, means for converting said extracted digital data bits into an analog signal form with the same analog signal level range being employed regardless of the digital significance range, and means for displaying said analog signal whereby the transmission characteristics of said time division multiplexed transmission system are advantageously obtained by visual analysis.

Claim 3

The apparatus in accordance with claim 1 wherein the means for selective bit extraction comprises means for identifying a group of m'' digital data bits in said time division multiplexed data signal, means for selecting a group of n digital data bits from said group of m'' data bits, with n being less than m'', means for inhibiting a group of ((m-1)-n)data bits, with m representing the number of data bits in a digital word of said time division multiplexed data signal, m being greater than n but less than m'', means for selecting a sign bit from said m-bit digital data word, and means for shifting said group of n data bits to positions adjacent in significance to said sign bit.

Claim 4

The apparatus in accordance with claim 2 wherein said extracting means includes means for periodically generating bit clock pulses, and said identifying means includes means for periodically generating frame clock pulses which are in time coincidence with an initial one of a first predetermined number of said bit clock pulses, said frame clock pulses having a recurrence period much greater than the recurrence period of said bit clock pulses, means for counting a second predetermined number of bit clock pulses provided by said bit clock pulse generating means following the occurrence of said frame clock pulse provided by said frame clock pulse generating means, and a gated data register having said time division multiplexed data signal applied thereto, said gated register controlled by said counting means whereby said time division multiplexed data signal is inhibited from entering said gated register during the occurrence of said second predetermined number of bit clock pulses.

Claim 5

The apparatus in accordance with claim 3 wherein the means for counting comprises a synchronous decade counter having load gates at the input to each stage, a plurality of thumbwheel switches for manually programming the limits of the count, means for activating said counter load gates, whereby said count limits are applied to said decade counter from said thumbwheel switches, means for detecting count end when the number of bit clock pulses counted equals the count limits set by said thumbwheel switches, and means for inhibiting bit clock pulses from entering said counter when said count end is detected.

Claim 6

Apparatus for extracting a group of n digital data bits and a sign bit from an m-bit data word in a time division multiplexed digital data signal with m greater than n said apparatus comprising means for periodically generating a bit clock signal, means for periodically generating a frame clock signal, first counting means for generating a pulse count enable signal in response to said frame clock signal and said bit clock signal after a first predetermined number of bit clock signals have occurred following said frame clock signal, second counting means for generating data enable gating signals and data shift clock signals in response to said bit clock signals and said pulse count enable signal when a second predetermined number of bit clock signals have occurred following said pulse count enable signal with said second counting means further generating an additional data enable gating signal and a data shift clock signal after a third predetermined number of bit clock signals following said pulse count enable signal, a shift register, means controlled by all of said data enable gating signals for gating said n bits and said sign bit of said time division multiplexed data signal into said shift register, and means controlled by said data shift clock signals for shifting said group of n data bits to positions adjacent in significance to said sign bit.

Claim 7

Apparatus for extracting a group of n digital data bits and a sign bit from an m-bit data word in a time division multiplexed digital data signal with m greater than n said apparatus comprising means for periodically generating a bit clock signal, means for periodically generating a frame clock signal, first counting means for generating a pulse count enable signal in response to said frame clock signal and said bit clock signal after a first predetermined number of bit clock signals have occurred following said frame clock signal, second counting means for generating data enable gating signals and data shift clock signals in response to said bit clock signals and said pulse count enable signal when a second predetermined number of bit clock signals have occurred following said pulse count enable signal with said second counting means further generating an additional data enable gating signal and a data shift clock signal after a third predetermined number of bit clock signals following said pulse count enable signal, a shift register, means controlled by all of said data enable gating signals for gating said n bits and said sign bit of said time division multiplexed data signal into said shift register, and means controlled by said data shift clock signals for shifting said group of n data bits to positions adjacent in significance to said sign bit.

Claim 8

A technique for testing a time division multiplexed digital data transmission system comprising the steps of transmitting a digital data signal over a time division multiplexed data channel, said data signal including recurrent intervals of bits in time sequence positions of different binary significance, splitting said digital data signal into first and second parts with said first part remaining in said data channel without interruption of signal continuity, extracting a selected group of digital data bits from said second signal part, converting said extracted digital data bits into an analog signal form, with the same analog signal level range being employed regardless of the digital significance range, displaying said analog signal whereby the transmission characteristics of said time division multiplexed transmission system are advantageously obtained by visual analysis.

Claim 9

A technique for testing a time division multiplexed digital data transmission system comprising the steps of transmitting a digital data signal over a time division multiplexed data channel, said data signal including recurrent intervals of bits in time sequence positions of different binary significance, splitting said digital data signal into first and second parts with said first part remaining in said data channel without interruption of signal continuity, extracting a selected group of digital data bits from said second signal part, converting said extracted digital data bits into an analog signal form, with the same analog signal level range being employed regardless of the digital significance range, displaying said analog signal whereby the transmission characteristics of said time division multiplexed transmission system are advantageously obtained by visual analysis.

Claim 10

The technique in accordance with claim 6 wherein the extracting step further comprises the stEps of identifying a group of m'' digital data bits in said time division multiplexed data signal, selecting a group of n digital data bits from said group of m'' data bits, n having a value less than m'', inhibiting a group of ((m-1)-n)data bits, with m representing the number of data bits in a digital word of said time division multiplexed data signal, m having a value greater than n but less than m'', selecting a sign bit from said m-bit digital data word, and shifting said group of n data bits to positions adjacent in significance to said sign bit.

Claim 11

A technique for testing a time division multiplexed digital data transmission system comprising the steps of transmitting a digital data signal over a time division multiplexed data channel, said data signal including recurrent intervals of bits in time sequence positions of different binary significance, splitting said digital data signal into first and second parts with said first part remaining in said data channel without interruption of signal continuity, extracting a group of n digital data bits out of a group of m such bits in said second signal part with m being greater than n, extracting a sign bit out of said group of m digital data bits, shifting said group of n data bits to positions adjacent in significance to said sign bit, converting said extracted digital data bits into an analog signal format with the same analog signal level range being employed regardless of the digital significance range, and displaying said analog signal whereby the transmission characteristics of said time division multiplexed transmission system are advantageously obtained by visual analysis.

Claim 12

A technique for testing a time division multiplexed digital data transmission system comprising the steps of transmitting a digital data signal over a time division multiplexed data channel, said data signal including recurrent intervals of bits in time sequence positions of different binary significance, splitting said digital data signal into first and second parts with said first part remaining in said data channel without interruption of signal continuity, extracting a group of n digital data bits out of a group of m such bits in said second signal part with m being greater than n, extracting a sign bit out of said group of m digital data bits, shifting said group of n data bits to positions adjacent in significance to said sign bit, converting said extracted digital data bits into an analog signal format with the same analog signal level range being employed regardless of the digital significance range, and displaying said analog signal whereby the transmission characteristics of said time division multiplexed transmission system are advantageously obtained by visual analysis.