Regenerative line access module
First Claim
1. A line access module having input and output, and adapted to be connected in a series relationship to a digital data transmission line carrying a data pulse stream, said module comprising:
- pulse regeneration means for receiving attenuated and distorted data signals at the input of said module, and for producing reshaped data signals at the output of said module, said pulse regeneration means comprising a dual comparator having a selectable reference threshold voltage;
timing extraction means electrically connected to and receiving signals from said pulse regeneration means, for producing a clock signal having a fundamental frequency equal to the fundamental frequency of the data pulse stream, said timing extraction means comprising means for filtering out a fundamental sinusoidal signal from the reshaped data pulses and shifting the phase of the filtered signal from the phase of the fundamental component of the reshaped data pulses, and square wave generation means responsive to the zero crossings of the filtered sinusoidal signal for producing said clock signal;
data gating means having two states, said data gating means electrically connected between said pulse regeneration means and said output of said module for passing the reshaped data signals to said output when said gating means is in the first of said states, and for blocking the reshaped data signals from reaching said output when said gating means is in the second of said states, said data gating means also connected to said timing extraction means to receive the clock signals therefrom; and
relay means having contacts connected to said data gating means whereby operation of said relay means places said data gating means in said second state in response to externally-generated data signals and connects externally-generated data signals to said data gating means.
0 Assignments
0 Petitions
Accused Products
Abstract
A device for permanent installation in series with a time division multiplex digital data transmission line for accessing data signals carried by the line without interruption or degradation of the signals. This novel device is a regenerative line access module (RLAM) that receives incoming data signals that may be attenuated and distorted, and regenerates or reshapes the pulses thereof. The regenerated signals are passed to the output of the RLAM, amplified, and retransmitted on the transmission line, and are also used for generating a clock signal having a fundamental signal equal in frequency to the fundamental frequency of the incoming data signals but delayed slightly therefrom. When it is desired to access a selected subscriber channel, the RLAM blocks the throughput of the incoming bit stream during the period of the selected subscriber data byte. The data byte thus deleted may be dropped for local use if desired. The delay in the outgoing bit stream provides time for the recognition and deletion of the selected byte, and for the generation and insertion of a locally generated substitute byte. A principal application of the RLAM is as an element in a test system for verifying the integrity of individual subscriber channels of the digital data bit stream, and the substitued bytes may be test codes to determine channel characteristics. Through the use of a duplex arrangement having a RLAM in both the SEND and RECEIVE transmission lines, the response to the inserted test code data in the SEND line can be extracted from the RECEIVE line by means of a loop-back connection, and analysis of the received code provides the required test data. Importantly, the accessing of an individual channel of the data bit stream is accomplished without interruption or degradation of the other subscriber channels.
20 Citations
12 Claims
-
1. A line access module having input and output, and adapted to be connected in a series relationship to a digital data transmission line carrying a data pulse stream, said module comprising:
-
pulse regeneration means for receiving attenuated and distorted data signals at the input of said module, and for producing reshaped data signals at the output of said module, said pulse regeneration means comprising a dual comparator having a selectable reference threshold voltage; timing extraction means electrically connected to and receiving signals from said pulse regeneration means, for producing a clock signal having a fundamental frequency equal to the fundamental frequency of the data pulse stream, said timing extraction means comprising means for filtering out a fundamental sinusoidal signal from the reshaped data pulses and shifting the phase of the filtered signal from the phase of the fundamental component of the reshaped data pulses, and square wave generation means responsive to the zero crossings of the filtered sinusoidal signal for producing said clock signal; data gating means having two states, said data gating means electrically connected between said pulse regeneration means and said output of said module for passing the reshaped data signals to said output when said gating means is in the first of said states, and for blocking the reshaped data signals from reaching said output when said gating means is in the second of said states, said data gating means also connected to said timing extraction means to receive the clock signals therefrom; and relay means having contacts connected to said data gating means whereby operation of said relay means places said data gating means in said second state in response to externally-generated data signals and connects externally-generated data signals to said data gating means. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. A line access module for connection in a series relationship to a digital data transmission line carrying a data pulse stream in a 50 percent duty cycle bipolar format comprising:
-
pulse regeneration means for receiving attenuated and distorted bipolar data signals at an input of said module and producing reshaped first unipolar data signals; timing extraction means electrically connected to said pulse regeneration means for producing a clock signal having a fundamental frequency equal to the fundamental frequency of the data pulse stream; data gating means electrically connected to receive the reshaped first unipolar data signals form said pulse regeneration means for passing the first unipolar data signals when said gating means is in a first state, and for blocking the first unipolar data signals when said gating means is in a second state, said data gating means also connected to said timing extraction means to receive the clock signal therefrom; data segment generation means connected to said data gating means for generating segments of second unipolar data signals to be inserted into said data pulse stream, said data gating means arranged to pass such second unipolar data signals when said data gating means is in the second state; and polarity control means electrically connected to said data gating means for receiving the reshaped first unipolar data signals and the second unipolar data signals and for alternately reversing the polarity of successive unipolar pulses, thereby producing a composite bipolar data pulse stream consisting of a regenerated version of the attenuated and distorted bipolar data signals at the input of said module, and a bipolar version of the second unipolar data segments. - View Dependent Claims (9, 10)
-
-
11. A device installable in a series relationship in a transmission line carrying a digital time division multiplexed data bit stream for accessing individual subscriber channels within the bit stream comprising:
-
regeneration means for reshaping pulses of the incoming data bit stream; timing means for generating clock signals in synchronism with the incoming data bit stream; location means for receiving the reshaped data from said regeneration means for determining the location of the incoming data bit stream of a selected subscriber data segment; delay means connected to said regeneration means and to said timing means for providing a selected delay to reshaped pulses from said regeneration means, said delay means comprising flipflop means controlled by said timing means for temporarily storing such reshaped pulses, and data gating means for passing the reshaped data to the outgoing transmission line when in an unblocked state and for blocking the reshaped data from the outgoing transmission line when in a blocked state; and control means connected to said location means and said gating means, said control means responsive to said location means to place said gating means in the blocked state during the period of a selected subscriber data segment and controlling said gating means to pass a substitute data segment to said outgoing transmission line during such period. - View Dependent Claims (12)
-
Specification