Abstract: A selected one of a plurality of unique N-bit digital code words that corresponds to an associated signaling message is continuously transmitted until it is desired to transmit a different signaling message. Decoder logic in the receiver looks at a new group of N-signaling bits during each signaling bit interval, without reference to the start of a transmitted code word, and makes a decision during each signaling bit interval as to what signaling message was transmitted. In this manner a keep-alive signal is virtually continuously provided in the receiver. Latch circuitry repeats the previous decision from the decoder logic when the current group of N-signaling bits does not correspond to one of the unique code words or an ordered permutation thereof. In an alternate embodiment a memory circuit requires that the decoder logic repeat the same decision as to what signaling message was transmitted for P consecutive groups of N-signaling bits (i.e.

Abstract: A selected one of a plurality of unique N-bit digital code words that corresponds to an associated signaling message is continuously transmitted until it is desired to transmit a different signaling message. Decoder logic in the receiver looks at a new group of N-signaling bits during each signaling bit interval, without reference to the start of a transmitted code word, and makes a decision during each signaling bit interval as to what signaling message was transmitted. In this manner a keep-alive signal is virtually continuously provided in the receiver. Latch circuitry repeats the previous decision from the decoder logic when the current group of N-signaling bits does not correspond to one of the unique code words or an ordered permutation thereof. In an alternate embodiment a memory circuit requires that the decoder logic repeat the same decision as to what signaling message was transmitted for P consecutive groups of N-signaling bits (i.e.

Abstract: Method and apparatus is disclosed for identifying faults in a subscriber carrier telephone system utilizing out-of-band pilot signals and comprising pluralities of cables and repeaters that are alternately connected in series between carrier equipment at a central office location and a subscriber station. Equipment at the office location transmits selected numbers of test pulses, having a test frequency that is between the transmitted and received channel and pilot frequencies, to the first cable. The pulses are detected at the first repeater and counted. A microprocessor is responsive to the test pulse count in the repeater for initiating associated tests on the cable and/or repeater, or for retransmitting test pulses on the next cable to the next repeater for causing it it perform designated tests. The results of the tests are sent to the office equipment in the form of reply pulses having a frequency that is below the lowest channel frequency.

Abstract: The output of an LF transmitter that operates at a prescribed frequency is coupled to an electrically conductive rodent shield on a buried optical fiber cable. The rodent shield operates as an elongated underground antenna that transversely radiates an electromagnetic field that preferably propagates beyond the surface of the ground. A receiver that is located on a piece of earth working equipment generates a warning signal when the equipment moves a receiving antenna such that it picks up signals of the prescribed frequency that are radiated by the buried optical fiber cable. Unique tone signals that can be modulated onto the prescribed signal are assigned to associated cable companies. A prescribed signal that is modulated with a single tone signal is only applied to optical fiber cables of the associated cable company to provide an equipment operator with the identity of the owner of the cable that he is near.

Abstract: Method and apparatus is disclosed for identifying faults in a subscriber carrier telephone system utilizing out-of-band pilot signals and comprising pluralities of cables and repeaters that are alternately connected in series between carrier equipment at a central office location and a subscriber station. Equipment at the office location transmits selected numbers of test pulses, having a test frequency that is between the transmitted and received channel and pilot frequencies, to the first cable. The pulses are detected at the first repeater and counted. A microprocessor is responsive to the test pulse count in the repeater for initiating associated tests on the cable and/or repeater, or for retransmitting test pulses onto the next cable to the next repeater for causing it to perform designated tests. The results of the tests are sent to the office equipment in the form of reply pulses having a frequency that is below the lowest channel frequency.

Abstract: In satellite telephone communication equipment, the phase detector of a phase-lock loop compares the phase of a master oscillator signal from the loop oscillator with that of a pilot tone signal and produces an error control voltage which it combines with a constant sweep voltage that is stepped at a variable rate. When the loop is out of lock, a first count of the number of excursions of the beat or difference frequency signal from the phase detector that exceed a prescribed threshold level is generated, a second count is incremented for every n counts in the first count, and a constant amplitude step of the stepped sweep voltage is produced for each unique value of the second count. The steps in the sweep voltage occur at a variable rate that is related to the difference frequency of the beat signal. Since the difference between the oscillator and pilot frequencies decreases as the loop approaches lock, the rate at which the sweep voltage is stepped also decreases.

Abstract: Method and apparatus is disclosed for identifying faults in a subscriber carrier telephone system utilizing out-of-band pilot signals and comprising pluralities of cables and repeaters that are alternately connected in series between carrier equipment at a central office location and a subscriber station. Equipment at the office location transmits selected numbers of test pulses, having a test frequency that is between the transmitted and received channel and pilot frequencies, to the first cable. The pulses are detected at the first repeater and counted. A microprocessor is responsive to the test pulse count in the repeater for initiating associated tests on the cable and/or the repeater, or for retransmitting test pulses on the next cable to the next repeater for causing it it perform designated tests. The results of the tests are sent to the office equipment in the form of reply pulses having a frequency that is below the lowest channel frequency.

Abstract: A log-periodic antenna comprises two arrays of dimensionally tapered radiating elements disposed in the E-plane and each fed by a balanced line consisting of the inner conductors of two coaxial cables. In one embodiment the elements of each array are dipoles and in another embodiment are formed of continuous conductive strips in zig-zag patterns on non-conductive support members. Each array preferably has two sets of elements disposed in planes, respectively, which converge toward the smaller end of the array with vertically aligned radiating elements of each set projecting in opposite directions from the array axis. Periodic gain dropout anomalies across the antenna operating band are eliminated by use of a shielded feed line.

Abstract: The modulator comprises a serial to parallel converter which separates alternate bits of a serial-binary data stream into I and Q bit streams that are stored in associated shift registers, a pair of ROMs that drive associated D/A converters, and a quadrature-phase modulator. Each bit of the I and Q bit streams has a duration of 2T, where T is the bit interval or period of a data bit. Each of the ROMs comprises blocks of memory that contain a plurality of digital words. The present and immediate past I and Q bits in the shift registers, and a baud clock signal of one-half the data signal rate, are applied to address inputs of the ROMs for selecting associated memory blocks in the 2 ROMs. A counter then clocks the ROMs for sequentially outputting the contents of the addressed memory blocks to the converters which produce analog voltages that phase modulate a carrier signal for moving a resultant signal vector with a constant envelope during each bit interval.

Abstract: Apparatus is provided for pulling very long lengths of optical fiber and coaxial cable from a single pulling location through a polyethylene for polyvinyl chloride (PVC) subduct which extends continuously between input and output manholes through lengths of buried duct pipe and intermediate manholes. Jacketed aramid fiber pulling tape is located in the subduct with its pulling end extending out of the output end of the subduct and connected to a power driven reel. The other end of the tape extends out of the input end of the subduct and is attached to one end of the cable. Liquid silicone lubricant is poured into the input end of the subduct ahead of the cable. The power drive is energized to cause the reel to move the tape in the subduct for pulling the one end of the cable slowly into and then rapidly through the subduct with less than a prescribed maximum pulling tension on the cable. In an alternate embodiment, the lubricant is silicone grease.

Abstract: A method is provided for pulling very long lengths of optical fiber and coaxial cable from a single pulling location through a polyethylene or polyvinyl chloride (PVC) subduct which extends continuously between input and output manholes through lengths of buried duct pipe and intermediate manholes. Jacketed aramid fiber pulling tape is located in the subduct with its pulling end extending out of the output end of the subduct and connected to a power driven reel. The other end of the tape extends out of the input end of the subduct and is attached to one end of the cable. Liquid silicone lubricant is poured into the input end of the subduct ahead of the cable. The power drive is energized to cause the reel to move the tape in the subduct for pulling the one end of the cable slowly into and then rapidly through the subduct with less than a prescribed maximum pulling tension on the cable. In an alternate embodiment, the lubricant is silicone grease.

Abstract: The A and B leads of a telephone circuit are resistively connected to the drain and source of an FET switch having its gate connected to the emitter of an optoelectric transistor that is also resistively connected across these leads. The collector of a control transistor is also connected to the gate, with its base-emitter diode and emitter bias resistor connected across the source bias resistor for turning on the control transistor and limiting current in the FET when conduction of the latter exceeds a prescribed rate.

Abstract: A modulo 2.sup.2n -1 adder employing adders which may all be standard binary adders. A first binary adder sums binary input signals a and b to produce a first sum signal in which the n+2 more significant bits represent the integer part of (a+b)/2.sup.2n (i.e., of a+b taken modulo 2.sup.2n). A second binary adder subtracts these n+2 more significant bits from a 2n bit shifted (less significant bits) version thereof for producing a first difference signal which is subtracted from the first sum signal in a third binary adder to produce a binary signal R. The signal R is applied to one input of a fourth binary adder which produces the desired modulo 2.sup.2n -1 signal. A comparator circuit applies a constant (2.sup.2n -1) to a difference input of the fourth binary adder only when R is greater than or equal to this constant.

Abstract: The apparatus is slide mounted on elongated bumper support members between the grill and front bumper of a pickup truck. The apparatus is powered by a hydraulic power take-off unit which is selectively connected through a selector valve assembly to a hydraulic tool circuit, and to a series connected tension control unit and speed control valve which feed hydraulic fluid to and return it from a motor that supports a capstan. The control unit bypasses fluid away from the pump when the hydraulic pressure exceeds a maximum allowable value which corresponds to a maximum allowable pull force on the cable. The control unit includes a valve that can be manually actuated for bypassing hydraulic fluid back to the power take-off unit when the speed control valve is closed and/or it is desired to manually terminate a cable pull. Only when it is desired to pull cable is the capstan extended beyond a fender and connected to a take-up reel, with an idler pulley being raised above the reel.

Abstract: A residue to analog converter associated with residue numbers {m1,m2,m3} of the residue number system defined by the moduli set {p1=2.sup.n -1, p2=2.sup.n, p3=2.sup.n +1} and which does not require memory comprises five standard binary adder circuits, apparatus for performing multiplication by bit shifting, and a modulo p1 p3 adder circuit. First and second binary adders combine the residue signals m1 and m3 to produce sum and difference signals which are bit shifted by grounding 2n-1 and n-1 lines, respectively, and locating them as less significant bit lines ahead of these sum and difference signal lines. A modulo p1*p3 adder sums these bit shifted signals. A third binary adder, which ignores overflow, performs a modulo p2=2.sup.n subtraction of m2 from the n less significant bits of the modulo p1*p3 sum signal to produce a second difference signal.

Abstract: An echo canceller is connected in the four-wire, voice-frequency path of a communication circuit and includes an end delay analyzer which is bridged between the four-wire transmit and receive paths, and a variable delay and an echo synthesizer connected in series between the received signal path and one input of a summation circuit. The other input to the summation circuit is connected to the four-wire transmit path along which the return echo signal is propagating. Any difference appears as a residual echo at the output of the summation circuit.The end delay analyzer, in response to the received signal and the echo return signal, provides an output control signal that adjusts the variable delay to compensate for the terminal circuit delay which occurs between the echo canceller and the four-wire to two-wire hybrid.

Abstract: A method is disclosed for accomplishing modulo 2.sup.2n -1 addition with apparatus requiring adders that may be all standard binary adders. The method requires summing binary input signals a and b to produce a first sum signal in which the n+2 more significant bits thereof represent the integer part of a+b taken modulo 2.sup.2n. These n+2 more significant binary bits are subtracted from a 2n bit shifted product representation thereof for producing a first difference signal. This difference signal is subtracted from the first sum signal to produce a binary signal R. When R is greater than or equal to the constant (2.sup.2n -1), this constant is subtracted from the signal R for producing a binary signal that is the first sum signal a+b taken modulo 2.sup.2n -1 .

Abstract: In a residue number system defined by the moduli set {p1=2.sup.n -1, p2=2.sup.n, p3=2.sup.n +1}, a method of converting residue numbers {m1,m2,m3} to associated analog signals r(m1,m2,m3) comprises the steps of selecting a first binary signal satisfying the relationships .vertline.m1*S3+m3*S1.vertline..sub.p1*p3 (where the constant S1=p1*p2/2 and S3=p2*p3/2) from a first look-up table; and summing the n less significant bits of this first digital signal and the negative of the residue digit signal m2 in a first binary adder for generating a second binary signal that is representative of the difference therebetween, taken modulo p2. This second binary signal addresses a second look-up table containing third binary signals which correspond to possible values of the product of the second binary signal and p1 and p3. Selected first and third binary signals are summed in a second binary adder for producing a binary output signal r(m1,m2,m3) that is representative of the residue number {m1,m2,m3}.

Abstract: In a residue number system defined by the moduli set {p1=2.sup.n -1, p2=2.sup.n, p3=2.sup.n +1}, a method of converting residue number signals {m1,m2,m3} to associated analog signals r(m1,m2,m3), and that does not require memory devices, comprises the steps of generating a pair of binary signals that are the sum and difference of the residue numbers m1 and m3, bit shifting these sum and difference signals by inserting 2n-1 and n-1 binary 0's as less significant bits thereof, and summing these bit shifted signals modulo p1*p3 to produce a two dimensional binary signal r(m1,m3). A correction signal is generated by modulo p2=2.sup.n summing the n less significant bits of the signal r(m1,m3 ) and the negative of the residue signal m2 to produce a second difference signal, bit shifting this second difference signal by inserting 2n binary 0's as less significant bits thereof and subtracting the second difference signal from this bit shifted signal to produce the correction signal.

Abstract: A residue to analog converter associated with residue numbers {m1,m2,m3} of the RNS defined by the moduli set {p1=2.sup.n -1, p2=2.sup.n, p3=2.sup.n +1} comprises a pair of ROMs and a pair of standard binary adders. The first ROM stores a look-up table of summations, taken modulo p1*p2, of possible values of m1*S3 and m3*S1 product terms, where S1=(p1*p2)/2 and S3=(p2*p3)/2, with associated memory locations being addressed by m1 and m3. The first binary adder performs a modulo 2.sup.n summation of a binary signal stored by the first ROM and -m2 by ignoring any overflow. The second ROM stores a look-up table of possible values of the products of p1, p3 and the modulo 2.sup.n signal. The second binary adder sums output signals of the two ROMs for producing a binary signal r(m1,m2,m3) that is representative of the residue signal {m1,m2,m3}. The corresponding analog signal is produced with a standard D/A converter.