Abstract: A circuit which can be appliqued to external terminals of a prior art key telephone line circuit to protect the circuit from prematurely cancelling a customer-applied holding condition when the central office exhibits an open switching interval (OSI) condition is described. The appliqued circuit monitors a contact of the key system hold relay, and when that relay is released by the appearance of an OSI condition, temporarily reconnects the winding of the hold relay across the line so that the hold relay can respond to the reappearance of central office line current if it appears after a normal OSI interval and which disconnects the hold relay if line current does not appear as during a permanent signal condition.

Abstract: A method of automatically detecting fraudulent telephone calls in telephone systems having a plurality of trunks served by automatic message accounting equipment. The trunks are normally scanned to detect changes in supervisory states for automatic message accounting purposes. When predetermined supervisory state sequences are detected at any one of the trunks, a special test control signal is generated and, responsive to the appearance of the special test control signal, the transmission path of the suspected trunk is seized to monitor whatever call signaling information may appear thereon during an interval when such signaling would not appear on a normal call to verify the existence of the fraudulent usage.

Abstract: A circuit is provided for improving the manner in which tone signaling-to-dial pulse converters interface with prior art dial pulse registers. Instead of allowing the converter to operate the register's line supervisory relay, the converter directly operates the dial pulse counting relays of the register. In this way, changes in battery and ground potential and impedance which may be noticeable each time the conversion apparatus pulses the line relay are eliminated, and the line relay in the register is allowed, uninterruptedly, to supply battery and ground to the multifrequency signaling station throughout the duration of signaling. The direct operation of the pulse counting relays permits faster pulsing speeds because neither the distributed capacitance of the line nor the lumped capacitors used in connection with the line relay are in the pulsing path.

Abstract: An extrusion die is disclosed for producing a compound extrusion in the form of a lined tubing where the materials forming the main tubing wall and the lining are difficult to bond. The die includes a plenum chamber in which there is spider-mounted a torpedo section passed which the main extrudate flows. The torpedo section is equipped with the circumferential orifice for orthogonally injecting the secondary extrudate as an internal lining. The combined extrudate is then caused to flow through a conical passageway which increasingly confines the combined extrudate and enhances the bonding therebetween. Thereafter, the combined extrudate passes through a passgeway having a constant clearance dimension wherein the bonded materials are stablized before they are permitted to exit the die.

Abstract: An automatic trunk test arrangement is disclosed which performs transmission path monitoring on idle trunks in the normal manner and which routinely scans the supervisory states of trunks primarily for call charging purposes. When predetermined supervisory states are detected at any trunk, the routine testing of idle trunks is interrupted. The identity of the idle trunk under test is stored, and the test multiple is seized to connect the busy trunk exhibiting the predetermined supervisory states to the test multiple so that call signalling appearing on its transmission path conductors may be monitored. The connection of the transmission path monitoring apparatus is thus restricted to only those busy trunks exhibiting a predetermined supervisory state.

Abstract: The reliable detection of call disposition signals to identify the ultimate dispositions of calls switched over a cross-office connection is achieved by attaching monitoring equipment to the sender that has been seized by an incoming trunk circuit of a telephone switching office. Sender release which normally occurs after the completion of outpulsing is inhibited to maintain the trunk in the split condition normally assumed during outpulsing. A tone detector, attached to the called side of the prolonged split, samples the returning call disposition tones or speech signals and allows a call disposition monitor to preliminarily classify them. The output of the tone detector is also sent to a computer for more detailed and complete analysis.

Abstract: A telephone line transformer having less iron in its core can be achieved by providing the transformer with a third winding to balance out the DC magnetization produced by the tip and ring windings. This winding must be bypassed by a capacitor of fairly large size to provide sufficiently low impedance at voice frequencies to prevent voice currents from flowing through the balancing winding. A capacitor of large enough size, however, may prevent the development of sufficient voltage change during dial pulsing for reliable dial pulse detection. This problem is solved by providing a dynamic capacitor bypass arrangement which includes a negative feedback operational amplifier together with a balancing winding bypass capacitor of reasonable size. The dynamic circuit magnifies the bypass capacitance with respect to voice frequency signals but saturates during dial pulsing and thus leaves the capacitance temporarily unamplified. The arrangement thus yields an effective bypass capacitance of approximately 35,000.mu.

Abstract: A line transformer circuit in which the DC component of magnetization produced in the tip and ring windings by the battery supplying loop current to the telephone set microphone may be neutralized by an oppositely-poled, serially-connected balancing winding is disclosed. One end of the balancing winding is connected to the supply battery and is, therefore, at AC ground. The other end is kept at a point of high AC impedance to ground by the collector of a transistor so that audio frequency voltages induced in the balancing winding cannot load the transformer. The AC currents in the tip and ring windings are provided with a virtual ground return path by means of a differential amplifier controlled Darlington pair in circuit between the tip and ring windings and the balancing winding. The AC components of the Darlington pair collector current are bypassed to ground by a shunt capacitor at the junction of the Darlington pair collector terminal and the third winding.

Abstract: A line circuit is disclosed employing a transformer having tip and ring windings and a third balancing winding designed to be serially connected in circuit with the tip and ring windings and poled so as to balance out their DC magnetization. The AC components of longitudinal current flowing through the tip and ring windings are prevented from flowing through the balancing winding by a capacitor bypass which offers a low impedance path compared to that of the balancing winding. This capacitor is prevented from short circuiting the AC voice frequency voltages induced by transformer action in the balancing winding by driving the balancing winding from the collector terminal of a transistor biased to remain out of saturation and which, therefore, exhibits a high impedance to changes in collector voltage. The resistance in the emitter circuit of this transistor determines the level of DC current delivered through the balancing winding to the tip and ring windings and the telephone line.

Abstract: An arrangement for frequency division of a symmetrical pulse train by N/2 where N is an odd integer greater than 1; this arrangement does not require the use of any one-shot multivibrators or delay elements and employs only log.sub.2 (N+1) flip-flops in its design. In one embodiment a two state gating circuit selectively allows either the input pulse train or its inverse to be fed to a modulo (N+1)/2 counter. The state of the gating circuit is controlled by a flip-flop which toggles whenever the counter reaches its maximum count. In addition, the counter produces an output pulse as it advances through each of its counting sequences. Thus, the counter, which advances in response to falling pulse edges, alternates between counting falling edges of the input pulse train and the inverted input pulse train thereby counting to N+1 in N pulse periods while yielding two equally-spaced output pulses.

Abstract: An arrangement for measuring the load handling capacity of a stored program control process control system. The process control system is first operated in a monitor mode without any load in order to identify the instructions which must be executed independently of load and therefore, may be characterized as "overhead work" instructions. While operating in the no load or monitor mode, each instruction which is executed is flagged by placing "1" in a flag position of the instruction word. The machine includes provisions for executing instructions so flagged with standard machine timing and for executing unflagged instructions with extended machine timing. The unflagged instructions are termed "load related work" instructions and by extending the time required to execute such instructions, the apparent load to the machine is increased, increasing the machine's apparent occupancy. The time for executing a "load related work" instruction is extended by integral numbers of clock frames.

Abstract: A PCM coder/decoder circuit is disclosed employing a counter that counts clock pulses until a transmitting ramp voltage equals that of an outgoing speech sample. The encoded count is transmitted in complemented form to the distant station where it is eventually entered into a counter similar to that of the transmitting station. Clock pulses are then applied to the receiving counter until a carry is generated at which time a receiving ramp waveform is disconnected from a decoding capacitor. The counter at the receiving station is enabled prematurely to generate the count so that the "reaction time" of the physical circuit components is compensated for. Compensation of this reaction time is important in reducing the nonlinear distortion that would otherwise be introduced when the ramp waveforms that are employed are of the companded type. The circuit operates in an overlap fashion, encoding and receiving in one field and decoding and transmitting in another field.

Abstract: A time-sampled port circuit is shown in which the charges impressed by the telephone set on the shunt capacitor of a low-pass filter associated with the port are passively sampled for transmission to the other port circuits, but which capacitor is impulse driven at a repetition rate equal to twice the cut off frequency of the filter with speech samples received from the other port circuits. By employing passive sampling in the transmitting leg instead of actual charge transfer, as in conventional resonant transfer design, the series inductor normally required in resonant transfer circuits may be omitted with the result that the port circuit switches may be integrated on one chip together with the digital circuitry for encoding and decoding the amplitude samples. Further, all need for amplifier gain adjustment in the port circuit is eliminated by applying different amplitude send and receive ramp signals to the encoder and decoder circuits.

Abstract: The speech path in an escrow coin telephone system wherein coins may be deposited throughout the talking state is maintained free of potentially disruptive coin collection signals. After the serving switching office has calculated the rate for the particular call but prior to called party answer, it transmits a series of rate metering impulses to the station set. A pulse generator at the station set is then preset at a frequency corresponding to the calculated rate and allows the credit balance to be reduced after each unit interval. Logic is provided to collect the coin of highest denomination while the cell is in progress and to ensure a fair coin refund after hangup so that large denomination coins are not collected when smaller ones are available.

Abstract: A conference port for permitting simultaneous voice communication among a plurality of local stations and an external or central office line is shown. The stations may be part of a time division PBX or may be arranged as a time-sampled key telephone system having access to the same line. The conference port includes a first operational amplifier for summing the station port voltages on a capacitor during an interval that is a predetermined fraction of the resonant transfer interval. This first, or quasi-resonant, interval is sufficient to reduce the initial voltage on each of the station port sampling capacitors to a predetermined fraction of their initial level. At the conclusion of this interval the voltage on the summing capacitor in the conference port is multiplied by an appropriate factor in a second operational amplifier and is applied back simultaneously to all of the conference ports together with the signal incoming over the external or central office line.

Abstract: The integrity of switched, time-division multiplexed digital trunks in a telephone switching system is verified on an individual and in-service basis wherein the digital check is accomplished incident to the conventional D.C. network path continuity verification by the switching system common controller. The terminal circuits serving the channel allow a common multiplexer-demultiplexer to insert a test code during the allocated time slot of the channel being tested and detect the same test code from a similarly-functioning testing arrangement at the far end of the digital channel. Failure of a comparison between sent and received codes results in the inhibition of a positive D. C. path check indication to the common controller.

Abstract: A customer controlled gain circuit allows a customer to control the transmission amplifier gain in a trunk circuit by means of multifrequency signals. The trunk circuit contains a multifrequency receiver which receives and decodes gain control commands. The commands are applied to a bidirectional shift register containing a single circulating bit. One gain command causes the bit to shift in one direction while another gain command causes the bit to shift in the other direction. The bit appearing at the outputs of the shift register drives a plurality of FET gate circuits which switch various feedback paths in the trunk transmission amplifier.

Abstract: A stored program controlled time division telephone switching system is disclosed in which apparatus is provided for permitting the main processor to cope with the after-effects of a main memory unit failure. Upon detecting that the memory unit has been restored to operation (but not necessarily its information content) the processor executes a sequence of operations to interrogate the time division network to ascertain the identity of stable calls in progress. A scratch pad memory is employed to accrue a count of which time slots have at least two ports assigned thereto. These are stable calls. Thereafter the main memory is accessed using the port numbers from the scratch pad to write idle progress marks in the main memory progress mark registers for calls having less than two ports assigned and special progress marks for other existing calls.

Abstract: A power driven rotary lawn mower is disclosed in which an auxiliary power drive is provided for engageably coupling engine power to a tine-bearing shaft located between the front drive wheels. The tine-bearing shaft is supported between arms that can be raised and lowered from a linkage controllable at the handle. The combination permits thatching, grass cutting and mulching at the same time and may be used in combination with a rearwardly mounted seed-drill for immediately reseeding of a thatched lawn.

Abstract: A combination power driven lawn mower and lawn care chemical dispensing machine is disclosed in which a hopper for dry granular chemicals is affixed to the top of the lawn mower frame in such a manner that the chemical may be dispensed over an area defined by the swath of lawn cut by the blade. In one embodiment, a trough type of hopper is positioned between the rear axles of the mower and has a dispensing area whose width is the diameter of the blade arc. In an alternative embodiment, a special type of dispensing blade is employed which is connected to the hopper by means of a communicating trunk cut through the bedplate of the mower.