Abstract: A method for connecting together two twisted pair lines in a LAN so as to avoid common mode current. The invention recognizes that the impedance to ground is different for each wire in the twisted pair line. Moreover, this impedance is different from spool-to-spool for lines having the same purported impedance. A balun is placed at the connection between the lines.

Abstract: A LAN which uses flat telephone cable having at least four conductors. The inner conductors are joined together and the outer conductors are joined together at each node thereby making reversals of the inner and outer conductors, which may occur at connectors, impossible. Each node uses two baluns to provide an unbalanced zone between the baluns for connecting to the DTE.

Abstract: A method for measuring the current flowing through a cow is disclosed. The method uses a four-terminal resistor precision measurement technique to accurately measure the electric current flowing through a cow as a result of voltages found on dairy farms. The four-terminal resistor technique allows the present invention to measure the current without the need to account for unpredictable environmental conditions on the dairy farm that may effect electrical contact resistances. The present invention uses Ohm's Law to determine current by dividing the voltage drop across a conductive path in the cow by the resistance of the conductive path. The elements utilized do not restrict cow movements and allow the cow to move about freely so as to enable dairy farmers to monitor conveniently and continuously for electric currents resulting from stray voltages on the dairy farm without interfering with daily farm activity.

Abstract: Enhanced collision detection in an Ethernet network, particularly useful for passive nodes using receive mode collision detection. When a transmitting node detects a collision, for example, using transmit mode collision detection, it activates a current sink at the node further reducing the DC potential on the line. This reduced DC potential assists in overcoming the low frequency impedance which may exist between the transmitting node and a remotely located passive node.

Abstract: EMI suppression technique that pseudorandomizes the positive or negative going transitions that are used to represent one binary state in a transmitted digital signal such as in MLT-3 data format. By pseudorandomizing the selection of these transitions, substantial spreading of the spectral energy occurs. Descrambling need not occur since each transition is recognized as the encoded binary state. Thus, the data sender can encode the data and suppress EMI without any changes to the receiver's equipment.

Abstract: A LAN which uses flat telephone cable having at least four conductors. The inner conductors are joined together and the outer conductors are joined together at each node thereby making reversals of the inner and outer conductors, which may occur at connectors, impossible. Each node uses two baluns to provide an unbalanced zone between the baluns for connecting to the DTE.

Abstract: An apparatus for monitoring and testing a twisted pair, particularly useful for an Ethernet network. First and second DC currents alternated with one another are applied to both ends of the line, asynchronously. By monitoring the potential on the line, a determination is made as to the condition of the line. For example, shorted, crossed, improperly terminated or open conditions can be detected. A visual indication of the condition of the line is provided and additionally, the visual indication provides an indication of the traffic level in the network.

Abstract: An apparatus for monitoring and testing a twisted pair, particularly useful for an Ethernet network. First and second DC currents alternated with one another are applied to both ends of the line, asynchronously. By monitoring the potential on the line, a determination is made as to the condition of the line. For example, shorted, crossed, improperly terminated or open conditions can be detected. A visual indication of the condition of the line is provided and additionally, the visual indication provides an indication of the traffic level in the network.

Abstract: EMI suppression technique that pseudorandomizes the positive or negative going transitions that are used to represent one binary state in a transmitted digital signal such as in an MTL-3 data format. By pseudorandomizing the selection of these transitions, substantial spreading of the spectral energy occurs. Descrambling need not occur since each transition is recognized as the encoded binary state. Thus, the data sender can encode the data and suppress EMI without any changes to the receiver's equipment.

Abstract: An apparatus for monitoring and testing a twisted pair, particularly useful for an Ethernet network. First and second DC currents alternated with one another are applied to both ends of the line, asynchronously. By monitoring the potential on the line, a determination is made as to the condition of the line. For example, shorted, crossed, improperly terminated or open conditions can be detected. A visual indication of the condition of the line is provided and additionally, the visual indication provides an indication of the traffic level in the network.

Abstract: A method and apparatus for power line communications which utilizes common mode transmission and reception of communication signals over power lines. The communication signals are sent and received between the power and neutral lines, and the ground line. A common mode choke in the power lines presents a relatively high impedance to the communication signals and prevents them from being shorted to the ground line. The choke is substantially transparent to the power delivery current.

Abstract: In a power line communications apparatus an improvement for blanking or snubbing impulse noise. The impulse noise is detected and used to snub the detected signal. The duration of the snubbing pulses is controlled to assure complete blanking of noise including the trailing noise signals following a main noise pulse which may not otherwise be detectable. Also, the number of snubbing pulses which can occur are limited to prevent too much energy from being snubbed during any given baud period.

Abstract: An amplifier for use with a twisted pair LAN. Each stage of the amplifier provides amplification including higher frequency emphasis for a predetermined length of line. The correct number of stages are automatically activated within the amplifier. Thus a singly configured amplifier may be used for different line lengths.

Abstract: Apparatus and method of sequencing nucleic acid molecules, including DNA and RNA molecules. Several copies of the molecules are labeled with a radioactive tracer and divided into separate groups. The groups of molecules are then each chemically cleaved to produce labeled fragments of varying length which terminate in predetermined bases. The groups of fragments are then introduced into separate columns of electrophoresis gel and voltage is applied across the gel to cause subgroups of the fragments to propagate along the columns at a velocity which is a function of the length of the fragments in the subgroup. Radiation detectors are used to detect the subgroups of fragments as they pass a predetermined position along the gel column, and data corresponding to the order in which the subgroups of fragments are detected is stored in a memory. Such data is then used to determine the bases sequence of the molecules.

Abstract: An improvement in a bus where the propagation time between two of the transmitters on the bus is appreciable compared to the period of the bus cycles. High impedance drivers are used by the transmitters to permit signals on the bus to be superimposed on one another. This permits signals from one transmitter to be propagated even when that transmission occurs while another signal is propagating past that transmitter.

Abstract: The present invention comprises a balun for intercoupling an at least partially unbalanced line and a substantially balanced line having similar line impedances which is capable of passing differential signals over a wide bandwidth while substantially attenuating any common mode signals. The balun comprises a pair of transformers with bifilar windings, each connected as a choke. Each conductor of the unbalanced line is coupled to a different one of two substantially identical inductances of the first transformer and the other side of each inductance is coupled through the second transformer to a different one of the two conductors of the balanced line. Each of the connections between the two transformers is coupled to ground with a substantially identical capacitance. The capacitance in conjunction with the inductance acts to filter out the common mode signals while allowing the differential mode signals to pass through the balun.

Abstract: A method and apparatus for transmitting data over a line where the data is received for transmission at a fixed rate. The data is buffered and transmitted over the line at a rate faster than the fixed rate to create "dead" times used for calibration. Calibration signals are transmitted over the line during the dead time to determine the characteristics of the line.

Abstract: The present invention comprises a balun for intercoupling an at least partially unbalanced line and a substantially balanced line having similar line impedances which is capable of passing differential signals over a wide bandwidth while substantially attenuating any common mode signals. The balun comprises a pair of transformers with bifilar windings, each connected as a choke. Each conductor of the unbalanced line is coupled to a different one of two substantially identical inductances of the first transformer and the other side of each inductance is coupled through the second transformer to a different one of the two conductors of the balanced line. Each of the connections between the two transformers is coupled to ground with a substantially identical capacitance. The capacitance in conjunction with the inductance acts to filter out the common mode signals while allowing the differential mode signals to pass through the balun.

Abstract: An improved architecture for a computerized branch exchange particularly for a time division multiplexed bus used in the exchange. An intershelf bus includes a unidirectional source bus which receives signals from expanders and a unidirectional destination bus which transmits signals to the expanders. The expanders, through another bus, communicate with line cards which interface with telephone station sets, commercial lines, etc. A time division multiplexed controller updates distributed connection tables contained in each of the expanders and controls the flow of data onto and from the unidirectional buses. The distributed connection tables eliminate the need to broadcast addresses during each time slot. The arrangement is particularly useful in reducing blocking associated with prior art bidirectional buses.

Abstract: A circuit for converting an AC potential to a regulated DC potential which circuit consumes a minimum of power and is relatively inexpensive to build is described. A capacitor is used to couple the AC potential to a rectifier. The duration of current flow through the capacitor is controlled to obtain the regulation. An on or off switching device is used such as an SCR, eliminating the current flow regulation devices often used in regulative power supplies. The invented circuit is particularly useful for providing a regulated DC potential in a switching power supply.