Abstract: A data network switch for switching data between a plurality of data links is disclosed and includes a programmable controller which adapts the data switching in accordance with the state of the switch and the state of the data links. The programmable controller has detection apparatus which detects a problem in the operation of the switch, a memory which stores information on possible problems, their causes, and possible solutions, and a controller. The controller determines from the information stored in the memory the possible causes of the problem according to the nature of the problem detected and determines from the possible causes a ranked series of possible solutions.

Abstract: A transformed current sensing relay with reduced AC impedance of the operating coil is accomplished by adding a shorted secondary winding to an otherwise conventional current sensing reed relay. The shorted secondary winding is preferably implemented with a copper tube over the existing coil and inside the magnetic circuit. This transformed current sensing relay is particularly advantageous for the line current sensing function in switched network communications equipment such as high speed modems, where the transformed relay exhibits substantially lower impedance at high frequencies than the conventional current sensing relay. This transformed current sensing relay allows for the elimination of bypass capacitors and results in significant cost and space savings. Moreover, the transformer nature of the transformed current sensing relay allows for the elimination of suppression resistors from the interface resulting in additional cost and space savings.

Abstract: A connector system having an electrical switch capability for connecting a first electrical conductor to a second electrical conductor is provided and includes a spring biased contact element having a first portion for making electrical contact with the first electrical conductor, a second tapered contact portion for mating with a conductive rim of a hole of the second conductor, and a spring portion for biasing the tapered contact portion in the closed position where the second tapered contact portion mates with the conductive rim, and an actuation member for bringing the tapered contact portion into the open position. The actuation member may be a plunger or the like which enters the hole with which the tapered contact portion is mated from the rear side and pushes the tapered contact portion out of contact.

Abstract: Apparatus and methods in both modem transmitters and receivers are provided for accommodating secondary channel data without disturbing the trellis encoding, mapping, and Viterbi decoding of primary channel data, and without disturbing distribution preserving Tomlinson precoding and decoding of the primary channel data. In order to accommodate the secondary channel data, the secondary channel data are used to make quadrant decisions in a mapper, and concurrently therewith, dummy data or tertiary channel data corresponding in time with the secondary channel data are provided to the trellis encoder so that the continuous working of the trellis encoder can be maintained.

Abstract: A contact element for an electrical connector or an integrated circuit which is used with a hold-down mechanism has a base portion, a spring portion having at least partially helical spring elements, and a tapered contact portion which mates in a biased manner with the conductive rim of a hole. The contact element is particularly useful for surface mount applications. The spring portion is preferably arranged with a partially helical spring configuration so that compression of the spring also effects a torsional rotation of the contact portion. The contact element can be fabricated from: a flat sheet with punching, rolling, and/or forming operations, thin walled drawn parts, or modular parts. Additionally, spring sections may be arranged in tandem, in either a co-rotational or counter-rotational manner to provide additional degrees of design freedom with respect to compression range, axial spring rate, and rotational rate.

Abstract: A grounding spring clip for modular jacks includes a stamped or etched plate having an opening substantially coextensive with the plug receiving opening in a modular jack and a bent tab to provide at least one springy finger extending out from the plate adjacent the opening and partially occluding the opening. Two opposite edges of the plate are bent backward to provide curls which wrap around corresponding edges of the face plate of a snap-in modular jack. One edge of the plate is bent to provide a tab stop and the edge opposite the tab stop is left straight. The grounding spring clip is slid onto the face plate of a snap-in modular jack before the jack is mounted in a chassis panel. When the jack is snapped into the chassis panel, the curled edges of the spring clip are biased between the face plate of the jack and the surface of the chassis panel thereby making a good electrical connection with the chassis.

Abstract: An automatic detection and selection circuit resident in a DCE is provided. The circuit is coupled to the DCE interface connector and detects receipt by the DCE of V.35 and RS-232 transmit data signals, distinguishes between those signals, and selects circuitry for passing the data therethrough. The circuit comprises a switch coupled to a first TX data terminal (pin 2 or P) of the DCE interface connector, first and second line receiving circuits, a microprocessor, and a relay. The first line receiving circuit is coupled to a first pole of the switch and to the second TX data terminal (pin S) of the DCE interface connector and provides indications as to whether or not an input signal is present at at least one of pins P and S. The second line receiving circuit is coupled to the second pole of the switch and provides indications as to whether or not a valid RS-232 transmit data signal is detected.

Abstract: A method for identifying a V.fast modem within already standard automatic interworking procedures are provided. The method comprises utilizing standard methods for identifying a V.32/V.32bis modem up and through the standard ranging sequence, and after ranging and during the undefined 8192 baud period before an S signal would be sent by a V.32 or V.32bis modem the answering mode modem sends a predetermined signal (VFS) which does not resemble an S signal. Simultaneous with the answer modem sending VFS, the call mode modem looks for VFS. Upon detecting VFS, the call mode modem confirms receipt by sending a confirming signal (VFC) to the answer mode modem. Upon receiving VFC, if the communicating modems are not already in a problem mode, the modems will probe the line and continue according to whatever V.fast standards will be adopted. Preferably, VFS contains at least two tones. If desired, VFS can be a spectrum, with energy in frequency bands surrounding the S tone frequencies suppressed.

Abstract: A transmitter is provided with a distribution preserving Tomlinson coder which predistorts shaped data signals such that the power of each data signal exiting the coder is substantially similar to the power of the data signal entering the coder and such that upon transmission of the predistorted data signal over a channel, the effect of ISI of the channel is substantially removed. The transmitter is primarily intended for coded modulation systems utilizing a "coset" code, and the predistortion is preferably accomplished according to a linear function ##EQU1## where r.sub.k is a data signal entering the coder, a and.sub.i b.sub.i are the coefficients of polynomials relating to the channel impulse response, x.sub.k is the predistorted data signal exiting the coder, and s.sub.k is chosen to cause the signal power of x.sub.k on average to approximately equal the signal power of r.sub.k on average. Different methods for so choosing s.sub.k are disclosed.

Abstract: Methods for improving modem performance and apparatus incorporating the methods are provided. The preferred methods comprise measuring the signal/noise ratio and intermodulation distortion (IMD) relating to signals being transmitted over a channel, and adjusting the transmitting power of the transmitting modem below a maximum permissable power in response to the measurements in order to reduce the error rate of the data transmission, the error rate being a function of both the signal/noise ratio and the IMD. Theoretically, the power can be adjusted to an optimal level, as the decrease in power increases the error rate due to signal/noise ratio according to a first function, but decreases the error rate due to IMD according to a second function. A first preferred manner of determining the final power level to be utilized is to calibrate a modem according to the techniques (e.g., Trellis precoding, etc.

Abstract: A transmitter is provided with a distribution preserving Tomlinson coder which predistorts shaped data signals such that the power of each data signal exiting the coder is substantially similar to the power of the data signal entering the coder and such that upon transmission of the predistorted data signal over a channel, the effect of ISI of the channel is substantially removed. The transmitter is primarily intended for coded modulation systems utilizing a "coset" code, and the predistortion is preferably accomplished according to a linear function ##EQU1## where r.sub.k is a data signal entering the coder, a.sub.l and b.sub.l are the coefficients of polynomials relating to the channel impulse response, x.sub.k is the predistorted data signal exiting the coder, and s.sub.k is a multiple of a given value (N) which is chosen to cause x.sub.k and r.sub.k to occupy identical defined regions in space, where the total length of each defined region is the given value N.

Abstract: A pluggable electrical connector is provided having contact elements with first ends soldered to a daughter board, mid-sections which are crimped and bent through ninety degrees, and second ends which have a converging portion and which terminate in bifurcated conical contact portions which make contact with the rims of contact-quality plated through holes of a mother board. By causing contact between the rim and the cone surface, normal forces greater than the mating force are generated. The connector housing includes self-centering funnel openings adjacent the mother board for centering the converging portions of the contact elements therein in a nominal position and for acting as a preloading stop. The housing also includes side-wall locking tabs which hold adjacent rows of contacts at identical fixing points relative to the ninety-degree bend to ensure identical spring parameters for all contact elements.

Abstract: Electrical connectors are provided with spring contact elements each having a tapered contact portion for mating with the plated rim of a hole. The tapered contact portion can be configured as a bifurcated cone, a suitably shaped wire, or other tapered, flexible contact. Besides the contact portion, the contact elements also include spring portions which can assume various configurations and tail portions which can also assume various configurations. Where the tapered contact portion is a suitably shaped wire, the spring portion and the contact portion are essentially the same. The tail portions can be arranged to have tapered contact portions where permanent connection of the tail is not desired. The disclosed electrical connectors have housings for the spring contact elements, and a first make, last break function can be provided by configuring the housings appropriately. The holes with which the tapered spring contact elements mate can be part of a printed circuit board, a flex circuit, or other object.

Abstract: An integrated circuit package is provided with a plurality of contact element leads, each lead having a first portion for making electrical connection with the integrated circuit and a second tapered contact portion for mating with a conductive rim of the hole of a circuit board. In conjunction with the integrated circuit package, a fastener is provided for holding the tapered contact elements in mating relationship with the conductive rims. The tapered contact portion of the lead of the integrated circuit package may take any of various forms, as long as the lead is tapered and resilient so that proper mating with a conductive rim can be accomplished. Likewise, the fastener which holds the tapered contact elements in mating relationship with the conductive rims may take any of numerous forms. All that is required is that the fastener couple to both the circuit board and the integrated circuit package, and that the integrated circuit package be removable from the fastener.

Abstract: Apparatus and methods for automatically determining the bit rate of an incoming signal are provided. The apparatus includes a counter, a logic circuit, and a histogram generating circuit. The counter counts the number of fast reference clock cycles which fit within each pulse of the incoming signal for a statistically significant number of pulses and provides indications thereof to the logic circuit. The logic circuit associates each of the indications with one of a plurality of allowable bit rates. The histogram generating circuit tracks the numbers of times the counts are associated with each allowable bit rate. In one embodiment, the allowable bit rate most often chosen is determined to be the bit rate of the incoming signal. In another embodiment, if a DDS1 line rate is determined to be the bit rate most often chosen, the DDS2 rate associated with the DDS1 line rate is provisionally selected.

Abstract: Methods for embedding additional information (e.g. a password function) in a handshake of communicating modems is provided. An auxiliary packet containing the additional information is placed in the handshake sequence of an originating modem in such a manner that it cannot be confused by the receiving modem with other signals which are required to be sent by the originating modem in the modem handshake. The answering modem looks for the auxiliary packet, and if the auxiliary packet is not received, or if the information in the auxiliary packet is not sufficient to establish authorization, the answering modem causes the call to be dropped. In V.32 type modems, the auxiliary packet is placed by the originating modem somewhere in the training sequence (TRN) after the required twelve hundred eighty symbol intervals, and before the R2 sequence, and the auxiliary packet is generated in such a manner that it cannot be confused with the R2 sequence.

Abstract: A mapping technique for an 8D, sixty-four state convolutionally coded 19.2 Kbit/second modem utilizes twenty-nine bits for defining all points of an 8D constellation. The 8D constellation which is mapped is comprised of a desired subset of a concatenation of four 2D constellations, where each 2D constellation has one hundred ninety-two points. The mapping technique generally comprises: dividing each 2D constellation into six different energy groups of thirty-two points each, the concatenation of four groups, one from each 2D constellation, comprising an 8D grouping; choosing five hundred twelve 8D groupings from the possible one thousand two hundred ninety-six (6.sup.

Abstract: A mapping technique for an 8D, sixty-four state convolutionally coded 19.2 Kbit/second modem utilizes twenty-nine bits for defining all points of an 8D constellation. The 8D constellation which is mapped is comprised of a desired subset of a concatenation of four 2D constellations, where each 2D constellation has one hundred sixty points. The mapping technique generally comprises: dividing each 2D constellation into five different energy groups of thirty-two points each, the concatenation of four groups, one from each 2D constellation, comprising an 8D grouping; choosing five hundred twelve 8D groupings from the possible six hundred twenty-five (5.sup.

Abstract: A pluggable electrical connector is provided having contact elements with first ends soldered to a daughter board, midsections which are crimped and bent through ninety degrees, and second ends which have a converging portion and which terminate in bifurcated conical contact portions which make contact with the rims of contact-quality plated through holes of a mother board. By causing contact between the rim and the cone surface, normal forces greater than the mating force are generated. The connector housing includes self-centering funnel openings adjacent the mother board for centering the converging portions of the contact elements therein in a nominal position and for acting as a preloading stop. The housing also includes side-wall locking tabs which hold adjacent rows of contacts at identical fixing points relative to the ninety-degree bend to ensure identical spring parameters for all contact elements.

Abstract: A system under the hand held control of a user for providing three dimensions of input to a computer processor while operating on an essentially planar surface is disclosed.