Abstract: Space feedback comprising a shield over the tuning elements of a FET radio frequency amplifier provides positive feedback between the gate and drain terminals to raise the gain of the amplifier above what it would be without the space feedback, while simultaneously lowering the noise figure. Not only is the relative noise lowered, but the absolute amount of noise is lowered.

Abstract: Current regulating apparatus for connecting a plurality of different impedance loads in series across a high voltage power source with protection means in the event of the failure in the shorted or open condition of the series connected load portions.

Abstract: If each data channel comprising a set of multiplexed data channels contains channel identity information, a single framing detector operating on one channel can provide a framing detection operation regardless of where the search is commenced thereby avoiding a search of all of the channels to obtain framing information. By having unique tag or identity bits incorporated in each of the multiplexed data channels, the timing problems for obtaining synchronized parallel output bits from each of the channels can be logically ascertained and the channels can be rerouted and individual channels of the rerouted channels can be time delayed to obtain the time synchronization.

Abstract: Actual customer data is routed through a composite muldem which comprises a high speed section and a plurality of low speed sections with the signals being switched or transferred between the high speed and low speed sections all at a common frequency. This same customer data is then tested by a bit by bit comparison circuit which tests the data after it is split, rerouted in various datapath configurations and compared in a logical fashion to first detect datapath failure and then isolate the failure to a specific part of the composite muldem by a set of logical deductions.

Abstract: A way to reduce costs in a communication network is to use through-repeaters for any signal channels that do not need to have data dropped or inserted at a given site. This however complicates any protective switching involved to bridge failed data channels. The present system incorporates a master computer at one end of the switching network which communicates to a plurality of slave computer controllers at all the remaining sites having drop and insert channels whereby it can maintain an up to date table of the system configuration and thereby use segments of the protection channel to bridge various failed portions of the entire system.

Abstract: An interface device for use between a North American PCM channel bank and a CCITT PCM channel bank which allows data to stay in digital format rather than being converted to voice frequency. The interface takes care of not only the completely different serial data rates, but the different transfer characteristics of the channel data words. Synchronization is obtained by dividing the serial data stream into enough channel banks so that there is less than one-half cycle time period difference between the frequency of the incoming and outgoing data streams for one cycle of channel data words.

Abstract: The present invention uses digital values of MSK-like waveshapes which can be stored in a storage media such as a ROM and then output in a prescribed fashion such as in phase quadrature through the use of an addressing technique to the ROM. The digital values, each of N bits, are then multiplied in quadrature times a data representative signal which is divided into phase quadrature components. These N+1 bit products are summed to produce a composite digital signal representing analog bipolar values. A digital-to-analog conversion provides the modulated analog output signal.

Abstract: A block diagram and concept approach for use in conjunction in decision feedback equalization of providing positive decision feedback to enhance the amplitude of the present bit at the same time as delayed intersymbol interference feedback is provided to provide a larger eye pattern in the compensated and equalized output signal as compared to that obtained without the positive decision feedback pulse amplitude enhancement.

Abstract: The present invention provides error checking for data dependent coding circuitry which checking is complicated by a considerable amount of circuitry which is activated only when the incoming data conforms to specific requirements (i.e., three or more consecutive logic zeros). Except for these occurrences, the output from the coding circuitry is straightforward representation of the nonreturn to zero input data. The present invention uses a straightforward detecting circuit to normally pass the data and a data compare circuit which compares the output of the detector with the output of the data dependent circuitry except for times when the specific condition of three consecutive logic zeros occurs. At that time, the data compare circuitry checks to make sure that both the code detector and the encoding circuit have detected the occurrence of this condition.

Abstract: A slightly flexible and generally C-shaped cable support apparatus for quick attachment and detachment from a sheet material support structure to which a plurality of cables can be tied using cable ties and which locks in place after the cable support apparatus is temporarily deformed and moved laterally into position. Removal is accomplished by temporarily deforming the support apparatus and removing in the opposite direction from the insertion. The holding means used in the insertion process are devised to accept different thicknesses of sheet material support structure. An edge of the C-shaped portion of the cable support apparatus is designed to reduce cable insulation damage on sharp edges of the sheet material by extending over and covering same.

Abstract: A circuit approach is illustrated for simplifying a count divider circuit by applying selected outputs of the counter to a J-K flip-flop as input to the J-K terminals whereby a comparatively high speed response is returned for presetting the counter as compared to the prior art approach which either required much more circuitry or intolerable time delays.

Abstract: By exchanging the position of the input and output resonator means relative to other resonator elements in a mechanical filter, the lengths of the bridging wires used to control the steepness of the bandpass characteristic of the filter can be reduced. Reducing the length of the bridging wires reduces both flexural spurious mode problems and extensional coupling variation problems.

Abstract: Monitoring or error checking equipment for use with multiplexing circuitry at the transmission end of a communication line is disclosed which accomplishes a large reduction in circuitry by using transmitter generated low speed timing signals and clock signals to demultiplex the output data into nonsymmetrical or timing irregular data. The plurality of channels of nonsymmetrical data are then each checked for parity and framing pulses as well as clock activity by time multiplexed switching equipment on a cyclical basis.

Abstract: If the timing of detection of an analog signal, by an A/D converter, with respect to its theoretical value is optimum, the most significant error bit output by the A/D converter will integrate to a zero value. The present invention takes the information indicative of the most recent history of amplitude variation of the analog signal to logically modify (affect polarity) the most significant error bit and apply it to an integrator. The integrated value is used to adjust a variable time delay clock circuit use in determining the detection time in the A/D converter.

Abstract: Apparatus for searching for range indicating pulse signals received as part of distance measuring equipment which first form a list of distance indications in a first search time. The distance indications obtained in a second search time are then logically combined with those indications in the first list and any combination that results in a difference value of less than a prescribed amount is retained for list updating purposes until there is only a single distance indication left in the list. The apparatus can then change to a track mode by placing a search window around the single distance indication thereby reducing the amount of extraneous information to be manipulated by the receiving apparatus.

Abstract: A torsional-mode resonator is produced by using an extensional mode transducer on a piece of material such as a metal bar where the transducer lies at an angle between the longitudinal axis of the material and the transverse axis. Placing the midpoint of the transducer at approximately the midpoint of the material such as the bar, optimizes the torsional effect. Further optimization may be obtained by making the transducer in the shape of a rhomboid.

Abstract: The overhead format for DS1C data must be removed and the data broken into two DS1 format data signals before being transmitted over DS2 or DS3 transmission lines. The present invention demonstrates a method whereby the stuff bit code for appropriate frames of a high speed transmission line can be violated and remotely detected whereby the signal is looped back at the destination end of the desired signal whether the remote signals are in the DS1C or DS1 data format.

Abstract: When an A/D converter is converting a multilevel analog signal into a plurality of distinct digital words, it needs to have a very accurate reference voltage which is tied to the voltage levels of the analog signal being converted for high accuracy. The present invention takes the most significant bit and an error bit signal from the analog-to-digital converter and logically combines these signals in such a way that error feedback signals are generated which are integrated over the long term and used to adjust the reference voltages supplied to the analog-to-digital converter wherein the feedback error signals average to zero.

Abstract: A phase detection function is obtained by performing two series retiming operations on a data input signal in accordance with a local clock and exclusive OR'ing the signals involved in the two retiming operations. The first exclusive OR'ing provides a variable pulse width signal and the second exclusive OR'ing provides a fixed pulse width signal which may be used as a reference. The combination of the two signals can then be used to provide an indication of phase of the clock with respect to the data. By taking the phase detected signal and supplying it in integrated format to a VCO and using the output of the VCO to provide the clock input to the retiming means, a circuit is provided which provides not only data regeneration, but also clock recovery from the data input and assures that the leading edge of the recovered clock is centered between positive going and negative going transitions of the data to be regenerated.

Abstract: An auto-equalizer for passing data pulses of the type which tries to restore the relative amplitude of the first and third harmonics of the data signal frequency while deemphasizing the amplitude of other higher harmonics. The present invention accomplishes the relative harmonic amplitude restoration by controlling the resistance in a tuned circuit element affecting the gain of a signal passing amplifier. The adjustment of the resistance directly affects the Q of the tuned circuit involved.