Abstract: A programmable signal generator is disclosed which includes a source of a user control signal. A controlled clock signal generator produces one of a predetermined setof respective clock signals responsive to the user control signal. Means are coupled to the clock signal generator for converting the clock signals to an analog sine-wave.

Abstract: A drawer slide device for suspending and supporting a drawer which permits the drawer to be opened and closed and limits the travel of the drawer includes a guide bar ridgedly attached to a drawer holder and having a slot therein, and a slide bar suspended from the guide bar slot by screws such that the screw heads can not pass through but may slide within the slot while holding the slide bar. The slide bar has a slot from which a drawer is suspended by screws that are similarly free to slide within the slide bar slot while holding the drawer. Friction reducing washers are interposed between bearing surfaces to permit ease of operation. The travel of the drawer is limited to a portion of the total of the slot lengths.

Abstract: A ringing signal generator includes a low power signal generator for generating a relatively low power signal representing a ringing signal, a bipolar pulse generator for generating a series of bipolar pulses having widths representing the amplitude of the low power signal, wherein adjoining pulses have opposite polarities, and a high power ringing signal generator for producing a high power ringing signal in response to the series of bipolar pulses. An analog sine wave signal is superimposed upon a DC bias signal to produce the low power signal.

Abstract: An overload protection circuit for power supplies and telecommunications apparatus such as multifrequency ringing generators causes the output voltage to become zero when a current overload is detected. The voltage is kept at zero for a predetermined period of time. Then the output voltage is restored. If an overload is still detected, the output voltage is again brought to zero.

Abstract: A series ringing signal generator is disclosed which comprises a source of a user control signal. A programmable ringing signal generator is provided for generating an analog sine wave signal having a selectable amplitude and frequency in response to a selection signal. Finally, sequencing means, coupled between the source of the user control signal and the programmable ringing signal generator, is provided for generating a sequence of selection signals in response to said user control signal.

Abstract: The present invention describes a robust register circuit for protecting critical control points in data transmission and telecommunications equipment against software included failures. A circuit is provided wherein duplicated data words are written into a pair of registers of any desired bit length. A digital comparator determines whether the two data words are the same, and initiates a data transfer into a third register for transmission to critical hardware control points only when two identical sequential data words are recognized. When no such recognition occurs, new data is not transferred to the third register, and the hardware control points remain controlled by the previous data in the third register.

Abstract: A frequency multiplier is disclosed for producing an output signal having a frequency greater than the frequency of an input signal by a factor (1+N/M). The frequency multiplier comprises an input terminal and an output terminal; and a plurality of frequency multiplying stages, coupled between the input and output terminals, each producing an output signal having a frequency greater than the frequency of its input signal by a factor having the general form (1+1/P).

Abstract: A circuit and method which eliminates the voltage spike generated by inductive kick, and generates a signal which is active while a relay is being released and for a given period thereafter. This signal can be used to power down circuits supplying signals to relay contacts, thereby allowing the relay to release without current or voltage potentials at its contact, e.g. dry switching. The generated signal may also be used to disable sensors which might give false indications while the relay contacts are switching. In telephone line circuits, the generated signal can be used to disable the telephone hook switch detector or to power down the battery feed circuit feeding the subscriber line. The relay coil energy generates a signal which is active while the relay is being released. The invention uses a minimum number of components and the circuit is adjustable as to how long the generated signal remains active after the relay is released.

Abstract: A probe tip is employed to measure electromagnetic fields without the use of a metallic conducting wire or cable which would otherwise distort the field being measured. The probe tip includes a variety of different circuits, each of which contains a separate battery, a powered field measurement sensor and an amplifier. A light source, which is internal to the probe tip and coupled to the amplifier, operates to convert the measured field to an analog optical signal. The analog optical signal is transmitted via an optical fiber to a receiver/preamplifier circuit which converts the optical signal to an electrical signal at the fiber's far end. This receiver/preamplifier device can be coupled directly to an oscilloscope or other instrument which are employed and used for the display or recording the magnitude of the electromagnetic field as measured by the probe.

Abstract: A programmable ring signal generator includes a source of a user control signal. A controlled clock signal generator produces one of a set of respective clock signals responsive to the user control signal. A switched capacitor filter is coupled to the clock signal generator for converting the clock signals to an analog sine-wave. Finally, a power amplifier, coupled to the sine-wave converter, produces the ring signal.

Abstract: A telecommunication system is provided consisting of a plurality of functional units each one producing a status signal. A maintenance processor is coupled to each of the functional units and receives the status signals. This processor produces signals representative of the status of the system. A remote alarm reporting unit is coupled to the processor and generates optically isolated alarm signals corresponding to the status representative signals generated by the processor.

Abstract: Telecommunications equipment used in outdoor environments are subjected to harsh electrical conditions. Circuits which utilize sequential components, such as microprocessors, can therefore become confused due to extraneous power surges which may occur in the harsh conditions existing around the equipment. Furthermore, maintenance of the equipment has become much more automated, often leaving the equipment unattended for extended periods of time. In accordance with the invention, a circuit which automatically and reliably recognizes the failure conditions in the microprocessor, and automatically forces the microprocessor to recover is described.

Abstract: The present invention provides a power drive circuit which is transformer isolated from the circuit developing the drive signals, but which does not lose its DC reference voltage. This technique results in the desired isolation without the undesirable possibility of operating the output transistors in an unsafe DC region, which is a particular problem when the output transistors are FET devices. In accordance with the present invention, pulse transformers are used to drive the power FET devices.

Abstract: The invention provides a combination in a SLIC for telecommunication applications of ac impedance synthesis, e.g. raising the impedance of battery feed resistances by feedback techniques; in combination with real battery feed resistors and a dc block transformer. A dc blocked transformer is coupled to line current feed resistors and a feedback loop network to synthesize the desired input impedance, such that the feedback network incorporates both positive and negative feedback. A loop stabilizing resistor is used in shunt with the dc blocked transformer secondary to reduce gain peaking and phase shift.

Abstract: A digital activity detection circuit is provided for monitoring digital input signals such as telecommunications DS1 or DS2 signals, and for generating an alarm when a predetermined input signal loss threshold is reached, such that the input signal loss threshold does not vary with temperature, with component value or with power supply variations. Precise resolution and simplified hardware are achieved in a novel arrangement of counters in the signal activity detector to determine the resolution and signal loss threshold of the detector, all in a digital arrangement without the use of analog devices or retriggerable monostable multivibrators, and in an ASIC fabricable integrated circuit technology such as CMOS.

Abstract: A retiming circuit is provided which accurately converts half-width dual rail data with up to one unit interval of jitter with respect to the data clock, into full-width data. The circuit is comprised of D-flip-flops and associated logic elements which capture and hold a data pulse until the captured data pulse can be accurately transferred to the next circuit stage by a positive clock transition.

Abstract: A circuit and method for more efficiently implementing ZBTSI encoding with minimum processing delay of the ZBTSI algorithm and hardware complexity is provided in a ZBTSI encoder for use in a ZBTSI codec. The ZBTSI encoder is optimized for the ZBTSI algorithm and includes an architecture for use as an improved ZBTSI codec in application-specific integrated circuit (ASIC) technology.

Abstract: A Violating All Zero Octet (VAZO) detector for a ZBTSI clear channel data transmission system is described, which is optimized for minimum logic gate count, minimum circuit complexity, minimum external control signals and minimum signal processing delay, in a VLSI hardware embodiment which is advantageously implemented in application specific integrated circuit (ASIC) technology. An array of logic NOR gates scans input data for zero strings of data that could combine with an all-zero octet to violate the zero string criterion enables a zero string search to be performed with a minimum of circuit complexity. The use of an input shift register to buffer input data for other portions of the associated ZBTSI encoder provides for a minimized number of gates in a VLSI implementation.

Abstract: A high resolution digital phase-lock loop circuit is described, which is implemented with an input clock reference frequency which is approximately the same as the output frequency of the phase-lock loop. The output is derived from delaying the input clock a variable number of gate delays ranging from no delay to one period of the input clock. A shift register controls the number of gate delays and a 360 degree phase detector initializes the shift register when the output is delayed by one period of the input clock to provide no delay. Gate delay variations due to integrated circuit process, voltage and temperature are compensated for to provide a relatively constant clock phase correction.

Abstract: The present invention uses the input resistances of transconductance amplifiers in a SLIC to isolate battery ground overshoots from the rest of the SLIC circuitry. This is accomplished by allowing the voltages within each driving operational amplifier to rise with any overshoot, and is achieved by powering each operational amplifier with battery ground voltage, which overshoots, instead of with low voltage ground (LVG), which remains at ground. When a lightning surge hits, an overshoot at the SLIC output will occur. However, since the supply voltage of the driving operational amplifiers rises with the overshoot, the voltage stress to the SLIC circuit components is greatly reduced. The remaining SLIC circuitry stays at a low potential and is isolated from the overshoot. In accordance with the present invention, ground overshoot voltages are isolated across a few high ohmic valued resistors instead of appearing across active circuit components.