Northern Telecom Limited

Other

Luminos Industries Ltd.

Norhtern Telecom Limited

Stephen G Harman

John Duncan McNicol

Murray R Harman

A moving fiber optical switch of the type having two opposed supports carrying optical fibers with a gap between the fiber ends, with at least one of the supports being flexibly mounted for pivotal movement relative to the other support, and in which: (1) an actuator means, which provides pivotal movement of one or both supports between two orientations corresponding to first and second relative positions of the fiber supports, is connected to a connecting member or housing by means of a flexure; (2) the switch has means for adjusting the length of the gap between the fiber ends; and (3) the switch has means for adjusting the alignment of the optical fiber ends in a direction perpendicular to the movement provided by the pivotal movement of the flexibly mounted support or supports.

Moving fiber optical switch

A positioning device suitable for accurately positioning objects such as optical fibers includes a first support, a movable support restrained for movement relative to the first support with one degree of freedom and carrying a holder for the object to be positioned, and an intermediate support which is connected to the first support by a pair of first spaced flexible elements of equal length and which is connected to the movable support by a pair of second spaced flexible elements, the second pair also being equal in length to each other. The first and second flexible elements are oppositely arranged and dimensioned so that arc-errors in the movement of the intermediate support caused by bending of the first flexible elements are substantially compensated by arc movements of the second flexible elements to produce a desired movement of the movable support, which may be rectilinear or angular movement about an axis. An actuator causes movement of the movable support with bending of all the flexible elements, and a control member connects the first support, the intermediate support and the movable support so that the degree of movement of the intermediate support is one half the movement of the movable support.

Positioning device especially for assembling optical components

A voltage regulator for an electronic circuit card includes a FET with a source supplied via an input LC filter with a voltage to be regulated, a drain for delivering a regulated output voltage via a current-sensing resistor and an output LC circuit, and a gate which is supplied with a current drive from a linear transconductance amplifier having a differential input responsive to the regulated output voltage relative to a reference voltage. The regulator provides large bandwidth low voltage drop regulation without requiring higher voltage supply for the gate of the FET. A current limiting circuit reduces the current drive in response to excessive current through the current-sensing resistor, and a turn-on control circuit reduces the current drive to provide a controlled turn-on for hot insertion of the card into electronic equipment.

Voltage regulator including a linear transconductance amplifier

In a QAM microwave radio communications system an IF (intermediate frequency) input signal is amplified and predistorted, and the amplified IF signal is mixed with a local oscillator signal to produce an RF (radio frequency) signal which is amplified in a power amplifier for transmission, the predistortion compensating for non-linearity of the power amplifier. Adaptive phase control of the predistorter is provided by mixing the local oscillator signal with part of the RF signal to produce an IF output signal representative of the output of the power amplifier, detecting phase differences between the IF input and IF output signals to produce a phase difference signal, selectively inverting the phase difference signal in dependence upon whether or not an IF signal amplitude exceeds a comparison level, and integrating the selectively inverted phase difference signal to produce a phase control signal for the predistorter.

Adaptive phase control for a power amplifier predistorter

In a QAM microwave radio communications system an IF (intermediate frequency) input signal is amplified and predistorted, and the amplified IF signal is mixed with a local oscillator signal to produce an RF (radio frequency) signal which is amplified in a power amplifier for transmission, the predistortion compensating for non-linear gain of the power amplifier. Clipping in the power amplifier is controlled by down-converting part of the RF signal to produce an IF output signal, monitoring amplitude distortion of the RF signal by comparing the IF output signal with the IF input signal, and controlling the IF amplifier gain in dependence upon the monitored amplitude distortion.

Controlling clipping in a microwave power amplifier

A frequency converter for a transmitter of a microwave radio communications system comprises an image reject mixer for mixing an IF signal with an LO or carrier frequency signal to produce an RF signal, and a nulling circuit for providing d.c. offsets to the image reject mixer to reduce carrier leak to the RF signal. The nulling circuit includes a source of phase quadrature chopper signals which are cross modulated with the LO signal to produce a modulated signal, and a single-ended mixer for mixing the modulated signal with part of the RF signal. The output of the single-ended mixer is low pass filtered and the resulting filtered signal is cross demodulated with the chopper signals to produce phase quadrature correction signals, which are integrated to produce the d.c. offsets for the image reject mixer. The arrangement avoids the need for, and expense of, a subsequent carrier frequency filter.

Frequency converter for a radio communications system

A signal cuber for producing the third harmonic of an input signal, for use in a signal distortion correction circuit, comprises a split-ring mixer having two ports, at which there is produced a signal at the second harmonic of the input signal, unequally terminated, whereby the second harmonic signal is reflected into the mixer to be mixed with the input signal to produce the third harmonic. The mixer can consist of transformers and diodes, which can be Schottky diodes which are forward biassed by a potential difference supplied to the ports via the unequal terminations, which may be constituted by a single resistor.

Signal cuber

An intermediate frequency preamplifier of a microwave radio receiver includes an amplifier circuit having a negative feedback path including a directional coupler constituted by two transformers. One port of the directional coupler is terminated with a complex impedance, producing a controlled mis-match, which is adjustable to optimize the input return loss of the amplifier without changing the noise figure of the preamplifier. The amplifier circuit has a low impedance output constituted by a common-collector transistor so that the signal reflected back into the directional coupler by the mis-match does not significantly affect the output of the amplifier.

Negative feedback amplifiers including directional couplers

A performance monitor for determining the error density of a digitally transmitted signal in which the magnitude of a d-c offset voltage applied to one regenerator is controlled in a feedback loop so as to maintain a constant error rate between the output of it and another regenerator; the magnitude of the voltage being a measure of the degradation of the received signal and hence its error density.

Digital signal performance monitor

A transformer coupled split-ring diode modulator for digital phase modulation of a data stream in which the diodes are back-biased so as to provide additional attenuation of in-band fold-over side lobes which appear in the pass-band; the additional attenuation resulting from a cosine attenuation function which is dependent upon the switching time of the diodes and hence the bias voltage applied thereto.

Growing community of inventors

Nepean, Canada

Stephen G Harman