Abstract: An optical fibre interferometer particularly adapted to provide a light output that is modulated in relation to the intensity of an electromagnetic field includes a single-mode fibre of substantially non-electrooptic material (20, 22 and 24) to which has been spliced (at 26 and 28) a single-mode fibre of substantially electrooptic material (30). When the interferometer is placed in an electromagnetic field, the optical characteristics of the substantially electooptic fibre are varied, but the optical characteristics of the substantially non-electrooptic fibre are not. As a result, the light passing through the substantially non-electrooptic and electrooptic fibres undergoes a differential phase shift, causing interference upon light recombination that provides the desired light output modulation. Embodiments in which the fibre of substantially electooptic material is replaced by an optical waveguide of substantially electrooptic material, either formed separately (50, FIG. 3) or directly (70, FIG.

Abstract: An optical scanner/pulse iniator used for deriving power consumption data from a power meter has a pair of light sources modulated by a square wave having a repetition rate R and an OFF period P. The light beams produced by the light sources are positioned to reflect off of spatially separated points on the rotor (disc) in a power meter so that as the rotor rotates a non-reflective stripe will block the light beams one after the other. A first light sensor is positioned to receive the first light beam after being reflected off the rotor and provides an output signal indicating when the first beam is OFF for a period of time that greater than P. A second light sensor is positioned to receive the second light beam after being reflected by the rotor and it also provides an output signal indicating when the second beam is OFF for a period of time greater than P.

Abstract: A technique is disclosed for use in an electronic raster-scan display system, for generating characters of variable size using a stroke-vector technique. An incoming data signal defines the type of character to be displayed, the horizontal X and vertical Y character field dimensions, the character drawing point, and any character rotation or reflection. Using that part of the data signal that defines the character type as a memory address, a character microprogram is retrieved containing a stroke-vector character mask and a stroke resolution factor representing the number x of horizontal stroke-vectors in a straight line and the number y of vertical stroke-vectors in a straight line that are used by said character mask to represent said character within a normalized character field.

Abstract: A novel stroke-vector character generator is disclosed for generating characters or the like in a raster-scan video display system. An external data signal defines the type of character to be displayed, the character field dimensions, the character drawing point, and any character rotation or reflection. Using that part of the data signal that defines the character type as a memory address, the character generator retrieves from memory a character microprogram containing a plurality of encoded binary valued stroke-drawing directives. These directives are instructions to a decoder how to generate all of the shape dependent attributes for a series of chain related stroke-vectors that define the overall shape of the character to be displayed. Once defined in the system, each stroke-vector is scaled so that the character cell size matches the character field dimensions defined by the external data signal.

Abstract: A novel method is disclosed for use in an electronic raster-scan display system, for generating characters using a stroke-vector technique. An incoming data signal defines the type of character to be displayed, the character field dimensions, the character drawing point, and any character rotation or reflection. Using that part of the data signal that defines the character type as a memory address, a character microprogram is retrieved containing a plurality of encoded binary valued stroke-drawing directives. These directives are instructions detailing how to generate all of the shape dependent attributes for a series of chain related stroke-vectors that define the overall shape of a character to be displayed. The encoded drawing directives are decoded and sequentially applied to a set of initial values that define an initial virtual stroke-vector, and thereby generating all of the character-shape dependent stroke attributes to for a series of chain related stroke-vectors that define a character shape.

Abstract: In a DC switching regulator circuit, a circuit to demagnetize the transformer during OFF periods to extend the duty cycle range of the regulator. The regulator uses a transformer in series with an FET switch device to cause the primary transformer current to be switched ON and OFF in response to the power needs of an electrical load connected to the secondary circuit. A first diode, connected to the junction of the primary winding and a series switch, conducts the demagnetizing energy out of the primary circuit into a shunt connected storage capacitor. A second FET switch, operating out of phase with the first switch, allows the storage capacitor to discharge through an inductor back to the unregulated input source. A shunt diode between the inductor and the second FET switch provides a path for the inductor to discharge through when the second switch opens the path between the storage capacitor and the inductor.

Abstract: In satellite telephone communication equipment, the phase detector of a phase-lock loop compares the phase of a master oscillator signal from the loop oscillator with that of a pilot tone signal and produces an error control voltage which it combines with a constant sweep voltage that is stepped at a variable rate. When the loop is out of lock, a first count of the number of excursions of the beat or difference frequency signal from the phase detector that exceed a prescribed threshold level is generated, a second count is incremented for every n counts in the first count, and a constant amplitude step of the stepped sweep voltage is produced for each unique value of the second count. The steps in the sweep voltage occur at a variable rate that is related to the difference frequency of the beat signal. Since the difference between the oscillator and pilot frequencies decreases as the loop approaches lock, the rate at which the sweep voltage is stepped also decreases.

Abstract: A circuit which controls access of host and remote processors to a single memory. A first flip-flop indicates acceptance or refusal of the processor's memory access requests. A second flip-flop provides a wait signal to the host processor when the remote processor is accessing the memory. A gating circuit causes the first flip-flop to accept the remote processor's access request when both the host and remote processors request memory access at the same time.

Abstract: Differential encoding is commonly used in data transmission systems because it allows correct recovery of the data even though the polarity may have changed during transmission. However, single errors which are introduced result in double errors, i.e., error of an even number following the differential decoding process. Because many error detection schemes rely upon parity checks, which look for an odd number to determine if an error has occurred, the conversion of the single error to a double error means that single errors normally would not be detected. A precoder is used to introduce correlation by modulo two addition of the precoded present digit with a selected combination of past digits. The differential decoder will still provide double errors but a subsequent decoder, which reverses the precoding process, at least partially changes double errors into errors of an odd number.

Abstract: A parallel cyclic redundancy checking circuit which determines the validity of digital, binary, cyclical data. The parallel structure of this circuit enables it to check high frequency data. Shift registers are used to store sequentially occurring parallel groups of data and a feedback network comprising exclusive-or gates provide a coding arrangement which produces a resultant data pattern to indicate the validity of the cyclical parallel input data.

Abstract: An improved method of manufacturing a printed wiring board having the characteristics of one with a solder mask over bare copper for circuit traces and ground planes. The method includes the step of electroplating a very thin coating of tin-lead over the circuit traces, ground planes, holes and circuit pads prior to selectively coating only the pads and holes with a relatively thick coating of tin-lead solder plate. After removing the plating resist which defines the areas for selective solder coating, the board is chemically etched and then mechanically scrubbed to roughen the surface of and reduce the thickness of the thin solder plate. A solder mask may be applied over circuit traces and ground planes prior to reflowing the thick coating of solder plate. Assembled printed wiring boards may then be wave soldered without wrinkling of the solder mask.

Abstract: Apparatus for synchronizing the frequency of locally generated pilot signals with those of remotely generated pilot signals where frequency errors are introduced during transmission. A pair of demodulated pilot signals F1' and F2' are filtered and mixed to derive a third signal having a frequency equal to F2'-F1'. The difference frequency has no frequency error component so the third signal is used in a phase locked loop to regenerate a reference frequency (fr) signal.Two methods are disclosed to extract a control signal which is proportional to the error frequency. In one embodiment one of the received pilots (F1') is divided in frequency by 1/k1 and then subtracted from fr to yield 1/k1 times the error frequency df. By integrating this signal it becomes usable as an AFC signal to control a local oscillator.

Abstract: Two pilot signals, derived so that there is a predetermined ratio between the frequency difference of the tones and the absolute frequency of either of the pilot signals, are transmitted from a reference station to each of a number of remote stations. At each receiving station, the frequency error is derived from the frequency difference of the two pilot signals, and this frequency error is used to adjust the frequency of the local oscillator.

Abstract: A parallel cyclic redundancy checking circuit which determines the validity of digital, binary, cyclical data. The parallel structure of this circuit enables it to check high frequency data. Shift registers store sequentially occurring parallel groups of data and a feedback network comprising exclusive-or gates provides a coding arrangement which produces a resultant data pattern to indicate the validity of the cyclical parallel input data. Resultant data patterns are periodically stored in a random-access-memory which initializes the shift registers to provide a time sharing operation. A comparator detects invalid data by comparing the resultant patterns with expected values.

Abstract: The present invention relates to an automatic meter reading transponder. The transponder is comprised of a receiver for receiving an external instruction and a transmitter for transmitting data. A CPU is connected to the receiver and the transmitter. A ROM is connected to the CPU and ROM contains a program for controlling the operation of the CPU. A real time clock is connected to the CPU for determining sequential predetermined time periods. Three input terminals are connected to the CPU for receiving data to be stored in a RAM. One of the three input terminals has pulses impressed thereon, the number of pulses being representative of electric power consumption. The one input terminal is also connected, via the CPU to a time-of-day memory.