Abstract: An equalizer for a digital video disk player which is capable of obtaining a 5-tap transversal filter effect by providing a 3-tap transversal filter, reducing the number of elements, and obtaining a reliable 5-tap frequency characteristic. The equalizer includes first through third buffers for preventing a jittering problem of an RF signal due to a delay time, a 2T delay unit for 2T-delaying an output signal from the first buffer, a 4T delay unit for 4T-delaying an output signal from the third buffer, a summing unit for summing output signals from the first and third buffers with an output signal from the second buffer, and a low pass filter for allowing the summed output signals from the summing unit to have an equalizer characteristic suggested in the DVDP specification.

Abstract: A telephone service system in an ATM private network, includes: a PSTN interface unit for performing PCM with an analog telephone signal transmitted from a channel in a PSTN, converting the modulated data into a CEPT frame before sending it to a subscriber, performing the PCM with CEPT frame data, from a subscriber, and converting the modulated data into an analog telephone signal, before forwarding it to the PSTN; a first ATM cell processing unit for converting the CEPT frame data from the PSTN interface unit into an ATM cell, converting an ATM cell from a subscriber into CEPT frame data, and sending it to the PSTN interface unit; an ATM switching unit for switching the ATM cell from the first ATM processing unit to the subscriber, and switching the ATM cell from the subscriber to the PSTN; a second ATM processing unit for converting the ATM cell from the ATM switching unit into CEPT frame data before sending it to the subscriber, and converting the CEPT frame data from the subscriber into an ATM cell before

Abstract: An optical CATV system having enhanced transmission efficiency of communication channels, which offers voice telephone and narrow-band ISDN services, includes: a distribution center for transmit a voice telephone data frame and a narrow-band ISDN data frame over one E1 frame; and a subscriber unit separately generating the voice telephone and narrow-band ISDN data frames from the E1 frame transferred from the distribution center.

Abstract: GPS satellite signals are received, and a C/A code is synchronized by utilizing the non-coherent DLL so as to remove the unique code of the GPS satellite. There are generated 1/2-bit lagging, 1/2-bit leading and normal satellite codes. Then a correlation between the former and a down-converted intermediate frequency signals is carried out. Mixers mix the correlated three different phase signals with signals of a local oscillator. The output signals of the mixers are filtered by a band filter, and envelopes are detected from the filtered signals by an envelope detecting section. The detected envelopes are subtracted from each other. The output signals of the subtractor are filtered by a loop filter, and the filtered signals are controlled by a voltage control oscillator. The oscillated signals are inputted as clock signals into a satellite code generating section.

Abstract: A channel alignment circuit which is capable of separating six frame signals of 51.84 Mbps (Mega Bit Per Second) for six channels by expanding a control signal from a channel alignment block into three signals for a reframer of a cable television system. The circuit includes a CIB detector for detecting 51.84 Mbps of six descrambled channels and generating a 12-bit channel number data, a control signal generator for generating a 3-bit channel alignment control signal by using a 3-bit data among the channel number data from the CIB detector, and a channel alignment unit for separating the data inputted into six channels in accordance with a control signal from the control signal generator.

Abstract: An improved framing identification and timing signal extraction apparatus for a very small aperture terminal system and a method thereof, which includes a clock signal divider for dividing a clock signal inputted and an inverter delay clock signal into a predetermined number of signals, generating a dividing signal having a different frequency, and an output enable signal and a write enable signal, a first memory for storing and outputting a predetermined data by using one dividing signal among the dividing signals outputted from the clock divider as its address signal, a second memory for receiving the output signal from the first memory and the divider as an address signal, converting the state by using the received address signal, and outputting a corresponding state value, and a control logic unit for extracting a control signal and a framing identification and timing (FIT) data in accordance with the output from the second memory and the control signal from the divider.

Abstract: A load line type phase displacement unit which is capable of reducing the time which is required for designing the system and increasing the system fabrication efficiency by simply adjusting a phase difference of an input signal by adjusting the length of a stub after the impedances of a main line and a stub are made identical with a characteristic impedance. The unit a main line unit having a main line having a characteristic impedance Z.sub.0 and an identical impedance Z.sub.c and a plurality of stubs having an impedance Z.sub.c of the main line and an identical impedance and being capable of changing a phase difference of an input signal, and a sub-line unit having a stub having an impedance which is identical with the characteristic impedance Z.sub.0 of the main line and a sub-line which is connected in parallel with the stub for compensating for error information based on the malfunction of the main line unit.

Abstract: An output signal measuring apparatus for a multiple frequency oscillator device and output signal measuring and correcting methods therefor which are capable of accurately and rapidly measuring a signal from each terminal of a multiple frequency oscillator device and minimizing a measuring and correcting time by automatically performing a correction required for a measurement. The apparatus is capable of measuring each terminal of a multiple frequency oscillator based on a switching circuit in accordance with control of a computer by integrating a plurality of measuring equipment into one system for satisfying a corresponding measuring item with respect to all terminals of the multiple frequency oscillator, automatically correcting with respect to each such terminal, and accurately and rapidly measuring each terminal of the multiple frequency oscillator by using a predetermined time and manpower, thus implementing mass production.

Abstract: An electro-optical apparatus transforms a single frequency, linearly polarized laser input beam (18) from a light source (10) into an output beam (36) having two collinear orthogonally polarized output beam components (32,33) differing in frequency from each other by the frequency of a stabilized electrical signal (40) provided from an electronic oscillator (38). The output of the oscillator (38) is provided to a power amplifier (42) which is used to drive a piezoelectric transducer (46) affixed to an acousto-optical Bragg cell (52) through which the input beam (18) passes and is transformed into the output beam (36) composed of two beam components (32,33). The electrical output (44) of the power amplifier (42) is adjusted so that each of the output beam components (32,33) has approximately a preselected fraction of the intensity of the input beam (18).

Abstract: A method and apparatus for synchronizing the measurements of at least two interferometers (40,41) using at least two light sources (20,22), respectively. Each light source (20,22) provides a single linearly polarized output beam (21,23). Acousto-optic devices (30,31) transform each input beam (21,23) into two orthogonally polarized beams (70,72) separated by a frequency difference determined by an oscillation source (10). The oscillation source (10) drives both acousto-optic devices (30,31) with separate amplifiers (12,13) synchronizing both light sources. The two orthogonally polarized beam pairs (70,72) transverse the interferometers (40,41). The beams from the interferometers (71,73) return to the optical receivers (50,51). The optical receivers (50,51) mix the two return beam pairs (71,73) and send the resultant beat frequency (51,53) to the measurement electronics (60,62).

Abstract: Optical system for measuring surface topography, comprised of a light source (30), a diffractive optical assembly (70,72,73) comprised of two or more diffraction gratings, holograms or like diffractive optics (120, 130;122, 132;123, 133), electronic detection means and digital signal processing means (10, 110) for determining surface height from interference data. The diffractive optical assembly (70,72,73) divides the incident light into two beams (150,160;152,162;153,163), which subsequently impinge upon the object (20) at the same place on the object surface (70) but at two different angles of incidence. After reflection from the object surface, the beams pass separately back through the diffractive optical assembly (70,72,73), after which they combine once again and form an interference pattern representative of the surface topography. The equivalent wavelength of the resultant interference pattern is much greater than the illumination wavelength.

Abstract: A method and system for measuring the phase difference between two orthogonally polarized components of a test beam as well as the intensities of these two components. A partially-polarizing beamsplitter (101) divides a polarized test beam (103) into first and second spatially-separated beams (154,104). The first beam (154) passes through a wave plate (160) oriented so as to retard the phase of the s polarization component with respect to the p polarization component. The first beam (154) then passes through a first polarizing beamsplitter (155), to produce a first pair of spatially separated output beams (156,157) with mutually-orthogonal linear polarizations. The second beam (104) is likewise passed through a second polarizing beamsplitter (105) to produce a second pair of linearly-polarized output beams (106,107). Photodetectors (108,109,158,159) send an electrical signals proportional to the intensities of the beams (106,107,156,157) to a computer (99).