39results about How to "Reduce dispersion effect" patented technology

A system (100) for transmitting digital information includes a transmitting apparatus (102) for generating an optical signal bearing digital information, a dispersive optical channel (104), and a receiving apparatus (110) for receiving the optical signal. The dispersive optical channel (104) is disposed to convey the optical signal from the transmitting apparatus (102) to the receiving apparatus (110). The transmitting apparatus includes an encoder (114) for encoding digital information into a series of blocks, each including a plurality of data symbols corresponding with one or more bits of digital information. A signal generator (118) generates a time-varying signal corresponding with each of said blocks. An optical transmitter (136) is arranged to apply the time-varying signal to an optical source (138) to produce an optical signal which includes an optical carrier and substantially only a single information bearing optical sideband in an optical frequency domain, the sideband corresponding with the time-varying signal. The receiving apparatus (110) includes an optical detector (146) for detecting the optical signal to produce a corresponding received time-varying electrical signal. The receiver further includes means (166) for generating a series of received data blocks from the time-varying electrical signal. An equalizer (168) performs an equalization of received data symbols included in each data block to mitigate the effect of dispersion of the optical channel, thereby enabling the transmitted data symbols to be recovered.

In a combined battery pack of a plurality of battery cells, a comparison circuit compares a voltage appearing at a common connection point between two adjacent battery cells with a reference voltage. Based on a result of the comparison, an electric discharging operation of an electric discharging circuit connected between both terminals of each of the battery cells is carried out. The comparison circuit is driven to operate with a power supply voltage appearing between a positive-side terminal of a battery cell provided on a higher-potential side of a common connection point and the negative-side terminal of the battery cell provided on a lower-potential side of the common connection point.

A system for determining characteristics associated with a communication channel includes a transmitter for transmitting a first signal via the communication channel. The system includes a receiver for receiving a second signal via the communication channel in response to the first signal. The second signal is associated with the first signal. The system includes a correlator for performing frequency domain correlation between a frequency domain representation of the second signal and frequency domain representations of a plurality of time-delayed versions of the first signal to generate frequency domain correlation information. The system includes an analyzer for identifying correlation peaks in a magnitude of the frequency domain correlation information to determine locations of discontinuities of the communication channel. The identified correlation peaks are associated with the locations of the discontinuities of the communication channel.

A method of communicating digital information over a dispersive optical channel includes encoding the digital information into a plurality of data blocks, each of which includes a number of bits of the information. A time-varying electrical signal is generated which corresponds with each of said data blocks. The time-varying electrical signal is applied to an optical transmitter (122) to generate an optical signal which includes an asymmetrically amplitude limited transmitted signal modulated onto an optical carrier. The optical signal is then transmitted over the dispersive optical channel (106). At a receiving apparatus (104) the optical signal is detected to produce an electrical signal which corresponds with the asymmetrically amplitude limited transmitted signal. A frequency domain equalization of the electrical signal mitigates the effect of dispersion of the optical channel (106) on the transmitted optical signal, and the equalized signal is decoded to recover the encoded data blocks and the corresponding transmitted digital information. The method enables bipolar signals to be transmitted over a dispersive unipolar optical channel, and reduces or eliminates the need to apply a high optical bias level at the transmitter, thereby improving optical power efficiency and enabling output power levels to be maintained below applicable safe levels, while simultaneously enabling the effects of channel dispersion to be substantially mitigated.

Mitigating errors caused by the dispersion of optical or electrical signals. Errors caused by dispersion in high frequency system are mitigated by passing a received signal through an adjustable linear filter that counteracts a channel response of a channel on which the received signal has traveled to produce an electrical signal. The adjustable linear filter has a number of coefficients. A figure of merit is calculated for the electrical signal, where the figure of merit includes the second and fourth moments of the electrical signal. The coefficients of the linear filter are adjusted based on the value of the figure of merit so as to minimize the figure of merit.

The invention relates to a hollow cube-corner prism optical delay line device with an endogenous scale light source. The hollow cube-corner prism optical delay line device comprises a scale light source, a photoelectric sensor, an optical fiber coupler, a wavelength division multiplexer, collimators Z1 and Z2, plane reflecting mirrors F1 and F2, polarization controllers P1 and P2, a single-mode optical fiber, a rotary disk, hollow cube-corner prisms and a motor, wherein a scale light source signal is divided into two paths of light signals by the optical fiber coupler; the first path of light signals passes through the polarization controller P1 and the collimator Z1, is emitted to the plane reflecting mirror F1, returns along the same road and is received by the photoelectric sensor; and the second path of light signals passes through the polarization controller P2, the wavelength division multiplexer and the collimator Z2, is emitted to the hollow cube-corner prisms which are uniformly distributed on the rotary disk along the circumference, is guided for 180 DEG and then emitted to the plane reflecting mirror F2 and returns along the same road, and a returned signal is received by the photoelectric sensor and interferes with the first path of signals. The hollow cube-corner prism optical delay line device is simple in installation process and high in measuring speed, and signal to noise ratio and measuring accuracy are improved.

A device for transmitting synchronized timing including a receiver, a transmitter, one or more processors, memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including instructions for receiving through the receiver a timing signal comprising first time information that is synchronized to a time standard, determining second time information based at least partially on the first time information, composing a message formatted in accordance with a global navigation satellite system (GNSS) standard, wherein the message comprises the second time information, and transmitting the message through the transmitter on a radio signal having a frequency in the frequency modulation (FM) radio frequency band.

The invention discloses an OLT optical assembly and an optical module without a refrigerator for 10G-PON applications. The invention adopts a special 1577nm directly modulated laser (DML), which can reduce the dispersion effect and meet the transmission requirements of 10G-PON downlink; the invention does not need a semiconductor cooler (TEC) to control the temperature of the DML in the package design; The present invention adopts a heater on the package, and when the temperature is too low, the heater starts to work, effectively reducing the working temperature range of the laser, so that the wavelength drift of the DML does not exceed 10G- The range specified by PON (1575nm‑1580nm). The invention does not need a semiconductor refrigerator, reduces power consumption, simplifies the packaging structure, improves packaging yield, and greatly reduces the cost of 10G-PON OLT optical components and optical modules.