1055 results about "Frequency-division multiplexing" patented technology

A system and method for supplying power to a headset, and for transmitting multiple signals generated in the headset to a terminal using frequency division multiplexing. An audio signal and a carrier signal are generated in the terminal and summed together to form a composite uplink signal. The composite uplink signal is provided to a headset over a first physical channel. At the headset, the audio and carrier signals are separated, and the carrier signal is used to generate power in the headset. Signals generated by a plurality of acoustic sensors in the headset are combined using frequency division multiplexing to generate a composite downlink signal, which is transmitted to the terminal over a second physical channel. One or more carrier signals used to generate the composite downlink signal are provided by either a carrier source in the headset, or by recovering the carrier signal from the composite uplink signal.

A method and system for providing broadband access to a data network via gas pipes is disclosed. Embodiments of the present invention utilize Orthogonal Frequency-Division Multiplexing (OFDM) or Frequency-Division Multiplexing (FDM) as a modulation technique in order to protect against the effects of dispersion in the gas pipes. An OFDM transceiver modulates a digital data stream into an OFDM signal, RF up-converts the OFDM signal, and transmits the RF up-converted OFDM modulated signal through a gas pipe.

An oversampling pulse oximeter includes an analog to digital converter with a sampling rate sufficient to take multiple samples per source cycle. In one embodiment, a pulse oximeter (100) includes two or more light sources (102) driven by light source drives (104) in response to drive signals from a digital signal processing unit (116). The source drives (104) may drive the sources (102) to produce a frequency division multiplex signal. The optical signals transmitted by the light sources (102) are transmitted through a patient's appendage (103) and impinge on a detector (106). The detector (106) provides an analog current signal representative of the received optical signals. An amplifier circuit (110) converts the analog current signal to an analog voltage signal in addition to performing a number of other functions. The amplifier circuit (110) outputs an analog voltage signal which is representative of the optical signals from the sources (102). This analog voltage signal is received by a fast A / D converter (112) which samples the analog voltage signal to generate a digital voltage signal which can be processed by the digital signal processing unit (116). The fast A / D converter (112) operates at a rate sufficient to take multiple samples per source cycle and may have a sampling frequency, for example, of over 41 kHz. The digital signal processing unit (116) implements software for averaging the samples over a source cycle for improved measurement consistency, improved signal to noise ratio and reduced A / D converter word length.

An OFDM system uses a normal mode which has a symbol length T, a guard time TG and a set of N sub-carriers, which are orthogonal over the time T, and one or more fallback modes which have symbol lengths KT and guard times KTG where K is an integer greater than unity. The same set of N sub-carriers is used for the fallback modes as for the normal mode. Since the same set of sub-carriers is used, the overall bandwidth is substantially constant, so alias filtering does not need to be adaptive. The Fourier transform operations are the same as for the normal mode. Thus fallback modes are provided with little hardware cost. In the fallback modes the increased guard time provides better delay spread tolerance and the increased symbol length provides improved signal to noise performance, and thus increased range, at the cost of reduced data rate.

A method is described for operating a cellular network, where the cellular network uses a plurality of frequency division multiplexing (FDM) bands for wireless communication from user equipment (UE) to a base station (NodeB). At least one band-specific cell parameter is computed for at least one the plurality of FDM bands by a serving NodeB. The band-specific cell parameters are transmitted from the NodeB serving a first cell to a NodeB serving a second cell. The band-specific cell parameters may be computed in response to scheduling information and / or channel specific measurements made by the NodeB. A UE receives a first Power Configuration, a Second Power Configuration, and a Scheduling Message indicative of an FDM band from the set comprising at least from First FDM band and Second FDM band. The UE transmits with the First Power Configuration if the Scheduling Message was indicative of First FDM band, and with the Second Power Configuration otherwise.