摘要:
A quadrature demodulator not requiring analog mixers. The demodulation is made using a first integrator and a second integrator which are controlled by square logic signals at twice the frequency of the carrier, the received signal being alternatively integrated by the first integrator and the second integrator over periods of time equal to a quarter period of time of the carrier frequency. The samples of the first and second integrators are sampled and subtracted from each other. The successive samples are combined in a first and a second combining module for providing in-phase and quadrature component samples. This demodulator can further be provided with a synchronization module IQ and a symbol synchronization module.
摘要:
A Bluetooth Low Energy (BLE) device, having a demodulator configured to translate in-phase and quadrature components of a received BLE signal into a differential phase signal; an estimator configured to estimate a frequency offset of the differential phase signal; and a detector configured to detect information in the differential phase signal corrected by the estimated frequency offset.
摘要:
Apparatus and method for performing entirely digital timing recovery for high bandwidth radio frequency communications. The received digital data source can be sampled from any (minimum 2×) non-integer oversampled transmitted data. This method re-samples the data through interpolation and phase adjustment. The output phase error adjusts the receiver's Analog-to-digital Convertor sampling clock to improve synchronization with the transmitter's Digital-to-analog Convertor clock phase, thus improving transmitted symbol recovery.
摘要:
One embodiment relates to a low intermediate frequency (IF) receiver. The low-IF receiver includes an analog front end that is configured to receive a modulated IQ data signal and provide an in-phase signal and a quadrature signal, where the in-phase signal is phase shifted by approximately 90° relative to the quadrature signal. The low-IF receiver further includes a digital processing block, and a single path that provides only one of the in-phase signal and the quadrature signal to the digital processing block. Other receivers and methods are also disclosed.
摘要:
A filter circuit includes two parallel digital filters, a DAC, and an LPF. The DAC includes two parallel decoders, a parallel-to-serial converter, a switch driver, and a switch. A PLL circuit supplies a reference clock to the DAC. A frequency divider provided in the DAC divides the frequency of the reference clock by two, and supplies the half frequency clock to a parallel processing section (the two decoders and the parallel-to-serial converter) of the DAC and the two digital filters. This makes it easy to secure a timing margin, permitting use in high-speed communication on the order of several GHz.
摘要:
A receiver apparatus and method are provided blind amplitude estimation for a received complex signal, wherein the complex signal is analyzed to determine first and second order statistics of real part and imaginary part of the complex signal. Based on a predetermined non-linear function, amplitude scaling information is pre-calculated and used to derive a desired amplitude scaling information for said determined first and second order statistics. Thereby, a low complexity method for blind amplitude estimation for unknown data symbols distorted by an unknown amount of noise can be provided.
摘要:
Systems and methodologies are described that facilitate computing discriminator signals for frequency tracking in wireless communications. The discriminator signal can be computed based at least in part on representations of a received signal shifted upward by a portion of a frequency tone and downward by the portion of the frequency tone. The shifted signals can be summed, and a dot product of the summed signals and a channel estimation of the original signal can be computed to remove uncertain frequency response due to fading. The discriminator signal can be computed as the imaginary portion of the dot product. A frequency error offset can be determined from the discriminator signal and applied to a receiver to tune alignment of the receiver with frequencies of received signals.
摘要:
A demodulator system and method is disclosed. In an embodiment, the demodulator system can include a Coordinate Rotation Digital Computer (CORDIC) mixer to mix a first signal substantially to baseband using a first input frequency and to mix a second signal substantially to baseband using a second input frequency. In another embodiment, the demodulator system can include a phase detector to receive a pilot signal and to generate a control signal to adjust a decimation rate based on the pilot signal. In another embodiment, the demodulator system can include a symbol decoder to determine a symbol from a phase signal.
摘要:
A cellular wireless packet data communication system containing transmit-only endpoint devices which transmit to receive-only base stations. The system is configured to allow for large area coverage (e.g., a metropolitan area) with far fewer number base stations than are required with conventional two-way cellular systems. The base station coverage areas are configured to overlap, allowing for reception of packets at multiple base stations. A data concentrator resolves redundantly received messages. The network is configurable as a WAN, a LAN, or a combination of the two. Novel modulation techniques (e.g., a 16QAM submodulation together with a 7FSK modulation) are used such that low cost components can be used in the transmitters and receivers while achieving outstanding probability of success performance. The endpoint devices are battery operated and accordingly, are designed for low power consumption and multi-year battery life. The system is used in a variety of applications including remote monitoring and mobile communications.
摘要:
Reference phase is a radio communication system using orthogonal M-ary modulation is determined, so that a coherent detection system for a CDMA radio communication system is readily achieved. The determination of reference phase is performed by the step of determining a reference phase in a radio communication system, which uses orthogonal M-ary codes comprising the steps of determining the correlation values of an in-phase component and quadrature component corresponding to respective Hadamard matrices resulting from fast Hadamard transform or inverse Hadamard transform of a signal, which possesses said in-phase component and quadrature component, and which is sent from the sending end by phase shift keying an orthogonal M-ary code computing the sum of the squares of the respective correlation values of said in-phase component and quadrature component and selecting either said fast Hadamard transform or inverse Hadamard transform output, which outputs a maximum value of said computed sum of the squares.