Abstract:
A method for reducing a dynamic range of a received radio frequency signal includes receiving digital IQ signals corresponding to an in-phase component of the received radio frequency signal and a quadrature component of the received radio frequency signal. The method includes demodulating the digital IQ signals to generate an instantaneous frequency signal. The method includes selecting a center frequency of a selectable filter according to whether an interfering signal is detected in a target frequency band of the received radio frequency signal. The center frequency is selected from a predetermined frequency and an estimated center frequency determined using the instantaneous frequency signal. The method includes filtering the digital IQ signals using the selectable filter configured using the center frequency to generate output digital IQ signals.
Abstract:
Apparatus for downconverting a received frequency modulated communication signal is provided. The apparatus comprises processing circuitry to: obtain first digital frequency domain data based on the received frequency modulated communication signal; process the first digital frequency domain data in the frequency domain to provide downconverted digital frequency domain data, wherein the processing is to comprise frequency shifting data based on at least a portion of the first digital frequency domain data, wherein the downconverted digital frequency domain data has fewer data points than the first digital frequency domain data; and convert the downconverted digital frequency domain data into the time domain.
Abstract:
Disclosed are systems, methods, and structures for DSP-free coherent receiver architectures applicable for short-reach optical links. Operationally, a received optical signal is down-converted by mixing it with a local oscillator (LO) laser signal using a 90-degree hybrid followed by balanced photodiodes. Other receiver functions are performed using analog signal processing thereby avoiding power-hungry, high-speed analog-to-digital converters and high-speed digital signal processing. Carrier phase recovery is performed by an electrical phase-locked loop employing a multiplier-free phase estimator stage that - while designed for quaternary phase-shift keying signals - may be employed in designs exhibiting higher modulation formats. Since carrier phase recovery is performed in the electrical domain, LO laser frequency modulation or LO laser integration is not employed. Polarization demultiplexing - if employed - may be performed by the addition of an optical polarization controller prior to the hybrid and may advantageously be realized by cascading multiple phase shifters driven by low- speed circuitry.
Abstract:
A diversity receiver synchronizes and mixes multiple input signals. In one embodiment, the receiver demodulates the multiple input signals prior to synchronizing, converts the demodulated multiple input signals from analog signals to digital signals, synchronizes the demodulated digital signals, converts the synchronized demodulated digital signals to analog signals and mixes the synchronized demodulated analog signals based on a characteristic of the input signals existing prior to the demodulating.
Abstract:
The disclosure relates to a multi-modulation receiver (50) configured to receive a multicarrier signal comprising data transmitted from multiple transmitters; wherein at least one of the transmitters is a transmitter using a modulation scheme other than Orthogonal Frequency- Division Multiplexing, OFDM, and wherein data transmitted from different transmitters are mapped to different subcarriers in the frequency domain. The multi-modulation receiver (50) comprises a radio unit (51) configured to receive the multicarrier signal. The multi- modulation receiver (50) also comprises a cyclic prefix unit (53) configured to remove a Cyclic Prefix, CP, from the received multicarrier signal. The multi-modulation receiver (50) comprises additionally comprises a Fast Fourier Transform, FFT, unit (55) configured to separate data received from the individual transmitters into mutually orthogonal subcarriers by transforming the multicarrier signal in the time domain to multiple orthogonal subcarrier signals in the frequency domain. The multi-modulation receiver (50) further comprises a demapping unit (57) configured to, for each of the multiple transmitters, demap the corresponding subcarrier signals in accordance with the modulation scheme of the respective transmitter. The disclosure also relates to corresponding methods and to a receiver for receiving data transmitted by the multi-modulation transmitter.