摘要:
An IC modulation processor (28) may be configured to operate in a single chip mode to accommodate baud rates up to a maximum clock rate for the processor (28) and in a dual chip mode to accommodate baud rates in excess of the maximum clock rate. The IC modulation processor (28) performs digital processing on a communication signal which conveys an input data stream (22). A pulse shaping filter (54-57) is provided following a phase mapper (50). The pulse shaping filter (54-57) is implemented as a pair of half-filters. Pulse shaping is distributed between two IC modulation processors (28) in the dual chip mode. An interpolator (86) and linearizer (106) follow the pulse shaping filters (54-57).
摘要:
A node controller (30) within a data communication network (22) provides network access for a digital data stream (32). A processor (42) partitions the digital data stream (32) into a constant data rate component (44) having a predictable data rate and a data packet component (46) having an unpredictable data rate. The constant data rate component (44) is then transferred over a first portion (74) of a network data stream (26) reserved for a circuit transmission protocol, and the data packet component (46) is packetized and transferred over a second portion (76) of the network data stream (26) reserved for a packet transmission protocol.
摘要:
A digital communication receiver (10) takes one complex sample (20) of a baseband analog signal (12) per symbol. A rectangular to polar converter (26) separates phase attributes of the complex samples from magnitude attributes. A phase processor (28) identifies clock adjustment opportunities which occur when relatively large phase changes take place between consecutive symbols. A magnitude processor (32) influences symbol timing only during clock adjustment opportunities. The magnitude processor (32) advances symbol timing in a phase locked loop when decreasing magnitude changes are detected during clock adjustment opportunities and retards symbol timing when increasing magnitude changes are detected during clock adjustment opportunities. An interpolator (66) may be used to estimate magnitude values between samples so that magnitude change is determined between sampled magnitude values and estimated magnitude values.
摘要:
A low SNR symbol synchronizer utilizes two quadrature channels and a delay and multiply technique to produce four product signals. Two of the product signals are same-channel products and two are cross-channel products. When combined and applied to a synchronizing apparatus such as a Costas loop, the signals provide improved performance at low SNR and avoid the need to know the carrier frequency when setting the delay.
摘要:
A numerically controlled oscillator wherein only one quadrant of a sinusoidially shaped wave is stored in a read-only-memory and the address of the read-only-memory is generated so that the entire numerically controlled oscillator and the read-only memory are contained on a single semiconductor chip. The data required to reproduce the quadrant is stored in a decomposed format so as to reduce the size of the read-only-memory.
摘要:
A signal processing system according to various aspects of the present invention includes an excursion signal generator, a scaling system and a filter system. The excursion signal generator identifies a peak portion of a signal that exceeds a threshold and generates a corresponding excursion signal. The scaling system applies a real scale factor to contiguous sets of excursion samples in order to optimize peak-reduction performance. The filter system filters the excursion signal to remove unwanted frequency components from the excursion signal. The filtered excursion signal may then be subtracted from a delayed version of the original signal to reduce the peak. The signal processing system may also control power consumption by adjusting the threshold. The signal processing system may additionally adjust the scale of the excursion signal and/or individual channel signals, such as to meet constraints on channel noise and output spectrum, or to optimize peak reduction. The magnitude threshold, excursion signal and/or individual channel signals may also be adaptively adjusted based on, for example, a channel signal quality such as a noise level specification.
摘要:
A signal processing system according to various aspects of the present invention includes an excursion signal generator, a scaling system and a filter system. The excursion signal generator identifies a peak portion of a signal that exceeds a threshold and generates a corresponding excursion signal. The scaling system applies a real scale factor to contiguous sets of excursion samples in order to optimize peak-reduction performance. The filter system filters the excursion signal to remove unwanted frequency components from the excursion signal. The filtered excursion signal may then be subtracted from a delayed version of the original signal to reduce the peak. The signal processing system may also control power consumption by adjusting the threshold. The signal processing system may additionally adjust the scale of the excursion signal and/or individual channel signals, such as to meet constraints on channel noise and output spectrum, or to optimize peak reduction. The magnitude threshold, excursion signal and/or individual channel signals may also be adaptively adjusted based on, for example, a channel signal quality such as a noise level specification.
摘要:
A signal processing system according to various aspects of the present invention includes an excursion signal generator, a scaling system and a filter system. The excursion signal generator identifies a peak portion of a signal that exceeds a threshold and generates a corresponding excursion signal. The scaling system applies a real scale factor to contiguous sets of excursion samples in order to optimize peak-reduction performance. The filter system filters the excursion signal to remove unwanted frequency components from the excursion signal. The filtered excursion signal may then be subtracted from a delayed version of the original signal to reduce the peak. The signal processing system may also control power consumption by adjusting the threshold. The signal processing system may additionally adjust the scale of the excursion signal and/or individual channel signals, such as to meet constraints on channel noise and output spectrum, or to optimize peak reduction. The magnitude threshold, excursion signal and/or individual channel signals may also be adaptively adjusted based on, for example, a channel signal quality such as a noise level specification.
摘要:
A communication and/or amplifier system according to various aspects of the present invention includes an excursion signal generator and a filter system. The excursion signal generator identifies a peak portion of a signal that exceeds a threshold, such as a magnitude threshold. The filter system filters a corresponding excursion signal having a magnitude and waveform corresponding to the portion exceeding the threshold to remove unwanted frequency components from a delayed version of the excursion signal. The filtered excursion signal may then be subtracted from the original signal to reduce the peak. In one embodiment, the communication and/or amplifier system operates in conjunction with signals having multiple channels and subchannels. The system may include a magnitude adjustment system configured to adjust magnitudes of the excursion signal subchannels according to magnitudes of the first signal subchannels. The system may also adjust the excursion signal magnitude in a time division environment according to the magnitude of the original signal in the same time slot.
摘要:
A time division multiple access digital communications system (12) is provided. The system (12) has a base station (14) configured to generate a receive baud clock (86) and has a receiver (18) and a transmitter (20). The system also has a subscriber unit (16) configured to generate a transmit baud clock (50), and has a transmitter (28) and a receiver (26). The subscriber unit transmitter (28) is configured to transmit a reverse channel signal (54) that incorporates the transmit baud clock (50) as a component thereof. The base station receiver (18) is configured to receive the reverse channel signal (54) from the subscriber unit (16) and produce a phase-error signal (&mgr;′) in response to a phase difference between the transmit baud clock (50) and the receive baud clock (86). The base station transmitter (20) is configured to transmit the phase-error signal (&mgr;′) to the subscriber unit receiver (26). The subscriber unit transmitter (28) contains an interpolator (122) configured to adjust the phase of the transmit baud clock (50) in response to the phase-error signal.