摘要:
In accordance with the teachings described herein, system and methods are provided for a GPS acquisition correlation scheme with a reduced memory requirement. An example system may include a memory, a local PRN code generator, correlators, adder trees, an accumulator, and an output memory. The memory may be used to store an input PRN code. The local PRN code generator generates a replica PRN code and outputs a replica PRN code. The local PRN code generator may also shift the replica PRN code for each output epoch. One or more correlators receive the input PRN code and the replica PRN code and compare a bit of the input PRN code to a bit of the replica PRN code and generates a comparison. The adder trees add the comparisons and generate a comparison output. An accumulator accumulates the comparison output and outputs an accumulated output to an output memory.
摘要:
Apparatus having corresponding methods and non-transitory computer-readable media comprise: a sampler configured to sample a signal, wherein the signal is modulated with a waveform having a known period, wherein the sampler obtains K samples in each period, and wherein each of the samples is N bits long, wherein K is an integer greater than 0, and N is an integer greater than 1; a memory bank, wherein the memory bank has M columns and K rows, wherein each column is N bits wide, and wherein M is an integer greater than 0; a write controller configured to write the samples to the memory bank in column order; a read controller configured to read the samples from the memory bank in row order; and an integrator configured to integrate the samples read from the memory bank, wherein the integrator provides a respective integration result for each row.
摘要:
In one embodiment, an analog-to-digital converter (ADC) receives a radio frequency (RF) signal and converts the RF signal into a digital signal at an intermediate frequency. The ADC uses a sampling frequency that is a multiple of the intermediate frequency to perform the conversion. A selector receives the digital signal and outputs a combined in phase and quadrature signal at a plurality of sampling points based on the sampling frequency. A filter receives the combined in phase and quadrature signal and outputs a baseband in phase baseband signal and a baseband quadrature baseband signal.
摘要:
In accordance with the teachings described herein, system and methods are provided for a GPS PRN code interpolation scheme with a reduced memory requirement. An example GPS receiver system may include a memory, a local PRN code generator, and an interpolator. The memory may be used to store GPS PRN code received from a global positioning satellite. The local PRN code generator generates a replica PRN code having a repeating code that includes at least a first epoch and a second epoch. The interpolator determines an offset point in the first epoch of replica PRN code and interpolates the replica PRN code at a predetermined sample rate to generate an interpolated replica PRN code for use in correlating with the GPS PRN code.
摘要:
In a method for generating a preamble of a data unit for transmission via a multiple input, multiple output (MIMO) communication channel, a first field of the preamble is generated. The first field provides a plurality of indicators to a plurality of receivers. Each one of the plurality of indicators indicates a set of a plurality of training sequences that corresponds to transmission of the data unit to a corresponding one of the plurality of receivers. The plurality of training sequences is included in a second field of the preamble. The preamble is formatted such that the first field of the preamble will be transmitted prior to the second field of the preamble being transmitted.
摘要:
In a method for generating a preamble of a data unit for transmission via a communication channel, an indication of a first number of spatial or space-time streams is included in a first field of the preamble. The first number of spatial or space-time streams corresponds to transmission of the data unit to a first receiver. One or more training sequences are included in a second field of the preamble. The preamble is formatted such that the first field of the preamble will be transmitted prior to the second field of the preamble being transmitted.
摘要:
In a method for generating a data unit for transmission via a communication channel, wherein the data unit conforms to a first communication protocol, a preamble of the data unit is generated. The preamble includes a first field having information that indicates a duration of the data unit, the first field being formatted such that the first field is decodable by a receiver device that conforms to a second communication protocol but does not conform to the first communication protocol to determine the duration of the data unit based on the first field. Additionally, the preamble is formatted such that a portion of the preamble is decodable by a receiver device that conforms to a third communication protocol but does not conform to the first communication protocol. Also, the preamble is formatted such that a receiver device that conforms to the first communication protocol can determine that the data unit conforms to the first communication protocol. A data portion of the data unit that conforms to the first communication protocol and does not conform to either (i) the second communication protocol or (ii) the third communication protocol is generated.
摘要:
In a method for generating a preamble of a data unit for transmission via a communication channel, an indication of a first number of spatial or space-time streams is included in a first field of the preamble. The first number of spatial or space-time streams corresponds to transmission of the data unit to a first receiver. One or more training sequences are included in a second field of the preamble. The preamble is formatted such that the first field of the preamble will be transmitted prior to the second field of the preamble being transmitted.
摘要:
A simplified architecture is disclosed for use in wireless receiver applications, particularly for ADC conversion of received in-phase I and quadrature Q signals. Circuit area is substantially reduced by sharing a single ADC to convert both signals, switching the ADC input alternately between the i and q signals. In an embodiment, the ADC is clocked at an increased sample rate, and the digital output signals are aligned to compensate for the phase difference resulting from the implementation of a single ADC.
摘要:
Method and system for carrier recovery and estimation of Doppler shift from a signal source that is moving relative to a signal receiver. A pure carrier preamble for the received signal is processed through each of two stages of a linear predictor to obtain a successively more accurate estimation of a Doppler frequency offset for the carrier. The received signal is downconverted by each stage estimation of the Doppler frequency offset, and the downconverted signal is processed through a decision feedback phase locked loop to provide a signal in which substantially all of the Doppler offset and/or phase angle are identified and removed. The system has low complexity, is fast, and is accurate to within an estimated few tens of Hertz and will work with signals having relatively low signal-to-noise ratios. The invention is useful for receipt of signals from satellites in low earth orbits (LEOs) and other non-geosynchronous orbits, and wherever a transmitter and receiver are moving relative to each other.