Dynamic frequency correction in delta-sigma based software defined receiver

Patent metadata

Field	Value
Publication number	US-2018109273-A1
Application number	US-201715646409-A
Country	US
Kind code	A1
Filing date	Jul 11, 2017
Priority date	Oct 18, 2016
Publication date	Apr 19, 2018
Grant date	—

Abstract

A method and apparatus for dynamically modifying filter characteristics of a Delta-Sigma modulator to accommodate for Doppler shift. A transceiver in a wireless cellular communication system for adapt to changes in the RF carrier frequency for maintaining signal integrity by applying a pilot tone in calibration to determine a frequency shift response for a bandpass filter. During operation, the system is operative to determine a Doppler shift and to shift the bandpass filter in response.

First claim

What is claimed is:

1 . A method comprising:
configuring a filter response having a first bandwidth and a first center frequency; filtering a pilot signal having a second center frequency; determining a frequency offset between the first center frequency and the second center frequency; generating a configuration parameter in response to the frequency offset; and storing the configuration parameter in a memory.

2 . The method of claim 1 wherein configuring the filter involves setting a frequency response of a bandpass filter.

3 . The method of claim 1 wherein generating the configuration parameter involves determining an amplitude of the pilot signal.

4 . The method of claim 1 further comprising demodulating the pilot signal to generate a demodulated pilot signal using a sigma delta demodulator algorithm.

5 . A method of configuring a software definable radio comprising:
retrieving a first configuration parameter; configuring a filter response in response to the first configuration parameter; filtering an RF signal; determining an offset between a center frequency of the RF signal and a center frequency of the filter response; retrieving a second configuration parameter associated with the offset; reconfiguring the filter response in response to the second configuration parameter; and filtering the RF signal.

6 . The method of claim 5 wherein the reconfiguration the filter involves changing the center frequency of a bandpass filter.

7 . The method of claim 5 wherein the reconfiguration the filter involves changing the bandwidth of a bandpass filter.

8 . The method of claim 5 wherein the filtering is performed with a sigma delta modulator operable to demodulate the RF signal.

9 . The method of claim 5 wherein the filter response includes a filter bandwidth and a filter center frequency.

10 . The method of claim 5 the second configuration parameter is determined in response to the offset and a vehicle speed.

11 . A software definable radio comprising:
a source of a pilot signal operable to generate a pilot signal at a first center frequency; a filter having a configurable filter response in response to a configuration parameter; a processor operative to generate a control signal in order to apply the pilot signal to the filter, for determining the first center frequency and for generating the configuration parameter in response to the first center frequency; and a memory for storing the configuration parameter in a memory.

12 . The software definable radio of claim 11 wherein the processor is operative to determine a second center frequency, to retrieve a second configuration parameter associated with the second center frequency and to couple the second configuration parameter to the filter.

13 . The software definable radio of claim 12 wherein the filter is operative to reconfigure a filter response in response to the second configuration parameter.

14 . The software definable radio of claim 12 wherein the processor is operative to couple the second configuration parameter to the memory and wherein the memory is operative to store the second configuration parameter.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Talty Timothy J
• Baringer Cynthia D
• Ahmed Mohiuddin
• Kang Jongchan
• Kuan Yen-Cheng
• Li James Chingwei
• Sovero Emilio A

Classifications

• H04B1/0003 Primary

  Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain (digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00) · CPC title

• H04B1/0039

  using DSP [Digital Signal Processor] quadrature modulation and demodulation · CPC title

• H04B7/0413

  MIMO systems · CPC title

• H04L27/2601

  Multicarrier modulation systems · CPC title

• H04B1/0042 Primary

  Digital filtering (H04B1/0035 takes precedence; digital filters per se H03H17/00) · CPC title