First adjacent canceller (FAC) with improved blending using a parametric filter

Active Publication Date: 2015-10-22
IBIQUITY DIGITAL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Signals from adjacent radio channels can interfere with

Method used

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  • First adjacent canceller (FAC) with improved blending using a parametric filter
  • First adjacent canceller (FAC) with improved blending using a parametric filter
  • First adjacent canceller (FAC) with improved blending using a parametric filter

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Embodiment Construction

[0016]The following description describes various embodiments of a method and apparatus that provide improved First Adjacent Canceller (FAC) performance by weighting the blending of at least a portion of an original input signal with an FAC-processed signal.

[0017]The first adjacent canceller mitigates the effects of first-adjacent analog FM interference on spectrally coincident primary digital sidebands of an IBOC signal. The potential spectral overlap of first-adjacent analog and digitally modulated portions of an IBOC signal is illustrated in FIG. 1. FIG. 1 is a schematic diagram of a hybrid FM IBOC signal 10 in a first channel 12 that spans about ±200 kHz from this center frequency fo. Signal 10 includes an analog modulated carrier 14 and pluralities of digitally modulated subcarriers in lower and upper primary sidebands 16 and 18 (also referred to in this description as digital sidebands). Each sideband includes a plurality of subcarriers that are modulated by a digital signal u...

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PUM

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Abstract

A method for processing a radio signal includes: receiving an FM in-band on-channel radio signal including a plurality of digitally modulated subcarriers in upper and lower sidebands; sampling the FM in-band on-channel radio signal to produce an input signal including complex digital samples of a combination of a desired one the upper and lower sidebands and an FM interferer; removing FM interferer components from the first signal by notch filtering to produce a notch-filtered signal; weighting the notch-filtered signal to produce a weighted notch-filtered signal; using a parametric filter to filter the input signal to produce a parametric-filtered input signal; and combining the weighted notch-filtered signal and the parametric-filtered input signal to produce an output signal. A radio receiver that implements the method is also included.

Description

FIELD OF THE INVENTION[0001]This invention relates to methods and apparatus for receiving and processing in-band, on-channel radio signals, and more particularly to methods and apparatus for reducing the effects of interference from FM signals in adjacent radio channels.BACKGROUND OF THE INVENTION[0002]The iBiquity Digital Corporation HD Radio™ system is designed to permit a smooth evolution from current analog amplitude modulation (AM) and frequency modulation (FM) radio to a fully digital in-band on-channel (IBOC) system. This system delivers digital audio and data services to mobile, portable, and fixed receivers from terrestrial transmitters in the existing medium frequency (MF) and very high frequency (VHF) radio bands.[0003]IBOC signals can be transmitted in a hybrid format including an analog modulated carrier in combination with a plurality of digitally modulated subcarriers, or in an all-digital format wherein the analog modulated carrier is not used. Using the hybrid forma...

Claims

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Application Information

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IPC IPC(8): H04B1/10
CPCH04B1/1036H04B2001/1045H04B2001/1063H04B1/109H04H20/31H04H2201/183
Inventor KROEGER, BRIAN W.PEYLA, PAUL J.
Owner IBIQUITY DIGITAL CORP
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