Method and apparatus for reduction of interference in FM in-band on-channel digital audio broadcasting receiver

A technology of digital audio broadcasting and in-band co-frequency, which is applied in the field of receiver and signal processing technology, and can solve the problems of different distribution and non-uniform destruction of subcarrier frequency

Inactive Publication Date: 2003-08-13
IBIQUITY DIGITAL CORP
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the subcarrier frequency corruption may not be uniform in some cases, and the distribution of su

Method used

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  • Method and apparatus for reduction of interference in FM in-band on-channel digital audio broadcasting receiver
  • Method and apparatus for reduction of interference in FM in-band on-channel digital audio broadcasting receiver
  • Method and apparatus for reduction of interference in FM in-band on-channel digital audio broadcasting receiver

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Embodiment Construction

[0018] See attached picture, figure 1 is a schematic diagram of the frequency allocation (spectral layout) and relative power spectral density of the signal components of the hybrid FM IBOC DAB signal 10. The hybrid form comprises a conventional FM stereo analog signal 12 whose power spectrum is represented by a triangle 14 in a central portion 16 or central frequency band of the channel. The power spectral density (PSD) of a typical analog FM broadcast signal is an approximate triangle with a slope of -0.35dB / kHz from the center frequency. A plurality of evenly distributed digitally modulated sub-carriers are located on both sides of the analog FM signal, ie, in the upper sideband 18 and the lower sideband 20, and are transmitted simultaneously with the analog FM signal. All carriers transmit at power levels that fall under FCC Channel Mask 22.

[0019] In one example of a hybrid FM IBOC modulation form, 95 evenly spaced orthogonal frequency division multiplexing (OFDM) dig...

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PUM

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Abstract

The invention provides a method for reducing radio frequency interference in an FM in-band co-frequency digital audio broadcasting receiver. The method comprises the steps of: receiving a composite signal comprising a useful signal and an interference signal, demodulating the composite signal to generate a first demodulated signal, calculating a first binary soft decision from the first demodulated signal, processing the composite signal to generate a processed signal, demodulating the processed signal to generate a second demodulated signal, computing a second binary soft decision from the second demodulated signal, and combining the first and second binary soft decisions meta soft decision to generate an output signal. Also included is a radio receiver utilizing the method described above.

Description

technical field [0001] The present invention relates to methods of reducing radio frequency interference, and more particularly to signal processing techniques for Digital Audio Broadcasting (DAB) receivers and receivers utilizing such techniques. Background technique [0002] Digital Audio Broadcasting is a medium for providing audio in digital quality that is superior to existing forms of analog broadcasting. Both AM and FM DAB signals can be transmitted as a hybrid of digitally modulated signals co-existing with current broadcast analog AM or FM signals, or in all digital form without analog. In-band-on-channel (IBOC) DAB systems do not require new spectrum allocations because each DAB signal is transmitted simultaneously within the spectrum mask of existing AM or FM channel allocations. The IBOC system improves spectrum economics and enables broadcasters to deliver digital-quality audio to their current listener base stations. Several IBOC DAB methods have been propose...

Claims

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Application Information

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IPC IPC(8): H04L27/01H03D3/00H04B1/16H04H20/30H04J11/00H04L27/26
CPCH04H20/30H04H2201/20H04L27/2647H04H2201/183H03D3/007H04B1/06
Inventor 布赖恩·W·克罗哲杰弗里·S·白尔德
Owner IBIQUITY DIGITAL CORP
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