Standardised measurement method for measuring the modulation of an amplitude-modulated radio signal and method for filtering the radio signal

Patent metadata

Field	Value
Publication number	US-10498376-B2
Application number	US-201716330473-A
Country	US
Kind code	B2
Filing date	Sep 7, 2017
Priority date	Sep 12, 2016
Publication date	Dec 3, 2019
Grant date	Dec 3, 2019

Abstract

A method for filtering an amplitude-modulated radio signal, the radio signal having a bandwidth, the method including: transforming the radio signal into baseband, determining a frequency range close to the center frequency, measuring the level of the radio signal, by frequency steps, in the frequency range, determining a standardized modulation level in the radio signal, corresponding to the sum of the level measurements by frequency steps, in the frequency range under consideration, divided by the measurement of the level of the radio signal in baseband calculated around the center frequency, comparing the standardized noise level thus determined with a predetermined threshold, on the basis of the comparison, choosing a first filter applied to the amplitude-modulated radio signal.

First claim

The invention claimed is:

1. A method for filtering an amplitude-modulated radio signal, comprising implementing a method for measuring a standardized modulation level in an amplitude-modulated radio signal, said amplitude-modulated radio signal having a bandwidth and a carrier, said measurement method comprising:
transforming said amplitude-modulated radio signal into baseband, such that the representation of a Fourier transform of said radio signal as a function of frequency has a bandwidth centered on a center frequency equal to 0 Hz,
determining a frequency range between 200 Hz and 1.5 kHz,
measuring a level of the amplitude-modulated radio signal, by frequency steps, in said frequency range,
determining a standardized modulation level in the amplitude-modulated radio signal, corresponding to a sum of the level measurements by frequency steps, in the frequency range under consideration, divided by the measurement of the level of the amplitude-modulated radio signal in baseband calculated around the center frequency equal to 0 Hz, corresponding to the level of the carrier of the amplitude-modulated radio signal,

said filtering method moreover comprising:
comparing the standardized modulation level thus determined with a predetermined threshold,
on the basis of said comparison, selecting a first filter applied to the amplitude-modulated radio signal.

2. The method for filtering an amplitude-modulated radio signal as claimed in claim 1 , moreover comprising selecting a second filter, symmetrical to the first filter about the center frequency of the amplitude-modulated radio signal transformed into baseband, applied to said amplitude-modulated radio signal.

3. The method for filtering an amplitude-modulated radio signal as claimed in claim 1 , wherein the amplitude-modulated radio signal comprises a message consisting of an audio signal formed of a human voice.

4. The method for filtering an amplitude-modulated radio signal as claimed in claim 1 , wherein the first filter is chosen in real time so as to ensure dynamic selectivity in the amplitude-modulated radio signal.

5. The method for filtering an amplitude-modulated radio signal as claimed in claim 1 , wherein the first filter is a finite impulse response filter.

6. A modulation sensor configured so as to measure levels in an amplitude-modulated radio signal, by frequency steps, in a frequency range, and so as to determine a standardized modulation level of the radio signal in said frequency range, said standardized modulation level corresponding to a sum of the level measurements by frequency steps, in said frequency range, divided by a measurement of the level of the radio signal in baseband around the center frequency equal to 0 Hz, so as to implement the method for measuring a standardized modulation level as claimed in claim 1 .

7. A radio receiver comprising a modulation level sensor as claimed in claim 6 .

8. A motor vehicle comprising a radio receiver as claimed in claim 7 .

9. The method for filtering an amplitude-modulated radio signal as claimed in claim 2 , wherein the amplitude-modulated radio signal comprises a message consisting of an audio signal formed of a human voice.

Assignees

• Continental Automotive France
• Continental Automotive Gmbh

Inventors

• Hivert Grégoire
• Lin Chao

Classifications

• H04L27/06

  Demodulator circuits; Receiver circuits · CPC title

• H04B1/1027 Primary

  assessing signal quality or detecting noise/interference for the received signal · CPC title

• H04B17/345

  Interference values ({signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]} H04B17/336) · CPC title

• G10L25/81

  for discriminating voice from music · CPC title