Method for limiting radio noise, in particular in the FM band, by polynomial interpolation

Patent metadata

Field	Value
Publication number	US-10404301-B2
Application number	US-201716085654-A
Country	US
Kind code	B2
Filing date	Mar 17, 2017
Priority date	Mar 18, 2016
Publication date	Sep 3, 2019
Grant date	Sep 3, 2019

Abstract

A method for limiting impulse noise in a radio signal, in particular in the FM band, that is multiplexed and intended to be received by an FM receiver that is for example located on-board a vehicle. The method includes detecting impulse noise by way of a calculation of a score IND, for a sequence of successive samples of the demodulated radio signal FM MPX, while taking into the account, on the one hand, a capacity to detect a drop in the modulus of the ratio I/Q, which is dependent in particular on data derived from a sensor level, and, on the other hand, a capacity to detect high-frequency noise, which in particular depends on data derived from a sensor modulation.

First claim

The invention claimed is:

1. A method for limiting noise in a received radio signal, especially in an FM band, said received radio signal being multiplexed according to a quadrature amplitude modulation scheme, said modulated received radio signal comprising an in-phase component and a quadrature component, the received radio signal being demodulated in order to consist of a succession of samples, and said radio signal including a risk of impulse noise liable to degrade a returned radio signal, said method comprising:
detecting a drop in a modulus of a ratio between the in-phase component and the quadrature component of the modulated received radio signal, depending on an average modulus over time of the modulated received radio signal;
detecting high-frequency noise in the demodulated received radio signal, depending on a threshold, said threshold being determined dynamically depending on the modulation of the modulated received radio signal;
calculating an impulse noise score, said impulse noise score being dependent on the drop on the modulus detection and on the high-frequency noise detection;
depending on the impulse noise score calculated, determining a number of samples, forming a sequence of samples to be substituted, between a last preserved non-noisy sample and a restart non-noisy sample, in the demodulated received radio signal;
creating a sequence of substitution samples, by polynomial interpolation between the last preserved non-noisy sample and the restart non-noisy sample; and
returning a modified demodulated radio signal corresponding to the demodulated received radio signal in which the sequence of samples to be substituted has been replaced by the sequence of substitution samples.

2. The method as claimed in claim 1 , wherein, the polynomial interpolation is based on a polynomial estimated depending on a plurality of non-noisy samples located before the sequence to be substituted in the demodulated received radio signal and on a plurality of non-noisy samples located after the sequence to be substituted in the demodulated received radio signal.

3. The method as claimed in claim 1 , wherein the detecting detec drop n the drop in the modulus of the ratio between the in-phase component and the quadrature component of the received radio signal equals:

norm
⁡

(

I
n

,

Q
n

)

⁢

1

≷

0

⁢

Thr

drop
n

where Thr drop n =f(Sensor level) and f(⋅) is a linear function.

4. The method as claimed in claim 1 , wherein the detecting detec noise n , depending on the dynamically determined threshold, the high-frequency noise in the demodulated received radio signal, equals:

HPF
⁡

(

MPX
n

)

⁢

1

≷

0

⁢

Thr

noise
n

where Thr noise n =f(Modulation sensor) and f(⋅) is a linear function.

5. The method as claimed in claim 1 , wherein, a score IND is equal to:
Σ n=0 N−1 (detec drop n & detec noise n )

where N is the number of samples of the demodulated received radio signal (FM MPX) of which account is taken, corresponding for example to the size of a dedicated buffer memory.

6. The method as claimed claim 1 , wherein the polynomial interpolation is implemented between a preceding sequence of clean samples terminating with the last preserved sample and a subsequent sequence of clean samples starting with the restart sample.

7. A radio-receiving device able to receive and to demodulate a multiplexed radio signal, comprising a noise-limiting device comprising means for implementing the method for limiting noise in a received radio signal, as claimed in claim 1 .

8. The radio receiving device as claimed on claim 7 , wherein the received radio signal is in the FM band.

9. The method as claimed in claim 3 , wherein the detecting detec drop n the drop in the modulus of the ratio between the in-phase component and the quadrature component of the received radio signal equals:

norm
⁡

(

I
n

,

Q
n

)

⁢

1

≷

0

⁢

Thr

drop
n

where Thr drop n =f(Sensor level) and f(⋅) is a linear function.

10. The method as claimed in claim 2 , wherein the detecting detec noise n , depending on the dynamically determined threshold, the high-frequency noise in the demodulated received radio signal, equals:

HPF
⁡

(

MPX
n

)

⁢

1

≷

0

⁢

Thr

noise
n

Assignees

• Continental Automotive France
• Continental Automotive Gmbh

Inventors

• Lin Chao
• Potereau Cyrille

Classifications

• H04B1/1669

  of the demodulated composite stereo signal · CPC title

• H04B1/123 Primary

  using adaptive balancing or compensation means (adaptive filter circuits and algorithms H03H) · CPC title

• H04L25/0214

  of a single coefficient · CPC title

• H04B1/1036

  with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters (H04B1/123 takes precedence; filter circuits H03H) · CPC title