Method of signal processing in the presence of interference

• US 7,295,635 B2
• Filed: 03/07/2003
• Issued: 11/13/2007
• Est. Priority Date: 03/22/2002
• Status: Expired due to Fees

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Issler, Jean-Luc, Revol, Marc, Coatantiec, Blandine, Martin, Nicolas
• Primary Examiner(s): Payne; David C.
• Assistant Examiner(s): Nguyen; Leon-Viet Q
• Application Number:
  US10/507,742
• Publication Number:
  US 20050169409A1
• Time in Patent Office: 1,712 Days
• Field of Search: 375/148, 375/346
• US Class Current: 375/346
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop
• CPC Class Codes: H04B 1/71 the interference being narrowband interference
• CPC Class Codes: H04B 1/7101 with estimation filters
• CPC Class Codes: H04B 2201/70707 Efficiency-related aspects
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]

Abstract

The invention relates to methods of processing signals subjected to interference. It consists, when this signal is formed of a first wideband channel and of a second narrowband channel modulating one and the same carrier in which these signals are cut off for the duration of the interference, in using a single phase loop and a single code loop to process these two channels simultaneously. It makes it easier to process signals in satellite based navigation systems of the GPS type when they are scrambled by the DME-type distance measuring system signals, as well as more generally making it possible to increase the robustness of the processing by joint processing of the bands broadcast to the users.

Claims

1. A method for processing a first and a second signal, the first signal being spread over a wide band channel and the second signal being spread over a narrowband channel, and modulating one and the same carrier in a single carrier phase tracking loop controlled by a carrier phase discriminator, comprising the steps of:

generating two components sine and cosine phase shifted of a local carrier at the frequency of the carrier,

demodulating the first and second signals with the sine and cosine phase shifted components of the local carrier so as to obtain a first couple of quadrature demodulated components I_WB, Q_WB for the first wide spread signal and a second couple of quadrature demodulated components I_NB, Q_NB for the second narrow spread signal, in a single code tracking loop controlled by a code discriminator,

generating a code clock signal,

on the base of the code clock signal, generating, a first punctual code and a first Δ

code, and a second punctual code and a second Δ

code compatible with the pseudorandom code,

correlating the first couple of quadrature demodulated components I_WB, Q_WB with the first local punctual and Δ

codes in order to obtain four demoduladed and dc-spread signal components I_PWB, I<sub>Δ

WB</sub>, Q_PWB and Q<sub>Δ

WB</sub> issued from the wide channel,

correlating the second couple of quadrature demodulated components I_NB, Q_NB with the second local punctual and Δ

codes in order to obtain four demodulated and de-spread signal components I_PNB, I<sub>Δ

NB</sub>, Q_PNB and Q<sub>Δ

NB</sub> issued from the narrow channel,

generating an input signal for the phase discriminator mixing the demodulated and de-spread signal components I_PWB, Q_PWB, I_PNB, Q_PNB issued from the correlations of the wide (WB) and narrow (NB) channel signals with the punctual codes, and

generating an input signal for the code discriminator, mixing the demodulated and de-spread signal components I_PWB, I<sub>Δ

WB</sub>, Q_PWB, Q<sub>Δ

WB</sub>, I_PNB, Q<sub>Δ

NB</sub> issued from the correlations of the wide (WB) and narrow channel (NB) signals with the Δ

codes; and

wherein, the input signal for the phase discriminator has its quadrature components I_{p opt} Q_{p opt} defined by mixing the signal components I_PWB, Q_PWB, I_PNBQ_PNBissued from the correlations of the wide and narrow channel signals with the punctual codes according the formula;

I_{p opt}=α

I_pWB+β

I_{p NB}

Q_{p opt}=α

Q_pWB+β

Q_{p NB}

α

, β

being weighting parameter.

2. The method as claimed in claim 1, wherein the parameters α

and β

are determined by the formula;

3. A method for processing a first and a second signal, the first signal being spread over a wide band channel and the second signal being spread over a narrowband channel, and modulating one and the same carrier in a single carrier phase tracking loop controlled by a carrier phase discriminator, comprising the steps of:

generating two components sine and cosine phase shifted of a local carrier at the frequency of the carrier.

demodulating the first and second signals with the sine and cosine phase shifted components of the local carrier so as to obtain a first couple of quadrature demodulated components I_WB, Q_WB for the first wide spread signal and a second couple of quadrature demodulated components I_NB, Q_NB for the second narrow spread signal, in a signal code tracking loon controlled by a code discriminator,

generating a code clock signal,

on the base of the code clock signal, generating, a first punctual code and a first Δ

code, and a second punctual code and a second Δ

code compatible with the pseudorandom code,

correlating the first couple of quadrature demodulated components I_NB, Q_NB with the first local punctual and Δ

codes in order to obtain four demoduladed and de-spread signal components I_PNB, I<sub>Δ

PNB</sub> issued from the wide channel,

correlating the second couple of quadrature demodulated components I_NB, Q_NB with the second local punctual and Δ

codes in order to obtain four demodulated and de-spread signal components I_PNB, I<sub>Δ

NB</sub>, Q_PNB and Q<sub>Δ

NB</sub> issued from the narrow channel,

generating an input signal for the phase discriminator mixing the demodulated and de-spread signal components I_PWB, Q_PWB, I_PNB, Q_PNB issued from the correlations of the wide (WB) and narrow (NB) channel signals with the punctual codes, and

generating an input signal for the code discriminator, mixing the demodulated and de-spread signal components I_PWB, I<sub>Δ

WB</sub>, Q_PWB, Q<sub>Δ

WB</sub>, I<sub>Δ

NB</sub>, Q_PNB, Q<sub>Δ

NB</sub> issued from the correlations of the wide (WB) and narrow channel (NB) signals with the Δ

codes;

wherein, the input signal for the phase discriminator has its quadrature components I_{p opt}, Q_{p opt} defined by mixing the signal components I_PWB, Q_PWB, I_PNB, Q_PNB, issued from the correlations of the wide and narrow channel signals with the punctual codes according the formula;

Q_{p opt}=α

I_pWB+β

I_{p NB}

Q_{p opt}=α

Q_{p WB}+β

Q_{p NB}

α

, β

being weighting parameter; and

wherein the input signal for the code discriminator has its quadrature components I<sub>Δ

opt</sub>, Q<sub>Δ

opt</sub> defined by mixing the signal components I<sub>Δ

WB</sub>, Q<sub>Δ

WB</sub>, I<sub>Δ

NB</sub>, Q<sub>Δ

NB</sub> issued from the correlations of the wide and narrow channel signals with the Δ

codes according the formula;

I<sub>Δ

opt</sub>=(α

l<sub>Δ

WB</sub>+bI<sub>Δ

NB</sub>)

Q<sub>Δ

opt</sub>=(α

Q<sub>Δ

WB</sub>+bQ<sub>Δ

NB</sub>)

a, b being weighting parameters.

4. The method as claimed in claim 3, wherein the parameters a and b are determined by the formula: